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  • Aircraft Propulsion and Power
  • Earth model, also for more shallow analyses !
  • 1995-1999
  • 1990-1994  (28)
  • 1950-1954  (5)
  • 1994  (28)
  • 1954  (5)
Collection
Keywords
Publisher
Years
  • 1995-1999
  • 1990-1994  (28)
  • 1950-1954  (5)
Year
  • 1
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    Constraints on Himalayan deformation inferred from vertical velocity fields in Nepal and Tibet (1994)
    In:  J. Geophys. Res., Amsterdam, Schweizerbart'sche Verlagsbuchhandlung, vol. 99, no. 2, pp. 13897-13912, pp. L07302, (ISSN 0016-8548, ISBN 3-510-50045-8)
    Details
    Publication Date: 1994
    Keywords: China ; Tectonics ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Deep seismic sounding (espec. cont. crust) ; Velocity depth profile ; Earth model, also for more shallow analyses ! ; JGR
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Structures and kinematics in the northeastern Mediterranean: A study of an irregular plate boundary (1994)
    In:  Tectonophys., New York, Allerton Press, vol. 234, no. 13, pp. 5-18, pp. L13315, (ISSN: 1340-4202)
    Details
    Publication Date: 1994
    Keywords: Earth model, also for more shallow analyses ! ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Plate tectonics ; Turkey
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
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    The density contrast at the Mohorovicic discontinuity (1994)
    In:  Geophys. J. Int., Zagreb, 3-4, vol. 117, no. 3, pp. 539-544, pp. B06305, (ISSN: 1340-4202)
    Details
    Publication Date: 1994
    Keywords: Mohorovicic disc. ; Earth model, also for more shallow analyses ! ; Physical properties of rocks ; Gravimetry, Gravitation ; GJI
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    BIBLIOGRAPHY SEISMOLOGY
  • 4
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    Regional scale tectonic evolution and the seismic velocity structure of the lithosphere and upper mantle: The Mediterranean region (1994)
    In:  J. Geophys. Res., London, Geological Society, vol. 99, no. 11, pp. 12091-12108, pp. L11303, (ISBN 1-86239-117-3)
    Details
    Publication Date: 1994
    Keywords: Tectonics ; Turkey ; Earth model, also for more shallow analyses ! ; Tomography ; JGR
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    BIBLIOGRAPHY SEISMOLOGY
  • 5
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    Seismic velocities and Q-factors in the uppermost crust beneath the SVEKA profile in Finland (1994)
    In:  Tectonophys., Warszawa, Icelandic Meteorological Office, Ministry for the Environment,, vol. 230, no. 4, pp. 1-19, pp. 1567, (ISBN: 0534351875, 2nd edition)
    Details
    Publication Date: 1994
    Keywords: Seismics (controlled source seismology) ; Attenuation ; Earth model, also for more shallow analyses ! ; Velocity depth profile ; Quality factor
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    BIBLIOGRAPHY SEISMOLOGY
  • 6
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    Pn velocities beneath continental collision zones: The Turkish-Iranian Plateau (1994)
    In:  Geophys. J. Int., Oxford and Edinburgh, Blackwell Scientific Publications, vol. 117, no. 1, pp. 273-283, pp. 1549, (ISBN: 0534351875, 2nd edition)
    Details
    Publication Date: 1994
    Keywords: P-waves ; Plate tectonics ; Velocity analysis ; earth mantle ; Mohorovicic disc. ; Earth model, also for more shallow analyses ! ; Velocity depth profile ; GJI
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    BIBLIOGRAPHY SEISMOLOGY
  • 7
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    Seismological constraints on the gabbro-eclogite transition in subducted oceanic crust (1994)
    In:  Earth planet. Sci. Lett., Kleinmachnow, Dt. Geophys. Ges. e. V., vol. 122, no. 6, pp. 89-101, pp. B05401, (ISBN: 0534351875, 2nd edition)
    Details
    Publication Date: 1994
    Keywords: Seismology ; Earth model, also for more shallow analyses ! ; Subduction zone ; phase ; transition
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    BIBLIOGRAPHY SEISMOLOGY
  • 8
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    Shear-wave velocity variations in the upper mantle beneath central Europe (1994)
    In:  Geophys. J. Int., Kunming, China, 3-4, vol. 117, no. 1, pp. 695-715, pp. B05S18, (ISSN: 1340-4202)
    Details
    Publication Date: 1994
    Keywords: Shear waves ; Earth model, also for more shallow analyses ! ; Velocity depth profile ; earth mantle ; GJI
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    BIBLIOGRAPHY SEISMOLOGY
  • 9
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    Differenti tipi di litosfera e differenti stili di subduzione negli Appennini (1994)
    Gruppo Nazionale di Geofisica della Terra Solida
    In:  Atti del 13. Convegno Annuale del Gruppo Nazionale di Geofisica della Terra Solida, Roma, Gruppo Nazionale di Geofisica della Terra Solida, vol. C 560, 183 pp., no. 70, pp. 13-24, (ISBN 3-933346-037)
    Details
    Publication Date: 1994
    Keywords: Subduction zone ; Italy ; Earth model, also for more shallow analyses ! ; Elasticity
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    BIBLIOGRAPHY SEISMOLOGY
  • 10
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    Angolo di subduzione in astenosfera in moto (1994)
    Gruppo Nazionale di Geofisica della Terra Solida
    In:  Atti del 13. Convegno Annuale del Gruppo Nazionale di Geofisica della Terra Solida, Roma, Gruppo Nazionale di Geofisica della Terra Solida, vol. C 560, 183 pp., no. 78 (?), pp. 193-210, (ISBN 3-933346-037)
    Details
    Publication Date: 1994
    Keywords: Subduction zone ; Italy ; Earth model, also for more shallow analyses ! ; Elasticity
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    BIBLIOGRAPHY SEISMOLOGY
  • 11
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    Flight Research Using F100 Engine P680063 in the NASA F-15 Airplane (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The value of flight research in developing and evaluating gas turbine engines is high. NASA Dryden Flight Research Center has been conducting flight research on propulsion systems for many years. The F100 engine has been tested in the NASA F-15 research airplane in the last three decades. One engine in particular, S/N P680063, has been used for the entire program and has been flown in many pioneering propulsion flight research activities. Included are detailed flight-to-ground facility tests; tests of the first production digital engine control system, the first active stall margin control system, the first performance-seeking control system; and the first use of computer-controlled engine thrust for emergency flight control. The flight research has been supplemented with altitude facility tests at key times. This paper presents a review of the tests of engine P680063, the F-15 airplanes in which it flew, and the role of the flight test in maturing propulsion technology.
    Keywords: Aircraft Propulsion and Power
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    NASA TECHNICAL REPORTS
  • 12
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    Effects of Mistuning on the Forced Response of Turbomachinery Rotors (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The basic purpose of this research has been to develop a fundamental understanding of the effects of blade-to-blade dissimilarities, or mistuning, on the dynamics of nearly cyclic bladed-disk assemblies. This topic is of importance as mistuning has been shown to increase the forced response amplitudes of some blades significantly, and even to lead to blade failure. Furthermore, the current trend toward high performance propulsion turbomachinery designed for finite service life demands an accurate prediction of system performance and dynamics at the design stage. This objective has been achieved by carrying out the following tasks. First, the investigation of the free and forced responses of representative, yet sufficiently simple blade assembly models that capture all the important characteristics of typical turbomachinery rotors. Second, the development of computational methods that predict the effects of mistuning in a systematic and reliable way, along with the development of a systematic reduced-order modeling procedure for mistuned bladed disks. Third, the application of these findings and the tools developed to an industrial rotor, namely the first stage of turbine blades of the oxidizer turbopump in the space shuttle main rocket engine (SSME). The research supported by NASA has led to the development of a coherent theory for mistuned blade assemblies. The further implementation of these computational tools into the forced response prediction system currently under development in the Structural Dynamics Branch-FREPS-would enable the designer and the analyst to: (1) identify types of blade assemblies highly sensitive to mistuning in various frequency and other parameter ranges and (2) characterize mistuning effects on their forced response by predicting true response amplitudes and fatigue life estimates.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-205484 , NAS 1.26:205484
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  • 13
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    In Operation Detection and Correction of Rotor Imbalance in Jet Engines Using Active Vibration Control (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Jet Engines may experience severe vibration due to the sudden imbalance caused by blade failure. This research investigates employment of on board magnetic bearings or piezoelectric actuators to cancel these forces in flight. This operation requires identification of the source of the vibrations via an expert system, determination of the required phase angles and amplitudes for the correction forces, and application of the desired control signals to the magnetic bearings or piezo electric actuators. This paper will show the architecture of the software system, details of the control algorithm used for the sudden imbalance correction project described above, and the laboratory test results.
    Keywords: Aircraft Propulsion and Power
    Type: SAE-TP-941151 , (ISSN 0148-7191)|Aerospace Atlantic Conference and Exposition; Apr 18, 1994 - Apr 22, 1994; Dayton, OH; United States
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    NASA TECHNICAL REPORTS
  • 14
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    Analytical Studies of Prompt NO(x) Emissions from Aircraft Gas Turbine Combustors (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The reduction of oxides of nitrogen (NO(x)) emissions from aircraft gas turbines is a vital part of the NASA High Speed Research Program (HSRP). Emissions reduction studies are critical to the feasibility of future civil aircraft operating at supersonic speeds in the stratosphere. It is believed that large fleets of supersonic aircraft using conventional gas turbine engines would emit levels of NO(x) that are harmful to the stratospheric ozone layer.
    Keywords: Aircraft Propulsion and Power
    Type: 31st AIAA/SAE/ASME/ASEE Joint Propulsion Conference; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 15
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    Measurements of Forward Flight Effects on the Advanced Ducted Propulsion Demonstrator Engine (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The performance of the Pratt & Whitney Advanced Ducted Propulsion (ADP) UHB concept has been recently evaluated with studies of a 17 in. diameter fan simulator. Following the model scale tests, a 118 in. diameter demonstrator was tested at the NASA Ames 40- by 80-Foot Wind Tunnel. The 18 blade fan was driven by the low compressor shaft of a PW2037 core through a reduction gear system fabricated by Fiat with approximately 1:3.7 reduction ratio. ne variable pitch fan was hydraulically actuated with settings for take-off, cruise, feather, and reverse thrust. The low-pressure turbine was built by MTU to provide higher shaft power in comparison with the standard PW2037. The demonstrator was provided with 45 vanes located 2.6 fan chords downstream of the rotor, and 10 case struts approximately 1 fan chord downstream of the vanes. The inlet, mid-duct, and exhaust linings were acoustically treated. Acoustic surveys were taken in the for-ward thrust mode for fan speeds of 898, 1120, 1205, and 1302 R.P.M., and at tunnel speeds of 25, 50, 100, and 140 kts. The lowest speed was achieved with the wind tunnel fans at flat pitch, but with the engine pumping the test section Microphone signals were recorded for 30 seconds at 5 deg. increments. These measurements will be used to assess the effects of forward speed on UHB engines, to compare these effects with the corresponding characteristics of conventional bypass ratio engines, and to discuss the various aspects of testing large engines in the wind tunnel.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA/ASME/ASEE Joint Propulsion and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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    NASA TECHNICAL REPORTS
  • 16
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    Flight Testing of Hypersonic Airbreathing Propulsion for Developing Computational Design Technology (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The objective of this paper is to present and discuss a scenario and the requirements for flight testing of hypersonic airbreathing propulsion leading to the development of computational design technology. Flight Testing for this development is a significant part of a triad/synergistic, design approach which integrates computations, flight testing, and ground testing. These three complementary, design developmental tools have various capabilities and limitations. An incremental approach is necessary to use and to develop these tools effectively and efficiently. This computational technology must be developed keeping in focus the aerospace plane that is to be developed. The criteria for selecting the right plane are presented and consequently, the appropriate flight tests are identified. Two conceptual, flight-test systems are suggested considering the following: (1) the relevant, lessons learned from previous and current United States hypersonic programs, from the Apollo program, from the Space Shuttle program, and from the space station program; (2) the current need for a low risk, affordable access to space; and (3) the design challenge for hypersonic airbreathing propulsion testing. How these systems may be used for developing the computational design technology is described. The requirements for conducting propulsion- design computations, sources of uncertainties in these computations, and a guide for establishing the credibility of these computations are also presented.
    Keywords: Aircraft Propulsion and Power
    Type: Second European Symposium on Aerothermodynamics for Space Vehicles; Nov 22, 1994 - Nov 25, 1994; Noordwijk; Netherlands|Fourth European High-Speed Database Workshop; Nov 22, 1994 - Nov 25, 1994; Noordwijk; Netherlands
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    NASA TECHNICAL REPORTS
  • 17
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    Simulation of Unsteady Combustion in a Ramjet Engine Using a Highly Parallel Computer (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Combustion instability in ramjets is a complex phenomenon that involve nonlinear interaction between acoustic waves, vortex motion and unsteady heat release in the combustor. To numerically simulate this 3-D, transient phenomenon, enormous computer resources (time, memory and disk storage) are required. Although current generation vector supercomputers are capable of providing adequate resources for simulations of this nature, their high cost and limited availability, makes such machines less than satisfactory for routine use. The primary focus of this study is to assess the feasibility of using highly parallel computer systems as a cost-effective alternative for conducting such unsteady flow simulations. Towards this end, a large-eddy simulation model for combustion instability was implemented on the Intel iPSC/860 and a careful study was conducted to determine the benefits and the problems associated with the use of such machines for transient simulations. Details of this study along with the results obtained from the unsteady combustion simulations carried out on the iPSC/860 are discussed in this paper.
    Keywords: Aircraft Propulsion and Power
    Type: 1994 Simulation Multi Conference; Apr 10, 1994 - Apr 15, 1994; San Diego, CA; United States
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    NASA TECHNICAL REPORTS
  • 18
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    Large Scale Scramjet Propulsion Testing In The Mach 8 and 16 Regime At NASA Ames Research Center (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The objective of this paper is to describe the affordable, large scale scramJet test capability for flight Mach numbers between 8 and 16 which has been developed at the NASA Ames Research Center. Details of the Direct Connect Arc Facility DCAF, which can produce combustor test conditions with fuel-on testing for 10 seconds at conditions representative of Mach 8 - 12 flight, are presented and typical test results are described. Likewise, a description of the full scale combustor test capability of the 16 inch shock tunnel is outlined. This facility is characterized by long run times (〉 5 milliseconds) for an impulse facility, and it can provide conditions representative of flight conditions from Mach 12 - 16. Typical test results for this shock tunnel are discussed as well. Future upgrades to both facilities are outlined and new uses for their capabilities are discussed.
    Keywords: Aircraft Propulsion and Power
    Type: Twelfth International Symposium on Airbreathing Engines; Sep 10, 1995 - Sep 15, 1995; Melbourne; Australia
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    NASA TECHNICAL REPORTS
  • 19
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    High temperature turbine engine structure (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.
    Keywords: Aircraft Propulsion and Power
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    NASA TECHNICAL REPORTS
  • 20
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    Low NO.sub.x combustor (1994)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: A combustor includes a dome assembly having radially outer and inner liners joined thereto and defining therebetween a combustion zone. The dome assembly includes at least one annular dome having a pair of axially extending first flanges between which are disposed a plurality of circumferentially spaced apart carburetors for discharging a fuel/air mixture into the combustion zone for generating combustion gases. An annular heat shield includes a pair of axially extending legs integrally joined to a radially extending face in a generally U-shaped configuration, with the face including a plurality of circumferentially spaced apart ports disposed concentrically with perspective ones of the carburetors for allowing the fuel/air mixture to be discharged therefrom through the heat shield. At least one of the heat shield legs includes a plurality of circumferentially spaced apart mounting holes disposed adjacent to a respective one of the dome flanges, and a plurality of mounting pins are fixedly joined to the dome flange and extend radially through respective ones of the mounting holes without interference therewith for allowing unrestrained thermal movement between the heat shield and the dome while supporting the heat shield against axial pressure loads thereon. In a preferred embodiment, the dome assembly includes three domes having respective ones of the heat shield, and respective baffles are spaced from the heat shields for providing impingement cooling thereof.
    Keywords: Aircraft Propulsion and Power
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    NASA TECHNICAL REPORTS
  • 21
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    Combustor liner support assembly (1994)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: A support assembly for a gas turbine engine combustor includes an annular frame having a plurality of circumferentially spaced apart tenons, and an annular combustor liner disposed coaxially with the frame and including a plurality of circumferentially spaced apart tenons circumferentially adjoining respective ones of the frame tenons for radially and tangentially supporting the liner to the frame while allowing unrestrained differential thermal radial movement therebetween.
    Keywords: Aircraft Propulsion and Power
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    NASA TECHNICAL REPORTS
  • 22
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    Jet mixer noise suppressor using acoustic feedback (1994)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The present invention generally relates to providing an improved jet mixer noise suppressor for high speed jets that rapidly mixes high speed air flow with a lower speed air flow, and more particularly, relates to an improved jet mixer noise suppressor that uses feedback of acoustic waves produced by the interaction of sheer flow instability waves with an obstacle downstream of the jet nozzle.
    Keywords: Aircraft Propulsion and Power
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    NASA TECHNICAL REPORTS
  • 23
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    Investigation of Methods for the Structural Weight Analysis of a Mach 2.4 Axisymmetric Inlet (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Structural design and analysis tools appropriate for estimating the structural weight of an axisymmetric inlet designed for Mach 2.4 cruise were evaluated. Little information regarding the inlet mechanical design is available in the preliminary design phase, so it is necessary to first develop a reasonable structural design before estimating the inlet weight. The Internally Pressurized Structure Synthesis and Optimization (IPSSO) program, employing an analytical approach, was chosen for evaluation due to its combined design and analysis capabilities. The inlet design produced by IPSSO was then analyzed using the NASTRAN finite element program. The finite element analysis was performed to help identify the limitations of the analytically based code as well as to evaluate NASTRAN for this application. Comparison between the IPSSO inlet weight and that of a similar inlet developed by the Boeing Commercial Airplane Group was also made. Program evaluation concluded that the combined use of IPSSO to create an initial design and NASTRAN to perform a numerical analysis would provide the capability to evaluate a limited number of inlet design The development of a new tool for the minimum weight design and analysis of inlet structures would be required for greater flexibility in evaluating inlet conceptual designs.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-106693 , E-9048 , NAS 1.15:106693
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  • 24
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    Sound suppression mixer (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A gas turbine engine flow mixer includes at least one chute having first and second spaced apart sidewalls joined together at a leading edge, with the sidewalls having first and second trailing edges defining therebetween a chute outlet. The first trailing edge is spaced longitudinally downstream from the second trailing edge for defining a septum in the first sidewall extending downstream from the second trailing edge. The septum includes a plurality of noise attenuating apertures.
    Keywords: Aircraft Propulsion and Power
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  • 25
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    Rotating stall suppression (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Rotating stall in an axial-flow compressor is suppressed by the positioning of a fixed inlet flow divider in the annular inlet flow passage upstream of the compressor. The inlet flow divider is aligned with the flow of fluid through the duct and acts to block or interfere with any rotating wave in the inlet and thereby suppresses rotating stall in the compressor.
    Keywords: Aircraft Propulsion and Power
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    NASA TECHNICAL REPORTS
  • 26
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    Control of an Axisymmetric Jet Using Vortex Generators (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The results of an experimental investigation on the effect of vortex generators, in the form of small tabs at the nozzle exit on the evolution of a jet, are reported in this paper. Primarily tabs of triangular shape are considered, and the effect is studied up to a jet Mach number of 1.8. Each tab is found to produce a dominant pair of counter-rotating streamwise vortices having a sense of rotation opposite to that expected from the wrapping of the boundary layer. This results in an inward indentation of the mixing layer into the core of the jet. A triangular-shaped tab with its apex leaning downstream, referred to as a delta tab, is found to be the most effective in producing such vortices, with a consequential large influence on the overall jet evolution. Two delta tabs, spaced 180 deg apart, completely bifurcate the jet. Four delta tabs stretch the mixing layer into four 'fingers,' resulting in a significant increase in the jet mixing downstream. For six delta tabs the mixing layer distortion settles back to a three finger configuration through an interaction of the streamwise vortices. The tabs are found to be equally effective in jets with turbulent or laminar initial boundary layers. Two sources of streamwise vorticity are postulated for the flow under consideration. One is the upstream 'pressure hill,' generated by the tab, which constitutes the main contributor of vorticity to the dominant pair. Another is due to vortex filaments shed from the sides of the tab and reoriented downstream by the mean shear of the mixing layer. Depending on the orientation of the tab, the latter source can produce a vortex pair having a sense of rotation opposite to that of the dominant pair. In the case of the delta tab, vorticity from the two sources add, explaining the strong effect in that configuration.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-204348 , NAS 1.26:204348 , E-7637 , Phys. Fluids (ISSN 1070-6631); 6; 2; 778-793
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  • 27
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    Liner mounting assembly (1994)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: A mounting assembly includes an annular supporting flange disposed coaxially about a centerline axis which has a plurality of circumferentially spaced apart supporting holes therethrough. An annular liner is disposed coaxially with the supporting flange and includes a plurality of circumferentially spaced apart mounting holes aligned with respective ones of the supporting holes. Each of a plurality of mounting pins includes a proximal end fixedly joined to the supporting flange through a respective one of the supporting holes, and a distal end disposed through a respective one of the liner mounting holes for supporting the liner to the supporting flange while unrestrained differential thermal movement of the liner relative to the supporting flange.
    Keywords: Aircraft Propulsion and Power
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    NASA TECHNICAL REPORTS
  • 28
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    Ramjet bypass duct and preburner configuration (1994)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: A combined turbofan and ramjet aircraft engine includes a forward bypass duct which allows the engine to operate more efficiently during the turbofan mode of operation. By mounting a ramjet preburner in the forward duct and isolating this duct from the turbofan bypass air, a transition from turbofan operation to ramjet operation can take place at lower flight Mach numbers without incurring pressure losses or blockage in the turbofan bypass air.
    Keywords: Aircraft Propulsion and Power
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  • 29
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    Investigation of Noise Field and Velocity Profiles of an Afterburning Engine (1954)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Sound pressure levels, frequency spectrum, and jet velocity profiles are presented for an engine-afterburner combination at various values of afterburner fuel - air ratio. At the high fuel-air ratios, severe low-frequency resonance was encountered which represented more than half the total energy in the sound spectrum. At similar thrust conditions, lower sound pressure levels were obtained from a current fighter air craft with a different afterburner configuration. The lower sound pressure levels are attributed to resonance-free afterburner operation and thereby indicate the importance of acoustic considerations in afterburner design.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-E54G07
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    NASA TECHNICAL REPORTS
  • 30
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    An Investigation in the Ames 40- by 80-Foot Wind Tunnel of a YT-56A Turboprop Engine Incorporating a Decoupler and a Controlled-Feathering Device (1954)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: An investigation of a decoupler and a controlled-feathering device incorporated with the YT-56A turboprop engine has been made to determine the effectiveness of these devices in reducing the high negative thrust (drag) which accompanies power failure of this type of engine. Power failures were simulated by fuel cut-off, both without either device free to operate, and with each device free to operate singly. The investigation was made through an airspeed range from 50 to 230 mph. It was found that with neither device free to operate, the drag levels realized after power failures at airspeeds above 170 mph would impose vertical tail loads higher than those allowable for the YC-130, the airplane for which the test power package was designed. These levels were reached in approximately one second. The maximum drag realized after power failure was not appreciably altered by the use of the decoupler although the decoupler did put a limit on the duration of the peak drag. The controlled-feathering device maintained a level of essentially zero drag after power failure. The use of the decoupler in the YT-56A engine complicates windmilling air-starting procedures and makes it necessary to place operating restrictions on the engine to assure safe flight at low-power conditions,
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SA54I09
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 31
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    Unknown
    Preliminary Altitude Operational Characteristics of a J57-P1 Turbojet Engine (1954)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The operational characteristics of a J57-P1 turbojet engine have been investigated at altitudes between 15,000 and 66,000 feet in the Lewis altitude wind tunnel. Included in this study is a discussion of fuel nozzle coking, the altitude operating limits with and without the standard engine control, the compressor surge characteristics, and the engine starting and windmilling characteristics. Severe circumferential turbine outlet temperature gradients which occurred at high altitude as a result of fuel nozzle coking were alleviated by the manufacturer's change in the fuel flow divider schedule and in a nozzle gasket material. Compressor air bleed is required to prevent surge of the outboard compressor in the low engine speed region. The maximum altitude at which the engine was operated without the control was about 66,000 feet at 0.8 flight Mach number and at a reduced engine speed to avoid compressor surge; with the engine control in operation, the altitude operating limit is reduced to approximately 59,000 feet. The maximum altitude at which the engine was started was about 40,000 feet.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE54C31
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unknown
    Design and Evaluation of a Turbojet Exhaust Simulator, Utilizing a Solid-Propellant Rocket Motor, for use in Free-Flight Aerodynamic Research Models (1954)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: A method has been developed for modifying a rocket motor so that its exhaust characteristics simulate those of a turbojet engine. The analysis necessary to the design is presented along with tests from which the designs are evaluated. Simulation was found to be best if the exhaust characteristics to be duplicated were those of a turbojet engine at high altitudes and with the afterburner operative.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-L54I15
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 33
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    Unknown
    Experimental Permeability Measurements on a Strut-Supported Transpiration-Cooled Turbine Blade with Stainless-Steel Shell made by the Federal-Mogul Corporation under Bureau of Aeronautics Contract N0as 51613-C (1954)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A turbine blade with a porous stainless-steel shell sintered to a supporting steel strut has been fabricated for tests at the NACA by Federal-Mogul Corporation under contract from the Bureau of Aeronautics, Department of the Navy. The apparent permeability of this blade, on the average, more nearly approaches the values specified by the NAGA than did two strut-supported bronze blades in a previous investigation. Random variations of permeability in the present blade are substantialy greater than those of the bronze blades, but projected improvements in certain phases of the fabrication process are expected to reduce these variations.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE54D29
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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