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  • 1
    facet.materialart.
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    In:  CASI
    Publikationsdatum: 2004-12-03
    Beschreibung: This note reports tests in a shock tunnel in which a fully integrated scramjet configuration produced net thrust. The experiments not only showed that impulse facilities can be used for assessing thrust performance, but also were a demonstration of the application of a new technique to the measurement of thrust on scramjet configurations in shock tunnels. These two developments are of significance because scramjets are expected to operate at speeds well in excess of 2 km/sec, and shock tunnels offer a means of generating high Mach number flows at such speeds.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Shock Tunnel Studies of Scramjet Phenomena 1993; p 19-27
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  • 2
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2004-12-03
    Beschreibung: The two-dimensional thrust nozzle presents a challenging problem. The loading is not axisymmetric as in the case of a cone and the internal flow presents some design difficulties. A two-sting system has been chosen to accomodate the internal flow and achieve some symmetry. The situation is complicated by the fact that with the small ramp angle and the internal pressure on the nozzle walls, loading is predominantly transverse. Yet it is the axial thrust which is to be measured (i.e., the tensile waves propagating in the stings). Although bending stress waves travel at most at only 60% of the speed of the axial stress waves, the system needs to be stiffened against bending. The second sting was originally only used to preserve symmetry. However, the pressures on each thrust surface may be quite different at some conditions, so at this stage the signals from both stings are being averaged as a first order approximation of the net thrust. The expected axial thrust from this nozzle is not large so thin stings are required. In addition, the contact area between nozzle and sting needs to be maximized. The result was that it was decided to twist the stings through 90 deg, without distorting their cross-sectional shape, just aft of the nozzle. Finite element analysis showed that this would not significantly alter the propagation of the axial stress wave in the sting, while the rigidity of the system is greatly increased. A Mach 4 contoured nozzle is used in the experiments. The thrust calculated by integrating the static pressure measurements on the thrust surfaces is compared with the deconvolved strain measurement of the net thrust for the cases of air only and hydrogen fuel injected into air at approximately 9 MJ/kg nozzle supply enthalpy. The gain in thrust due to combustion is visible in this result.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Shock Tunnel Studies of Scramjet Phenomena 1993; p 29-36
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  • 3
    Publikationsdatum: 2004-12-03
    Beschreibung: This paper describes tests which were conducted in the hypersonic impulse facility T4 on a fully integrated axisymmetric scramjet configuration. In these tests the net force on the scramjet vehicle was measured using a deconvolution force balance. This measurement technique and its application to a complex model such as the scramjet are discussed. Results are presented for the scramjet's aerodynamic drag and the net force on the scramjet when fuel is injected into the combustion chambers. It is shown that a scramjet using a hydrogen-silane fuel produces greater thrust than its aerodynamic drag at flight speeds equivalent to 260 m/s.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Shock Tunnel Studies of Scramjet Phenomena 1993; p 15-18
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  • 4
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: There have been many cases in which the crew of a multi-engine airplane had to use engine thrust for emergency flight control. Such a procedure is very difficult, because the propulsive control forces are small, the engine response is slow, and airplane dynamics such as the phugoid and dutch roll are difficult to damp with thrust. In general, thrust increases are used to climb, thrust decreases to descend, and differential thrust is used to turn. Average speed is not significantly affected by changes in throttle setting. Pitch control is achieved because of pitching moments due to speed changes, from thrust offset, and from the vertical component of thrust. Roll control is achieved by using differential thrust to develop yaw, which, through the normal dihedral effect, causes a roll. Control power in pitch and roll tends to increase as speed decreases. Although speed is not controlled by the throttles, configuration changes are often available (lowering gear, flaps, moving center-of-gravity) to change the speed. The airplane basic stability is also a significant factor. Fuel slosh and gyroscopic moments are small influences on throttles-only control. The background and principles of throttles-only flight control are described.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 159-169
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  • 5
    Publikationsdatum: 2013-08-31
    Beschreibung: This paper describes the design, development, and ground testing of the propulsion controlled aircraft (PCA) flight control system. A backup flight control system which uses only engine thrust, the PCA system utilizes collective and differential thrust changes to steer an aircraft that experiences partial or complete failure of the hydraulically actuated control surfaces. The objective of the program was to investigate, in flight, the throttles-only control capability of the F-15, using manual control, and also an augmented PCA mode in which computer-controlled thrust was used for flight control. The objective included PCA operation in up-and-away flight and, if performance was adequate, a secondary objective to make actual PCA landings. The PCA design began with a feasibility study which evaluated many control law designs. The study was done using off-line control analysis, simulation, and on-line manned flight simulator tests. Control laws, cockpit displays, and cockpit controls were evaluated by NASA test pilots. A flight test baseline configuration was selected based on projected flight performance, applicability to transport and fighter aircraft, and funding costs. During the PCA software and hardware development, the initial design was updated as data became available from throttle-only flight experiments conducted by NASA on the F-15. This information showed basic airframe characteristics that were not observed in the F-15 flight simulator and resulted in several design changes. After the primary objectives of the PCA flight testing were accomplished, additional PCA modes of operation were developed and implemented. The evolution of the PCA system from the initial feasibility study, control law design, simulation, hardware-in-the-loop tests, pilot-in-the-loop tests, and ground tests is presented.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Dryden Flight Research Center, An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 170-192
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  • 6
    Publikationsdatum: 2013-08-31
    Beschreibung: The performance seeking control algorithm optimizes total propulsion system performance. This adaptive, model-based optimization algorithm has been successfully flight demonstrated on two engines with differing levels of degradation. Models of the engine, nozzle, and inlet produce reliable, accurate estimates of engine performance. But, because of an observability problem, component levels of degradation cannot be accurately determined. Depending on engine-specific operating characteristics PSC achieves various levels performance improvement. For example, engines with more deterioration typically operate at higher turbine temperatures than less deteriorated engines. Thus when the PSC maximum thrust mode is applied, for example, there will be less temperature margin available to be traded for increasing thrust.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 146-156
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  • 7
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    Unbekannt
    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: Flight testing of the performance seeking control (PSC) excitation mode was successfully completed at NASA Dryden on the F-15 highly integrated digital electronic control (HIDEC) aircraft. Although the excitation mode was not one of the original objectives of the PSC program, it was rapidly prototyped and implemented into the architecture of the PSC algorithm, allowing valuable and timely research data to be gathered. The primary flight test objective was to investigate the feasibility of a future measurement-based performance optimization algorithm. This future algorithm, called AdAPT, which stands for adaptive aircraft performance technology, generates and applies excitation inputs to selected control effectors. Fourier transformations are used to convert measured response and control effector data into frequency domain models which are mapped into state space models using multiterm frequency matching. Formal optimization principles are applied to produce an integrated, performance optimal effector suite. The key technical challenge of the measurement-based approach is the identification of the gradient of the performance index to the selected control effector. This concern was addressed by the excitation mode flight test. The AdAPT feasibility study utilized the PSC excitation mode to apply separate sinusoidal excitation trims to the controls - one aircraft, inlet first ramp (cowl), and one engine, throat area. Aircraft control and response data were recorded using on-board instrumentation and analyzed post-flight. Sensor noise characteristics, axial acceleration performance gradients, and repeatability were determined. Results were compared to pilot comments to assess the ride quality. Flight test results indicate that performance gradients were identified at all flight conditions, sensor noise levels were acceptable at the frequencies of interest, and excitations were generally not sensed by the pilot.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 133-142
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  • 8
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: Aircraft with flight capability above 1.4 normally have an RPM lockup or similar feature to prevent inlet buzz that would occur at low engine airflows. This RPM lockup has the effect of holding the engine thrust level at the intermediate power (maximum non-afterburning). For aircraft such as military fighters or supersonic transports, the need exists to be able to rapidly slow from supersonic to subsonic speeds. For example, a supersonic transport that experiences a cabin decompression needs to be able to slow/descend rapidly, and this requirement may size the cabin environmental control system. For a fighter, there may be a desire to slow/descend rapidly, and while doing so to minimize fuel usage and engine exhaust temperature. Both of these needs can be aided by achieving the minimum possible overall net propulsive force. As the intermediate power thrust levels of engines increase, it becomes even more difficult to slow rapidly from supersonic speeds. Therefore, a mode of the performance seeking control (PSC) system to minimize overall propulsion system thrust has been developed and tested. The rapid deceleration mode reduces the engine airflow consistent with avoiding inlet buzz. The engine controls are trimmed to minimize the thrust produced by this reduced airflow, and moves the inlet geometry to degrade the inlet performance. As in the case of the other PSC modes, the best overall performance (in this case the least net propulsive force) requires an integrated optimization of inlet, engine, and nozzle variables. This paper presents the predicted and measured results for the supersonic minimum thrust mode, including the overall effects on aircraft deceleration.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 121-128
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  • 9
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: Measured reductions in turbine temperature which resulted from the application of the F-15 performance seeking control (PSC) minimum fan turbine inlet temperature (FTIT) mode during the dual-engine test phase is presented as a function of net propulsive force and flight condition. Data were collected at altitudes of 30,000 and 45,000 feet at military and partial afterburning power settings. The FTIT reductions for the supersonic tests are less than at subsonic Mach numbers because of the increased modeling and control complexity. In addition, the propulsion system was designed to be optimized at the mid supersonic Mach number range. Subsonically at military power, FTIT reductions were above 70 R for either the left or right engines, and repeatable for the right engine. At partial afterburner and supersonic conditions, the level of FTIT reductions were at least 25 R and as much as 55 R. Considering that the turbine operates at or very near its temperature limit at these high power settings, these seemingly small temperature reductions may significantly lengthen the life of the turbine. In general, the minimum FTIT mode has performed well, demonstrating significant temperature reductions at military and partial afterburner power. Decreases of over 100 R at cruise flight conditions were identified. Temperature reductions of this magnitude could significantly extend turbine life and reduce replacement costs.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 99-110
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  • 10
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: Measured reductions in acceleration times which resulted from the application of the F-15 performance seeking control (PSC) maximum thrust mode during the dual-engine test phase is presented as a function of power setting and flight condition. Data were collected at altitudes of 30,000 and 45,000 feet at military and maximum afterburning power settings. The time savings for the supersonic acceleration is less than at subsonic Mach numbers because of the increased modeling and control complexity. In addition, the propulsion system was designed to be optimized at the mid supersonic Mach number range. Recall that even though the engine is at maximum afterburner, PSC does not trim the afterburner for the maximum thrust mode. Subsonically at military power, time to accelerate from Mach 0.6 to 0.95 was cut by between 6 and 8 percent with a single engine application of PSC, and over 14 percent when both engines were optimized. At maximum afterburner, the level of thrust increases were similar in magnitude to the military power results, but because of higher thrust levels at maximum afterburner and higher aircraft drag at supersonic Mach numbers the percentage thrust increase and time to accelerate was less than for the supersonic accelerations. Savings in time to accelerate supersonically at maximum afterburner ranged from 4 to 7 percent. In general, the maximum thrust mode has performed well, demonstrating significant thrust increases at military and maximum afterburner power. Increases of up to 15 percent at typical combat-type flight conditions were identified. Thrust increases of this magnitude could be useful in a combat situation.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 111-120
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  • 11
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: The minimum fuel mode of the NASA F-15 research aircraft is designed to minimize fuel flow while maintaining constant net propulsive force (FNP), effectively reducing thrust specific fuel consumption (TSFC), during cruise flight conditions. The test maneuvers were at stabilized flight conditions. The aircraft test engine was allowed to stabilize at the cruise conditions before data collection initiated; data were then recorded with performance seeking control (PSC) not-engaged, then data were recorded with the PSC system engaged. The maneuvers were flown back-to-back to allow for direct comparisons by minimizing the effects of variations in the test day conditions. The minimum fuel mode was evaluated at subsonic and supersonic Mach numbers and focused on three altitudes: 15,000; 30,000; and 45,000 feet. Flight data were collected for part, military, partial, and maximum afterburning power conditions. The TSFC savings at supersonic Mach numbers, ranging from approximately 4% to nearly 10%, are in general much larger than at subsonic Mach numbers because of PSC trims to the afterburner.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 91-98
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  • 12
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    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: Hardware and software design of the performance seeking control (PSC) for the NASA F-15 research aircraft are described. The hardware architecture, vehicle management system computer (VMSC), pilot interface, and PSC mode selection are discussed. The PSC software is distributed among the VMSC, central computer, digital electronic engine controls (DEEC's), and electronic air inlet controllers (EAIC's). The major PSC modules, VMSC logic, VMSC channel C memory requirements, VMSC channel C timing, and navigation control indicator (NCI) variables and where they are located are presented.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Dryden Flight Research Center, An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 61-89
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  • 13
    facet.materialart.
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    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: A brief description of the NASA F-15 research aircraft propulsion system is given. The F-15 is powered by two PW1128 afterburning turbofan engines which are growth versions of the F100-PW-100 engine. The PW1128 is controlled by a full-authority digital electronic engine control (DEEC). The F-15 inlet is a two-dimensional, three-ramp, external compression design with partially cut back side plates. Each inlet is independently controlled by an electronic air inlet controller (EAIC).
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Dryden Flight Research Center, An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 37-40
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  • 14
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    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: An overview of the performance seeking control (PSC) algorithm and details of the important components of the algorithm are given. The onboard propulsion system models, the linear programming optimization, and engine control interface are described. The PSC algorithm receives input from various computers on the aircraft including the digital flight computer, digital engine control, and electronic inlet control. The PSC algorithm contains compact models of the propulsion system including the inlet, engine, and nozzle. The models compute propulsion system parameters, such as inlet drag and fan stall margin, which are not directly measurable in flight. The compact models also compute sensitivities of the propulsion system parameters to change in control variables. The engine model consists of a linear steady state variable model (SSVM) and a nonlinear model. The SSVM is updated with efficiency factors calculated in the engine model update logic, or Kalman filter. The efficiency factors are used to adjust the SSVM to match the actual engine. The propulsion system models are mathematically integrated to form an overall propulsion system model. The propulsion system model is then optimized using a linear programming optimization scheme. The goal of the optimization is determined from the selected PSC mode of operation. The resulting trims are used to compute a new operating point about which the optimization process is repeated. This process is continued until an overall (global) optimum is reached before applying the trims to the controllers.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Dryden Flight Research Center, An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 41-60
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  • 15
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    In:  CASI
    Publikationsdatum: 2013-08-31
    Beschreibung: The Performance Seeking Control (PSC) program evolved from a series of integrated propulsion-flight control research programs flown at NASA Dryden Flight Research Center (DFRC) on an F-15. The first of these was the Digital Electronic Engine Control (DEEC) program and provided digital engine controls suitable for integration. The DEEC and digital electronic flight control system of the NASA F-15 were ideally suited for integrated controls research. The Advanced Engine Control System (ADECS) program proved that integrated engine and aircraft control could improve overall system performance. The objective of the PSC program was to advance the technology for a fully integrated propulsion flight control system. Whereas ADECS provided single variable control for an average engine, PSC controlled multiple propulsion system variables while adapting to the measured engine performance. PSC was developed as a model-based, adaptive control algorithm and included four optimization modes: minimum fuel flow at constant thrust, minimum turbine temperature at constant thrust, maximum thrust, and minimum thrust. Subsonic and supersonic flight testing were conducted at NASA Dryden covering the four PSC optimization modes and over the full throttle range. Flight testing of the PSC algorithm, conducted in a series of five flight test phases, has been concluded at NASA Dryden covering all four of the PSC optimization modes. Over a three year period and five flight test phases 72 research flights were conducted. The primary objective of flight testing was to exercise each PSC optimization mode and quantify the resulting performance improvements.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 31-36
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  • 16
    Publikationsdatum: 2013-08-31
    Beschreibung: The NASA Dryden Flight Research Center has been conducting integrated flight-propulsion control flight research using the NASA F-15 airplane for the past 12 years. The research began with the digital electronic engine control (DEEC) project, followed by the F100 Engine Model Derivative (EMD). HIDEC (Highly Integrated Digital Electronic Control) became the umbrella name for a series of experiments including: the Advanced Digital Engine Controls System (ADECS), a twin jet acoustics flight experiment, self-repairing flight control system (SRFCS), performance-seeking control (PSC), and propulsion controlled aircraft (PCA). The upcoming F-15 project is ACTIVE (Advanced Control Technology for Integrated Vehicles). This paper provides a brief summary of these activities and provides background for the PCA and PSC papers, and includes a bibliography of all papers and reports from the NASA F-15 project.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program; p 1-28
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  • 17
    Publikationsdatum: 2013-08-31
    Beschreibung: Measurements have been made of the propulsive effect of supersonic combustion ramjets incorporated into a simple axisymmetric model in a free piston shock tunnel. The nominal Mach number was 6, and the stagnation enthalpy varied from 2.8 MJ kg(exp -1) to 8.5 MJ kg(exp -1). A mixture of 13 percent silane and 87 percent hydrogen was used as fuel, and experiments were conducted at equivalence ratios up to approximately 0.8. The measurements involved the axial force on the model, and were made using a stress wave force balance, which is a recently developed technique for measuring forces in shock tunnels. A net thrust was experienced up to a stagnation enthalpy of 3.7 MJ kg(exp -1), but as the stagnation enthalpy increased, an increasing net drag was recorded. pitot and static pressure measurements showed that the combustion was supersonic. The results were found to compare satisfactorily with predictions based on established theoretical models, used with some simplifying approximations. The rapid reduction of net thrust with increasing stagnation enthalpy was seen to arise from increasing precombustion temperature, showing the need to control this variable if thrust performance was to be maintained over a range of stagnation enthalpies. Both the inviscid and viscous drag were seen to be relatively insensitive to stagnation enthalpy, with the combustion chambers making a particularly significant contribution to drag. The maximum fuel specific impulse achieved in the experiments was only 175 sec., but the theory indicates that there is considerable scope for improvement on this through aerodynamic design.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Shock Tunnel Studies of Scramjet Phenomena 1994; 54 p
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  • 18
    Publikationsdatum: 2019-06-28
    Beschreibung: An experimental study was conducted in annular combustor model to provide a better understanding of the flowfield. Combustor model configurations consisting of primary jets only, annular jets only, and a combination of annular and primary jets were investigated. The purpose of this research was to provide a better understanding of combustor flows and to provide a data base for comparison with computational models. The first part of this research used a laser Doppler velocimeter to measure mean velocity and statistically calculate root-mean-square velocity in two coordinate directions. From this data, one Reynolds shear stress component and a two-dimensional turbulent kinetic energy term was determined. Major features of the flowfield included recirculating flow, primary and annular jet interaction, and high turbulence. The most pronounced result from this data was the effect the primary jets had on the flowfield. The primary jets were seen to reduce flow asymmetries, create larger recirculation zones, and higher turbulence levels. The second part of this research used a technique called marker nephelometry to provide mean concentration values in the combustor. Results showed the flow to be very turbulent and unsteady. All configurations investigated were highly sensitive to alignment of the primary and annular jets in the model and inlet conditions. Any imbalance between primary jets or misalignment of the annular jets caused severe flow asymmetries.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-191060 , NAS 1.26:191060 , E-9866 , NIPS-96-07712
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  • 19
    Publikationsdatum: 2019-06-28
    Beschreibung: The primary objective of this study was the development of a computational fluid dynamics (CFD) based turbomachinery airfoil analysis and design system, controlled by a graphical user interface (GUI). The computer codes resulting from this effort are referred to as the Turbomachinery Analysis and Design System (TADS). This document is intended to serve as a user's manual for the computer programs which comprise the TADS system. TADS couples a throughflow solver (ADPAC) with a quasi-3D blade-to-blade solver (RVCQ3D) in an interactive package. Throughflow analysis capability was developed in ADPAC through the addition of blade force and blockage terms to the governing equations. A GUI was developed to simplify user input and automate the many tasks required to perform turbomachinery analysis and design. The coupling of various programs was done in a way that alternative solvers or grid generators could be easily incorporated into the TADS framework.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-198441 , NAS 1.26:198441 , E-10059 , NIPS-96-06878
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  • 20
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    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: NASA-Lewis and NASA-Ames have sponsored a series of studies over the last few years to identify key high speed rotorcraft propulsion and airframe technologies. NASA concluded from these studies that for near term aircraft with cruise speeds up to 450 kt, tilting rotor rotorcraft concepts are the most economical and technologically viable. The propulsion issues critical to tilting rotor rotorcraft are: (1) high speed cruise propulsion system efficiency and (2) adequate power to hover safely with one engine inoperative. High speed cruise propeller efficiency can be dramatically improved by reducing rotor speed, yet high rotor speed is critical for good hover performance. With a conventional turboshaft, this wide range of power turbine operating speeds would result in poor engine performance at one or more of these critical operating conditions. This study identifies several wide speed range turboshaft concepts, and analyzes their potential to improve performance at the diverse cruise and hover operating conditions. Many unique concepts were examined, and the selected concepts are simple, low cost, relatively low risk, and entirely contained within the power turbine. These power turbine concepts contain unique, incidence tolerant airfoil designs that allow the engine to cruise efficiently at 51 percent of the hover rotor speed. Overall propulsion system efficiency in cruise is improved as much as 14 percent, with similar improvements in engine weight and cost. The study is composed of a propulsion requirement survey, a concept screening study, a preliminary definition and evaluation of selected concepts, and identification of key technologies and development needs. In addition, a civil transport tilting rotor rotorcraft mission analysis was performed to show the benefit of these concepts versus a conventional turboshaft. Other potential applications for this technology are discussed.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-198380 , E-9860 , NAS 1.26:198380
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  • 21
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    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: NASA Lewis Research Center is currently engaged in a research effort as a team member of the High Alpha Technology Program within the NASA agency. This program uses a specially-equipped F/A-18A aircraft called the High Alpha Research Vehicle (HARV), in an effort to improve the maneuverability of high performance military aircraft at low-subsonic-speed, high-angle-of-attack conditions. The overall objective of the NASA Lewis effort is to develop inlet analysis technology towards efficient airflow delivery to the engine during these maneuvers. One portion of this inlet analysis technology uses computational fluid dynamics to predict installed inlet performance. Most of the F/A-18A HARV geometry, which includes the ramp/splitter plate, side diverter and slot, inlet lip and upper diverter, and deflected leading-edge flap has been modeled. The empennage and rear fuselage have not. A pair of vortex generators located on the bottom wall of the inlet were not modeled initially. These vortex generators were installed to alleviate any flow separation that may be induced by the wheel well protrusion into the inlet wall. Calculations completed with the PARC3D code showed that the pressure recovery has been underpredicted and the flow distortion over-predicted. To improve the correlation of PARC3D predictions with flight and wind tunnel tests, the vortex generators were included in the grid geometry and the results are presented in this report. The grid totals 27 blocks or 1.3 million grid points for the half model, which includes the vortex generator grid blocks. Two flight cases were calculated, a high speed case with a Mach number of 0.8 and angle of attack of 3.4; and a low speed case with a Mach number of 0.43 and angle of attack of 32.2. The vortex generators have a significant effect on the inlet boundary layers at high speed, low angle of attack; and have no effect at low speed, high angle of attack.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-195456 , NAS 1.26:195456 , E-9744 , NIPS-95-06844
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  • 22
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: A sleeve valve is under development for ground-based forced response testing of air compression systems. This valve will be used to inject air and to impart momentum to the flow inside the first stage of a multi-stage compressor. The valve was designed to deliver a maximum mass flow of 0.22 lbm/s (0.1 kg/s) with a maximum valve throat area of 0.12 sq. in (80 sq. mm), a 100 psid (689 KPA) pressure difference across the valve and a 68 F, (20 C) air supply. It was assumed that the valve mass flow rate would be proportional to the valve orifice area. A static flow calibration revealed a nonlinear valve orifice area to mass flow relationship which limits the maximum flow rate that the valve can deliver. This nonlinearity was found to be caused by multiple choking points in the flow path. A simple model was used to explain this nonlinearity and the model was compared to the static flow calibration data. Only steady flow data is presented here. In this report, the static flow characteristics of a proportionally controlled sleeve valve are modelled and validated against experimental data.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107072 , NAS 1.15:107072 , E-9936 , NIPS-95-06833
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  • 23
    Publikationsdatum: 2019-06-28
    Beschreibung: This paper introduces a new technique for providing memoryless integrator windup protection which utilizes readily available optimization software tools. This integrator windup protection synthesis provides a concise methodology for creating integrator windup protection for each actuation system loop independently while assuring both controller and closed loop system stability. The individual actuation system loops' integrator windup protection can then be combined to provide integrator windup protection for the entire system. This technique is applied to an H(exp infinity) based multivariable control designed for a linear model of an advanced afterburning turbofan engine. The resulting transient characteristics are examined for the integrated system while encountering single and multiple actuation limits.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107035 , NAS 1.15:107035 , E-9855 , NIPS-95-06274
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  • 24
    Publikationsdatum: 2019-06-28
    Beschreibung: A new method for computing the effect that small changes in the airfoil shape and cascade geometry have on the aeroacoustic and aeroelastic behavior of turbomachinery cascades is presented. The nonlinear unsteady flow is assumed to be composed of a nonlinear steady flow plus a small perturbation unsteady flow that is harmonic in time. First, the full potential equation is used to describe the behavior of the nonlinear mean (steady) flow through a two-dimensional cascade. The small disturbance unsteady flow through the cascade is described by the linearized Euler equations. Using rapid distortion theory, the unsteady velocity is split into a rotational part that contains the vorticity and an irrotational part described by a scalar potential. The unsteady vorticity transport is described analytically in terms of the drift and stream functions computed from the steady flow. Hence, the solution of the linearized Euler equations may be reduced to a single inhomogeneous equation for the unsteady potential. The steady flow and small disturbance unsteady flow equations are discretized using bilinear quadrilateral isoparametric finite elements. The nonlinear mean flow solution and streamline computational grid are computed simultaneously using Newton iteration. At each step of the Newton iteration, LU decomposition is used to solve the resulting set of linear equations. The unsteady flow problem is linear, and is also solved using LU decomposition. Next, a sensitivity analysis is performed to determine the effect small changes in cascade and airfoil geometry have on the mean and unsteady flow fields. The sensitivity analysis makes use of the nominal steady and unsteady flow LU decompositions so that no additional matrices need to be factored. Hence, the present method is computationally very efficient. To demonstrate how the sensitivity analysis may be used to redesign cascades, a compressor is redesigned for improved aeroelastic stability and two different fan exit guide vanes are redesigned for reduced downstream radiated noise. In addition, a framework detailing how the two-dimensional version of the method may be used to redesign three-dimensional geometries is presented.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NIPS-95-05590 , NASA-CR-199569 , NAS 1.26:199569
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  • 25
    Publikationsdatum: 2019-06-28
    Beschreibung: Hypersonic airbreathing propulsion utilizing scramjets can change transatmospheric accelerators for low earth-to-orbit and return transportation. The value and limitation of ground tests, of flight tests, and of computations are presented, and scramjet development requirements are discussed. It is proposed that near full-scale hypersonic propulsion flight tests are essential for developing computational design technology so that it can be used for designing this system. In order to determine how these objectives should be achieved, some lessons learned from past programs are presented. A conceptual two-stage-to-orbit (TSTO) prototype/experimental aerospace plane is recommended as a means of providing access-to-space and for conducting flight tests.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-108857-REV , NAS 1.15:108857-REV , ESA, Proceedings of the 2nd European Symposium on Aerothermodynamics for Space Vehicles; p 469-48
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  • 26
    Publikationsdatum: 2019-06-28
    Beschreibung: The primary objective of this study was the development of a CFD (Computational Fluid Dynamics) based turbomachinery airfoil analysis and design system, controlled by a GUI (Graphical User Interface). The computer codes resulting from this effort are referred to as TADS (Turbomachinery Analysis and Design System). This document is the Final Report describing the theoretical basis and analytical results from the TADS system, developed under Task 18 of NASA Contract NAS3-25950, ADPAC System Coupling to Blade Analysis & Design System GUI. TADS couples a throughflow solver (ADPAC) with a quasi-3D blade-to-blade solver (RVCQ3D) in an interactive package. Throughflow analysis capability was developed in ADPAC through the addition of blade force and blockage terms to the governing equations. A GUI was developed to simplify user input and automate the many tasks required to perform turbomachinery analysis and design. The coupling of the various programs was done in such a way that alternative solvers or grid generators could be easily incorporated into the TADS framework. Results of aerodynamic calculations using the TADS system are presented for a highly loaded fan, a compressor stator, a low speed turbine blade and a transonic turbine vane.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-198440 , NAS 1.26:198440 , E-10058 , NIPS-96-08139
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  • 27
    Publikationsdatum: 2019-06-28
    Beschreibung: This paper summarizes the major conclusions and some of the key supporting analyses resulting from the calibration and application of two small seven hole probes at NASA Lewis Research Center. These probes can produce reasonably accurate and rapid surveys of unknown steady flow fields which may include flow angles up to 70 degrees and Mach numbers up to 0.8. The probes were calibrated with both 'complete' and 'reduced' test matrices. Both types of test matrices produced similar results suggesting the the reduced matrices are adequate for most purposes. The average accuracy fo the calibration was about the same as that achieved in previous seven hole probe calibrations. At the higher Mach numbers, the calibration was sensitive to the diameter of the free jet in the calibration facility. Over a narrow angular range at the higher Mach numbers, the system had serious repeatability problems. This lack or repeatability apparently results from aliasing of high frequency (20 to 40 Hz) noise with the data acquisition system sampling frequency of 10 Hz. Analyses show that these noise frequencies are probably not related to airflow dynamics in the connecting tubing.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NIPS-95-05135 , NASA-TM-107040 , NAS 1.15:107040 , E-9868
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  • 28
    Publikationsdatum: 2019-06-28
    Beschreibung: Boundary layers in supersonic reacting flows are not well understood. Recently a technique has been developed which makes more extensive surface measurements practical, increasing the capability to understand the turbulent boundary layer. A significant advance in this understanding would be the formulation of an analytic relation between the transfer of momentum and the transfer of heat for this flow, similar to the Reynolds Analogy that exists for laminar flow. A gauge has been designed and built which allows a thorough experimental investigation of the relative effects of heat transfer and skin friction in the presence of combustion. Direct concurrent measurements made at the same location, combined with local flow conditions, enable a quantitative analysis to obtain a relation between the surface drag and wall heating, as well as identifying possible ways of reducing both.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-110196 , NAS 1.15:110196
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  • 29
    Publikationsdatum: 2019-06-28
    Beschreibung: A new analytical bleed boundary condition is used to compute flowfields for a strong oblique shock wave/boundary layer interaction with a baseline and three bleed rates at a freestream Mach number of 2.47 with an 8 deg shock generator. The computational results are compared to experimental Pitot pressure profiles and wall static pressures through the interaction region. An algebraic turbulence model is employed for the bleed and baseline cases, and a one equation model is also used for the baseline case where the boundary layer is separated.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-198368 , E-9807 , NAS 1.26:198368
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  • 30
    Publikationsdatum: 2019-06-28
    Beschreibung: This paper presents a dynamic model of an internal combustion engine coupled to a variable pitch propeller. The low-order, nonlinear time-dependent model is useful for simulating the propulsion system of general aviation single-engine light aircraft. This model is suitable for investigating engine diagnostics and monitoring and for control design and development. Furthermore, the model may be extended to provide a tool for the study of engine emissions, fuel economy, component effects, alternative fuels, alternative engine cycles, flight simulators, sensors, and actuators. Results show that the model provides a reasonable representation of the propulsion system dynamics from zero to 10 Hertz.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107006 , E-9789 , NAS 1.15:107006
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  • 31
    Publikationsdatum: 2019-06-28
    Beschreibung: The F/A-18A aircraft has experienced engine stalls at high angles-of-attack and yaw flight conditions which were outside of its flight envelope. Future aircraft may be designed to operate routinely in this flight regime. Therefore, it is essential that an understanding of the inlet flow field at these flight conditions be obtained. Due to the complex interactions of the fuselage and inlet flow fields, a study of the flow within the inlet must also include external effects. Full Navier-Stokes (FNS) calculations on the F/A-18A High Alpha Research Vehicle (HARV) inlet for several angles-of-attack with sideslip and free stream Mach numbers have been obtained. The predicted forebody/fuselage surface static pressures agreed well with flight data. The surface static pressures along the inlet lip are in good agreement with the numerical predictions. The major departure in agreement is along the bottom of the lip at 30 deg and 60 deg angle-of-attack where a possible streamwise flow separation is not being predicted by the code. The circumferential pressure distributions at the engine face are in very good agreement with the numerical results. The variation in surface static pressure in the circumferential direction is very small with the exception of 60 angle-of-attack. Although the simulation does not include the effect of the engine, it appears that this omission has a second order effect on the circumferential pressure distribution. An examination of the unsteady flight test data base has shown that the secondary vortex migrates a significant distance with time. In fact, the extent of this migration increases with angle-of-attack with increasing levels of distortion. The effects of the engine on this vortex movement is unknown. This implies that the level of flow unsteadiness increases with increasing distortion. Since the computational results represent an asymptotic solution driven by steady boundary conditions, these numerical results may represent an arbitrary point in time. A comparison of the predicted total pressure contours with flight data indicates that the numerical results are within the excursion range of the unsteady data which is the best the calculations can attain unless an unsteady simulation is performed.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107130 , NAS 1.15:107130 , E-10056 , NIPS-96-08122
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  • 32
    Publikationsdatum: 2019-06-28
    Beschreibung: The primary objective of this study was the development of a computational fluid dynamics (CFD) based turbomachinery airfoil analysis and design system, controlled by a graphical user interface (GUI). The computer codes resulting from this effort are referred to as the Turbomachinery Analysis and Design System (TADS). This document describes the theoretical basis and analytical results from the TADS system. TADS couples a throughflow solver (ADPAC) with a quasi-3D blade-to-blade solver (RVCQ3D) in an interactive package. Throughflow analysis capability was developed in ADPAC through the addition of blade force and blockage terms to the governing equations. A GUI was developed to simplify user input and automate the many tasks required to perform turbomachinery analysis and design. The coupling of various programs was done in a way that alternative solvers or grid generators could be easily incorporated into the TADS framework. Results of aerodynamic calculations using the TADS system are presented for a highly loaded fan, a compressor stator, a low-speed turbine blade, and a transonic turbine vane.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-198440 , NAS 1.26:198440 , E-10058 , NIPS-96-06885
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  • 33
    Publikationsdatum: 2019-06-28
    Beschreibung: An off-design axial-flow compressor code is presented and is available from COSMIC for predicting the aerodynamic performance maps of fans and compressors. Steady axisymmetric flow is assumed and the aerodynamic solution reduces to solving the two-dimensional flow field in the meridional plane. A streamline curvature method is used for calculating this flow-field outside the blade rows. This code allows for bleed flows and the first five stators can be reset for each rotational speed, capabilities which are necessary for large multistage compressors. The accuracy of the off-design performance predictions depend upon the validity of the flow loss and deviation correlation models. These empirical correlations for the flow loss and deviation are used to model the real flow effects and the off-design code will compute through small reverse flow regions. The input to this off-design code is fully described and a user's example case for a two-stage fan is included with complete input and output data sets. Also, a comparison of the off-design code predictions with experimental data is included which generally shows good agreement.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-198362 , E-9764 , NAS 1.26:198362
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  • 34
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: An analytical method for determining the minimum weight design of an axisymmetric supersonic inlet has been developed. The goal of this method development project was to improve the ability to predict the weight of high-speed inlets in conceptual and preliminary design. The initial model was developed using information that was available from inlet conceptual design tools (e.g., the inlet internal and external geometries and pressure distributions). Stiffened shell construction was assumed. Mass properties were computed by analyzing a parametric cubic curve representation of the inlet geometry. Design loads and stresses were developed at analysis stations along the length of the inlet. The equivalent minimum structural thicknesses for both shell and frame structures required to support the maximum loads produced by various load conditions were then determined. Preliminary results indicated that inlet hammershock pressures produced the critical design load condition for a significant portion of the inlet. By improving the accuracy of inlet weight predictions, the method will improve the fidelity of propulsion and vehicle design studies and increase the accuracy of weight versus cost studies.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106948 , E-9686 , NAS 1.15:106948
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  • 35
    Publikationsdatum: 2019-06-28
    Beschreibung: This report details experimentally derived operational characteristics of numerous two-dimensional planar inlet-combustor isolator configurations at a Mach number of 4. Variations in geometry included (1) inlet cowl length; (2) inlet cowl rotation angle; (3) isolator length; and (4) utilization of a rearward-facing isolator step. To obtain inlet-isolator maximum pressure-rise data relevant to ramjet-engine combustion operation, configurations were mechanically back pressured. Results demonstrated that the combined inlet-isolator maximum back-pressure capability increases as a function of isolator length and contraction ratio, and that the initiation of unstart is nearly independent of inlet cowl length, inlet cowl contraction ratio, and mass capture. Additionally, data are presented quantifying the initiation of inlet unstarts and the corresponding unstart pressure levels.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TP-3502 , L-17422 , NAS 1.60:3502
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  • 36
    Publikationsdatum: 2019-06-28
    Beschreibung: A laser anemometer system was used to provide detailed surveys of the three-dimensional velocity field within the NASA low-speed centrifugal impeller operating with a vaneless diffuser. Both laser anemometer and aerodynamic performance data were acquired at the design flow rate and at a lower flow rate. Floor path coordinates, detailed blade geometry, and pneumatic probe survey results are presented in tabular form. The laser anemometer data are presented in the form of pitchwise distributions of axial, radial, and relative tangential velocity on blade-to-blade stream surfaces at 5-percent-of-span increments, starting at 95-percent-of-span from the hub. The laser anemometer data are also presented as contour and wire-frame plots of throughflow velocity and vector plots of secondary velocities at all measurement stations through the impeller.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TP-3527 , E-9390 , NAS 1.60:3527 , ARL-TR-333
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  • 37
    Publikationsdatum: 2019-06-28
    Beschreibung: Detailed flow field measurements are presented for compressible flow through a diffusing rectangular-to-semiannular transition duct. Comparisons are made with published computational results for flow through the duct. Three-dimensional velocity vectors and total pressures were measured at the exit plane of the diffuser model. The inlet flow was also measured. These measurements are made using calibrated five-hole probes. Surface oil flow visualization and surface static pressure data were also taken. The study was conducted with an inlet Mach number of 0.786. The diffuser Reynolds based on the inlet centerline velocity and the exit diameter of the diffuser was 3,200,000. Comparison of the measured data with previously published computational results are made. Data demonstrating the ability of vortex generators to reduce flow separation and circumferential distortion is also presented.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-4660 , E-9582 , NAS 1.26:4660
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  • 38
    Publikationsdatum: 2019-06-28
    Beschreibung: A study was made to examine the effect of advanced technology engines on the performance of subsonic airplanes and provide a vision of the potential which these advanced engines offered. The year 2005 was selected as the entry-into-service (EIS) date for engine/airframe combination. A set of four airplane classes (passenger and design range combinations) that were envisioned to span the needs for the 2005 EIS period were defined. The airframes for all classes were designed and sized using 2005 EIS advanced technology. Two airplanes were designed and sized for each class: one using current technology (1995) engines to provide a baseline, and one using advanced technology (2005) engines. The resulting engine/airframe combinations were compared and evaluated on the basis on sensitivity to basic engine performance parameters (e.g. SFC and engine weight) as well as DOC+I. The advanced technology engines provided significant reductions in fuel burn, weight, and wing area. Average values were as follows: reduction in fuel burn = 18%, reduction in wing area = 7%, and reduction in TOGW = 9%. Average DOC+I reduction was 3.5% using the pricing model based on payload-range index and 5% using the pricing model based on airframe weight. Noise and emissions were not considered.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: E-9488
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  • 39
    Publikationsdatum: 2019-06-28
    Beschreibung: This report describes a procedure for enhancing the use of the basic rotating microphone system so as to determine the forward propagating mode components of the acoustic field in the inlet duct at the microphone plane in order to predict more accurate far-field radiation patterns. In addition, a modification was developed to obtain, from the same microphone readings, the forward acoustic modes generated at the fan face, which is generally some distance downstream of the microphone plane. Both these procedures employ computer-simulated calibrations of sound propagation in the inlet duct, based upon the current radiation code. These enhancement procedures were applied to previously obtained rotating microphone data for the 17-inch ADP fan. The forward mode components at the microphone plane were obtained and were used to compute corresponding far-field directivities. The second main task of the program involved finding the forward wave modes generated at the fan face in terms of the same total radial mode structure measured at the microphone plane. To obtain satisfactory results with the ADP geometry it was necessary to limit consideration to the propagating modes. Sensitivity studies were also conducted to establish guidelines for use in other fan configurations.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-195457 , E-9577 , NAS 1.26:195457
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  • 40
    Publikationsdatum: 2019-06-28
    Beschreibung: An object-oriented gas turbine engine simulation program was developed. This program is a prototype for a more complete, commercial grade engine performance program now being proposed as part of the Numerical Propulsion System Simulator (NPSS). This report discusses architectural issues of this complex software system and the lessons learned from developing the prototype code. The prototype code is a fully functional, general purpose engine simulation program, however, only the component models necessary to model a transient compressor test rig have been written. The production system will be capable of steady state and transient modeling of almost any turbine engine configuration. Chief among the architectural considerations for this code was the framework in which the various software modules will interact. These modules include the equation solver, simulation code, data model, event handler, and user interface. Also documented in this report is the component based design of the simulation module and the inter-component communication paradigm. Object class hierarchies for some of the code modules are given.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106970 , E-9731 , NAS 1.15:106970
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  • 41
    Publikationsdatum: 2019-06-28
    Beschreibung: This project provides an evaluation of the feasibility and desirability of applying a thermal barrier coating overlaid with a wear coating on the internal surfaces of the combustion area of rotary engines. Many experiments were conducted with different combinations of coatings applied to engine components of aluminum, iron and titanium, and the engines were run on a well-instrumented test stand. Significant improvements in specific fuel consumption were achieved and the wear coating, PS-200, which was invented at NASA's Lewis Research Center, held up well under severe test conditions.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-195445 , E-9493 , NAS 1.26:195445
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  • 42
    Publikationsdatum: 2019-06-28
    Beschreibung: A simulation model has been developed for use in piloted evaluations of takeoff, transition, hover, and landing characteristics of an advanced, short takeoff, vertical landing lift fan fighter aircraft. The flight/propulsion control system includes modes for several response types which are coupled to the aircraft's aerodynamic and propulsion system effectors through a control selector tailored to the lift fan propulsion system. Head-up display modes for approach and hover, tailored to their corresponding control modes are provided in the simulation. Propulsion system components modeled include a remote lift and a lift/cruise engine. Their static performance and dynamic response are represented by the model. A separate report describes the subsonic, power-off aerodynamics and jet induced aerodynamics in hover and forward flight, including ground effects.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-108866 , A-950048 , NAS 1.15:108866
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  • 43
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-28
    Beschreibung: Boundary-layer bleed in supersonic inlets is typically used to avoid separation from adverse shock-wave/boundary-layer interactions and subsequent total pressure losses in the subsonic diffuser and to improve normal shock stability. Methodologies used to determine bleed requirements are reviewed. Empirical sonic flow coefficients are currently used to determine the bleed hole pattern. These coefficients depend on local Mach number, pressure ratio, hole geometry, etc. A new analytical bleed method is presented to compute sonic flow coefficients for holes and narrow slots and predictions are compared with published data to illustrate the accuracy of the model. The model can be used by inlet designers and as a bleed boundary condition for computational fluid dynamic studies.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-195426 , E-9393 , NAS 1.26:195426 , AIAA PAPER 95-0038
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  • 44
    Publikationsdatum: 2019-06-28
    Beschreibung: NASA Lewis is currently engaged in a research effort as a team member of the High Alpha Technology Program (HATP) within NASA. This program utilizes a specially equipped F/A-18A, the High Alpha Research Vehicle (HARV), in an ambitious effort to improve the maneuverability of high performance military aircraft at low subsonic speed, high angle of attack conditions. The overall objective of the Lewis effort is to develop inlet technology that will ensure efficient airflow delivery to the engine during these maneuvers. One part of the Lewis approach utilizes computational fluid dynamics codes to predict the installed performance of inlets for these highly maneuverable aircraft. Wind tunnel tests were a major component of the Lewis program. Since the available wind tunnel was small (9 x 15 ft) as compared to the scale of the model of the F/A-18A (19.78 percent), there were questions about the capability to obtain useful inlet performance data. The blockage effects were expected to be very large. This report represents the results of an analysis to determine how the wind tunnel walls effect inlet performance at several angles of attack. The predictions for the external particle traces along the fuselage indicate the influence of the wind tunnel side wall under the model is greater at 30 deg angle of attack than at 50 deg angle of attack on the under Leading Edge Extension (LEX) vortex trajectory. The side wall above the model appears to have negligible influence on the under LEX vortex. This may be due to the LEX acting as 'shield' to the upper wall effects. As expected, the wind tunnel has a significant influence on the external forces. The lift and drag coefficients increase significantly for the wind tunnel model as compared to free stream conditions. The wind tunnel had a small effect on the inlet recovery and on inlet total pressure distortion patterns. The predicted recoveries for the wind tunnel model are within one percentage point of the model recoveries in free stream conditions.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-195429 , E-9416 , NAS 1.26:195429
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  • 45
    facet.materialart.
    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-07-27
    Beschreibung: Expressions for the thrust losses of a scramjet engine are developed in terms of irreversible entropy increases and the degree of incomplete combustion. A method is developed which allows the calculation of the lost vehicle thrust due to different loss mechanisms within a given flow-field. This analysis demonstrates clearly the trade-off between mixing enhancement and resultant increased flow losses in scramjet combustors. An engine effectiveness parameter is defined in terms of thrust loss. Exergy and the thrust-potential method are related and compared.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 95-6081 , AIAA, International Aerospace Planes and Hypersonics Technologies Conference; April, 3-7, 1995; Chattanooga, TN; United States|; 11 p.
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  • 46
    Publikationsdatum: 2019-07-13
    Beschreibung: Lean, prevaporized, premixed combustors are susceptible to combustion-acoustic instabilities. A model was developed to predict eigenvalues of axial modes for combustion-acoustic interactions in a premixed combustor. This work extends previous work by including variable area and detailed chemical kinetics mechanisms, using the code LSENS. Thus the acoustic equations could be integrated through the flame zone. Linear perturbations were made of the continuity, momentum, energy, chemical species, and state equations. The qualitative accuracy of our approach was checked by examining its predictions for various unsteady heat release rate models. Perturbations in fuel flow rate are currently being added to the model.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107024 , E-9834 , NAS 1.15:107024 , AIAA PAPER 95-2470 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 47
    Publikationsdatum: 2019-07-13
    Beschreibung: Flight research for the F-15 HIDEC (Highly Integrated Digital Electronic Control) program was completed at NASA Dryden Flight Research Center in the fall of 1993. The flight research conducted during the last two years of the HIDEC program included two principal experiments: (1) performance seeking control (PSC), an adaptive, real-time, on-board optimization of engine, inlet, and horizontal tail position on the F-15; and (2) propulsion controlled aircraft (PCA), an augmented flight control system developed for landings as well as up-and-away flight that used only engine thrust (flight controls locked) for flight control. In September 1994, the background details and results of the PSC and PCA experiments were presented in an electronic workshop, accessible through the Dryden World Wide Web (http://www.dfrc.nasa.gov/dryden.html) and as a compact disk.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-104278 , H-2020 , NAS 1.15:104278 , Jan 01, 1993; Edwards, CA; United States
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  • 48
    Publikationsdatum: 2019-07-13
    Beschreibung: Performance Seeking Control (PSC), an onboard, adaptive, real-time optimization algorithm, relies upon an onboard propulsion system model. Flight results illustrated propulsion system performance improvements as calculated by the model. These improvements were subject to uncertainty arising from modeling error. Thus to quantify uncertainty in the PSC performance improvements, modeling accuracy must be assessed. A flight test approach to verify PSC-predicted increases in thrust (FNP) and absolute levels of fan stall margin is developed and applied to flight test data. Application of the excess thrust technique shows that increases of FNP agree to within 3 percent of full-scale measurements for most conditions. Accuracy to these levels is significant because uncertainty bands may now be applied to the performance improvements provided by PSC. Assessment of PSC fan stall margin modeling accuracy was completed with analysis of in-flight stall tests. Results indicate that the model overestimates the stall margin by between 5 to 10 percent. Because PSC achieves performance gains by using available stall margin, this overestimation may represent performance improvements to be recovered with increased modeling accuracy. Assessment of thrust and stall margin modeling accuracy provides a critical piece for a comprehensive understanding of PSC's capabilities and limitations.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-4705 , H-2060 , NAS 1.15:4705 , AIAA PAPER 95-2361 , Jul 10, 1995 - Jul 12, 1995; US
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  • 49
    Publikationsdatum: 2019-07-13
    Beschreibung: The supersonic diffuser of a Mach 2.68 bifurcated, rectangular, mixed-compression inlet was analyzed using a two-dimensional (2D) Navier-Stokes flow solver. Parametric studies were performed on turbulence models, computational grids and bleed models. The computer flowfield was substantially different from the original inviscid design, due to interactions of shocks, boundary layers, and bleed. Good agreement with experimental data was obtained in many aspects. Many of the discrepancies were thought to originate primarily from 3D effects. Therefore, a balance should be struck between expending resources on a high fidelity 2D simulation, and the inherent limitations of 2D analysis. The solutions were fairly insensitive to turbulence models, grids and bleed models. Overall, the k-e turbulence model, and the bleed models based on unchoked bleed hole discharge coefficients or uniform velocity are recommended. The 2D Navier-Stokes methods appear to be a useful tool for the design and analysis of supersonic inlets, by providing a higher fidelity simulation of the inlet flowfield than inviscid methods, in a reasonable turnaround time.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107003 , E-9784 , NAS 1.15:107003 , Jul 10, 1995 - Jul 12, 1995; US
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  • 50
    Publikationsdatum: 2019-07-13
    Beschreibung: An existing three-dimensional Navier-Stokes code, modified to include film cooling considerations, has been used to study the effect of coolant velocity and temperature distribution at the hole exit on the heat transfer coefficient on three-film-cooled turbine blades, namely, the C3X vane, the VKI rotor, and the ACE rotor. Results are also compared with the experimental data for all the blades. Moreover, Mayle's transition criterion, Forest's model for augmentation of leading edge heat transfer due to freestream turbulence, and Crawford's model for augmentation of eddy viscosity due to film cooling are used. Use of Mayle's and Forest's models is relevant only for the ACE rotor due to the absence of showerhead cooling on this rotor. It is found that, in some cases, the effect of distribution of coolant velocity and temperature at the hole exit can be as much as 60% on the heat transfer coefficient at the blade suction surface, and 50% at the pressure surface. Also, different effects are observed on the pressure and suction surface depending upon the blade as well as upon the hole shape, conical or cylindrical.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106954 , E-9704 , NAS 1.15:106954 , ASME; Jun 05, 1995 - Jun 08, 1995; US
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  • 51
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: A numerical model has been developed which can predict the dynamic (and steady state) performance of a wave rotor, given the geometry and time dependent boundary conditions. The one-dimensional, perfect gas, CFD based code tracks the gasdynamics in each of the wave rotor passages as they rotate past the various ducts. The model can operate both on and off-design, allowing dynamic behavior to be studied throughout the operating range of the wave rotor. The model accounts for several major loss mechanisms including finite passage opening time, fluid friction, heat transfer to and from the passage walls, and leakage to and from the passage ends. In addition, it can calculate the amount of work transferred to and from the fluid when the flow in the ducts is not aligned with the passages such as occurs in off-design operation. Since it is one-dimensional, the model runs reasonably fast on a typical workstation. This paper will describe the model and present the results of some transient calculations for a conceptual four port wave rotor designed as a topping cycle for a small gas turbine engine.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106997 , E-9776 , NAS 1.15:106997 , AIAA PAPER 95-2800 , AIAA, ASME, SAE, and ASEE; Jul 10, 1995 - Jul 12, 1995; US
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  • 52
    Publikationsdatum: 2019-07-13
    Beschreibung: Combustion within the channels of a wave rotor is examined as a means of obtaining pressure gain during heat addition in a gas turbine engine. Several modes of combustion are considered and the factors that determine the applicability of three modes are evaluated in detail; premixed autoignition/detonation, premixed deflagration, and non-premixed compression ignition. The last two will require strong turbulence for completion of combustion in a reasonable time in the wave rotor. The compression/autoignition modes will require inlet temperatures in excess of 1500 R for reliable ignition with most hydrocarbon fuels; otherwise, a supplementary ignition method must be provided. Examples of combustion mode selection are presented for two core engine applications that had been previously designed with equivalent 4-port wave rotor topping cycles using external combustion.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107000 , E-9779 , NAS 1.15:107000 , AIAA PAPER 95-2801 , AIAA, ASME, SAE, and ASEE; Jul 10, 1995 - Jul 12, 1995; US
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  • 53
    Publikationsdatum: 2019-07-13
    Beschreibung: The benefits of wave rotor-topping in small (400 to 600 hp-class) and intermediate (3000 to 4000 hp-class) turboshaft engines, and large (80,000 to 100,000 lb(sub f)-class) high bypass ratio turbofan engines are evaluated. Wave rotor performance levels are calculated using a one-dimensional design/analysis code. Baseline and wave rotor-enhanced engine performance levels are obtained from a cycle deck in which the wave rotor is represented as a burner with pressure gain. Wave rotor-toppings is shown to significantly enhance the specific fuel consumption and specific power of small and intermediate size turboshaft engines. The specific fuel consumption of the wave rotor-enhanced large turbofan engine can be reduced while operating at significantly reduced turbine inlet temperature. The wave rotor-enhanced engine is shown to behave off-design like a conventional engine. Discussion concerning the impact of the wave rotor/gas turbine engine integration identifies tenable technical challenges.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106998 , E-9777 , NAS 1.15:106998 , ARL-TR-806 , AIAA PAPER 95-2799 , AIAA, ASME, SAE, and ASEE; Jul 10, 1995 - Jul 12, 1995; US
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  • 54
    Publikationsdatum: 2019-07-13
    Beschreibung: Partnerships between government agencies are an intellectually attractive method of conducting scientific research; the goal is to establish mutually beneficial participant roles for technology exchange that ultimately pays-off in a stronger R&D program for each partner. Anticipated and current aerospace research budgetary pressures through the 90's provide additional impetus for Government research agencies to candidly assess their R&D for those simulation activities no longer unique enough to warrant 'going it alone,' or for those elements where partnerships or teams can offset development costs. This paper describes a specific inter-agency system simulation activity that leverages the development cost of mutually beneficial R&D. While the direct positive influence of partnerships on complex technology developments is our main thesis, we also address on-going teaming issues and hope to impart to the reader the immense indirect (sometimes immeasurable) benefits that meaningful interagency partnerships can produce.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106962 , E-9718 , NAS 1.15:106962 , ARL-TR-793 , SAE; May 23, 1995; US
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  • 55
    Publikationsdatum: 2019-07-13
    Beschreibung: An axial compressor test rig has been designed for the operation of small turbomachines. A flow test was run to calibrate and determine the source and magnitudes of the loss mechanisms in the compressor inlet for a highly loaded two-stage axial compressor test. Several flow conditions and inlet guide vane (IGV) angle settings were established, for which detailed surveys were completed. Boundary layer bleed was also provided along the casing of the inlet behind the support struts and ahead of the IGV. Several computational fluid dynamics (CFD) calculations were made for selected flow conditions established during the test. Good agreement between the CFD and test data were obtained for these test conditions.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106999 , E-9778 , NAS 1.15:106999 , AIAA PAPER 95-3037 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 56
    Publikationsdatum: 2019-07-13
    Beschreibung: An existing three dimensional Navier-Stokes code, modified to include film cooling considerations, has been used to study the effect of spanwise pitch of shower-head holes and coolant to mainstream mass flow ratio on the adiabatic effectiveness and heat transfer coefficient on a film-cooled turbine vane. The mainstream is akin to that under real engine conditions with stagnation temperature = 1900 K and stagnation pressure = 3 MPa. It is found that with the coolant to mainstream mass flow ratio fixed, reducing P, the spanwise pitch for shower-head holes, from 7.5 d to 3.0 d, where d is the hole diameter, increases the average effectiveness considerably over the blade surface. However, when P/d= 7.5, increasing the coolant mass flow increases the effectiveness on the pressure surface but reduces it on the suction surface due to coolant jet lift-off. For P/d = 4.5 or 3.0, such an anomaly does not occur within the range of coolant to mainstream mass flow ratios analyzed. In all cases, adiabatic effectiveness and heat transfer coefficient are highly three-dimensional.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106955 , E-9705 , NAS 1.15:106955 , Gas Turbine and Aeroengine Congress and Exposition; Jun 05, 1995 - Jun 08, 1995; Houston, TX; United States
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  • 57
    Publikationsdatum: 2019-07-13
    Beschreibung: A numerical analysis methodology and solutions of the interaction between the power stream and multiply-connected multi-cavity sealed secondary flow fields are presented. Flow solutions for a multi-cavity experimental rig were computed and compared with experimental data of Daniels and Johnson. The flow solutions illustrate the complex coupling between the main-path and the cavity flows as well as outline the flow thread that exists throughout the subplatform multiple cavities and seals. The analysis also shows that the de-coupled solutions on single cavities is inadequate. The present results show trends similar to the T-700 engine data that suggests the changes in the CDP seal altered the flow fields throughout the engine and affected the engine performance.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106886 , E-9523 , NAS 1.15:106886 , Turbo Expo 1995; Jun 05, 1995 - Jun 08, 1995; Houston, TX; United States
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  • 58
    Publikationsdatum: 2019-07-13
    Beschreibung: Use of a wave rotor as a topping cycle for a gas turbine engine can improve specific power and reduce specific fuel consumption. Maximum improvement requires the wave rotor to be optimized for best performance at the mass flow of the engine. The optimization is a trade-off between losses due to friction and passage opening time, and rotational effects. An experimentally validated, one-dimensional CFD code, which includes these effects, has been used to calculate wave rotor performance, and find the optimum configuration. The technique is described, and results given for wave rotors sized for engines with sea level mass flows of 4, 26, and 400 lb/sec.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106951 , E-9689 , NAS 1.15:106951 , 1995 Aerospace Atlantic Conference and Exposition; May 23, 1995 - May 25, 1995; Dayton, OH; United States
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  • 59
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: The objective of this research was two-fold. The first objective was to complete the three-dimensional unsteady calculations of the flow through a new transonic turbine and study the effects of secondary flows due to the hub and casing, tip clearance vortices, and the inherent three-dimensional mixing of the flow. It should be noted that this turbine was and is still in the design phase and the results of the calculations have formed an integral part of the design process. The second objective of this proposal was to evaluate the capability of rotor-stator interaction codes to calculate tonal acoustics.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-197749 , NAS 1.26:197749 , MCAT-95-17
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  • 60
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: An experimental investigation has been conducted of the isothermal mixing of a turbulent jet injected perpendicular to a uniform crossflow through several different types of sharp-edged orifices. Jet penetration and mixing was studied using planar Mie scattering to measure time-averaged mixture fraction distributions of circular, square, elliptical, and rectangular orifices of equal geometric area injected into a constant velocity crossflow. Hot-wire anemometry was also used to measure streamwise turbulence intensity distributions at several downstream planes. Mixing effectiveness was determined using (1) a spatial unmixedness parameter based on the variance of the mean jet concentration distributions and (2) by direct comparison of the planar distributions of concentration and of turbulence intensity. No significant difference in mixing performance was observed for the six configurations based on comparison of the mean properties.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106865 , E-9477 , NAS 1.15:106865 , AIAA PAPER 95-0732 , Aerospace Sciences Meeting and Exhibit; Jan 09, 1995 - Jan 12, 1995; Reno, NV; United States
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  • 61
    Publikationsdatum: 2019-07-13
    Beschreibung: Premixed combustors, which are being considered for low NOx engines, are susceptible to instabilities due to feedback between pressure perturbations and combustion. This feedback can cause damaging mechanical vibrations of the system as well as degrade the emissions characteristics and combustion efficiency. In a lean combustor instabilities can also lead to blowout. A model was developed to perform linear combustion-acoustic stability analysis using detailed chemical kinetic mechanisms. The Lewis Kinetics and Sensitivity Analysis Code, LSENS, was used to calculate the sensitivities of the heat release rate to perturbations in density and temperature. In the present work, an assumption was made that the mean flow velocity was small relative to the speed of sound. Results of this model showed the regions of growth of perturbations to be most sensitive to the reflectivity of the boundary when reflectivities were close to unity.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106890 , E-9530 , NAS 1.15:106890 , Central/Western States Sections Joint Technical Meeting; Apr 23, 1995 - Apr 26, 1995; San Antonio, TX; United States
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  • 62
    Publikationsdatum: 2019-07-13
    Beschreibung: This research program deals with the application of high-performance computing methods to the numerical simulation of complete jet engines. The program was initiated in 1993 by applying two-dimensional parallel aeroelastic codes to the interior gas flow problem of a by-pass jet engine. The fluid mesh generation, domain decomposition and solution capabilities were successfully tested. Attention was then focused on methodology for the partitioned analysis of the interaction of the gas flow with a flexible structure and with the fluid mesh motion driven by these structural displacements. The latter is treated by an ALE technique that models the fluid mesh motion as that of a fictitious mechanical network laid along the edges of near-field fluid elements. New partitioned analysis procedures to treat this coupled 3-component problem were developed in 1994. These procedures involved delayed corrections and subcycling, and have been successfully tested on several massively parallel computers. For the global steady-state axisymmetric analysis of a complete engine we have decided to use the NASA-sponsored ENG10 program, which uses a regular FV-multiblock-grid discretization in conjunction with circumferential averaging to include effects of blade forces, loss, combustor heat addition, blockage, bleeds and convective mixing. A load-balancing preprocessor for parallel versions of ENG10 has been developed. It is planned to use the steady-state global solution provided by ENG10 as input to a localized three-dimensional FSI analysis for engine regions where aeroelastic effects may be important.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-CR-197440 , CU-CAS-95-03 , NAS 1.26:197440
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  • 63
    Publikationsdatum: 2019-07-13
    Beschreibung: Planar laser-induced fluorescence (PLIF) images of OH have been obtained from an optically accessible, lean burning high pressure combustor burning Jet-A fuel. These images were obtained using various laser excitation lines of the OH A (reverse arrow) X (1,0) band for several fuel injector configurations with pressures ranging from 1013 kPa (10 atm) to 1419 kPa (14 atm). Non-uniformities in the combusting flow, attributed to differences in fuel injector configuration, are revealed by these images. Contributions attributable to fluorescent aromatic hydrocarbons and complex fuel chemistries are also not evident.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106854 , E-9444 , NAS 1.15:106854 , AIAA PAPER 95-0173 , Aerospace Sciences Meeting and Exhibit; Jan 09, 1995 - Jan 12, 1995; Reno, NV; United States
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  • 64
    Publikationsdatum: 2019-07-13
    Beschreibung: A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NO, H2O, and a combination of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamically effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 95-6097 , ; 4 p.|AIAA International Aerospace Planes and Hypersonics Technologies Conference; Apr 03, 1995 - Apr 07, 1995; Chattanooga, TN; United States
    Format: text
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  • 65
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: A new scheme for relating the absolute value for the kinetic rate constant k to the thermodynamic constant Kp is developed for gases. In this report the forward and reverse rate constants are individually related to the thermodynamic data. The kinetic rate constants computed from thermodynamics compare well with the current kinetic rate constants. This method is self consistent and does not have extensive rules. It is first demonstrated and calibrated by computing the HBr reaction from H2 and Br2. This method then is used on other reactions.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107124 , NAS 1.15:107124 , E-10043 , AIAA PAPER 96-0218 , NIPS-96-07540 , Aerospace Sciences Meeting and Exhibit; Jan 15, 1996 - Jan 18, 1996; Reno, NV; United States
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  • 66
    Publikationsdatum: 2019-07-13
    Beschreibung: The supersonic diffuser of a Mach 2.68 bifurcated, rectangular, mixed-compression inlet was analyzed using a three-dimensional (3D) Navier-Stokes flow solver. A two-equation turbulence model, and a porous bleed model based on unchoked bleed hole discharge coefficients were used. Comparisons were made with experimental data, inviscid theory, and two-dimensional Navier-Stokes analyses. The main objective was to gain insight into the inlet fluid dynamics. Examination of the computational results along with the experimental data suggest that the cowl shock-sidewall boundary layer interaction near the leading edge caused a substantial separation in the wind tunnel inlet model. As a result, the inlet performance may have been compromised by increased spillage and higher bleed mass flow requirements. The internal flow contained substantial waves that were not in the original inviscid design. 3D effects were fairly minor for this inlet at on-design conditions. Navier-Stokes analysis appears to be an useful tool for gaining insight into the inlet fluid dynamics. It provides a higher fidelity simulation of the flowfield than the original inviscid design, by taking into account boundary layers, porous bleed, and their interactions with shock waves.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107123 , NAS 1.15:107123 , E-10038 , AIAA PAPER 96-0495 , NIPS-96-07539 , Aerospace Sciences Meeting and Exhibit; Jan 15, 1996 - Jan 18, 1996; Reno, NV; United States
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  • 67
    Publikationsdatum: 2019-07-13
    Beschreibung: The paper describes a proof-of-concept experiment on thin-film thermocouples used for localized heat transfer measurements applicable to experiments on hot parts of turbine engines. The paper has three main parts. The first part describes the thin-film sensors and manufacturing procedures. Attention is paid to connections between thin-film thermocouples and lead wires, which has been a source of problems in the past. The second part addresses the test arrangement and facility used for the heat transfer measurements modeling the conditions for upcoming warm turbine tests at NASA LeRC. The paper stresses the advantages of a modular approach to the test rig design. Finally, we present the results of bulk and local heat flow rate measurements, as well as overall heat transfer coefficients obtained from measurements in a narrow passage with an aspect ratio of 11.8. The comparison of bulk and local heat flow rates confirms applicability of thin-film thermocouples to upcoming warm turbine tests.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107045 , NAS 1.15:107045 , E-9890 , AIAA PAPER 95-2834 , NIPS-95-05322 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 68
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-07-13
    Beschreibung: Aeropropulsion technologies must progress to satisfy increasingly stringent global environmental requirements with economically viable air transportation systems. In this paper, key propulsion technologies to meet future needs are identified and the associated challenges are briefly discussed. Also discussed are NASA's vision, NASA's changing role in meeting today's challenge of a shrinking research budget, and propulsion technology impacts on the environment and air transport economics. Critical aeropropulsion technology drivers are identified and their impact evaluated. The aviation industry is critical to the nation's economy, job creation, and national security. NASA's advanced aeropropulsion technology programs and their relation to the aviation industry are discussed.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107048 , E-9893 , NAS 1.15:107048 , ISABE Conference; Sep 10, 1995 - Sep 15, 1995; Melbourne; Australia
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  • 69
    Publikationsdatum: 2019-07-13
    Beschreibung: This paper compares two previously published design procedures for two different multivariable control design techniques for application to a linear engine model of a jet engine. The two multivariable control design techniques compared were the Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) and the H-Infinity synthesis. The two control design techniques were used with specific previously published design procedures to synthesize controls which would provide equivalent closed loop frequency response for the primary control loops while assuring adequate loop decoupling. The resulting controllers were then reduced in order to minimize the programming and data storage requirements for a typical implementation. The reduced order linear controllers designed by each method were combined with the linear model of an advanced turbofan engine and the system performance was evaluated for the continuous linear system. Included in the performance analysis are the resulting frequency and transient responses as well as actuator usage and rate capability for each design method. The controls were also analyzed for robustness with respect to structured uncertainties in the unmodeled system dynamics. The two controls were then compared for performance capability and hardware implementation issues.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107060 , E-9915 , NAS 1.15:107060 , ASME 95-GT-258 , Gas Turbine and Aeroengine Congress and Exposition; Jun 05, 1995 - Jun 08, 1995; Houston, TX; United States
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  • 70
    Publikationsdatum: 2019-07-13
    Beschreibung: Time-accurate and steady three-dimensional viscous turbulent numerical simulations were performed to study the effect of upstream blade wake passing unsteadiness on the performance of film cooling on a downstream axial turbine blade. The simulations modeled the blade as spanwise periodic and of infinite span. Both aerodynamic and heat transfer quantities were explored. A showerhead film cooling arrangement typical of modern gas turbine engines was employed. Showerhead cooling was studied because of its anticipated strong sensitivity to upstream flow fluctuations. The wake was modeled as a region of zero axial velocity on the upstream computational boundary which translated with each iteration. This model is compatible with a planned companion experiment in which the wakes will be produced by a rotating row of cylindrical rods upstream of an annular turbine cascade. It was determined that a steady solution with appropriate upstream swirl and stagnation pressure predicted the span-average film effectiveness quite well. The major difference is a 2 to 3 percent overprediction of span-average film effectiveness by the steady simulation on the pressure surface and in the showerhead region. Local overpredictions of up to 8 percent were observed in the showerhead region. These differences can be explained by the periodic relative lifting of the boundary layer and enhanced mixing in the unsteady simulations.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107077 , NAS 1.15:107077 , AIAA PAPER 95-3044 , E-9949 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 71
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    Publikationsdatum: 2019-08-28
    Beschreibung: The critical issues concerning the application of constant-temperature hot-film anemometry to hypersonic flow are reviewed and extended. Mass-flux static calibrations were conducted in a Mach 10 helium flow, while mass-flux and total-temperature static calibrations were made in a Mach 6 air flow. In addition, comparative hot-film/hot-wire turbulence measurements were made in a Mach 11 helium boundary layer to provide insight into the dynamic response of the hot film. The measurements indicate that substrate conduction 'losses' dominate the static response of the hot-film probe, thus resulting in poor sensitivity to mass-flux and total temperature. Furthermore, it has been found that it is not possible to isolate mass-flux fluctuations at high overheat ratios for the current hot-film design. Thus, the sapphire-substrate hot-film anemometer is a robust, high-bandwidth instrument limited to qualitative transition and turbulence measurements. Finally, the extension of this technique to providing quantitative information is dependent upon the development of lower thermal-conductivity substrate materials.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AIAA PAPER 95-6110 , ; 10 p.|AIAA, Aerospace Planes and Hypersonics Technologies Conference; Apr 03, 1995 - Apr 07, 1995; Chattanooga, TN; United States
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  • 72
    Publikationsdatum: 2019-08-15
    Beschreibung: Particles from a J85-GE-5L turbojet engine were measured over a range of engine speeds at simulated altitude conditions ranging from near sea level to 45,000 ft and at flight Mach numbers of 0.5 and 0.8. Samples were collected from the engine by using a specially designed probe positioned several inches behind the exhaust nozzle. A differential mobility particle sizing system was used to determine particle size. Particle data measured at near sea-level conditions were compared with Navy Aircraft Environmental Support Office (AESO) particle data taken from a GE-J85-4A engine at a sea-level static condition. Particle data from the J85 engine were also compared with particle data from a J85 combustor at three different simulated altitudes.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106669 , E-9143 , NAS 1.15:106669
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  • 73
    Publikationsdatum: 2019-07-13
    Beschreibung: The results reported in this paper describe some of the main flow characteristics and NOx production results which develop in the mixing process in a constant cross-sectional cylindrical duct. A 3-dimensional numerical model has been used to predict the mixing flow field and NOx characteristics in a mixing section of an RQL combustor. Eighteen configurations have been analyzed in a circular geometry in a fully reacting environment simulating the operating condition of an actual RQL gas turbine combustion liner. The evaluation matrix was constructed by varying three parameter: (1) jet-to-mainstream momentum-flux ration (J), (2) orifice shape or orifice aspect ratio, and (3) slot slant angle. The results indicate that the mixing flow field and NOx production significantly vary with the value of the jet penetration and subsequently, slanting elongated slots generally improve the NOx production at high J conditions. Round orifices produce low NOx at low J due to the strong jet penetration. The NOx production trends do not correlate with the mixing non-uniformity parameters described herein.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106736 , E-9349 , NAS 1.15:106736 , AIAA PAPER 95-0733 , Aerospace Sciences Meeting and Exhibit; Jan 09, 1995 - Jan 12, 1995; Reno, NV; United States
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  • 74
    Publikationsdatum: 2019-08-15
    Beschreibung: Three dimensional turbulent reacting CFD analyses were performed on transverse jets injected into annular and cylindrical (can) confined crossflows. The goal was to identify and assess mixing differences between annular and can geometries. The approach taken was to optimize both annular and can configurations by systematically varying orifice spacing until lowest emissions were achieved, and then compare the results. Numerical test conditions consisted of a jet-to-mainstream mass-flow ratio of 3.2 and a jet-to-mainstream momentum-flux ratio (J) of 30. The computational results showed that the optimized geometries had similar emission levels at the exit of the mixing section although the annular configuration did mix-out faster. For lowest emissions, the density correlation parameter (C = (S/H) square root of J) was 2.35 for the annular geometry and 3.5 for the can geometry. For the annular geometry, the constant was about twice the value seen for jet mixing at low mass-flow ratios (i.e., MR less than 0.5). For the can geometry, the constant was about 1 1/2 times the value seen for low mass-flow ratios.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-106976 , AIAA Paper 95-2995 , E-9737 , NAS 1.15:106976 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 75
    Publikationsdatum: 2019-08-16
    Beschreibung: A two-dimensional Navier-Stokes code has been developed for rapid numerical simulation of axisymmetric flow fields, including flow fields with an azimuthal velocity component. The azimuthal-invariant Navier-Stokes equations in a cylindrical coordinate system are mapped to a general body-fitted coordinate system, with the streamwise viscous terms then neglected by applying the thin-layer approximation. Turbulence effects are modeled using an algebraic model, typically the Baldwin-Lomax turbulence model, although a modified Cebeci-Smith model can also be used. The equations are discretized using central finite differences and solved using a multistage Runge-Kutta algorithm with a spatially varying time step and implicit residual smoothing. Results are presented for calculations of supersonic flow over a waisted body-of-revolution, transonic flow through a normal shock wave in a straight circular duct of constant cross sectional area, swirling supersonic (inviscid) flow through a strong shock in a straight radial duct, and swirling subsonic flow in an annular-to-circular diffuser duct. Comparisons between computed and experimental results are in fair to good agreement, demonstrating that the viscous code can be a useful tool for practical engineering design and analysis work.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA-TM-107103 , NAS 1.15:107103 , AIAA PAPER 96-0449 , E-10001 , NIPS-95-06277 , Aerospace Sciences Meeting and Exhibit; Jan 15, 1996 - Jan 18, 1996; Reno, NV; United States
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  • 76
    Publikationsdatum: 2006-04-09
    Beschreibung: For several years the Department of Defense has been sponsoring fuel accommodation investigations with gas turbine engine manufacturers and supporting organizations to quantify the effect of changes in fuel properties and characteristics on the operation and performance of military engine components and systems. Inasmuch as there are many differences in hardware between the operational engines in the military inventories, due to differences in design philosophy and requirements, efforts were initially expended to acquire fuel effects data from rigs simulating the hot sections of these different engines. Correlations were then sought using the data acquired to produce more general, generic relationships that could be applied to all military gas turbine engines regardless of their origin. Finally, models could be developed from these correlations that could predict the effect of fuel property changes on current and future engines. This presentation describes some of the work performed by Pratt and Whitney Aircraft, under Naval Air Propulsion Center sponsorship, to determine the effect of fuel properties on the hot section and fuel system of the Navy's TF30-P-414 gas turbine engine.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 63-72
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  • 77
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    In:  CASI
    Publikationsdatum: 2006-04-09
    Beschreibung: In an attempt to rigorously study the fuel chemical property influence, UTRC (United Technologies Research Center) (under contract to NASA Lewis Research Center) has conducted an experimental program using 25 test fuels. The burner was a 12.7 cm dia cylindrical device consisting of six sheet metal louvers. A single pressure atomizing injector and air swirler were centrally mounted with the conical dome. Fuel physical properties were de-emphasized by using fuel injectors which produced highly atomized, and hence rapidly vaporizing sprays. A substantial fuel spray characterization effort was conducted to allow selection of nozzles which assured that such sprays were achieved for all fuels. The fuels were specified to cover the following wide ranges of chemical properties: hydrogen, 9.1 to 15 (wt) pct; total aromatics, 0 to 100 (vol) pct; and naphthalene, 0 to 30 (vol) pct. They included standard fuel (e.g., Jet A, JP4), specialty products (e.g., decalin, xylene tower bottoms) and special fuel blends. Included in this latter group were six, 4-component blends prepared to achieve parametric variations in fuel hydrogen, total aromatics and naphthalene contents.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 31-46
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  • 78
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    In:  CASI
    Publikationsdatum: 2006-02-14
    Beschreibung: Starting with the NASA-sponsored STAEBL program, optimization methods based primarily upon the versatile program COPES/CONMIN were introduced over the past few years to a broad spectrum of engineering problems in structural optimization, engine design, engine test, and more recently, manufacturing processes. By automating design and testing processes, many repetitive and costly trade-off studies have been replaced by optimization procedures. Rather than taking engineers and designers out of the loop, optimization has, in fact, put them more in control by providing sophisticated search techniques. The ultimate decision whether to accept or reject an optimal feasible design still rests with the analyst. Feedback obtained from this decision process has been invaluable since it can be incorporated into the optimization procedure to make it more intelligent. On several occasions, optimization procedures have produced novel designs, such as the nonsymmetric placement of rotor case stiffener rings, not anticipated by engineering designers. In another case, a particularly difficult resonance contraint could not be satisfied using hand iterations for a compressor blade, when the STAEBL program was applied to the problem, a feasible solution was obtained in just two iterations.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 18 p
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  • 79
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    In:  CASI
    Publikationsdatum: 2006-04-09
    Beschreibung: The study performed in Phase 1 of this program applies only to a T700/CT7 engine family type combustor functioning in the engine as defined and does not necessarily apply to other cycles or combustors of differing stoichiometry. The study was not extended to any of the fuel delivery accessories such as pumps or control systems, nor was there any investigation of potential systems problems which might arise as a consequence of abnormal properties such as density which might affect delivery schedules or aromatics content which might affect fuel system seals. The T700/CT7 engine is a front drive turboshaft or turboprop engine in the 1500-1800 shp (1120-1340 kW) class as currently configured with highpower core flows of about 10 lb/sec (4.5 kg/sec). It employs a straight-through annular combustion system less than 5 in. (12.5 cm) in length utilizing a machined ring film cooled construction and twelve low-pressure air blast fuel injectors. Commercial and Naval versions employ two 0.5 Joule capacitive discharge surface gap ignitors.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 89-98
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  • 80
    Publikationsdatum: 2006-04-09
    Beschreibung: Since the early 1970s, the cost and availability of aircraft fuel have changed drastically. These problems prompted a program to evaluate the effects of broadened specification fuels on current and future aircraft engine combustors employed by the USAF. Phase 1 of this program was to test a set of fuels having a broad range of chemical and physical properties in a select group of gas turbine engine combustors currently in use by the USAF. The fuels ranged from JP4 to Diesel Fuel number two (DF2) with hydrogen content ranging from 14.5 percent down to 12 percent by weight, density ranging from 752 kg/sq m to 837 kg/sq m, and viscosity ranging from 0.830 sq mm/s to 3.245 sq mm/s. In addition, there was a broad range of aromatic content and physical properties attained by using Gulf Mineral Seal Oil, Xylene Bottoms, and 2040 Solvent as blending agents in JP4, JP5, JP8, and DF2. The objective of Phase 2 was to develop simple correlations and models of fuel effects on combustor performance and durability. The major variables of concern were fuel chemical and physical properties, combustor design factors, and combustor operating conditions.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 47-62
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  • 81
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 05, p. 656, Accession no. A82-16909
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 183-189
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  • 82
    Publikationsdatum: 2011-08-19
    Beschreibung: Experimental results are presented for the case of titanium blade tip specimens of various geometrical configurations rubbing at 100 m/s against specimens of nickel-chromium sintered powder metal seal material, the latter being fed toward the rotating blades at an incursion rate of 0.0254 mm/s. Blade tips in the form of orthogonal cutting tools with about 85 deg negative rake angles exhibited desirable abrading capabilities, as measured by the tear-free appearance of the grooves they generated in the seal material, little wear of blade tips, low forces of interaction and low seal densification. Similar results have been obtained for blade specimens with tips of small radius of curvature, as well as for square-ended and slanted blade tips that are plasma-sprayed with abrasive particles. The relationship between the size of these particles and their abrading effectiveness is considered.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: ASME, Transactions, Journal of Tribology (ISSN 0742-4787); 106; 527-533
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  • 83
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 10, p. 1378, Accession no. A83-25957
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 135-142
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  • 84
    facet.materialart.
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The trajectory, penetration and mixing efficiency of lateral air jet injection into typical combustor flowfields in the absence of combustion were investigated so as to characterize the time-mean and turbulence flowfield for a variety of configurations and input parameters, recommend appropriate turbulence model advances, and implement and exhibit results of flowfield predictions. A combined experimental and theoretical approach was followed, in a modified version of the test facility, equipped initially with one and two lateral jets, located one test-section downstream of the inlet.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 11 p
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  • 85
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The accuracy and utility of current aerothermal models for gas turbine combustors must be improved. Three areas of concern are identified: improved numerical methods for turbulent viscous recirculating flows; flow interaction; and fuel injector-air swirl characterization. Progress in each area is summarized.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Turbine Engine Hot Section Technology, 1984; 4 p
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  • 86
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The Structural Tailoring of Engine Blades (STAEBL) program was initiated at NASA Lewis Research Center in 1980 to introduce optimal structural tailoring into the design process for aircraft gas turbine engine blades. The standard procedure for blade design is highly iterative with the engineer directly providing most of the decisions that control the design process. The goal of the STAEBL program has been to develop an automated approach to generate structurally optimal blade designs. The program has evolved as a three-phase effort with the developmental work being performed contractually by Pratt & Whitney Aircraft. Phase 1 was intended as a proof of concept in which two fan blades were structurally tailored to meet a full set of structural design constraints while minimizing DOC+I (direct operating cost plus interest) for a representative aircraft. This phase was successfully completed and was reported in reference 1 and 2. Phase 2 has recently been completed and is the basis for this discussion. During this phase, three tasks were accomplished: (1) a nonproprietary structural tailoring computer code was developed; (2) a dedicated approximate finite-element analysis was developed; and (3) an approximate large-deflection analysis was developed to assess local foreign object damage. Phase 3 is just beginning and is designed to incorporated aerodynamic analyses directly into the structural tailoring system in order to relax current geometric constraints.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 13 p
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  • 87
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The Liner Environment Effects Study Program is aimed at establishing a broad heat transfer data base under controlled experimental conditions by quantifying the effects of the combustion system conditions on the combustor liner thermal loading and on the flame radiation characteristics. Five liner concepts spanning the spectrum of liner design technology from the very simple to the most advanced concepts are investigated. These concepts comprise an uncooled liner, a conventional film cooled liner, an impingement/film cooled liner, a laser drilled liner approaching the concept of a porous wall, and a siliconized silicon carbide ceramic liner. Effect of fuel type is covered by using fuels containing 11.8, 12.8, and 14% hydrogen. Tests at 100, 200, and 300 psia provide a basis for evaluating the effect of pressure on the heat transfer. The effects of the atomization quality and spray characteristics are examined by varying the fuel spray Sauter mean diameter and the spray angle. Additional varied parameters include reference velocity, a wide range of equivalence ratio, cooling flow rate, coolant temperature and the velocity of the coolant stream on the backside of the liner.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Combust. Fundamentals Res.; p 275-284
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  • 88
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 07, p. 982, Accession no. A82-19221
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 77-84
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  • 89
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 10, p. 1378, Accession no. A83-25963
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 491-497
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  • 90
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 10, p. 1377, Accession no. A83-25910
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 453-461
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  • 91
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: It is expected that all-electric aircraft, whether military or commercial, will exhibit reduced weight, acquisition cost and fuel consumption, an expanded flight envelope and improved survivability and reliability, simpler maintenance, and reduced support equipment. Also noteworthy are dramatic improvements in mission adaptability, based on the degree to which control system performance relies on easily exchanged software. Flight-critical secondary power and control systems whose malfunction would mean loss of an aircraft pose failure detection and design methodology problems, however, that have only begun to be addressed. NASA-sponsored research activities concerned with these problems and prospective benefits are presently discussed.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: IEEE Transactions on Aerospace and Electronic Systems (ISSN 0018-9251); AES-20; 261-266
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  • 92
    Publikationsdatum: 2011-08-19
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 677-683
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  • 93
    Publikationsdatum: 2011-08-19
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 652-661
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  • 94
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    In:  Other Sources
    Publikationsdatum: 2011-08-18
    Beschreibung: Regulatory changes are proposed for new engine certification for multi-engine helicopters to account for contingency operations when one engine goes out at take-off. The new rules are needed because current regulations define category A and B conditions as one-engine out, land immediately, or continue take-off, respectively. Category A is seldom feasible while Category B requires oversize engines, implying lowered fuel efficiencies. However, NASA studies have shown that engines with large contingency power can operate more efficiently in normal conditions due to decreased coolant flow. Techniques for realizing up to a 50 percent power augmentation with minor modifications of existing engines are described.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Vertiflite (ISSN 0042-4455); 30; 34-38
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  • 95
    Publikationsdatum: 2011-08-18
    Beschreibung: A three-dimensional analysis of turbofan forced mixer nozzle aerodynamics demonstrates that the complex flow structure is dominated by geometrically induced secondary flow rather than by turbulence. The test apparatus consisted of a fixed upstream model section and a rotating shroud. The Mach number of the fan and core streams at the mixing plane (lobe exit) was 0.45, the bypass ratio was about 4, and the Reynolds number based on the shroud radius was 1,100,000. The three velocity components near the exit plane of the lobes were measured using flow angularity probes to provide information about the mixer inflow conditions for turbulent computations. The validity of a previous computer code was demonstrated in a comparison of the nozzle exit temperature data with the computed temperature distributions. The mechanism most responsible for the generation of secondary flow within the lobes is due to the turning of the fan and core streams in opposite radial directions.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AIAA Journal (ISSN 0001-1452); 22; 518-525
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  • 96
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 12, p. 1742, Accession no. A83-29822
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 278-286
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  • 97
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Modern jet engine design imposes extremely high loadings and temperatures on hot section components. A series of interdisciplinary modeling and analysis techniques which were specialized to address three specific components (combustor burner linings, hollow air-cooled turbine blades, and air-cooled turbine vanes) were developed and verified. These techniques will incorporate data as well as theoretical methods from many diverse areas, including cycle and performance analysis, heat transfer analysis, linear and nonlinear stress analysis, and mission analysis. Building on the proven techniques already available in these fields, the new methods developed will be integrated to predict temperature, deformation, stress, and strain histories throughout a complete flight mission.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 12 p
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  • 98
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A serious problem exists interfacing the output temperatures and temperature gradients from either the heat transfer codes or engine tests with the input to stress analysis codes. A thermal load transfer code was developed and was used in conjunction with a three-dimensional model of a combustor liner for verification. The 3D heat transfer and stress analysis models of combustor liners and turbine blades were used to validate the mapped temperature produced by the transfer module. Verification cases were made for both finite element and finite difference heat transfer codes. A user manual for the code was written and is available.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 9 p
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  • 99
    Publikationsdatum: 2016-06-07
    Beschreibung: A typical engine control design cycle consists of developing a dynamic engine simulation from steady-state component performance data, designing a control based upon this simulation, and then testing and modifying the control in an engine test cell to meet performance requirements. This design cycle was successful for state-of-the-art engines. However, for more advanced multivariable engines that exhibit strong variable interactions, this procedure will result in substantial trial and error modification of the control during the testing phase. One method to automate the design process and reduce control modification testing and development cost would be to identify accurate dynamic models directly from the closed-loop test data. These identified models would then be used in conjunction with a synthesis procedure to systematically refine the control. Recent advances in closed-loop identifiability present a methodology for this direct identification of engine model dynamics from closed-loop test data. The application of an identification method to simulated and actual closed-loop F100 engine data is described. This study was undertaken to determine if useful dynamic engine models could be identified directly from closed-loop engine test data.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: NASA. Langley Research Center NASA Aircraft Controls Research, 1983; p 221-238
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  • 100
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    In:  CASI
    Publikationsdatum: 2017-10-02
    Beschreibung: The problem of calculating turbine engine component durability is addressed. Nonlinear, finite-element structural analyses, cyclic constitutive behavior models, and an advanced creep-fatigue life prediction method called strainrange partitioning were assessed for their applicability to the solution of durability problems in hot-section components of gas turbine engines. Three different component or subcomponent geometries are examined: a stress concentration in a turbine disk; a louver lip of a half-scale combustor linear; and a squealer tip of a first-stage high-pressure turbine blade. Cyclic structural analyses were performed for all three problems. The computed strain-temperature histories at the critical locations of the combustor linear and turbine blade components were imposed on smooth specimens in uniaxial, strain-controlled, thermomechanical fatigue tests of evaluate the structural and life analysis methods.
    Schlagwort(e): AIRCRAFT PROPULSION AND POWER
    Materialart: AGARD Eng. Cyclic Durability by Analysis and Testing; 12 p
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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