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  • GEOPHYSICS  (3,532)
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  • 2020-2024
  • 2000-2004  (62)
  • 1970-1974  (9,473)
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  • 1
    Electronic Resource
    Electronic Resource
    Bleaching of corals on the Great Barrier Reef: differential susceptibilities among taxa (2000)
    Springer
    Coral reefs 19 (2000), S. 155-163 
    Details
    ISSN: 1432-0975
    Keywords: Key Words Acclimatization ; Coral reef ; Disturbance ; History ; Mortality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Large-scale coral bleaching episodes are potentially major disturbances to coral reef systems, yet a definitive picture of variation in assemblage response and species susceptibilities is still being compiled. Here, we provide a detailed analysis of the bleaching response of 4160 coral colonies, representing 45 genera and 15 families, from two depths at four sites on reefs fringing inshore islands on the Great Barrier Reef. Six weeks after the onset of large-scale bleaching in 1998, between 11 and 83% of colonies along replicate transects were affected by bleaching, and mortality was 1 to 16%. There were significant differences in bleaching response between sites, depths and taxa. Cyphastrea, Turbinaria and Galaxea were relatively unaffected by bleaching, while most acroporids and pocilloporids were highly susceptible. The hydrocorals (Millepora spp.) were the most susceptible taxa, with 85% mortality. Spatial variation in assemblage response was linked to the taxonomic composition of reef sites and their bleaching history. We suggest, therefore, that much of the spatial variation in bleaching response was due to assemblage composition and thermal acclimation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003380000086
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  • 2
    Electronic Resource
    Electronic Resource
    The discovery, scope, and puzzle of desiccation tolerance in plants (2000)
    Springer
    Plant ecology 151 (2000), S. 5-17 
    Details
    ISSN: 1573-5052
    Keywords: Angiosperm ; Biogeography ; Bryophyte ; Desiccation tolerance ; Growth form ; Habitat ; History
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The modern scientific study of desiccation tolerance began in 1702 when Anthony von Leeuwenhoek discovered that rotifers could survive without water for months. By 1860, the controversy over whether organisms could dry up without dying had reached such a pitch that a special French commission was convened to adjudicate the dispute. In 2000, we know that a few groups of animals and a wide variety of plants can tolerate desiccation in the active, adult stages of their life cycles. Among plants, this includes many lichens and bryophytes, a few ferns, and a very few flowering plants, but no gymnosperms nor trees. Some desiccation-tolerant species can survive without water for over ten years, recover from desiccation to unmeasurably low water potentials, and, when plants are desiccated, endure temperature extremes from −272 to 100 °C. Desiccation-tolerant plants occur on all continents but mainly in xeric habitats or microhabitats where the cover of desiccation-sensitive species is low. Two main puzzles arise from these patterns: What are the mechanisms by which plants tolerate desiccation? and Why are desiccation-tolerant plants not more ecologically widespread? Recent molecular and biochemical studies suggest that there are multiple mechanisms of tolerance, many of which involve protection from oxidants and from the loss of configuration of macromolecules during dehydration. Hypotheses to explain the restricted ecological range of desiccation-tolerance plants include inability to maintain a cumulative positive carbon balance during repeated cycles of wetting and drying and inherent trade offs between desiccation tolerance and growth rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026513800380
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  • 3
    Electronic Resource
    Electronic Resource
    Indicator Dilution Methods for Measuring Blood Flow, Volume, and Other Properties of Biological Systems: A Brief History and Memoir (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 836-848 
    Details
    ISSN: 1573-9686
    Keywords: Indicator-dilution ; Tracer-dilution ; Blood flow ; Blood volume ; Distribution volume ; History ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In 1824 Hering introduced an indicator-dilution method for measuring blood velocity. Not until 1897 was the method extended by Stewart to measure blood (volume) flow. For more than two decades, beginning in 1928, Hamilton and colleagues measured blood flow, including cardiac output. They proposed that the first-passsage indicator concentration-time curve could be recovered from observed curves that included recirculation by semilogarithmic extrapolation of the early downslope. Others followed with attempts to fit the complete first-passage curve by various forms, such as by the sum of three exponential terms (three well-stirred compartments in series). Stephenson (1948) thought of looking at indicator-dilution curves as convolutions of indicator input with a probability density function of traversal times through the system. Meier and I reached a similar conclusion, and extended it. The fundamental notion is that there exists a probability density function of transit times, h(t), through the system. We proved that mean transit time t=V/F, where V is volume in which the indicator is distributed. Thus, V, F, and t might all be calculated, or t alone might suffice if one wanted only to know relative blood flow. I extended the analysis to include residue detection of indicator remaining in the system, so that V, F, and t could be calculated by external monitoring. Chinard demonstrated the value of simultaneous multiple indicator-dilution curves with various volumes of distribution. Goresky extended the technique to study cell uptake and metabolism. He also found a transform of indicator-dilution output curves (equivalent to multiplying the ordinate by t and dividing the time by t) which made congruent the family of unalike curves obtained by simultaneous injection of indicators with different volumes of distribution. Bassingthwaighte showed the same congruency with the transform of outputs of a single indicator introduced into a system with experimentally varied blood flows. We showed the same congruency for the pulmonary circulation, adding a correction for delays. Success of these transforms suggests that the architecture of the vascular network is a major determinant of the shape of density functions of transit times through the system, and that there is in this architecture, a high degree of self-similarity, implying that the fractal power function is a component in shaping the observed density of transit times. I proposed that the distribution of capillary critical opening pressures, which describes recruitment of vascular paths, may be important in shaping indicator-dilution curves, and that h(t) may be derived from flow-pressure and volume-pressure curves under some circumstances. © 2000 Biomedical Engineering Society.PAC00: 8719Uv, 0630Bp
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.1308496
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    Kelvin's age of the Earth paradox revisited (2000)
    In:  J. Geophys. Res., Houston, Akademie-Verlag, vol. 105, no. B6, pp. 13,155-13,158, pp. L08310, (ISSN: 1340-4202)
    Details
    Publication Date: 2000
    Keywords: Geothermics ; Geomagnetics ; evolution ; 1739 ; History ; of ; geophysics ; JGR ; Solar/planetary ; relationships ; 1799 ; 5418 ; Planetology: ; solid ; surface ; planets ; Heat ; flow ; 9699 ; Information ; related ; to ; geologic ; time ; General ; or ; miscellaneous
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    BIBLIOGRAPHY SEISMOLOGY
  • 5
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    Test Medium Effects on Ignition, Combustion and Flameholding Processes in Scramjet Combustors (2000)
    In:  Other Sources
    Details
    Publication Date: 2011-08-23
    Description: The total temperatures (enthalpies) required to ground-test air-breathing (aero-propulsion) engines at high Mach number flight conditions can be achieved in a number of ways. Among these are: 1. Heat exchangers, including pre-heated ceramic beds. 2. direct electrical heating, e.g., arc discharge and resistance heaters. 3. Compression heating. 4. Shock heating, and 5. In-stream combustion, with oxygen replenishment to match air content. Each method has distinct advantages, disadvantages and limitations. All have a common characteristic of being designed for intermittent flow, due to the extreme energy required for continuous operation at simulated Mach numbers above about 3. All also distort the composition of atmospheric air to some degree, due to the high temperatures that occur in the plenum section prior to expansion of the flow to simulated flight conditions. In the case of in-stream combustion, the resulting test medium is commonly referred to as "vitiated air", being composed of oxygen, nitrogen and some fraction of combustion products.
    Keywords: Aircraft Propulsion and Power
    Type: JANNAF 25th Airbreathing Propulsion Subcommittee, 37th Combustion Subcommittee and 1st Modeling and Simultation Subcommittee Joint Meeting; Volume 1; 243-271; CPIA-Publ-703-Vol-1
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  • 6
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    General Aviation Propulsion Program and Beyond (2000)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The purpose of this presentation is to show flight demonstrations, complete preflight ground tests, and the assembling of the first QRT 4 engine.
    Keywords: Aircraft Propulsion and Power
    Type: 1999 NASA Seal/Secondary Air System Workshop; Volume 1; 61-78; NASA/CP-2000-210472/VOL1
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  • 7
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    Acoustics and Thrust of Separate Flow Exhaust Nozzles With Mixing Devices Investigated for High Bypass Ratio Engines (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Typical installed separate-flow exhaust nozzle system. The jet noise from modern turbofan engines is a major contributor to the overall noise from commercial aircraft. Many of these engines use separate nozzles for exhausting core and fan streams. As a part of NASA s Advanced Subsonic Technology (AST) program, the NASA Glenn Research Center at Lewis Field led an experimental investigation using model-scale nozzles in Glenn s Aero-Acoustic Propulsion Laboratory. The goal of the investigation was to develop technology for reducing the jet noise by 3 EPNdB. Teams of engineers from Glenn, the NASA Langley Research Center, Pratt & Whitney, United Technologies Research Corporation, the Boeing Company, GE Aircraft Engines, Allison Engine Company, and Aero Systems Engineering contributed to the planning and implementation of the test.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 8
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    Propulsion Aeroelastic Analysis Developed for Flutter and Forced Response (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The NASA Glenn Research Center at Lewis Field develops new technologies to increase the fuel efficiency of aircraft engines, improve the safety of engine operation, reduce emissions, and reduce engine noise. With the development of new designs for fans, compressors, and turbines to achieve these goals, the basic aeroelastic requirements are that there should be no flutter (self-excited vibrations) or high resonant blade stresses (due to forced response) in the operating regime. Therefore, an accurate prediction and analysis capability is required to verify the aeroelastic soundness of the designs. Such a three-dimensional viscous propulsion aeroelastic analysis capability has been developed at Glenn with support from the Advanced Subsonic Technology (AST) program. This newly developed aeroelastic analysis capability is based on TURBO, a threedimensional unsteady aerodynamic Reynolds-averaged Navier-Stokes turbomachinery code developed previously under a grant from Glenn. TURBO can model the viscous flow effects that play an important role in certain aeroelastic problems such as flutter with flow separation, flutter at high loading conditions near the stall line (stall flutter), flutter in the presence of shock and boundary-layer interaction, and forced response due to wakes and shock impingement. In aeroelastic analysis, the structural dynamics representation of the blades is based on normal modes. A finite-element analysis code is used to calculate these in-vacuum vibration modes and the associated natural frequencies. In an aeroelastic analysis using the TURBO code, flutter and forced response are modeled as being uncoupled. To calculate if a blade row will flutter, one prescribes the motion of the blade to be a harmonic vibration in a specified in-vacuum normal mode. An aeroelastic analysis preprocessor is used to generate the displacement field required for the analysis. The work done by aerodynamic forces on the vibrating blade during a cycle of vibration is calculated. If this work is positive, the blade is dynamically unstable, since it will extract energy from the flow, leading to an increase in the blade s oscillation amplitude. The forced-response excitations on a blade row are calculated by modeling the flow through two adjacent blade rows using the TURBO code. The blades are assumed to be rigid. As an option, a single blade row can be modeled with the upstream blade row influence represented by a time-varying disturbance (gust) at the inlet boundary. The unsteady forces on a blade row from such analyses are used in a structural analysis along with the blade structural dynamics characteristics and aerodynamic damping associated with blade vibration to calculate the resulting dynamic stresses on the blade.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 9
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    Accuracy of Numerical Simulations of Tip Clearance Flow in Transonic Compressor Rotors Improved Dramatically (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The tip clearance flows of transonic compressor rotors have a significant impact on rotor and stage performance. Although numerical simulations of these flows are quite sophisticated, they are seldom verified through rigorous comparisons of numerical and measured data because, in high-speed machines, measurements acquired in sufficient detail to be useful are rare. Researchers at the NASA Glenn Research Center at Lewis Field compared measured tip clearance flow details (e.g., trajectory and radial extent) of the NASA Rotor 35 with results obtained from a numerical simulation. Previous investigations had focused on capturing the detailed development of the jetlike flow leaking through the clearance gap between the rotating blade tip and the stationary compressor shroud. However, we discovered that the simulation accuracy depends primarily on capturing the detailed development of a wall-bounded shear layer formed by the relative motion between the leakage jet and the shroud.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 10
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    Turbine Blade and Endwall Heat Transfer Measured in NASA Glenn's Transonic Turbine Blade Cascade (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Higher operating temperatures increase the efficiency of aircraft gas turbine engines, but can also degrade internal components. High-pressure turbine blades just downstream of the combustor are particularly susceptible to overheating. Computational fluid dynamics (CFD) computer programs can predict the flow around the blades so that potential hot spots can be identified and appropriate cooling schemes can be designed. Various blade and cooling schemes can be examined computationally before any hardware is built, thus saving time and effort. Often though, the accuracy of these programs has been found to be inadequate for predicting heat transfer. Code and model developers need highly detailed aerodynamic and heat transfer data to validate and improve their analyses. The Transonic Turbine Blade Cascade was built at the NASA Glenn Research Center at Lewis Field to help satisfy the need for this type of data.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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  • 11
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    Numerical Propulsion System Simulation: An Overview (2000)
    In:  CASI
    Details
    Publication Date: 2017-10-04
    Description: The cost of implementing new technology in aerospace propulsion systems is becoming prohibitively expensive and time consuming. One of the main contributors to the high cost and lengthy time is the need to perform many large-scale hardware tests and the inability to integrate all appropriate subsystems early in the design process. The NASA Glenn Research Center is developing the technologies required to enable simulations of full aerospace propulsion systems in sufficient detail to resolve critical design issues early in the design process before hardware is built. This concept, called the Numerical Propulsion System Simulation (NPSS), is focused on the integration of multiple disciplines such as aerodynamics, structures and heat transfer with computing and communication technologies to capture complex physical processes in a timely and cost-effective manner. The vision for NPSS, as illustrated, is to be a "numerical test cell" that enables full engine simulation overnight on cost-effective computing platforms. There are several key elements within NPSS that are required to achieve this capability: 1) clear data interfaces through the development and/or use of data exchange standards, 2) modular and flexible program construction through the use of object-oriented programming, 3) integrated multiple fidelity analysis (zooming) techniques that capture the appropriate physics at the appropriate fidelity for the engine systems, 4) multidisciplinary coupling techniques and finally 5) high performance parallel and distributed computing. The current state of development in these five area focuses on air breathing gas turbine engines and is reported in this paper. However, many of the technologies are generic and can be readily applied to rocket based systems and combined cycles currently being considered for low-cost access-to-space applications. Recent accomplishments include: (1) the development of an industry-standard engine cycle analysis program and plug 'n play architecture, called NPSS Version 1, (2) A full engine simulation that combines a 3D low-pressure subsystem with a 0D high pressure core simulation. This demonstrates the ability to integrate analyses at different levels of detail and to aerodynamically couple components, the fan/booster and low-pressure turbine, through a 3D computational fluid dynamics simulation. (3) Simulation of all of the turbomachinery in a modern turbofan engine on parallel computing platform for rapid and cost-effective execution. This capability can also be used to generate full compressor map, requiring both design and off-design simulation. (4) Three levels of coupling characterize the multidisciplinary analysis under NPSS: loosely coupled, process coupled and tightly coupled. The loosely coupled and process coupled approaches require a common geometry definition to link CAD to analysis tools. The tightly coupled approach is currently validating the use of arbitrary Lagrangian/Eulerian formulation for rotating turbomachinery. The validation includes both centrifugal and axial compression systems. The results of the validation will be reported in the paper. (5) The demonstration of significant computing cost/performance reduction for turbine engine applications using PC clusters. The NPSS Project is supported under the NASA High Performance Computing and Communications Program.
    Keywords: Aircraft Propulsion and Power
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    Probabilistic Multi-Scale, Multi-Level, Multi-Disciplinary Analysis and Optimization of Engine Structures (2000)
    In:  CASI
    Details
    Publication Date: 2017-10-04
    Description: Aircraft engines are assemblies of dynamically interacting components. Engine updates to keep present aircraft flying safely and engines for new aircraft are progressively required to operate in more demanding technological and environmental requirements. Designs to effectively meet those requirements are necessarily collections of multi-scale, multi-level, multi-disciplinary analysis and optimization methods and probabilistic methods are necessary to quantify respective uncertainties. These types of methods are the only ones that can formally evaluate advanced composite designs which satisfy those progressively demanding requirements while assuring minimum cost, maximum reliability and maximum durability. Recent research activities at NASA Glenn Research Center have focused on developing multi-scale, multi-level, multidisciplinary analysis and optimization methods. Multi-scale refers to formal methods which describe complex material behavior metal or composite; multi-level refers to integration of participating disciplines to describe a structural response at the scale of interest; multidisciplinary refers to open-ended for various existing and yet to be developed discipline constructs required to formally predict/describe a structural response in engine operating environments. For example, these include but are not limited to: multi-factor models for material behavior, multi-scale composite mechanics, general purpose structural analysis, progressive structural fracture for evaluating durability and integrity, noise and acoustic fatigue, emission requirements, hot fluid mechanics, heat-transfer and probabilistic simulations. Many of these, as well as others, are encompassed in an integrated computer code identified as Engine Structures Technology Benefits Estimator (EST/BEST) or Multi-faceted/Engine Structures Optimization (MP/ESTOP). The discipline modules integrated in MP/ESTOP include: engine cycle (thermodynamics), engine weights, internal fluid mechanics, cost, mission and coupled structural/thermal, various composite property simulators and probabilistic methods to evaluate uncertainty effects (scatter ranges) in all the design parameters. The objective of the proposed paper is to briefly describe a multi-faceted design analysis and optimization capability for coupled multi-discipline engine structures optimization. Results are presented for engine and aircraft type metrics to illustrate the versatility of that capability. Results are also presented for reliability, noise and fatigue to illustrate its inclusiveness. For example, replacing metal rotors with composites reduces the engine weight by 20 percent, 15 percent noise reduction, and an order of magnitude improvement in reliability. Composite designs exist to increase fatigue life by at least two orders of magnitude compared to state-of-the-art metals.
    Keywords: Aircraft Propulsion and Power
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  • 13
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    Noise-Reduction Benefits Analyzed for Over-the-Wing-Mounted Advanced Turbofan Engines (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: As we look to the future, increasingly stringent civilian aviation noise regulations will require the design and manufacture of extremely quiet commercial aircraft. Also, the large fan diameters of modern engines with increasingly higher bypass ratios pose significant packaging and aircraft installation challenges. One design approach that addresses both of these challenges is to mount the engines above the wing. In addition to allowing the performance trend towards large diameters and high bypass ratio cycles to continue, this approach allows the wing to shield much of the engine noise from people on the ground. The Propulsion Systems Analysis Office at the NASA Glenn Research Center at Lewis Field conducted independent analytical research to estimate the noise reduction potential of mounting advanced turbofan engines above the wing. Certification noise predictions were made for a notional long-haul commercial quadjet transport. A large quad was chosen because, even under current regulations, such aircraft sometimes experience difficulty in complying with certification noise requirements with a substantial margin. Also, because of its long wing chords, a large airplane would receive the greatest advantage of any noise-shielding benefit.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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    Surge Flow in a Centrifugal Compressor Measured by Digital Particle Image Velocimetry (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: A planar optical velocity measurement technique known as Particle Image Velocimetry (PIV) is being used to study transient events in compressors. In PIV, a pulsed laser light sheet is used to record the positions of particles entrained in a fluid at two instances in time across a planar region of the flow. Determining the recorded particle displacement between exposures yields an instantaneous velocity vector map across the illuminated plane. Detailed flow mappings obtained using PIV in high-speed rotating turbomachinery components are used to improve the accuracy of computational fluid dynamics (CFD) simulations, which in turn, are used to guide advances in state-of-the-art aircraft engine hardware designs.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
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    Advanced Methods for Aircraft Engine Thrust and Noise Benefits: Nozzle-Inlet Flow Analysis (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: In this project, we continue to develop the previous joint research between the Fluid Mechanics and Acoustics Laboratory (FM&AL) at Hampton University (HU) and the Jet Noise Team (JNT) at the NASA Langley Research Center (NASA LaRC). The FM&AL was established at Hampton University in June of 1996 and has conducted research under two NASA grants: NAG-1-1835 (1996-99), and NAG-1-1936 (1997-00). In addition, the FM&AL has jointly conducted research with the Central AeroHydrodynamics Institute (TsAGI, Moscow) in Russia under a Civilian Research and Development Foundation (CRDF) grant #RE2-136 (1996-99). The goals of the FM&AL programs are twofold: (1) to improve the working efficiency of the FM&AUs team in generating new innovative ideas and in conducting research in the field of fluid dynamics and acoustics, basically for improvement of supersonic and subsonic aircraft engines, and (2) to attract promising minority students to this research and training and, in cooperation with other HU departments, to teach them basic knowledge in Aerodynamics, Gas Dynamics, and Theoretical and Experimental Methods in Aeroacoustics and Computational Fluid Dynamics (CFD). The research at the HU FM&AL supports reduction schemes associated with the emission of engine pollutants for commercial aircraft and concepts for reduction of observables for military aircraft. These research endeavors relate to the goals of the NASA Strategic Enterprise in Aeronautics concerning the development of environmentally acceptable aircraft. It is in this precise area, where the US aircraft industry, academia, and Government are in great need of trained professionals and which is a high priority goal of the Minority University Research and Education (MUREP) Program, that the HU FM&AL can make its most important contribution. The main achievements for the reporting period in the development of concepts for noise reduction and improvement in efficiency for jet exhaust nozzles and inlets for aircraft engines are as follows: (1) Publications- The AIAA Paper #99-1924 has been presented at the 5th AIAA/CEAS Aeroacoustics Conference, May 10-12, 1999, Seattle, WA; the AIAA Paper #00-3315 has been accepted for the 36th AIAA/ASME/ SAE/ASEE Joint Propulsion Conference, 17-19 July, 2000, Huntsville, AL; and another paper has been accepted for the International Environmental Congress, 14-16 June, 2000, St.-Petersburg, Russia. (2) Two patents were granted on July 20, 1999, and January 12, 2000. (3) Three reports/presentations at the NASA LaRC and GRC (06/22199, 09/26/ 99, and 06/25/00). (4) Grants and Proposals: Four proposals were submitted to the NASA and CRDF; a NASA Faculty Award was granted on January, 2000. A CRDF Young Investigator Program Award was granted for a 3 months visit of the Russian scientist to the HU FM&AL (03/99-05/99). (5) Theory and Numerical Simulations- Analytical theory, numerical simulation, comparison of theoretical with experimental results, and modification of theoretical approaches, models, grids etc. have been conducted for several complicated 2D and 3D nozzle and inlet designs using NASA codes based on full Euler and Navier-Stokes solvers: CFL3D, CRAFT, GODUNOV, and others. New approach for environmental monitoring via infrasound. (6) Experimental Tests: Experimental acoustic tests at the TsAGI, Moscow, with nozzles having Screwdriver or Axisymmetric Plug and Permeable Shells. A small scale working model of the NASA Low Speed Wind Tunnel (LSWT) has been installed in the Experimental Hall of the HU FM&AL (June, 1999). Preliminary preparations for experimental tests were made. (7) Students Research Activity: Involvement of the two graduate students as research assistants in the current research project.
    Keywords: Aircraft Propulsion and Power
    Type: HBCUs/OMUs Research Conference Agenda and Abstracts; 21; NASA/TM-2000-210042
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    Power Requirement for Nonequilibrium MHD-Bypass Scramjet (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: It has been suggested previously that the performance of scramjet propulsion system may be improved by the use of magnetohydrodynamic (MHD) energy bypass: an MHD generator could be made to decelerate the flow entering the combustor, thereby improving combustion efficiency, and the electrical power generated could be made to accelerate the flow exiting from the combustor prior to expanding through the nozzle. In one of such proposed schemes, the MHD generator is proposed to be operated at a low temperature and ionization is to be achieved under nonequilibrium by the application of an external power. In the present work, the required power of such an external source is calculated assuming a 100%-efficient nonequilibrium ionization scheme. The power required is that needed to prevent the degree of ionization from reaching equilibrium with the low gas temperature. The flow is seeded with potassium or cesium. Specific impulse is calculated with and without turbulent friction. The results show that, for typical intended flight conditions, the specific impulse obtained is substantially higher than that of a typical scramjet, but the required external-power is several times that of the power generated in the MHD generator.
    Keywords: Aircraft Propulsion and Power
    Type: 39th AIAA Aerospace Sciences Meeting; Jan 01, 2001; Reno, NV; United States
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    Load Capacity Estimation of Foil Air Journal Bearings for Oil-Free Turbomachinery Applications (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper introduces a simple "Rule of Thumb" (ROT) method to estimate the load capacity of foil air journal bearings, which are self-acting compliant-surface hydrodynamic bearings being considered for Oil-Free turbo-machinery applications such as gas turbine engines. The ROT is based on first principles and data available in the literature and it relates bearing load capacity to the bearing size and speed through an empirically based load capacity coefficient, D. It is shown that load capacity is a linear function of bearing surface velocity and bearing projected area. Furthermore, it was found that the load capacity coefficient, D, is related to the design features of the bearing compliant members and operating conditions (speed and ambient temperature). Early bearing designs with basic or "first generation" compliant support elements have relatively low load capacity. More advanced bearings, in which the compliance of the support structure is tailored, have load capacities up to five times those of simpler designs. The ROT enables simplified load capacity estimation for foil air journal bearings and can guide development of new Oil-Free turbomachinery systems.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209782 , E-12067 , ARL-TR-2334 , NAS 1.15:209782 , International Joint Tribology; Oct 01, 2000 - Oct 04, 2000; Seattle, WA; United States
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  • 18
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    Ensemble Diffraction Measurements of Spray Combustion in a Novel Vitiated Coflow Turbulent Jet Flame Burner (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An experimental investigation is presented of a novel vitiated coflow spray flame burner. The vitiated coflow emulates the recirculation region of most combustors, such as gas turbines or furnaces; additionally, since the vitiated gases are coflowing, the burner allows exploration of the chemistry of recirculation without the corresponding fluid mechanics of recirculation. As such, this burner allows for chemical kinetic model development without obscurations caused by fluid mechanics. The burner consists of a central fuel jet (droplet or gaseous) surrounded by the oxygen rich combustion products of a lean premixed flame that is stabilized on a perforated, brass plate. The design presented allows for the reacting coflow to span a large range of temperatures and oxygen concentrations. Several experiments measuring the relationships between mixture stoichiometry and flame temperature are used to map out the operating ranges of the coflow burner. These include temperatures as low 300 C to stoichiometric and oxygen concentrations from 18 percent to zero. This is achieved by stabilizing hydrogen-air premixed flames on a perforated plate. Furthermore, all of the CO2 generated is from the jet combustion. Thus, a probe sample of NO(sub X) and CO2 yields uniquely an emission index, as is commonly done in gas turbine engine exhaust research. The ability to adjust the oxygen content of the coflow allows us to steadily increase the coflow temperature surrounding the jet. At some temperature, the jet ignites far downstream from the injector tube. Further increases in the coflow temperature results in autoignition occurring closer to the nozzle. Examples are given of methane jetting into a coflow that is lean, stoichiometric, and even rich. Furthermore, an air jet with a rich coflow produced a normal looking flame that is actually 'inverted' (air on the inside, surrounded by fuel). In the special case of spray injection, we demonstrate the efficacy of this novel burner with a methanol spray in a vitiated coflow. As a proof of concept, an ensemble light diffraction (ELD) optical instrument was used to conduct preliminary measurements of droplet size distribution and liquid volume fraction.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-210466 , E-12462 , NAS 1.26:210466 , Mar 13, 2000 - Mar 14, 2000; Golden, CO; United States
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  • 19
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    Internal Designs Application for Inlet and Nozzle Aeroperformance Improvement (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The following research results are based on development of an approach previously proposed by the authors for optimum nozzle design to obtain maximum thrust. The design was denoted a Telescope nozzle. A Telescope nozzle contains one or several internal designs of certain location, which are inserted at certain locations into a divergent conical or planar main nozzle near its exit. Such a design provides additional thrust augmentation over 20% by comparison with the optimum single nozzle of equivalent lateral area. What is more, recent experimental acoustic tests have discovered an essential noise reduction due to Telescope nozzles application. In this paper, some additional theoretical results are presented for Telescope nozzles and a similar approach is applied for aeroperformance improvement of a supersonic inlet. In addition, a classic gas dynamics problem of a similar supersonic flow into a plate has been analyzed. In some particular cases, new exact analytical solutions are obtained for a flow into a wedge with an oblique shock wave. Numerical simulations were conducted for supersonic flow into a divergent portion of a 2D or axisymmetric nozzle with several plane or conuical designs as well as into a 2D or axisymmetric supersonic inlet with a forebody. The 1st order Kryko-Godunov marching numerical scheme for inviscid supersonic flows was used. Several cases were tested using the NASA CFL3d code based on full Navier-Stokes equations. Numerical simulation results have confirmed essential benefits of Telescope design applications in propulsion systems.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 00-3315 , 36th Joint Propulsion Conference; Jul 17, 2000 - Jul 19, 2000; Huntsville, AL; United States
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  • 20
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    A Probabilistic Approach to Aeropropulsion System Assessment (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A probabilistic approach is described for aeropropulsion system assessment. To demonstrate this approach, the technical performance of a wave rotor-enhanced gas turbine engine (i.e. engine net thrust, specific fuel consumption, and engine weight) is assessed. The assessment accounts for the uncertainties in component efficiencies/flows and mechanical design variables, using probability distributions. The results are presented in the form of cumulative distribution functions (CDFS) and sensitivity analyses, and are compared with those from the traditional deterministic approach. The comparison shows that the probabilistic approach provides a more realistic and systematic way to assess an aeropropulsion system.
    Keywords: Aircraft Propulsion and Power
    Type: Gas Turbine and Aeroengine Technical Congress; May 08, 2000 - May 11, 2000; Munich; Germany
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  • 21
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    The Numerical Propulsion System Simulation: An Overview (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Advances in computational technology and in physics-based modeling are making large-scale, detailed simulations of complex systems possible within the design environment. For example, the integration of computing, communications, and aerodynamics has reduced the time required to analyze major propulsion system components from days and weeks to minutes and hours. This breakthrough has enabled the detailed simulation of major propulsion system components to become a routine part of designing systems, providing the designer with critical information about the components early in the design process. This paper describes the development of the numerical propulsion system simulation (NPSS), a modular and extensible framework for the integration of multicomponent and multidisciplinary analysis tools using geographically distributed resources such as computing platforms, data bases, and people. The analysis is currently focused on large-scale modeling of complete aircraft engines. This will provide the product developer with a "virtual wind tunnel" that will reduce the number of hardware builds and tests required during the development of advanced aerospace propulsion systems.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209915 , E-12152 , NAS 1.15:209915 , Computational Aerosciences; Feb 15, 2000 - Feb 17, 2000; Moffett Field, CA; United States
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  • 22
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    Noise Reduction Potential of Large, Over-the-Wing Mounted, Advanced Turbofan Engines (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: As we look to the future, increasingly stringent civilian aviation noise regulations will require the design and manufacture of extremely quiet commercial aircraft. Indeed, the noise goal for NASA's Aeronautics Enterprise calls for technologies that will help to provide a 20 EPNdB reduction relative to today's levels by the year 2022. Further, the large fan diameters of modem, increasingly higher bypass ratio engines pose a significant packaging and aircraft installation challenge. One design approach that addresses both of these challenges is to mount the engines above the wing. In addition to allowing the performance trend towards large, ultra high bypass ratio cycles to continue, this over-the-wing design is believed to offer noise shielding benefits to observers on the ground. This paper describes the analytical certification noise predictions of a notional, long haul, commercial quadjet transport with advanced, high bypass engines mounted above the wing.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210025 , NAS 1.15:210025 , E-12222 , 14th International Symposium on Air Breathing Engines; Sep 05, 1999 - Sep 10, 1999; Florence; Italy
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  • 23
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    Heat Transfer and Flow on the Squealer Tip of a Gas Turbine Blade (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Experimental investigations are performed to measure the detailed heat transfer coefficient and static pressure distributions on the squealer tip of a gas turbine blade in a five-bladed stationary linear cascade. The blade is a 2-dimensional model of a modem first stage gas turbine rotor blade with a blade tip profile of a GE-E(sup 3) aircraft gas turbine engine rotor blade. A squealer (recessed) tip with a 3.77% recess is considered here. The data on the squealer tip are also compared with a flat tip case. All measurements are made at three different tip gap clearances of about 1%, 1.5%, and 2.5% of the blade span. Two different turbulence intensities of 6.1% and 9.7% at the cascade inlet are also considered for heat transfer measurements. Static pressure measurements are made in the mid-span and near-tip regions, as well as on the shroud surface opposite to the blade tip surface. The flow condition in the test cascade corresponds to an overall pressure ratio of 1.32 and an exit Reynolds number based on the axial chord of 1.1 x 10(exp 6). A transient liquid crystal technique is used to measure the heat transfer coefficients. Results show that the heat transfer coefficient on the cavity surface and rim increases with an increase in tip clearance. 'Me heat transfer coefficient on the rim is higher than the cavity surface. The cavity surface has a higher heat transfer coefficient near the leading edge region than the trailing edge region. The heat transfer coefficient on the pressure side rim and trailing edge region is higher at a higher turbulence intensity level of 9.7% over 6.1 % case. However, no significant difference in local heat transfer coefficient is observed inside the cavity and the suction side rim for the two turbulence intensities. The squealer tip blade provides a lower overall heat transfer coefficient when compared to the flat tip blade.
    Keywords: Aircraft Propulsion and Power
    Type: ASME Paper-2000-FT-0195 , ASME Turbo 2000; May 08, 2000 - May 11, 2000; Munich; Germany
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  • 24
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    Three-Dimensional Effects in Modeling of Dual-Mode Scramjets (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: A numerical investigation of an experimental dual-mode scramjet configuration is performed. Both experimental and numerical results indicate significant upstream interaction for this case. Several computational cases are examined: these include the use of jet-to-jet symmetry and entire half-duct modeling. Grid convergence, turbulence modeling, and wall temperature effects are studied in terms of wall pressure predictions and flow-field characteristics. Wall pressure comparisons between CFD and experiment show fair agreement for the jet-to-jet case. However, further computations of the entire half-duct show the development of a large sidewall separation zone extending much further upstream than the separation zone at the duct centerline. This sidewall separation is the dominant feature in the CFD-generated flowfield but is not evident in the experimental data, resulting in a unfavorable comparison between CFD and experimental data. Current work aimed at resolving this issue and at further understanding asymmetric flow-structures in dual-mode flow-fields is discussed.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 2000-3704
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  • 25
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    Lean direct wall fuel injection method and devices (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A fuel combustion chamber, and a method of and a nozzle for mixing liquid fuel and air in the fuel combustion chamber in lean direct injection combustion for advanced gas turbine engines, including aircraft engines. Liquid fuel in a form of jet is injected directly into a cylindrical combustion chamber from the combustion chamber wall surface in a direction opposite to the direction of the swirling air at an angle of from about 50.degree. to about 60.degree. with respect to a tangential line of the cylindrical combustion chamber and at a fuel-lean condition, with a liquid droplet momentum to air momentum ratio in the range of from about 0.05 to about 0.12. Advanced gas turbines benefit from lean direct wall injection combustion. The lean direct wall injection technique of the present invention provides fast, uniform, well-stirred mixing of fuel and air. In addition, in order to further improve combustion, the fuel can be injected at a venturi located in the combustion chamber at a point adjacent the air swirler.
    Keywords: Aircraft Propulsion and Power
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  • 26
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    Fatigue Failure of Development Space Shuttle Main Engine Turbine Blades (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: This presentation focuses on the use of single crystal material, uniaxial LCF specimen data, and on development blade failure analysis.
    Keywords: Aircraft Propulsion and Power
    Type: Fracture Control Methodology; Oct 31, 2000 - Nov 02, 2000; Huntsville, AL; United States
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  • 27
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    Internal Designs Application for Inlet and Nozzle Aeroperformance Improvement (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The following research results are based on development of an approach previously proposed by the authors for optimum nozzle design to obtain maximum thrust. The design was denoted a Telescope nozzle. A Telescope nozzle contains one or several internal designs of certain location, which are inserted at certain locations into a divergent conical or planar main nozzle near its exit. Such a design provides additional thrust augmentation over 20% by comparison with the optimum single nozzle of equivalent lateral area. What is more, recent experimental acoustic tests have discovered an essential noise reduction due to Telescope nozzles application. In this paper, some additional theoretical results are presented for Telescope nozzles and a similar approach is applied for aeroperformance improvement of a supersonic inlet. In addition, a classic gas dynamics problem of a similar supersonic flow into a plate has been analyzed. In some particular cases, new exact analytical solutions are obtained for a flow into a wedge with an oblique shock wave. Numerical simulations were conducted for supersonic flow into a divergent portion of a 2D or axisymmetric nozzle with several plane or conical designs as well as into a 2D or axisymmetric supersonic inlet with a forebody. The 1st order Kryko-Godunov march- ing numerical scheme for inviscid supersonic flows was used. Several cases were tested using the NASA CFL3d code based on full Navier-Stokes equations. Numerical simulation results have confirmed essential benefits of Telescope design applications in propulsion systems.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 2000-3315 , 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 17, 2000 - Jul 19, 2000; Huntsville, AL; United States
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  • 28
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    Augmentation of Stagnation Region Heat Transfer Due to Turbulence From a DLN Can Combustor (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Heat transfer measurements have been made in the stagnation region of a flat plate with a circular leading edge. Electrically heated aluminum strips placed symmetrically about the leading edge stagnation region were used to measure spanwise averaged heat transfer coefficients. The maximum Reynolds number obtained, based on leading edge diameter, was about 100,000. The model was immersed in the flow field downstream of an approximately half scale model of a can-type combustor from a low NO(x), ground based power-generating turbine. The tests were conducted with room temperature air; no fuel was added. Room air flowed into the combustor through six vane type fuel/air swirlers. The combustor can contained no dilution holes. The fuel/air swirlers all swirled the incoming airflow in a counter clockwise direction (facing downstream). A 5-hole probe flow field survey in the plane of the model stagnation point showed the flow was one big vortex with flow angles up to 36' at the outer edges of the rectangular test section. Hot wire measurements showed test section flow had very high levels of turbulence, around 28.5 percent, and had a relatively large axial-length scale-to-leading edge diameter ratio of 0.5. X-wire measurements showed the turbulence to be nearly isotropic. Stagnation heat transfer augmentation over laminar levels was around 77 percent and was about 14 percent higher than predicted by a previously developed correlation for isotropic grid generated turbulence.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210241 , E-12360 , NAS 1.15:210241 , ASME Paper 2000-GT-0215 , International Gas Turbine and Aeroengine Technical Congress; May 08, 2000 - May 11, 2000; Munich; Germany
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  • 29
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    Marquardt's Mach 4.5 Supercharged Ejector Ramjet (SERJ) High-Performance Aircraft Engine Project: Unfulfilled Aspirations Ca.1970 (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Supercharged Ejector Ramjet (SERJ) engine developments of the 1960s, as pursued by The Marquardt Corporation and its associated industry team members, are described. In just three years, engineering work on this combined-cycle powerplant type evolved, from its initial NASA-sponsored reusable space transportation system study status, into a U.S. Air Force/Navy-supported exploratory development program as a candidate 4.5 high-performance military aircraft engine. Bridging a productive transition from the spaceflight to the aviation arena, this case history supports the expectation that fully-integrated airbreathing/rocket propulsion systems hold high promise toward meeting the demanding propulsion requirements of tomorrow's aircraft-like Spaceliner class transportation systems. Lessons to be learned from this "SERJ Story" are offered for consideration by today's advanced space transportation and combined-cycle propulsion researchers and forward-planning communities.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 2000-3109 , Joint Propulsion; Jul 16, 2000 - Jul 19, 2000; Huntsville, AL; United States
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  • 30
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    Longitudinal-Mode Combustion Instabilities: Modeling and Experiments (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Combustion instabilities can lead to increased development time and cost for aeroengine gas turbines. This problem has been evident in the development of very-low emissions stationary gas turbines, and will likely be encountered in the newer, more aggressive aeroengine designs. In order to minimize development time and cost, it is imperative that potential combustion dynamics issues be resolved using analyses and smaller-scale experimentation. This paper discusses a methodology through which a problem in a full-scale engine was replicated in a single-nozzle laboratory combustor. Specifically, this approach is valid for longitudinal and "bulk" mode combustion instabilities. An explanation and partial validation of the acoustic analyses that were used to achieve this replication are also included. This approach yields a testbed for the diagnosis of combustion dynamics problems and for their solution through passive and active control techniques.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210067 , E-12316 , NAS 1.15:210067 , Active Control Technology for Enhanced Performance Operational Capabilities of Military Aircraft, Land Vehicles and Sea Vehicles; May 08, 2000 - May 11, 2000; Braunschweig; Germany
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  • 31
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    Implementation of a Compressor Face Boundary Condition Based on Small Disturbances (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A compressor-face boundary condition that models the unsteady interactions of acoustic and convective velocity disturbances with a compressor has been implemented into a three-dimensional computational fluid dynamics code. Locally one-dimensional characteristics along with a small-disturbance model are used to compute the acoustic response as a function of the local stagger angle and the strength and direction of the disturbance. Simulations of the inviscid flow in a straight duct, a duct coupled to a compressor, and a supersonic inlet demonstrate the behavior of the boundary condition in relation to existing boundary conditions. Comparisons with experimental data show a large improvement in accuracy over existing boundary conditions in the ability to predict the reflected disturbance from the interaction of an acoustic disturbance with a compressor.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209945 , E-12193 , NAS 1.15:209945 , ASME-2000-GT-0005 , International Gas Turbine and Aeroengine Technical Congress; May 08, 2000 - May 11, 2000; Munich; Germany
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  • 32
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    Engine System Loads Development for the Fastrac 60K Flight Engine (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Early implementation of structural dynamics finite element analyses for calculation of design loads is considered common design practice for high volume manufacturing industries such as automotive and aeronautical industries. However, with the rarity of rocket engine development programs starts, these tools are relatively new to the design of rocket engines. In the new Fastrac engine program, the focus has been to reduce the cost to weight ratio; current structural dynamics analysis practices were tailored in order to meet both production and structural design goals. Perturbation of rocket engine design parameters resulted in a number of Fastrac load cycles necessary to characterize the impact due to mass and stiffness changes. Evolution of loads and load extraction methodologies, parametric considerations and a discussion of load path sensitivities are discussed.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 00-XXXX , 41st Structures, Structural Dynamic and Materials Conference; Apr 04, 2000 - Apr 06, 2000; Atlanta, GA; United States
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  • 33
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    Performance and Durability of High Temperature Foil Air Bearings for Oil-Free Turbomachinery (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The performance and durability of advanced, high temperature foil air bearings are evaluated under a wide range (10-50 kPa) of loads at temperatures from 25 to 650 C. The bearings are made from uncoated nickel based superalloy foils. The foil surface experiences sliding contact with the shaft during initial start/stop operation. To reduce friction and wear, the solid lubricant coating, PS304, is applied to the shaft by plasma spraying. PS304 is a NiCr based Cr2O3 coating with silver and barium fluoride/calcium fluoride solid lubricant additions. The results show that the bearings provide lives well in excess of 30,000 cycles under all of the conditions tested. Several bearings exhibited lives in excess of 100,000 cycles. Wear is a linear function of the bearing load. The excellent performance measured in this study suggests that these bearings and the PS304 coating are well suited for advanced high temperature, oil-free turbomachinery applications.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209187/REV1 , NAS 1.15:209187/REV1 , ARL-TR-2202 , E-11697-1/REV1 , May 07, 2000 - May 11, 2000; Nashville, TN; United States
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  • 34
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    Performance Optimization of a Rotor Alone Nacelle for Acoustic Fan Testing (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the techniques, equipment, and results from the optimization of a two-axis traverse actuation system used to maintain concentricity between a sting-mounted fan and a wall-mounted nacelle in the 9 x 15 (9 Foot by 15 Foot Test Section) Low Speed Wind Tunnel (LSWT) at the NASA Glenn Research Center (GRC). The Rotor Alone Nacelle (RAN) system, developed at GRC by the Engineering Design and Analysis Division (EDAD) and the Acoustics Branch, used nacelle-mounted lasers and an automated control system to maintain concentricity as thermal and thrust operating loads displace the fan relative to the nacelle. This effort was critical to ensuring rig/facility safety and experimental consistency of the acoustic data from a statorless, externally supported nacelle configuration. Although the tip clearances were originally predicted to be about 0.020 in. at maximum rotor (fan) operating speed, proximity probe measurements showed that the nominal clearance was less than 0.004 in. As a result, the system was optimized through control-loop modifications, active laser cooling, data filtering and averaging, and the development of strict operational procedures. The resultant concentricity error of RAN was reduced to +/- 0.0031 in. in the Y-direction (horizontal) and +0.0035 in./-0.001 3 in. in the Z-direction (vertical), as determined by error analysis and experimental results. Based on the success of this project, the RAN system will be transitioned to other wind tunnel research programs at NASA GRC.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210599 , NAS 1.15:210599 , E-12557 , AIAA Paper 2001-0164 , Aerospace Sciences; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
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    Optical Measurement and Visualization in High-Pressure, High-Temperature, Aviation Gas Turbine Combustors (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Planar laser-induced fluorescence (PLIF), planar Mie scattering (PMie), and linear (1-D) spontaneous Raman scattering are applied to flame tube and sector combustors that burn Jet-A fuel at a range of inlet temperatures and pressures that simulate conditions expected in future high-performance civilian gas turbine engines. Chemiluminescence arising from C2 in the flame was also imaged. Flame spectral emissions measurements were obtained using a scanning spectrometer. Several different advanced concept fuel injectors were examined. First-ever PLIF and chemiluminescence data are presented from the 60-atm Gas turbine combustor facility.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210377 , E-12431 , NAS 1.15:210377 , EOS/SPIE Symposium on Applied Photonics; May 22, 2000 - May 25, 2000; Glasgow, Scotland; United Kingdom
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  • 36
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    Active Combustion Control for Aircraft Gas Turbine Engines (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Lean-burning combustors are susceptible to combustion instabilities. Additionally, due to non-uniformities in the fuel-air mixing and in the combustion process, there typically exist hot areas in the combustor exit plane. These hot areas limit the operating temperature at the turbine inlet and thus constrain performance and efficiency. Finally, it is necessary to optimize the fuel-air ratio and flame temperature throughout the combustor to minimize the production of pollutants. In recent years, there has been considerable activity addressing Active Combustion Control. NASA Glenn Research Center's Active Combustion Control Technology effort aims to demonstrate active control in a realistic environment relevant to aircraft engines. Analysis and experiments are tied to aircraft gas turbine combustors. Considerable progress has been shown in demonstrating technologies for Combustion Instability Control, Pattern Factor Control, and Emissions Minimizing Control. Future plans are to advance the maturity of active combustion control technology to eventual demonstration in an engine environment.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210346 , NAS 1.15:210346 , E-12393 , AIAA Paper 2000-3500 , 36th Joint Propulsion Conference and Exhibition; Jul 17, 2000 - Jul 19, 2000; Huntsville, AL; United States
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    Tribological Limitations in Gas Turbine Engines: A Workshop to Identify the Challenges and Set Future Directions (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The following report represents a compendium of selected speaker presentation materials and observations made by Prof O. Pinkus at the NASA/ASME/Industry sponsored workshop entitled "Tribological Limitations in Gas Turbine Engines" held on September 15-17, 1999 in Albany, New York. The impetus for the workshop came from the ASME's Research Committee on Tribology whose goal is to explore new tribological research topics which may become future research opportunities. Since this subject is of current interest to other industrial and government entities the conference received cosponsorship as noted above. The conference was well attended by government, industrial and academic participants. Topics discussed included current tribological issues in gas turbines as well as the potential impact (drawbacks and advantages) of future tribological technologies especially foil air bearings and magnetic beatings. It is hoped that this workshop report may serve as a starting point for continued discussions and activities in oil-free turbomachinery systems.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210059 , E-12261 , NAS 1.15:210059 , Tribological Limitations in Gas Turbine Engines; Sep 15, 1999 - Sep 17, 1999; Albany, NY; United States
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  • 38
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    The NPARC Alliance Verification and Validation Archive (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NPARC Alliance (National Project for Applications oriented Research in CFD) maintains a publicly-available, web-based verification and validation archive as part of the development and support of the WIND CFD code. The verification and validation methods used for the cases attempt to follow the policies and guidelines of the ASME and AIAA. The emphasis is on air-breathing propulsion flow fields with Mach numbers ranging from low-subsonic to hypersonic.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209946 , NAS 1.15:209946 , E-12196 , ASME-2000-FED-11233 , 2000 Fluids Engineering Summer Conference; Jun 11, 2000 - Jun 15, 2000; Boston, MA; United States
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  • 39
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    Performance of an Active Noise Control System for Fan Tones Using Vane Actuators (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An Active Noise Control (ANC) system for ducted fan noise was built that uses actuators located in stator vanes. The custom designed actuators A,ere piezoelectric benders manufactured using THUNDER technology. The ANC system was tested in the NASA Active Noise Control Fan rig. A total of 168 actuators in 28 stator vanes were used (six per vane). Simultaneous inlet and exhaust acoustic power level reductions were demonstrated for a fan modal structure that contained two radial modes in each direction. Total circumferential mode power levels were reduced by up to 9 dB in the inlet and 3 dB in the exhaust. The corresponding total 2BPF tone level reductions were by 6 dB in the inlet and 2 dB in the exhaust. Farfield sound pressure level reductions of up to 17 dB were achieved at the peak mode lobe angle. The performance of the system was limited by the constraints of the power amplifiers and the presence of control spillover. Simpler control/actuator systems using carefully selected subsets of the full system and random simulated failures of up to 7% of the actuators were investigated. (The actuators were robust and none failed during the test). Useful reductions still occurred under these conditions.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210229 , NAS 1.15:210229 , E-12348 , AIAA Paper 2000-1906 , 6th Aeroacoustics Conference and Exhibit; Jun 12, 2000 - Jun 14, 2000; Lahaina, HI; United States
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    Experimental and Numerical Investigation of Losses in Low-Pressure Turbine Blade Rows (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Experimental data and numerical simulations of low-pressure turbines have shown that unsteady blade row interactions and separation can have a significant impact on the turbine efficiency. Measured turbine efficiencies at takeoff can be as much as two points higher than those at cruise conditions. Several recent studies have revealed that the performance of low-pressure turbine blades is a strong function of the Reynolds number. In the current investigation, experiments and simulations have been performed to study the behavior of a low-pressure turbine blade at several Reynolds numbers. Both the predicted and experimental results indicate increased cascade losses as the Reynolds number is reduced to the values associated with aircraft cruise conditions. In addition, both sets of data show that tripping the boundary layer helps reduce the losses at lower Reynolds numbers. Overall, the predicted aerodynamic and performance results exhibit fair agreement with experimental data.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209910 , AIAA Paper 2000-0737 , NAS 1.15:209910 , E-12137 , 38th Aerospace Science Meeting; Jan 10, 2000 - Jan 13, 2000; Reno, NV; United States
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    Hyper-X Engine Testing in the NASA Langley 8-Foot High Temperature Tunnel (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Airframe-integrated scramjet engine tests have been completed at Mach 7 in the NASA Langley 8-Foot High Temperature Tunnel under the Hyper-X program. These tests provided critical engine data as well as design and database verification for the Mach 7 flight tests of the Hyper-X research vehicle (X-43), which will provide the first-ever airframe-integrated scramjet flight data. The first model tested was the Hyper-X Engine Model (HXEM), and the second was the Hyper-X Flight Engine (HXFE). The HXEM, a partial-width, full-height engine that is mounted on an airframe structure to simulate the forebody features of the X-43, was tested to provide data linking flowpath development databases to the complete airframe-integrated three-dimensional flight configuration, and to isolate effects of ground testing conditions and techniques. The HXFE, an exact geometric representation of the X-43 scramjet engine mounted on an airframe structure that duplicates the entire three-dimensional propulsion flowpath from the vehicle leading edge to the vehicle base, was tested to verify the complete design as it will be flight tested. This paper presents an overview of these two tests, their importance to the Hyper-X program, and the significance of their contribution to scramjet database development.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 2000-3605 , Joint Propulsion Conference; Jul 17, 2000 - Jul 19, 2000; Huntsville, AL; United States
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    Recommendations for Achieving Accurate Numerical Simulation of Tip Clearance Flows in Transonic Compressor Rotors (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The tip clearance flows of transonic compressor rotors are important because they have a significant impact on rotor and stage performance. While numerical simulations of these flows are quite sophisticated. they are seldom verified through rigorous comparisons of numerical and measured data because these kinds of measurements are rare in the detail necessary to be useful in high-speed machines. In this paper we compare measured tip clearance flow details (e.g. trajectory and radial extent) with corresponding data obtained from a numerical simulation. Recommendations for achieving accurate numerical simulation of tip clearance flows are presented based on this comparison. Laser Doppler Velocimeter (LDV) measurements acquired in a transonic compressor rotor, NASA Rotor 35, are used. The tip clearance flow field of this transonic rotor was simulated using a Navier-Stokes turbomachinery solver that incorporates an advanced k-epsilon turbulence model derived for flows that are not in local equilibrium. Comparison between measured and simulated results indicates that simulation accuracy is primarily dependent upon the ability of the numerical code to resolve important details of a wall-bounded shear layer formed by the relative motion between the over-tip leakage flow and the shroud wall. A simple method is presented for determining the strength of this shear layer.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210347 , E-12395 , NAS 1.15:210347 , International Gas Turbine Institute Exposition; Jul 07, 1999 - Jul 10, 1999; Indianapolis, IN; United States
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    A Probabilistic Approach to Aeropropulsion System Assessment (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A probabilistic approach is described for aeropropulsion system assessment. To demonstrate this approach, the technical performance of a wave rotor-enhanced gas turbine engine (i.e. engine net thrust, specific fuel consumption, and engine weight) is assessed. The assessment accounts for the uncertainties in component efficiencies/flows and mechanical design variables, using probability distributions. The results are presented in the form of cumulative distribution functions (CDFs) and sensitivity analyses, and are compared with those from the traditional deterministic approach. The comparison shows that the probabilistic approach provides a more realistic and systematic way to assess an aeropropulsion system.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210334 , E-12036-1 , NAS 1.15:210334 , International Gas Turbine and Aeroengine Technical Congress; May 08, 2000 - May 11, 2000; Munich; Germany
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    Numerical Propulsion System Simulation (NPSS) 1999 Industry Review (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The technologies necessary to enable detailed numerical simulations of complete propulsion systems are being developed at the NASA Glenn Research Center in cooperation with industry, academia, and other government agencies. Large scale, detailed simulations will be of great value to the nation because they eliminate some of the costly testing required to develop and certify advanced propulsion systems. In addition, time and cost savings will be achieved by enabling design details to be evaluated early in the development process before a commitment is made to a specific design. This concept is called the Numerical Propulsion System Simulation (NPSS). NPSS consists of three main elements: (1) engineering models that enable multidisciplinary analysis of large subsystems and systems at various levels of detail, (2) a simulation environment that maximizes designer productivity, and (3) a cost-effective, high-performance computing platform. A fundamental requirement of the concept is that the simulations must be capable of overnight execution on easily accessible computing platforms. This will greatly facilitate the use of large-scale simulations in a design environment. This paper describes the current status of the NPSS with specific emphasis on the progress made over the past year on air breathing propulsion applications. In addition, the paper contains a summary of the feedback received from industry partners in the development effort and the actions taken over the past year to respond to that feedback. The NPSS development was supported in FY99 by the High Performance Computing and Communications Program.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209795 , E-12085 , NAS 1.15:209795 , Oct 06, 1999 - Oct 07, 1999; Cleveland, OH; United States
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    Developing Conceptual Hypersonic Airbreathing Engines Using Design of Experiments Methods (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Designing a hypersonic vehicle is a complicated process due to the multi-disciplinary synergy that is required. The greatest challenge involves propulsion-airframe integration. In the past, a two-dimensional flowpath was generated based on the engine performance required for a proposed mission. A three-dimensional CAD geometry was produced from the two-dimensional flowpath for aerodynamic analysis, structural design, and packaging. The aerodynamics, engine performance, and mass properties arc inputs to the vehicle performance tool to determine if the mission goals were met. If the mission goals were not met, then a flowpath and vehicle redesign would begin. This design process might have to be performed several times to produce a "closed" vehicle. This paper will describe an attempt to design a hypersonic cruise vehicle propulsion flowpath using a Design of' Experiments method to reduce the resources necessary to produce a conceptual design with fewer iterations of the design cycle. These methods also allow for more flexible mission analysis and incorporation of additional design constraints at any point. A design system was developed using an object-based software package that would quickly generate each flowpath in the study given the values of the geometric independent variables. These flowpath geometries were put into a hypersonic propulsion code and the engine performance was generated. The propulsion results were loaded into statistical software to produce regression equations that were combined with an aerodynamic database to optimize the flowpath at the vehicle performance level. For this example, the design process was executed twice. The first pass was a cursory look at the independent variables selected to determine which variables are the most important and to test all of the inputs to the optimization process. The second cycle is a more in-depth study with more cases and higher order equations representing the design space.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 2000-2694 , Aerodynamic Measurement Technology and Ground Testing; Jun 19, 2000 - Jun 22, 2000; Denver, CO; United States
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    Numerical Zooming Between a NPSS Engine System Simulation and a One-Dimensional High Compressor Analysis Code (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Within NASA's High Performance Computing and Communication (HPCC) program, NASA Glenn Research Center is developing an environment for the analysis/design of aircraft engines called the Numerical Propulsion System Simulation (NPSS). NPSS focuses on the integration of multiple disciplines such as aerodynamics, structures, and heat transfer along with the concept of numerical zooming between zero-dimensional to one-, two-, and three-dimensional component engine codes. In addition, the NPSS is refining the computing and communication technologies necessary to capture complex physical processes in a timely and cost-effective manner. The vision for NPSS is to create a "numerical test cell" enabling full engine simulations overnight on cost-effective computing platforms. Of the different technology areas that contribute to the development of the NPSS Environment, the subject of this paper is a discussion on numerical zooming between a NPSS engine simulation and higher fidelity representations of the engine components (fan, compressor, burner, turbines, etc.). What follows is a description of successfully zooming one-dimensional (row-by-row) high-pressure compressor analysis results back to a zero-dimensional NPSS engine simulation and a discussion of the results illustrated using an advanced data visualization tool. This type of high fidelity system-level analysis, made possible by the zooming capability of the NPSS, will greatly improve the capability of the engine system simulation and increase the level of virtual test conducted prior to committing the design to hardware.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209913 , E-12144 , NAS 1.15:209913 , Computational Aerosciences; Feb 15, 2000 - Feb 17, 2000; Moffett Field, CA; United States
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    An Overview of the NASA Aviation Safety Program Propulsion Health Monitoring Element (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Aviation Safety Program (AvSP) has been initiated with aggressive goals to reduce the civil aviation accident rate, To meet these goals, several technology investment areas have been identified including a sub-element in propulsion health monitoring (PHM). Specific AvSP PHM objectives are to develop and validate propulsion system health monitoring technologies designed to prevent engine malfunctions from occurring in flight, and to mitigate detrimental effects in the event an in-flight malfunction does occur. A review of available propulsion system safety information was conducted to help prioritize PHM areas to focus on under the AvSP. It is noted that when a propulsion malfunction is involved in an aviation accident or incident, it is often a contributing factor rather than the sole cause for the event. Challenging aspects of the development and implementation of PHM technology such as cost, weight, robustness, and reliability are discussed. Specific technology plans are overviewed including vibration diagnostics, model-based controls and diagnostics, advanced instrumentation, and general aviation propulsion system health monitoring technology. Propulsion system health monitoring, in addition to engine design, inspection, maintenance, and pilot training and awareness, is intrinsic to enhancing aviation propulsion system safety.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210348 , E-12396 , NAS 1.15:210348 , ARL-TR-2272 , AIAA Paper 2000-3624 , Joint Propulsion; Jul 16, 2000 - Jul 19, 2000; Huntsville, AL; United States
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    Mixing of an Airblast-atomized Fuel Spray Injected into a Crossflow of Air (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The injection of a spray of fuel droplets into a crossflow of air provides a means of rapidly mixing liquid fuel and air for combustion applications. Injecting the liquid as a spray reduces the mixing length needed to accommodate liquid breakup, while the transverse injection of the spray into the air stream takes advantage of the dynamic mixing induced by the jet-crossflow interaction. The structure of the spray, formed from a model plain-jet airblast atomizer, is investigated in order to determine and understand the factors leading to its dispersion. To attain this goal, the problem is divided into the following tasks which involve: (1) developing planar imaging techniques that visualize fuel and air distributions in the spray, (2) characterizing the airblast spray without a crossflow, and (3) characterizing the airblast spray upon injection into a crossflow. Geometric and operating conditions are varied in order to affect the atomization, penetration, and dispersion of the spray into the crossflow. The airblast spray is first characterized, using imaging techniques, as it issues into a quiescent environment. The spray breakup modes are classified in a liquid Reynolds number versus airblast Weber number regime chart. This work focuses on sprays formed by the "prompt" atomization mode, which induces a well-atomized and well-dispersed spray, and which also produces a two-lobed liquid distribution corresponding to the atomizing air passageways in the injector. The characterization of the spray jet injected into the crossflow reveals the different processes that control its dispersion. Correlations that describe the inner and outer boundaries of the spray jet are developed, using the definition of a two-phase momentum-flux ratio. Cross-sections of the liquid spray depict elliptically-shaped distributions, with the exception of the finely-atomized sprays which show kidney-shaped distributions reminiscent of those obtained in gaseous jet in crossflow systems. A droplet trajectory analysis overpredicts the liquid mass penetration, and indicates a need for a more rigorous model to account for the three-dimensional mixing field induced by the jet-crossflow interaction. Nonetheless, the general procedures and criteria that are outlined can be used to efficiently assess and compare the quality of sprays formed under different conditions.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-210467 , E-12463 , NAS 1.26:210467 , UCI-ARTR-00-05
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    Multi-Disciplinary Design Optimization Using WAVE (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The current preliminary design tools lack the product performance, quality and cost prediction fidelity required to design Six Sigma products. They are also frequently incompatible with the tools used in detailed design, leading to a great deal of rework and lost or discarded data in the transition from preliminary to detailed design. Thus, enhanced preliminary design tools are needed in order to produce adequate financial returns to the business. To achieve this goal, GEAE has focused on building the preliminary design system around the same geometric 3D solid model that will be used in detailed design. With this approach, the preliminary designer will no longer convert a flowpath sketch into an engine cross section but rather, automatically create 3D solid geometry for structural integrity, life, weight, cost, complexity, producibility, and maintainability assessments. Likewise, both the preliminary design and the detailed design can benefit from the use of the same preliminary part sizing routines. The design analysis tools will also be integrated with the 3D solid model to eliminate manual transfer of data between programs. GEAE has aggressively pursued the computerized control of engineering knowledge for many years. Through its study and validation of 3D CAD programs and processes, GEAE concluded that total system control was not feasible at that time. Prior CAD tools focused exclusively on detail part geometry and Knowledge Based Engineering systems concentrated on rules input and data output. A system was needed to bridge the gap between the two to capture the total system. With the introduction of WAVE Engineering from UGS, the possibilities of an engineering system control device began to formulate. GEAE decided to investigate the new WAVE functionality to accomplish this task. NASA joined GEAE in funding this validation project through Task Order No. 1. With the validation project complete, the second phase under Task Order No. 2 was established to develop an associative control structure (framework) in the UG WAVE environment enabling multi-disciplinary design of turbine propulsion systems. The capabilities of WAVE were evaluated to assess its use as a rapid optimization and productivity tool. This project also identified future WAVE product enhancements that will make the tool still more beneficial for product development.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-210218 , E-12337 , NAS 1.26:210218
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    Numerical Simulation of Dual-Mode Scramjet Combustors (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Results of a numerical investigation of a three-dimensional dual-mode scramjet isolator-combustor flow-field are presented. Specifically, the effect of wall cooling on upstream interaction and flow-structure is examined for a case assuming jet-to-jet symmetry within the combustor. Comparisons are made with available experimental wall pressures. The full half-duct for the isolator-combustor is then modeled in order to study the influence of side-walls. Large scale three-dimensionality is observed in the flow with massive separation forward on the side-walls of the duct. A brief review of convergence-acceleration techniques useful in dual-mode simulations is presented, followed by recommendations regarding the development of a reliable and unambiguous experimental data base for guiding CFD code assessments in this area.
    Keywords: Aircraft Propulsion and Power
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    Full 3D Analysis of the GE90 Turbofan Primary Flowpath (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The multistage simulations of the GE90 turbofan primary flowpath components have been performed. The multistage CFD code, APNASA, has been used to analyze the fan, fan OGV and booster, the 10-stage high-pressure compressor and the entire turbine system of the GE90 turbofan engine. The code has two levels of parallel, and for the 18 blade row full turbine simulation has 87.3 percent parallel efficiency with 121 processors on an SGI ORIGIN. Grid generation is accomplished with the multistage Average Passage Grid Generator, APG. Results for each component are shown which compare favorably with test data.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-209951 , E-12205 , NAS 1.26:209951
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    Effect of Film-Hole Shape on Turbine Blade Film Cooling Performance (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The detailed heat transfer coefficient and film cooling effectiveness distributions as well as tile detailed coolant jet temperature profiles on the suction side of a gas turbine blade A,ere measured using a transient liquid crystal image method and a traversing cold wire and a traversing thermocouple probe, respectively. The blade has only one row of film holes near the gill hole portion on the suction side of the blade. The hole geometries studied include standard cylindrical holes and holes with diffuser shaped exit portion (i.e. fanshaped holes and laidback fanshaped holes). Tests were performed on a five-blade linear cascade in a low-speed wind tunnel. The mainstream Reynolds number based on cascade exit velocity was 5.3 x 10(exp 5). Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. The wake Strouhal number was kept at 0 or 0.1. Coolant blowing ratio was varied from 0.4 to 1.2. Results show that both expanded holes have significantly improved thermal protection over the surface downstream of the ejection location, particularly at high blowing ratios. However, the expanded hole injections induce earlier boundary layer transition to turbulence and enhance heat transfer coefficients at the latter part of the blade suction surface. In general, the unsteady wake tends to reduce film cooling effectiveness.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-209932 , E-12176 , NAS 1.26:209932
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    Unsteady High Turbulence Effects on Turbine Blade Film Cooling Heat Transfer Performance Using a Transient Liquid Crystal Technique (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Unsteady wake effect, with and without trailing edge ejection, on detailed heat transfer coefficient and film cooling effectiveness distributions is presented for a downstream film-cooled gas turbine blade. Tests were performed on a five-blade linear cascade at an exit Reynolds number of 5.3 x 10(exp 5). Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. Coolant blowing ratio was varied from 0.4 to 1.2; air and CO2 were used as coolants to simulate different density ratios. Surface heat transfer and film effectiveness distributions were obtained using a transient liquid crystal technique; coolant temperature profiles were determined with a cold wire technique. Results show that Nusselt numbers for a film cooled blade are much higher compared to a blade without film injection. Unsteady wake slightly enhances Nusselt numbers but significantly reduces film effectiveness versus no wake cases. Nusselt numbers increase only slic,htly but film cooling, effectiveness increases significantly with increasing, blowing ratio. Higher density coolant (CO2) provides higher effectiveness at higher blowing ratios (M = 1.2) whereas lower density coolant (Air) provides higher 0 effectiveness at lower blowing ratios (M = 0.8). Trailing edge ejection generally has more effect on film effectiveness than on the heat transfer, typically reducing film effectiveness and enhancing heat transfer. Similar data is also presented for a film cooled cylindrical leading edge model.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-209929 , E-12173 , NAS 1.26:209929
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    Unsteady Analysis of Inlet-Compressor Acoustic Interactions Using Coupled 3-D and 1-D CFD Codes (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: It is well known that the dynamic response of a mixed compression supersonic inlet is very sensitive to the boundary condition imposed at the subsonic exit (engine face) of the inlet. In previous work, a 3-D computational fluid dynamics (CFD) inlet code (NPARC) was coupled at the engine face to a 3-D turbomachinery code (ADPAC) simulating an isolated rotor and the coupled simulation used to study the unsteady response of the inlet. The main problem with this approach is that the high fidelity turbomachinery simulation becomes prohibitively expensive as more stages are included in the simulation. In this paper, an alternative approach is explored, wherein the inlet code is coupled to a lesser fidelity 1-D transient compressor code (DYNTECC) which simulates the whole compressor. The specific application chosen for this evaluation is the collapsing bump experiment performed at the University of Cincinnati, wherein reflections of a large-amplitude acoustic pulse from a compressor were measured. The metrics for comparison are the pulse strength (time integral of the pulse amplitude) and wave form (shape). When the compressor is modeled by stage characteristics the computed strength is about ten percent greater than that for the experiment, but the wave shapes are in poor agreement. An alternate approach that uses a fixed rise in duct total pressure and temperature (so-called 'lossy' duct) to simulate a compressor gives good pulse shapes but the strength is about 30 percent low.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210247 , E-12367 , NAS 1.15:210247
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    Undulated Nozzle for Enhanced Exit Area Mixing (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: A nozzle having an undulating surface for enhancing the mixing of a primary flow with a secondary flow or ambient air, without requiring an ejector. The nozzle includes a nozzle structure and design for introducing counter-rotating vorticity into the primary flow either through (i) internal surface corrugations where an axisymmetric line through each corrugation is coincident with an axisymmetric line through the center of the flow passageway or (ii) through one or more sets of alternating convexities and cavities in the internal surface of the nozzle where an axisymmetric line through each convexity and cavity is coincident with an axisymmetric line through the center of the flow passageway, and where the convexities contract from the entrance end towards the exit end. Exit area mixing is also enhanced by one or more chevrons attached to the exit edge of the nozzle. The nozzle is ideally suited for application as a jet engine nozzle. When used as a jet engine nozzle, noise suppression with simultaneous thrust augmentation/minimal thrust loss is achieved.
    Keywords: Aircraft Propulsion and Power
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    Effect of Jet Injection Angle and Number of Jets on Mixing and Emissions From a Reacting Crossflow at Atmospheric Pressure (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The mixing of air jets into hot, fuel-rich products of a gas turbine primary zone is an important step in staged combustion. Often referred to as "quick quench," the mixing occurs with chemical conversion and substantial heat release. An experiment has been designed to simulate and study this process, and the effect of varying the entry angle (0 deg, 22.5 deg and 45 deg from normal) and number of the air jets (7, 9, and 11) into the main flow, while holding the jet-to-crossflow mass-low ratio, MR, and momentum-flux ratio, J, constant (MR = 2.5;J = 25). The geometry is a crossflow confined in a cylindrical duct with side-wall injection of jets issuing from orifices equally spaced around the perimeter. A specially designed reactor, operating on propane, presents a uniform mixture to a module containing air jet injection tubes that can be changed to vary orifice geometry. Species concentrations of O2, CO, CO2, NO(x) and HC were obtained one duct diameter upstream (in the rich zone), and primarily one duct radius downstream. From this information, penetration of the jet, the spatial extent of chemical reaction, mixing, and the optimum jet injection angle and number of jets can be deduced.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-209949 , E-12202 , NAS 1.26:209949
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    On Flowfield Periodicity in the NASA Transonic Flutter Cascade (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The transonic flutter cascade facility at NASA Glenn Research Center was redesigned based on a combined program of experimental measurements and numerical analyses. The objectives of the redesign were to improve the periodicity of the cascade in steady operation, and to better quantify the inlet and exit flow conditions needed for CFD predictions. Part I of this paper describes the experimental measurements, which included static pressure measurements on the blade and endwalls made using both static taps and pressure sensitive paints, cobra probe measurements of the endwall boundary layers and blade wakes, and shadowgraphs of the wave structure. Part II of this paper describes three CFD codes used to analyze the facility, including a multibody panel code, a quasi-three-dimensional viscous code, and a fully three-dimensional viscous code. The measurements and analyses both showed that the operation of the cascade was heavily dependent on the configuration of the sidewalls. Four configurations of the sidewalls were studied and the results are described. For the final configuration, the quasi-three-dimensional viscous code was used to predict the location of mid-passage streamlines for a perfectly periodic cascade. By arranging the tunnel sidewalls to approximate these streamlines, sidewall interference was minimized and excellent periodicity was obtained.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-209933/PT1 , NAS 1.15:209933/PT1 , E-12177/PT1
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    Fuel Plume Image Mixing Analysis Formulation With Proper Treatment of Non-Constant Velocity Flowfields (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: A previously developed technique allows an estimate of integral mixing to be obtained from an image of laser scattered light from particle seeded fuel in the hypervelocity flow through a scramjet combustor. This previous mixing analysis formulation contains an assumption of a constant velocity flowfield across the plane of the fuel plume image. For high-speed scramjet combustors, the velocity flowfield is quite uniform and an assumption of constant velocity works well. Applying this same mixing analysis technique to fuel plume images obtained from a mid-speed scramjet combustor makes it desirable to remove the constant velocity assumption. This is due to the non-uniform velocity flowfields present in mid-speed scramjet combustors. A new formulation of the mixing analysis methodology is developed and presented so that the technique can be applied to a mid-speed scramjet combustor without the need to assume a constant velocity flowfield.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-209868 , NAS 1.26:209868
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    Mixing and NOx Emission Calculations of Confined Reacting Jet Flows in Cylindrical and Annular Ducts (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Rapid mixing of cold lateral jets with hot cross-stream flows in confined configurations is of practical interest in gas turbine combustors as it strongly affects combustor exit temperature quality, and gaseous emissions in for example rich-lean combustion. It is therefore important to further improve our fundamental understanding of the important processes of dilution jet mixing especially when the injected jet mass flow rate exceeds that of the cross-stream. The results reported in this report describe some of the main flow characteristics which develop in the mixing process in a cylindrical duct. A three-dimensional computational fluid dynamics (CFD) code has been used to predict the mixing flow field characteristics and NOx emission in a quench section of a rich-burn/quick-mix/lean-burn (RQL) combustor. Sixty configurations have been analyzed in both circular and annular geometries in a fully reacting environment simulating the operating condition of an actual RQL gas turbine combustion liner. The evaluation matrix was constructed by varying the number of orifices per row and orifice shape. Other parameters such as J (momentum-flux ratio), MR (mass flowrate ratio), DR (density ratio), and mixer sector orifice ACd (effective orifice area) were maintained constant throughout the entire study. The results indicate that the mixing flow field can be correlated with the NOx production if they are referenced with the stoichiometric equivalence ratio value and not the equilibrium value. The mixing flowfields in both circular and annular mixers are different. The penetration of equal jets in both annular and circular geometries is vastly different which significantly affects the performance of the mixing section. In the computational results with the circular mixer, most of the NOx formation occurred behind the orifice starting at the orifice wake region. General trends have been observed in the NOx production as the number of orifices is changed and this appears to be common for all hole configurations and mixer types (circular or annular). The performance of any orifice shape (in producing minimum NOx) appears to be acceptable if the number of orifices can be freely varied in order to attain the optimum jet penetration.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-210672 , E-12579 , NAS 1.26:210672
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    Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Hypersonic Airbreathing Engines (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The prospects for realizing a magnetohydrodynamic (MHD) bypass hypersonic airbreathing engine are examined from the standpoint of fundamental thermodynamic feasibility. The MHD-bypass engine, first proposed as part of the Russian AJAX vehicle concept, is based on the idea of redistributing energy between various stages of the propulsion system flow train. The system uses an MHD generator to extract a portion of the aerodynamic heating energy from the inlet and an MHD accelerator to reintroduce this power as kinetic energy in the exhaust stream. In this way, the combustor entrance Mach number can be limited to a specified value even as the flight Mach number increases. Thus, the fuel and air can be efficiently mixed and burned within a practical combustor length, and the flight Mach number operating envelope can be extended. In this paper, we quantitatively assess the performance potential and scientific feasibility of MHD-bypass engines using a simplified thermodynamic analysis. This cycle analysis, based on a thermally and calorically perfect gas, incorporates a coupled MHD generator-accelerator system and accounts for aerodynamic losses and thermodynamic process efficiencies in the various engin components. It is found that the flight Mach number range can be significantly extended; however, overall performance is hampered by non-isentropic losses in the MHD devices.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TP-2000-210387 , M-986 , NAS 1.60:210387
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    Advanced Propulsion System Studies in High Speed Research (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Propulsion for acceptable supersonic passenger transport aircraft is primarily impacted by the very high jet noise characteristics of otherwise attractive engines. The mixed flow turbofan, when equipped with a special ejector nozzle seems to be the best candidate engine for this task of combining low jet noise with acceptable flight performance. Design, performance, and operation aspects of mixed flow turbofans are discussed. If the special silencing nozzle is too large, too heavy, or not as effective as expected, alternative concepts in mixed flow engines should be examined. Presented herein is a brief summary of efforts performed under cooperative agreement NCC3-193. Three alternative engine concepts, conceived during this study effort, are herein presented and their limitations and potentials are described. These three concepts intentionally avoid the use of special silencing nozzles and achieve low jet noise by airflow augmentation of the engine cycle.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2000-210035 , E-12233 , NAS 1.26:210035
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    The Archaeology of Geological Catastrophes (2000)
    London : The Geological Society
    Details
    Keywords: Geoarchäologie ; Naturkatastrophe ; Archaeological geology ; Archaeology ; Archaeology and natural disasters ; Archäologie ; Archéologie et catastrophes naturelles ; Catastrophes (Geology) ; Catastrophes naturelles ; Earthquakes ; Effect of environment on ; Geschichte ; History ; Human beings ; Methodology ; Tremblements de terre ; Volcanoes ; Volcans
    Description / Table of Contents: Preface / Iain Stewart / Geological Society, London, Special Publications, 171, vii-ix, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.01 --- Creation and destruction of travertine monumental stone by earthquake faulting at Hierapolis, Turkey / P. L. Hancock, R. M. L. Chalmers, E. Altunel, Z. Çakir and A. Becher-Hancock / Geological Society, London, Special Publications, 171, 1-14, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.02 --- Uses of volcanic products in antiquity / D. R. Griffiths / Geological Society, London, Special Publications, 171, 15-23, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.03 --- The advent of archaeoseismology in the Mediterranean / R. E. Jones and S. C. Stiros / Geological Society, London, Special Publications, 171, 25-32, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.04 --- A critical reappraisal of the classical texts and archaeological evidence for earthquakes in the Atalanti region, central mainland Greece / Victoria Buck and Iain Stewart / Geological Society, London, Special Publications, 171, 33-44, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.05 --- Aims and methods in territorial archaeology: possible clues to a strong fourth-century AD earthquake in the Straits of Messina (southern Italy) / Emanuela Guidoboni, Anna Muggia and Gianluca Valensise / Geological Society, London, Special Publications, 171, 45-70, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.06 --- Santorini (Greece) before the Minoan eruption: a reconstruction of the ring-island, natural resources and clay deposits from the Akrotiri excavation / Walter L. Friedrich, Marit-Solveig Seidenkrantz and Ole Bjørslev Nielsen / Geological Society, London, Special Publications, 171, 71-80, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.07 --- The eruption of the Santorini volcano and its effects on Minoan Crete / Jan Driessen and Colin F. MacDonald / Geological Society, London, Special Publications, 171, 81-93, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.08 --- Late Minoan IB marine ware, the marine environment of the Aegean, and the Bronze Age eruption of the Thera volcano / Peter Bicknell / Geological Society, London, Special Publications, 171, 95-103, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.09 --- Ground-penetrating radar mapping of Minoan volcanic deposits and the Late Bronze Age palaeotopography, Thera, Greece / James K. Russell and Mark V. Stasiuk / Geological Society, London, Special Publications, 171, 105-121, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.10 --- Precursory phenomena and destructive events related to the Late Bronze Age Minoan (Thera, Greece) and AD 79 (Vesuvius, Italy) Plinian eruptions; inferences from the stratigraphy in the archaeological areas / Raffaello Cioni, Lucia Gurioli, Alessandro Sbrana and Georges Vougioukalakis / Geological Society, London, Special Publications, 171, 123-141, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.11 --- A geographical information system for the archaeological area of Pompeii / M. T. Pareschi, G. Stefani, A. Varone, L. Cavarra, F. Giannini and A. Meriggi / Geological Society, London, Special Publications, 171, 143-158, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.12 --- Apulian Bronze Age pottery as a long-distance indicator of the Avellino Pumice eruption (Vesuvius, Italy) / Raffaello Cioni, Sara Levi and Roberto Sulpizio / Geological Society, London, Special Publications, 171, 159-177, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.13 --- Human response to Etna volcano during the classical period / D. K. Chester, A. M. Duncan, J. E. Guest, P. A. Johnston and J. J. L. Smolenaars / Geological Society, London, Special Publications, 171, 179-188, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.14 --- The Johnston-Lavis collection: a unique record of Italian volcanism / W. L. Kirk, R. Siddall and S. Stead / Geological Society, London, Special Publications, 171, 189-194, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.15 --- The archaeology of a Plinian eruption of the Popocatépetl volcano / Patricia Plunket and Gabriela Uruñuela / Geological Society, London, Special Publications, 171, 195-203, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.16 --- Timing of the prehistoric eruption of Xitle Volcano and the abandonment of Cuicuilco Pyramid, Southern Basin of Mexico / Silvia Gonzalez, Alejandro Pastrana, Claus Siebe and Geoff Duller / Geological Society, London, Special Publications, 171, 205-224, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.17 --- Volcanic disasters and cultural discontinuities in Holocene time, in West New Britain, Papua New Guinea / Robin Torrence, Christina Pavlides, Peter Jackson and John Webb / Geological Society, London, Special Publications, 171, 225-244, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.18 --- Tephrochronology of the Brooks River Archaeological District, Katmai National Park and Preserve, Alaska: what can and cannot be done with tephra deposits / James R. Riehle, Don. E. Dumond, Charles E. Meyer and Jeanne M. Schaaf / Geological Society, London, Special Publications, 171, 245-266, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.19 --- Endemic stress, farming communities and the influence of Icelandic volcanic eruptions in the Scottish Highlands / R. A. Dodgshon, D. D. Gilbertson and J. P. Grattan / Geological Society, London, Special Publications, 171, 267-280, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.20 --- Comparison and cross-checking of historical, archaeological and geological evidence for the location and type of historical and sub-historical eruptions of multiple-vent oceanic island volcanoes / S. J. Day, J. C. Carracedo, H. Guillou, F. J. Pais Pais, E. Rodriguez Badiola, J. F. B. D. Fonseca and S. I. N. Heleno / Geological Society, London, Special Publications, 171, 281-306, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.21 --- ‘A fire spitting volcano in our dear Germany’: documentary evidence for a low-intensity volcanic eruption of the Gleichberg in 1783? / J. P. Grattan, D. D. Gilbertson and A. Dill / Geological Society, London, Special Publications, 171, 307-315, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.22 --- Volcanic soils: their nature and significance for archaeology / Peter James, David Chester and Angus Duncan / Geological Society, London, Special Publications, 171, 317-338, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.23 --- The use of volcaniclastic material in Roman hydraulic concretes: a brief review / Ruth Siddall / Geological Society, London, Special Publications, 171, 339-344, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.24 --- Olmec stone sculpture: selection criteria for basalt / Patrick Hunt / Geological Society, London, Special Publications, 171, 345-353, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.25 --- Seismic and volcanic hazards affecting the vulnerability of the Sana’a area of Yemen / Richard Hughes and Adrian Collings / Geological Society, London, Special Publications, 171, 355-372, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.26 --- Archaeological, geomorphological and geological evidence for a major earthquake at Sagalassos (SW Turkey) around the middle of the seventh century AD / Marc Waelkens, Manuel Sintubin, Philippe Muchez and Etienne Paulissen / Geological Society, London, Special Publications, 171, 373-383, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.27 --- Fault pattern of Nisyros Island volcano (Aegean Sea, Greece): structural, coastal and archaeological evidence / Stathis C. Stiros / Geological Society, London, Special Publications, 171, 385-397, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.28 --- The geological origins of the oracle at Delphi, Greece / J. Z. De Boer and J. R. Hale / Geological Society, London, Special Publications, 171, 399-412, 1 January 2000, https://doi.org/10.1144/GSL.SP.2000.171.01.29
    Pages: Online-Ressource (IX, 412 Seiten) , Illustrationen, Diagramme, Karten
    ISBN: 1862390622
    URL: http://sp.lyellcollection.org/content/171/1
    Language: English
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    Gezielte Synthese von Sulfinato-O- und -S-Komplexen einiger Übergangsmetalle, VII. Sulfinato-Komplexe von Chrom (II), Mangan(II), Eisen(II), Kobalt(II) und Nickel(II) mit ein- und zweizähnigen Stickstoffliganden (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 211-219 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Directed Synthesis of Sulfinato-O and -S Complexes of some Transition Metals, VII. Sulfinato Complexes of Chromium(II), Manganese(II), Iron(II), Cobalt(II) and Nickel(II) with Mono- and Bidentate Nitrogen Ligands.The hitherto unknown, pseudooctahedral configurated bis(organosulfinato-O,O')dipyridine compounds of manganese(II), iron(II), cobalt(II) and nickel(II) 5a, b and 6a-8a are obtained by the reaction of the complexes (p-R-C6h4SO2)2M(OH2)2 1a, b and 2a-4a with pyridine according to equation (1). Linkage or stereo isomers cannot be detected.  -  White (p-CH3C6H4SO2)2Cr(OH2)2 (9) reacts with 2 moles of 2,2′-bipyridyl in water according to equation (2) to form the sulfinato-O complex 10, the corresponding manganese compound 1a adds only 1 mole of 2,2′-bipyridyl according to equation (3), yielding the sulfinato complex 11O,O'. In the case of 9 other solvents are not leading to linkage isomers. In contrast to this the sulfinato complex 11S, being linkage and structural isomeric to 11O,O' is obtained from 1a and 2,2′-bipyridyl in pyridine according to equation (4). The iron compound 2c reacts only in THF with 2 moles of 2,2-bipyridyl according to equation (5) to give the sulfinato complex 12O, which is in pyridine irreversibly converted into the S-isomer 12S according to equation (6). 12S can also be isolated from 2c and 2 moles of 2,2′-bipyridyl in pyridine according to equation (7). The newly prepared compounds are characterized on the basis of their i.r. and their electronic spectra as well as by magnetochemical investigations.
    Notes: Bei der Umsetzung der Komplexe (p-R C6H4SO2)2M(OH2)2 1a,b und 2a-4a mit Pyridin erhält man gemäß Gl. (1) die bisher unbekannten, pseudooktaedrisch konfigurierten Bis(organosulfinato-O,O')-dipyridin-Verbindungen von Mangan(II), Eisen(II), Kobalt(II) und Nickel(II) 5a, b und 6a-8a. Bindungs- oder Stereoisomere lassen sich nicht nachweisen.  -  Während (p-CH3C6H4SO2)2Cr(OH2)2 (9) in Wasser gemäß Gl. (2) 2 mol 2,2′-Bipyridyl unter Bildung des Sulfinato-O-Komplexes 10 aufnimmt, addiert die entsprechende Mangen-Verbindung 1a gemäß Gl. (3) nur 1 mol 2,2′-Bipyridyl, wobei der Sulfinato-Komplex 11O,O' entsteht. Andere Lösungsmittel führen bei 9 zu keinen Bindungsisomeren. Dagegen erhält man aus 1a und 2,2′-Bipyridyl in Pyridin entsprechend Gl. (4) den zu 11O,O' bindungs- und strukturisomeren Sulfinato-Komplex 11S. Die Eisen-Verbindung 2c setzt sich nur in THF mit 2 mol 2,2′-Bipyridyl gemäß Gl. (5) zum Sulfinato-O-Komplex 12O um, welcher in Pyridin irreversibel entsprechend Gl. (6) in das S-Isomere 12S übergeht 12S läßt sich gemäß Gl. (7) auch aus 2c und 2 mol 2,2′-Bipyridyl in Pyridin isolieren., Die neu dargestellten Verbindungen werden anhand ihrer IR- und Elektronenspektren, sowie durch magnetochemische Untersuchungen charakterisiert.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060126
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    Die Röntgenstrukturanalyse des 2 : 1-Cycloadditionsproduktes von Diazomethan und 4-Methyl-1,1-bis(trifluormethyl)-2-aza-1,3t-butadien (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 288-311 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: X-Ray Structure Analysis of the 2 : 1-Cycloaddition Product of Diazomethane and 4-Methyl-1,1-bis(trifluormethyl)-2-aza-1,3t-butadieneThe structure of 1-(4-methyl-1-pyrazolin-3-yl)-5,5-bis(trifluormethyl)-Δ2-1,2,3-triazoline (C8H9F6N5) (4a), which is the 2 : 1-cycloaddition product of diazomethane and 4-methyl-1,1-bis(trifluormethyl)-2-aza-1,3t-butadiene, was solved by direct methods. Space group: Pbca; a = 19.839 Å, b = 12.985 Å, c = 8.826 Å 8 molecules per unit cell. The refinement by least squares methods yielded a final R index of 5.5% (for 1900 observed reflexions). The hydrogen atoms have been included into the refinement.The constitution of the molecule, which on chemical and physical ways could not unambigously be determined, has been evaluated. The binding situation is discussed and including hydrogen atoms a detailed conformational analysis is carried out. The crystal structure is discussed, too. It contains an interesting type of a hydrogen-bridge system.
    Notes: Die Lösung der Struktur des 1-(4-Methyl-1-pyrazolin-3-yl)-5,5-bis(trifluormethyl)-Δ2-1,2,3-triazolins (C8H9F6N5) (4a), dem 2 : 1-Cycloadditionsprodukt von Diazomethan und 4-Methyl-1,1-bis(trifluormethyl)-2-aza-1,3t-butadien erfolgte mit direkten Methoden. Raumgruppe: Pbca; a = 19.839 Å, b = 12.985 Å, c = 8.826 Å, mit 8 Molekülen pro Elementarzelle. Die Verfeinerung nach der Methode der kleinsten Quadrate konvergierte unter Einschluß der H-Atome bei einem R-Wert von 5.5% (für 1900 beobachtete Reflexe).DIE KONSTITUTION der Molekel, die auf chemisch-physikalischem Wege nicht eindeutig bestimmt werden konnte, wurde festgelegt. Es werden die Bindungsverhältnisse diskutiert und unter Einbeziehung der Wasserstoffatome eine detaillierte Konformationsanalyse durchgeführt. Gleichfalls wird auf die Kristallstruktur, die einen interessanten Typ eines Wasserstoffbrückensystems enthält, eingegangen.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060133
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  • 65
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    Zur Hydrierung von Δ2-5-Isoxazolonen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 332-338 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Hydrogenation of Δ2-5-IsoxazolonesThe Δ2-5-isoxazolones 1, 5, 8a-c, and 11a, b are opened under conditions of the catalytic reduction to yield β-enamino-β'-ketocarboxylic acids 6a, b. In a second step, the derivatives 8a-c, 11a, b form diazepines 10a-c and pyrazoles 12, 13 by intramolecular cyclization. The structures are elucidated on the basis of the n.m.r. and i.r. spectra.
    Notes: Die Δ2-5-Isoxazolone 1, 5, 8a-c und 11a, b werden bei der katalytischen Hydrierung unter reduktiver Ringöffnung zu β-Enamino-β'-ketocarbonsäuren 6a, b gespalten Dabei cyclisieren die Derivate 8a-c, 11a, b intramolekular zu den Diazepinen 10a-c und Pyrazolen 12, 13. Die Strukturen werden durch NMR- und IR-Spektren bewiesen.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19731060136
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    Masthead (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060201
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    Abfangreaktionen kurzlebiger Radikale, IX1) Zum radikalisch induzierten Zerfall von Peroxycarbonsäureestern: SH2-Reaktion und radikalisch katalysierte Fragmentierung als konkurrierende Mechanismen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 411-420 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Short-Life Radicals, IX1) Radical-Induced Decomposition of Esters of Peroxycarboxylic Acids: SH2 Reaction and Radical-Catalysed Fragmentation as Competing MechanismsThe radical decomposition of peresters RC(O)—O—OC(CH3,)3 R = C6H5, CH3, C(CH3)3 (1a-c) is induced very strongly by triethyltin hydride. A SH2 reaction and a radicalcatalysed fragmentation (a new type of reaction) are found to be competing mechanisms here. In both cases the stannyl radical is the attacking species. In the former reaction, splitting of the O—O bridge occurs with formation of the stannyl esters 3a-c. In the latter R· +CO2 ·OC(CH3) are formed, while the attacking radical is recovered. All products have been identified and quantitatively determined. From hall-life times and rate constants in the range of 21 -3O°, the following values have been calculated for the two competing reactions at 25° in the case of 1c: for the SH2 reaction ΔG+ = 22.7 kcal/mole, ΔS≠ = -19 e. u.; for the fragmentation ΔG≠ = -22.4 kcal/mole, ΔS+ = - 12 e. u. With 1a, the SH2 reaction dominates under all conditions. The importance of the competing catalysed fragmentation, however, increases greatly in the sequence 1a 〈 1b 〈 1c, and can become the main reaction. Dissociation energies and inductive effects of R, stereochemistry of transition states, temperature, and polarity of solvents are found to be of considerable influence.
    Notes: Der radikalische Zerfall von Perestern RC(O)—O—OC(CH3)3, R = C6H5, CH3, C(CH3)3 (1a-c) wird durch Triäthylzinnhydrid sehr stark induziert. Als konkurrierende Mechanismen werden eine SH2-Reaktion und, als neuartiger Reaktionstyp, eine radikal-katalysierte Fragmentierung beobachtet. In beiden ist das Stannyl-Radikal angreifendes Agens, in einem Fall unter Spaltung der O—O-Brücke und Bildung der Stannylester 3a-c, im anderen unter Bildung von R· +CO2 + ·OC(CH3)3 und Rückgewinnung des angreifenden Radikals. Entstehende Produkte werden qualitativ und quantitativ bestimmt. Für 1c ergibt sich aus Halbwertszeiten und Geschwindigkeitskonstanten im Bereich 21-30° für SH2-Reaktion bzw. Fragmentierung bei 25°: ΔG≠ = 22.7 kcal/mol, ΔS≠ = -19 e. u. bzw. 22.4 kcal/mol, -12 e. u. - Bei 1a überwiegt stets die SH2-Reaktion. In der Reihe 1a 〈 1b 〈 1c tritt jedoch die konkurrierende katalysierte Fragmentierung immer stärker hervor und kann zur Hauptreaktion werden. Dissoziationsenergien und induktive Effekte von R, die Stereochemie der Übergangszustände, Temperatur und Polarität des Lösungsmittels haben hierauf beträchtlichen Einfluß.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19731060208
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    Tautomerie von Heterocyclen, I. Über die Tautomerie von “4-Chinazolylthioharnstoffen” und verwandter Verbindungen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 471-483 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tautomerism of Heterocyclic Compounds, I. The Prototropic Tautomerism of “4-Quinazolylthioureas” and Related CompoundsThe prototropic tautomerism and hydrogen-bonding interactions of 4-quinazolylthioureas, -thioamides and a thiocarbamic acid ester are studied by spectroscopic methods (i. r. and n. m. r.). In case of thiocarbamic acid ester both tautomeric forms (10 and 11) can be isolated as crystalline solids.
    Notes: Die Tautomerieerscheinungen und Wasserstoffbrückenbeziehungen bei 4-Chinazolylthioharnstoffen, -thioamiden und einem -thiourethan werden IR- und NMR-spektroskopisch untersucht. Im Falle des Thiourethans können beide Tautomeren (10 und 11) in Substanz isoliert werden.
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    URL: http://dx.doi.org/10.1002/cber.19731060213
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    Polyacetylenverbindungen, 2131) Neuartige natürliche Schwefelacetylen-Verbindungen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 497-504 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polyacetylenic Compounds, 2131) Novel Natural Sulphur Acetylenic CompoundsThe structures and configurations of four sulphur compounds isolated from Berkheya barbata (L. f.) Hutch. are established by synthesis of the two possible structure type (1 and 17)
    Notes: Die Konstitutionen und Konfigurationen von vier aus Berkheya barbata (L. f ) Hutch. isolierten Schwefel-Verbindungen werden durch Synthese der beiden möglichen Strukturtypen geklärt (1 und 17).
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    Masthead (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19731060101
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    Über eine [3 + 1]-Cycloaddition, II. Reaktionen von 4,5-Dihydro-1,3,5-oxazaphosph(V)olen, VI (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1-7 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a [3 + 1] Cycloaddition, II. Reactions of 4,5-Dihydro-1,3,5-oxazaphosph(V)olen, VI4,5-Dihydro-1,3,5-oxazaphosph(V)oles 1 react with isonitriles to yield disubstituted 3-imino-4,4-bis(trifluoromethyl)-1-azetines 2 with elimination of phosphoric acid esters. The reaction should proceed via nitrile ylides.
    Notes: 4,5-Dihydro-1,3,5-oxazaphosph(V)ole 1 reagieren mit Isonitrilen zu disubstituierten 3-Imino-4,4-bis(trifluormethyl)-1-azetinen 2 unter Ehmmierung von Phosphorsäureester Eine Nitrilylid-Zwischenstufe wird angenommen.
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    17β-Cyclobutenylsteroide (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 882-887 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 17β-CyclobutenylsteroidsThe 21-mesylate derivative 1c of 3β,21-diacetoxy-5α-pregnan-20-one (1a) reacts with dimethyl(methylene)sulfonium oxide to give the aldehyde 2. Reduction of the aldehyde leads to the corresponding alcohol 3, which is easily dehydrated with ring expansion to the cyclobutenyl derivative 4a. After saponification and oxidation 17β-(1-cyclobuten-1-yl)-5α-androstan-3-one (5) is obtained.
    Notes: Ausgehend vom 3β,21-Diacetoxy-5α-pregnan-20-on (1a) gelangt man durch Umsetzung des 21-Mesylats 1c mit Dimethyl(methylen)sulfoniumoxid zum Aldehyd 2. Nach Reduktion zum Alkohol 3 erfolgt leicht Dehydratisierung unter Ringerweiterung zum Cyclobutenyl-Derivat 4a. Nach Verseifung und Oxidation erhält man das 17β-(1-Cyclobuten-1-yl)-5α-androstan-3-on (5).
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    URL: http://dx.doi.org/10.1002/cber.19731060319
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    Bildungsmechanismus von 4-Amino-5-aminomethyl-2-methylpyrimidin aus 3-Äthoxy-2-(diäthoxymethyl)propionitril und Acetamidin (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 893-901 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mechanism of the Formation of 4-Amino-5-aminomethyl-2-methylpyrimidine from 2-(Diethoxymethyl)-3-ethoxypropionitrile and AcetamidineThe mechanism of the formation of 4-amino-5-aminomethyl-2-methylpyrimidine (3) from 2-(diethoxymethyl)-3-ethoxypropionitrile (5) and acetamidine has been investigated by means of labelled compounds 5 which contained the C ≡ 15N, 14C ≡ N, and 14CH(OC2H5)2, respectively. The labelled 3 was subjected to a series of degradation reactions. From the distribution of the isotopes it has been proved as follows: The nitrogen of the C ≡ N group is incorporated either into the 3-position or into the amino group at the 4-position of 3 in a ratio of ca. 1 : 1. The carbon atom at 6-position originates from HCO2R. The formation of 3 probably proceeds through the routes c and d.
    Notes: Der Bildungsmechanismus von 4-Amino-5-aminomethyl-2-methylpyrimidin (3) aus 3-Äthoxy-2-(diäthoxymethyl)propionitril (5) und Acetamidin wurde mittels markiertem 5, das die C ≡ 15N-, 14C ≡ N- bzw. die 14CH(OC2H5)2-Gruppe enthielt, untersucht. Das markierte 3 wurde einer Reihe von Abbaureaktionen unterworfen. Aus der Verteilung der Isotope ergibt sich, daß der Stickstoff der C ≡ N-Gruppe in 3-Stellung oder in die 4-Aminogruppe von 3 mit einer Wahrscheinlichkeit von ca. 1 : 1 eingebaut wird. Der Kohlenstoff in 6-Stellung leitet sich aus HCO2R ab. Die Bildung von 3 verläuft wahrscheinlich auf den Wegen c und d.
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    Tris(chlormethyl) amin und Bis(chlormethyl)methylamin. Darstellung und chemische Reaktionen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 69-77 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tris(chloromethyl)amine and Bis(chloromethyl)methylamine. Synthesis and Chemical ReactionsThe title compounds (1, 8) were synthesized by reaction of PCl5 with hexamethylenetetramine or 1,3,5-trimethylhexahydro-s-triazine, respectively. The reactions of 1 and/or 8 with SbCI5, SnCl4, sodium methylate, sodium acetate, phenyllithium, Grignard compounds, sec. amines and ethanethiol are described. The reaction products, tertiary amines, partially unknown as yet, are characterized.
    Notes: Die Titel-Verbindungen (1,8) wurden durch Umsetzung von PCl5 mit Hexamethylentetramin bzw. 1,3,5-Trimethylhexahydro-s-triazin dargestellt. Die Reaktionen von 1 und/oder 8 mit SbCl5. SnCl4, Natriummethylat, Natriumacetat, Phenyllithium, Grignard-Verbindungen, sek. Aminen und Äthanthiol werden beschrieben. Die Reaktionsprodukte, teilweise bislang nicht beschriebene tertiäre Amine, werden charakterisiert.
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    URL: http://dx.doi.org/10.1002/cber.19731060111
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    Fragmentierungsreaktionen an Carbonylverbindungen mit β-ständigen elektronegativen Substituenten, XXIII. cis- und trans-4.4.8.8-Tetraalkyl-2.6-dioxa-bicyclo[3.3.0]octane aus 1.6-Bis-p-toluolsulfonyloxy-2.2.5 5-tetraalkyl-hexandionen-(3.4) (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 91-104 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fragmentation Reactions of Carbonyl Compounds with Electronegative ß-Substituents, XXIII cis- and trans-4.4.8.8-Tetraalkyl-2.6-dioxabicyclo[3.3.0]octanes from 1.6-Bis(tosyloxy)-2.2.5.5-tetraalkyl-3.hexandionesDiketoditosylates 8 and 9a-c are prepared and reduced with NaBH4. 8 yields 16a and a cis-trans mixture of 23; 9a-c afford the tetrahydrofuranols 14a-c and the cis-2.6-dioxabicyclo[3.3.0]octanes 21a-c. 14a-c and 16a react with NaOH in methanol to form the pure trans-compounds 21a-c and 23. Solvolysis of 9a with excess NaOH in methanol leads to the tetrahydrofuranone 13a and to the bicyclo acetal 22a. Solvolysis of 9b with only 2 equivalents of NaOH yields thc intermediate 12, which can be isolated and converted to 13b and 22b.The trispiro compound 27 is isolated as an unexpected side product from the NaBH4-reduction of 9b.
    Notes: Die Diketo-ditosylate 8 und 9a-c werden dargestellt und mit NaBH4 reduziert. 8 liefert 16a und ein cis-trans-23-Gemisch, aus 9a-c werden die Tetrahydrofuranole 14a-c und die cis-2.6-Dioxa-bicyclo[3.3.0]octane 21a-c erhalten. 14a-c und 16a reagieren mit NaOH in Methanol zu den reinen trans-Verbindungen 21a-c und 23. Die Solvolyse von 9a mit überschüssigem NaOH in Methanol führt zu dem Tetrahydrofuranon 13a und dem bicyclischen Acetal 22a. Mit 2 Äquivv. NaOH kann aus 9b die Zwischenstufe 12 isoliert und erneut zu 13b und 22b umgesetzt werden.Als ungewöhnliches Nebenprodukt tritt bei der NaBH4-Reduktion von 9b die Trispiroverbindung 27 auf.
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    URL: http://dx.doi.org/10.1002/cber.19731060113
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    Asterane, IX. Synthese und Struktur von Tetramethyltetraasteranen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 150-156 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asteranes, IX. Synthesis and Structure of Tetramethyltetraasteranes1,2,7,8- and 1,4,5,8-tetramethylpentacyclo[6.4.0.02.7.04.11.05.10.]dodecane (3 and 6) are obtained by Wolff-Kishner reduction of the cage dimers from 2,3- and 2,5-dimethyl-p-benzoquinone via the tetrahydrazones 2 and 5. The structure of 6 is confirmed by X-ray-diffraction analysis.
    Notes: Wolff-Kishner-Reduktion überführt die Käfigdimeren aus 2,3- und 2,5-Dimethyl-p-benzochinon in 1,2,7,8- und 1,4,5,8-Tetramethylpentacyclo[6.4.0.02.7.04.11.05.10]dodecan (3 und 6), wobei es notwendig ist, die Tetrahydrazone 2 und 5 zu isolieren. Die Struktur von 6 wird durch Röntgenanalyse bestätigt.
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    URL: http://dx.doi.org/10.1002/cber.19731060118
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    Natürlich vorkommende Cumarin-Derivate, IX1) Über die Inhaltsstoffe der Gattung Gerbera (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 382-387 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Naturally Occuring Coumarin Derivatives, IX1) On the Constituents of the Genus GerberaThe roots of several Gerbera species contain the known polyynes 1 and 2. In addition from Gerbera crocea the acetophenon derivative 3 and two new coumarins (4 and 7) were isolated, the structures being elucidated by spectroscopic data as well as by synthesis.
    Notes: Die Wurzeln mehrerer Gerbera-Arten enthalten die bekannten Polyine 1 und 2. Aus Gerbera crocea wurden zusätzlich das Acetophenon-Derivat 3 und zwei neue Cumarine (4 und 7) isoliert, deren Strukturen durch spektroskopische Daten sowie durch Synthese geklärt werden.
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    URL: http://dx.doi.org/10.1002/cber.19731060203
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    Über Aminosäuren und Peptide, VII1) Syntheseversuche in der Reihe der 3,6-Epidithio-2,5-dioxopiperazin-Antibiotika Gliotoxin, Sporidesmin, Aranotin, Chaetocin und Verticillin, VII1) Über die Einführung von Sauerstoffunktionen in Prolyl-prolinanhydrid mit Bleitetraacetat: Ein neuer Weg zum Epidisulfid des Prolyl-prolinanhydrids (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 396-398 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Amino Acids and Peptides, VII1) Studies in the Synthesis of the Antibiotics Gliotoxin, Sporidesmin, Aranotin, Chaetocin, and Verticillin, VII1) On the Introduction of Oxygen Functions in Prolyl-proline Anhydride with Lead Tetraacetate: A New Way to Epidithioprolyl-proline AnhydrideOxidation of L-prolyl-L-proline anhydride (1a) with lead tetraacetate affords 3,6-diacetoxy-L-prolyl-D-proline anhydride (2b). Reaction of 2b with ethanethiole yields cis-3,6-bis(ethylthio)prolyl-proline anhydride (3a), with thiolacetic acid :trans-3,6-bis(acetylthio)prolyl-proline anhydride (4b) is formed. Solvolysis with diluted aqueous acid leads to cis-3,6-di-hydroxyprolyl-proline anhydride (5a). By means of the reactions 1a → 2b → 5a a new way to epidithioprolyl-proline anhydride 6 was found.
    Notes: L-Prolyl-L-prolinanhydrid (1a) wird mit Bleitetraacetat zum 3,6-Diacetoxy-L-prolyl-D-prolinanhydrid (2b) oxidiert. 2b bildet mit Äthylmercaptan cis-3, h-Bis(äthylmercapto)prolyl-prolinanhydrid (3a) und mit Thioessigsäure trans-3,6-Bis(acetylmercapto)prolyl-prolin-anhydrid (4b). Durch Solvolyse mit verdünnter wäßriger Säure erhält man cis-3,6-Dihydroxy-prolyl-prolinanhydrid (5a). Durch dic Reaktionsfolge 1a → 2b → 5a ist ein neuer Weg zum Epidithioprolyl-prolinanhydrid 6 gegeben.
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    Nucleoside, VII1) Synthese von 2′-O-, 3′-O- und 5′-O-Benzylcytidin (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 665-673 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, VIII1) Synthesis of 2′-O-, 3′-O- und 5′-O-BenzylcytidineThe synthesis of the three monobenzyl ethers of cytidine 14, 15 und 19 by benzylation of N6-benzoyl-3′,5′- (4), N6-benzoyl-2′,5′-di-O-tritylcytidine (3) and N6-benzoyl-2′,3′-O-isopropylidenecytidine (21) via the NaH-method as well as removal of the various blocking groups is described. The newly synthesized compounds were characterized by variuos spectra.
    Notes: Die Synthese der drei Mono-O-benzyläther des Cytidins 14, 15 und 19 durch Benzylierung des N6-Benzoyl-3′,5′- (4), N6-Benzoyl-2′,5′-di-O-tritylcytidins (3) und N6-Benzoyl-2′,3′-O-isopropylidencytidins (21) mit der NaH-Methode und nachfolgender Schutzgruppenabspaltung wird beschrieben. Die neu synthetisierten Substanzen werden durch Spektren charakterisiert.
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    URL: http://dx.doi.org/10.1002/cber.19731060232
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    Beiträge zur Chemie des Hydrazins und seiner Derivate, XXXIX1). Notiz zur Darstellung von 1,4-Dithia-2,3-diaza-1,1,4,4-cycloheptantetron (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 713-714 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19731060236
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    Über Metalltrifluorphosphin-Komplexe, XXXVIII1) Zur Kenntnis von (π-Dien)tris(trifluorphosphin)eisen(0)- Komplexen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 697-706 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metaltrifluorophosphine Complexes, XXXVIII1) On the Knowledge of (π-Diene)tris(trifluorophosphine)iron(0) ComplexesThe photochemical reaction between conjugated dienes 1′ - 13 and Pentakis(trifluorophosphine)iron(0) in ether solution yields (π-diene)tris(trifluorophosphine)iron(0) complexes. They are airstable and sublimable. Their 1H-n.m.r.-, i r - and mass spectra are discussed.
    Notes: Die photochemische Reaktion konjugierter Diene (1′ - 13′) mit Pentakis(trifluorphosphin)-eisen(0) in Äther führt zu luftstabilen, sublimierbaren Komplexen des Typs (π-Dien)tris(trifluorphosphin)eisen(0) (1-13). Ihre 1H-NMR-, IR- und Massenspektren werden diskutiert.
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    Beiträge zur Chemie des Hydrazins und seiner Derivate, XXXVIII1) Zur Synthese schwefelsubstituierter Hydrazinderivate durch Hydrosulfurierung einer N = N-Doppelbindung (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 707-712 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Hydrazine and its Derivatives, XXXVIII1) On the Synthesis of Sulfur-substituted Derivatives of Hydrazine by Hydrosulfuration of a N=N Double BondAddition of the S — H-functions of thiophenol, p-methylthiophenol, p-chlorothiophenol, p-bromothiophenol, m-benzenedithiol, and 1,2-ethanedithiol to the N = N double bond of diethyl azodicarboxylate afforded the sulfur-substituted derivatives of hydrazine 1-6, which were obtained as colourless crystalline compounds. They were identified by i.r., n.m.r., and mass spectroscopic investigations.
    Notes: Durch Addition der S—H-Funktionen von Thiophenol, p-Methylthiophenol, p-Chlorthiophenol, p-Bromthiophenol, m-Benzoldithiol und Äthan-l,2-dithiol an die N = N-Doppelbindung des Azodicarbonsäure-diäthylesters konnten die schwefelsubstituierten Hydrazin-derivate 1-6 als farblose kristalline Verbindungen dargestellt werden. Sie wurden durch IR-, NMR- und massenspektroskopische Untersuchungen charakterisiert.
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    Notiz zur Darstellung von 1,3-Dimercaptobenzol (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 719-720 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19731060239
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    Masthead (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973) 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060301
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    Reaktionen von Diazoalkanen mit α-Diketonen und Chinonen, XXI. Umsetzungen von Diazoalkanen mit 2,6-Dichlor-p-benzochinon (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 727-733 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Diazoalkanes with 2,6-Dichloro-p-benzoquinone. Reactions of Quinones and α-Dicarbonyl Compounds with Diazoalkanes, XXIIn the reaction of diazomethane and -ethane with 2,6-dichloro-p-benzoquinone (9) two diazoalkane molecules are added to the two C=C groups, one of the CO groups is epoxidized, and both NH groups are alkylated to form 7 (or 11). The intermediate products 5 and 6 (or 10) can be isolated. Diazoacetate reacts with 9 to yield the epoxide 15; 13 and 14 are assumed to be intermediates. Oxidative hydrolysis (with nitric acid) of 15 gives the dicarboxylic acid 12, which can be methylated with diazomethane to form the tetramethyl derivative 8. As expected, the latter is not identical with the isomer 4e, which is obtained from 2,5-dichloro-p-benzoquinone (1) and diazoacetate via the intermediate products 2c → 3d.
    Notes: Bei der Einwirkung von Diazomethan und -äthan auf 2,6-Dichlor-p-benzochinon (9) erfolgt Addition je einer Diazoalkan-Molekel an die beiden C=C-Doppelbindungen, Epoxidierung einer C=O-Gruppe und N-Alkylierung zu 7 bzw. 11, wobei die Chlor enthaltenden Zwischenprodukte 5, 6 bzw. 10 isoliert werden können. Mit Diazoessigester reagiert 9 unter Bildung des Epoxids 15, wobei 13 und 14 als Zwischenprodukte angenommen werden. Oxidierende Hydrolyse (mit Salpetersäure) baut das Epoxid 15 zur Dicarbonsäure 12 ab, die durch Diazomethan zum Diester 8 methyliert wird. Letzterer ist erwartungsgemäß nicht identisch mit dem aus 2,5-Dichlor-p-benzochinon (1) und Diazoessigester über die Zwischenprodukte 2e → 3d erhältlichen Diester 4e.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060302
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    Anlagerungs- und Eliminierungsreaktionen mit Schwefelsauerstoff-Verbindungen, II. Dihydroxyarylsulfone (und chinoide Folgeprodukte) durch Reaktion von Hydroxymethansulfinat (Rongalit C©) mit Chinonen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 798-802 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Addition and Elimination Reactions with Sulfur Oxygen Compounds, II. Dihydroxyarylsulfones (and Quinonoid Secondary Products) by Reaction of Hydroxymethanesulfinate (Rongalit C ©) with QuinonesThe reaction of hydroxymethanesulfinate with 1,4- and 1,2-benzoquinone as well as with 1,4-naphthoquinone. which can be generated in situ from the corresponding dihydroxyaryl compounds by oxidation, yields symmetrical bis(dihydroxyaryl) sulfones (e. g. 2,7). Oxidation of bis(2,5-dihydroxyaryl) sulfones of type 2 does not lead to bis-quinones 3, but to oxathiin S,S-dioxide monoquinones (4, 6) by cyclisation.
    Notes: Die Umsetzung von Hydroxymethansulfinat mit 1,4- und 1,2-Benzochinon sowie 1,4-Naphthochinon, die aus den entsprechenden Dihydroxyarylverbindungen oxidativ in situ erzeugt werden können, führt zu symmetrischen Bis(dihydroxyaryl)sulfonen (z. B. 2,7). Die Oxidation der Bis(2,5-dihydroxyaryl)sulfone vom Typ 2 ergibt keine Bis-chinone 3, sondern unter Ringbildung Oxathiin-S,S-dioxid-monochinone (4, 6).
    Type of Medium: Electronic Resource
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    Die Photoelektronen-Spektren der Benzocycloalkene (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 961-969 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Photoelectron Spectra of BenzocycloalkenesThe PE. spectra of benzocycloalkenes 3 (n) with n = 3 to 8 have been recorded. It is shown that an attempt to interpret the influence of the alkyl moiety  -  [CH2]n-2 on the π-orbital energies ε(b1 (π)) and ε(a2(π)) by the simple inductive/hyperconjugative Hückel molecular orbital model of alkyl groups demands that the methylene group CH2 in 3 (3) and the ethylene group -[CH2]2- in 3 (4) be assigned negative and zero inductive effects, respectively. This in turn leads to the interpretation that the destabilization of the highest occupied π-orbitals b1(π) in 3 (3) and 3 (4) is due to hyperconjugation. The highest occupied σ-orbitals of the hydrocarbons 3 (n) are localized mainly in the CC-bonds of the cycloalkene part if n = 3 or 4 and in the CH-bonds if n ≥ 5.
    Notes: Die PE-Spektren der Benzocycloalkene 3 (n) mit n = 3 -8 wurden aufgenommen. Will man den Einfluß der Alkyleinheit -[CH2]n-2 auf die Orbitalenergien ε(b1 (π)) und ε(a2(π)) mittels eines Orbitalmodells erklären, welches im Rahmen der Hückelschen Näherung nur induktive und hyperkonjugative Parameter zuläßt, so findet man, daß der Methylengruppe CH2 in 3 (3) ein negativer, der Äthylengruppe.- [CH2]2 in 3 (4) ein verschwindender induktiver Effekt zuzuordnen ist. Dieses Ergebnis verlangt, daß die Destabilisierung des obersten besetzten π-Orbitals b1 (π) in 3 (3) und 3 (4) auf hyperkonjugative Wechselwirkungen zurückgeführt wird. Das oberste besetzte σ-Orbital der Kohlenwasserstoffe 3 (n) ist für n = 3 und 4 vor allem in den CC-Bindungen, für n ≥ 5 in den CH-Bindungen der Cycloalken-Einheit lokalisiert.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19731060330
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    Zur Kenntnis des Triselenadiborolan-Systems (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1012-1018 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Triselenadiborolane SystemSeveral methods for the synthesis of triselenadiborolanes (R-B)2Se3 (1-6) are described, and the formation and structure of the five-membered ring are discussed. The reaction of R2B-X (X = J, H) with selenium or dicyclopentadienyltitanium pentaselenide yields the hitherto unknown diboryldiselenanes, which decompose thermally to form the five membered ring, selenium and R3B. Replacement of the Se2 bridge in the ring by N,N'-dimethyl-hydrazine leads to a new boron-nitrogen-selenium heterocycle (9, 10).
    Notes: Es werden mehrere Darstellungsmethoden für Triselenadiborolane (R-B)2Se3 (1-6) be-schrieben sowie die Bildung und Struktur des Fünfringes diskutiert. Bei Umsetzungen von R2B-X (X = J, H) mit Selen bzw. mit Dicyclopentadienyltitanpentaselenid entstehen die bisher unbekannten Diboryldiselenane R2B-Se-Se-BR2, welche thermisch in den Fünf-ring, Selen und R3B zerfallen. Substitution der Se2-Brücke im Ring durch N,N'-Dimethylhydrazin führt zu einem neuartigen Bor-Stickstoff-Selen-Heterocyclus (9, 10).
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19731060335
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    Die Struktur von 3-(Diphenylhydroxymethyl)-3H-azepin (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1033-1037 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Structure of 3-(Diphenylhydroxymethyl)-3H-azepineThe structure of a compound C19H17NO formed by reaction of N-alkoxycarbonylazepines with phenyl lithium has been determined by X-ray technique using direct methods. The compound was identified as 3-(diphenylhydroxymethyl)-3H-azepine. The boat-shaped sevenmembered ring with structural angles α = 31° and β = 55° has the substituent in equatorial position.
    Notes: Die Struktur des Reaktionsproduktes C19H17NO aus N-Alkoxycarbonylazepinen und Phenyllithium wurde röntgenographisch durch Anwendung direkter Methoden bestimmt. Die Verbindung wurde als 3-(Diphenylhydroxymethyl)-3H-azepin identifiziert. Der bootförmige Siebenring mit Strukturwinkel von α = 31° und β = 55° trägt den Substituenten in äquatorialer Position.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19731060338
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  • 90
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    Autoxidation und Wasserstoffperoxid-Oxidation von 2,4,6-Triphenyl-λ3-phosphorin (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1001-1011 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Autoxidation and Hydrogen Peroxide Oxidation of 2,4,6-Triphenyl-λ3-phosphorin2,4,6-Triphenyl-λ3-phosphorin (1) is slowly oxidized in benzene solution by dissolved oxygen. Two crystalline oxidation products were isolated. The structure of the lower melting substance is 4,4′0-dioxybis(1-hydroxy-1-oxo-2,4,6-triphenyl-λ5-1-phospha-2,5-cyclohexadiene) (2). Alkylation with triethyloxonium tetrafluoroborate leads to three stereoisomeric phosphinates 4E,E, 4E,Z, 4Z,Z, which by reduction with zinc in acetic acid yield two stereoisomeric ethyl hydroxyphosphinates 5E and Z. Steric assignment was made on the basis of the 1H n. m. r. data.Hydrogen peroxide oxidation of 1 yields 1-hydroxy-1-oxo-2,4,6-triphenyl-λ5-1-phospha-2,4- cyclohexadiene (3). Treatment with triethyloxonium tetrafluoroborate yields 1, 1-diethoxy-2,4,6-triphenyl-λ5-phosphorin (6) which was also prepared by another synthetic route and 1-ethoxy-6-ethyl-1-oxo-2,4,6-triphenyl-λ5-1-phospha-2,4-cyclohexadiene (13).
    Notes: 2,4,6-Triphenyl-λ3-phosphorin (1) wird in Benzol langsam durch den darin gelösten Luft-sauerstoff oxidiert. Zwei kristallisierte Oxidationsprodukte wurden isoliert. Die tieferschmelzende Verbindung ist 4,4′-Dioxybis(1-hydroxy-1-oxo-2,4,6-triphenyl-λ5-1-phospha-2,5-cyclohexadien) (2). Alkylierung mit Triathyloxonium-tetrafluoroborat liefert die drei stereoisomeren Phosphinsäureester 4E,E, 4E,Z, und 4Z,Z, deren Spaltung mit Zink und Eisessig zwei stereoisomere Hydroxyphosphinsäure-äthylester 5 E und Z ergibt. Die sterische Zu-ordnung gelang mit Hilfe der 1H-NMR-Spektren.Wasserstoffperoxid-Oxidation von 1 liefert 1-Hydroxy-1-oxo-2,4,6-triphenyl-λ5-1-phospha-2,4-cyclohexadiene (3). Mit Triäthyloxonium-tetrafluoroborat entsteht das auch auf anderem Wege aus 1 zugängliche 1,1 -Diäthoxy-2,4,6-triphenyl-λ5-phosphorin (6) neben 1-Äthoxy-6-äthyl-1-oxo-2,4,6-triphenyl-λ5-1-phospha-2,4-cyclohexadien (13).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19731060334
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    Berichtigung (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1054-1054 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060344
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    Masthead (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060401
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    Eine neue Synthese von Spirohex-4-en (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1076-1082 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Synthesis of Spirohex-4-eneSpirohex-4-ene (3) is obtained on a preparative scale by Corey-Winter elimination of 2. The n.m.r. data of 3 are compared with those of 3,3-dimethylcyclobutene (13) and cyclobutene.
    Notes: Spirohex-4-en (3) läßt sich in präparativem Maßstab durch Corey-Winter-Eliminierung aus 2 darstellen. Die NMR-Daten von 3, 3,3-Dimethylcyclobuten (13) und Cyclobuten werden vergleichend diskutiert.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19731060405
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    Heterocyclische Dicarbonsäureester, II. Zur Reaktion von 2,3-Bis(methoxycarbonyl)-4,5-dihydrofuranen mit Hydrazin und 1,2,3,6-Tetrahydropyridazin.  -  Synthese von 3-Hydroxy-4-(2-hydroxyalkyl)-5-pyrazolcarbonsäure-Derivaten (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1099-1106 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclic Dicarboxylic Acid Esters, II. Reaction of 2,3-Bis(methoxycarbonyl)-4,5-dihydrofurans with Hydrazine and 1,2,3,6-Tetrahydropyridazine.  -  Synthesis of 3-Hydroxy-4-(2-hydroxyalkyl)-5-pyrazolcarboxylic Acid DerivativesIn contrast to the 5,6-dihydro-4H-pyran and furan dicarboxylic acid esters 1 and 4, 2,3-bis-(methoxycarbonyl)-4,5-dihydrofurans 10a-c upon treatment with hydrazine do not yield the dihydrazides but undergo ring cleavage to the 3-hydroxy-4-(2-hydroxyalkyl)-5-pyrazolecarboxylic acid hydrazides 11a-c. Under mild conditions the intermediate ester 12a can be isolated. 12a as well as 11a, c can be hydrolyzed to the carboxylic acids 14a, b. Acyllactone rearrangement of the α-alkoxalyllactones 9a, d with hydrazine also yields the esters 12a, b. I.r. and n.m.r. data are discussed.
    Notes: Bei der Behandlung der 2,3-Bis(methoxycarbonyl)-4,5-dihydrofurane 10a-c mit überschüssigem Hydrazinhydrat entstehen, im Gegensatz zum Verhalten der analogen 5,6-Dihydro-4H-pyran- und Furandicarbonsäureester 1 und 4, nicht die entsprechenden Dihydrazide, sondern es tritt Ringöffnung zu den 3-Hydroxy-4-(2-hydroxyalky)-5-pyrazolcarbonsäure-hydraziden 11a-c ein. Unter schonenden Bedingungen läßt sich der 5-Pyrazolcarbonsäureester 12a isolieren. Sowohl 12a als auch 11a, c lassen sich zu den Carbonsäuren 14a, b verseifen. Die Ester 12a, b entstehen ebenfalls in einer Acyllacton-Umlagerung der α-Alkoxalyl-lactone 9a, d mit Hydrazin. Die IR- und NMR-Daten der dargestellten Verbindungen werden diskutiert.
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    URL: http://dx.doi.org/10.1002/cber.19731060407
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    Das System Azepin-Benzolimin (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 970-983 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The System Azepine-Benzene imineExtended Hückel calculations are utilized in a discussion of: (a) the equilibrium position of the valence isomerization of 1N-azepine-benzene-1,2-imine, (b) the strenght of the benzeneimine σ bond involved in the isomerization, and (c) the influence of electron accepting groups at the nitrogen atom on the equilibrium position and azepine stability.
    Notes: Mit Hilfe der erweiterten Hückel-Methode werden a) die Gleichgewichtslage der Valenz-isomerisierung 1H-Azepin-Benzol-1,2-imin, b) die Stärke der an dieser Isomerisierung beteiligten σ-Bindung im Benzolimin und c) der Einfluß von Akzeptoren am Stickstoff auf das Gleichgewicht und auf die Stabilität des Azepins diskutiert.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19731060331
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    Protonenresonanz-Spektroskopie ungesättigter Ringsysteme, XVIIIXVII. Mitteil.: D. Cremer und H. Günther, Liebigs Ann. Chem. 763, 87 (1972). Ein Benzolimin-1H-Azepin-Gleichgewicht (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 984-995 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Proton Resonance Spectroscopy of Unsaturated Ringsystems, XVIII.XVII. Mitteil.: D. Cremer und H. Günther, Liebigs Ann. Chem. 763, 87 (1972) A Benzeneimine-1 H-Azepine EquilibriumThe temperature dependence of the 1H n.m.r. spectrum of 4,5-bis(methoxycarbonyl)-3,6-diphenyl-1-p-tosyl-1H-azepine (11) is described. The results are interpreted on the basis of a benzeneimine-1H-azepine valence tautomerism (equilibrium distribution at room temperature ca. 3 : 97).
    Notes: Es wird über die Temperaturabhängigkeit des 1H-NMR-Spektrums von 4,5-Bis(methoxycarbonyl)-3,6-diphenyl-1 -p-tosyl-1H-azepin (11) berichtet. Die Befunde werden im Sinne einer Benzolimin-1H-Azepin-Valenztautomerie (Gleichgewichts-Verteilung bei Raumtemperatur ca. 3 : 97) interpretiert.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19731060332
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    Asymmetrische Synthesen mit 2-(Trifluormethyl)-3-oxazolin-5-onen, III. Synthese von N-Pivaloyl-L-tert-leucyl-L-valin, einem Acylpeptid mit hoher Gruppenhäufung (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1019-1022 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Syntheses with 2-(Trifluoromethyl)-3-oxazolin-5-ones, IIIThe reaction of 2-(trifluoromethyl)-3-oxazolin-5-ones with chiral α-aminoacid esters proceeds with high asymmetric induction1,2). It allows the synthesis of sterically hindered L-L (or D-D) dipeptide derivatives starting from the racematc of the N-terminal amino acid. The method is demonstrated with N-pivaloyl-L-tert-leucyl-L-valine (5), which is derived from oxazolinone 1 in 66% overall yield.
    Notes: Die bei der Umsetzung von 2-(Trifluormethyl)-3-oxazolin-5-onen mit chiralen α-Amino-säure-estern auftretende hohe asymmetrische Induktion1,2) erlaubt die Synthese sterisch gehinderter L-L(oder D-D)-Dipeptid-Derivate ausgehend vom Racemat der aminoendständigen Aminosäure. Die Methode wird am Beispiel des N-Pivaloyl-L-tert-leucyl-L-valins (5) demonstriert, das aus Oxazolinon 1 in einer Gesamtausbeute von 66% erhältlich ist.
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    Notiz zur Reaktion von α-Bromketonen mit Pyridinbasen (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1041-1046 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19731060340
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    Beiträge zur Chemie des Hydrazins und seiner Derivate, XL. Notiz über ein neues, einfaches Verfahren zur Darstellung von Tetramethylhydrazin (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1052-1053 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060343
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  • 100
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    (α-Methoxybenzyliden)triphenylphosphoran und (1-Methoxyäthyliden)triphenylphosphoran (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 1062-1068 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (α-Methoxybenzylidene)triphenylphosphorane and (1-Methoxyethylidene)triphenylphosphorane(α-Methoxybenzylidene)triphenylphosphorane (2a) and (l-Methoxyethylidene)triphenylphosphorane (2b) have been prepared from the corresponding phosphonium salts. While 2a reacts with benzaldehyde to form α-methoxystilbene (3, 4) and triphenylphosphine oxide by means of the Wittig-reaction, the expected olefin could not be found in the analogous reaction of 2b. Instead of that, however, α-methoxypropiophenone (10) and triphenylphosphine are formed.  -  α,α′-Dimethoxystilbene (6a, 7a) and triphenylphosphine result from the thermal decomposition of 2a.
    Notes: (α-Methoxybenzyliden)triphenylphosphoran (2a) und (l-Methoxyäthyliden)triphenylphosphoran (2b) wurden aus den entsprechenden Phosphoniumsalzen dargestellt. Während 2a mit Benzaldehyd im Sinne der Wittig-Reaktion zu α-Methoxystilben (3, 4) und Triphenylphosphinoxid reagiert, wurde bei der gleichen Reaktion mit 2b das erwartete Olefin nicht gefunden, statt dessen jedoch α-Methoxypropiophenon (10) und Triphenylphosphin.  -  Die thermische Zersetzung von 2a führt zu α,α′-Dimethoxystilben (6a, 7a) und Triphenylphosphin.
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    URL: http://dx.doi.org/10.1002/cber.19731060403
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