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  • Cell & Developmental Biology  (317)
  • AIRCRAFT PROPULSION AND POWER  (270)
  • 1995-1999
  • 1985-1989
  • 1980-1984
  • 1975-1979  (587)
  • 1940-1944
  • 1977  (587)
Collection
Keywords
Publisher
Years
  • 1995-1999
  • 1985-1989
  • 1980-1984
  • 1975-1979  (587)
  • 1940-1944
Year
  • 101
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    The application of the Routh approximation method to turbofan engine models (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Routh approximation technique is applied in the frequency domain to a 16th order state variable turbofan engine model. The results obtained motivate the extension of the frequency domain formulation of the Routh method to the time domain to handle the state variable formulation directly. The time domain formulation is derived and a new characterization, which specifies all possible Routh similarity transformations, is given. This characterization is computed by the solution of two eigenvalue-eigenvector problems. The application of the time domain Routh technique to the state variable engine model is described and some results are given. Additional computational problems are discussed including an optimization procedure which can improve the approximation accuracy by taking advantage of the transformation characterization.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
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    NASA TECHNICAL REPORTS
  • 102
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    Minimum-time acceleration of aircraft turbofan engines (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Minimum-time accelerations of the F100 turbofan engine are presented. A piecewise-linear engine model, having three state variables and four control variables, is used to obtain the minimum-time solutions. The linear model which applies at a given time in the trajectory is determined by calculating a normalized 'distance' from the current state to the equilibrium state associated with each linear model. The linear model associated with the closest equilibrium point is then used. The control histories for the minimum-time solutions are used as input to a nonlinear simulation of the F100 engine to verify the accuracy of the piecewise-linear solutions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
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  • 103
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    Frequency domain compensation of a DYNGEN turbofan engine model (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Following Rosenbrock's ideas regarding the advantages of dominance in linear multivariable control systems, a new graphical technique is used for the design of compensators that achieve dominance. The technique is illustrated with an application to the problem of designing compensators for a linear turbofan-engine model. The resulting design is put into perspective by examining it in the light of two other multivariable frequency-domain methods. One, MacFarlane's method of characteristic loci, is used to realize a final design for stability and low interaction. The other is a direct technique based upon the algebraic expansion of the determinant of the return difference in terms of it's elements. Results from simulations carried out on the NASA DYNGEN software are included.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
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    NASA TECHNICAL REPORTS
  • 104
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    Preliminary QCSEE program - Test results (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Preliminary results are reported for the Quiet Clean Short-haul Experimental Engine (QCSEE) program initiated by NASA in 1974 to develop propulsion system technology suitable for powered-lift short-range commercial aircraft. The QCSEE technology also has applications to the proposed U.S. Navy V/STOL aircraft. Emphasis in the QCSEE program is placed on developing engines with low noise characteristics; in addition, the power plants are required to conform to EPA 1979 pollutant emissions standards. Thrust performance, fan design, and thrust/weight ratio are discussed for both the over-the-wing and under-the-wing engine configurations under study.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 771008 , Aerospace Meeting; Nov 14, 1977 - Nov 17, 1977; Los Angeles, CA
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  • 105
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    High temperature environmental effects on metals (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The gas turbine engine was used as an example to predict high temperature environmental attack on metals. Environmental attack in a gas turbine engine derives from high temperature, combustion products of the air and fuel burned, and impurities. Of all the modes of attack associated with impurity effects, hot corrosion was the most complicated mechanistically. Solutions to the hot corrosion problem were sought semi-empirically in: (1) improved alloys or ceramics; (2) protective surface coating; (3) use of additives to the engine environment; and (4) air/fuel cleanup to eliminate harmful impurities.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73878 , Sagamore Army Materials Res., Conf. Risk and Failure Analysis for Reliability; Aug 22, 1977 - Aug 26, 1977; Bolton Landing, NY; United States
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  • 106
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    Preliminary QCSEE program test results (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The QCSEE (Quiet, Clean, Short-Haul Experimental Engine) program has entered the engine test phase. Overall design and advanced technology incorporated into the two engines in the program were described. In addition, preliminary engine test results are presented and compared to the technical requirements the engines were designed to meet.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73732 , 1977 Aerospace Meeting; Nov 14, 1977 - Nov 17, 1977; Los Angeles
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  • 107
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    General aviation energy-conservation research programs at NASA-Lewis Research Center (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The major thrust of NASA's nonturbine general aviation engine programs is directed toward (1) reduced specific fuel consumption, (2) improved fuel tolerance; and (3) emission reduction. Current and planned future programs in such areas as lean operation, improved fuel management, advanced cooling techniques and advanced engine concepts, are described. These are expected to lay the technology base, by the mid to latter 1980's, for engines whose total fuel costs are as much as 30% lower than today's conventional engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73884 , Conf. on Energy Conserv. in Gen. Aviation; Oct 10, 1977 - Oct 11, 1977; Kalamazoo, MI; United States
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  • 108
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    Flight-Effects on Predicted Fan Fly-By Noise (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The impact on PNLT (Perceived Noise Level, Tone corrected) and Fly-by EPNL (Effective Perceived Noise Level) when forward motion reduces the noise generated by the bypass fan of an aircraft engine was studied. Calculated noise spectra for a typical subsonic tip speed fan designed for blade passage frequency (BPF) tone cutoff were translated in frequency by systematically varying the BPF from 0.5 to 8 kHz. Two cases of predicted flight-effects on fan source noises were considered: reduced BPF tone level of 8 db and reduced broadband noise level of about 2 db in addition to reduced tone level. The maximum reduction in PNLT of the noise as emitted from the fan occurred when the BPF was at 4 kHz where the reductions were 7.4 and 10.0 db. The maximum reduction in EPNL of the noise as received during a 500-foot altitude fly-by occurred when the BPF was at 2.5 kHz where the reductions were 5.0 and 7.8 db.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73798 , Meeting of the Acoustical Soc. of Am.; Dec 13, 1977 - Dec 16, 1977; Miami, FL; United States
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  • 109
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    Aircraft Engine Emissions (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A conference on a aircraft engine emissions was held to present the results of recent and current work. Such diverse areas as components, controls, energy efficient engine designs, and noise and pollution reduction are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CP-2021 , E-9262 , May 18, 1977 - May 19, 1977; Cleveland
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  • 110
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    Evaluation of an F100 multivariable control using a real-time engine simulation (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design for the F100 turbofan engine was evaluated, as part of the F100 multivariable control synthesis (MVCS) program. The evaluation utilized a real-time, hybrid computer simulation of the engine and a digital computer implementation of the control. Significant results of the evaluation are presented and recommendations concerning future engine testing of the control are made.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73648 , E-9155 , Propulsion Conf.; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; United States
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  • 111
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    An Assessment of Technology for Turbojet Engine Rotor Failures (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Design considerations, objectives, and approaches used in containing rotor burst debris are discussed. Methods are given for determining the fracture resistance of various materials used in providing lightweight shielding from fragment impact.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CP-2017 , E-8305 , Mar 29, 1977 - Mar 31, 1977; Cambridge, MA; United States
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  • 112
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    The jet engine design that can drastically reduce oxides of nitrogen (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NOx pollution problem of hydrogen fueled turbojets and supersonic combustion ramjets (scramjets) was investigated to determine means of substantially alleviating the problem. Since the NOx reaction rates are much slower than the energy producing reactions, the NOx production depends mainly on the maximum local temperatures in the combustor and the NOx concentration is far from equilibrium at the end of a typical combustor (L approximately 1 ft). In diffusion flames, as used in present turbojets and scramjets combustor designs, the maximum local temperature occurs at the flame and is equal to the stoichiometric value. Whereas, in the heat conduction flames, wherein the flame propagates due to a heat conduction process away from the flame to the cooler oncoming premixed unburnt gases, the maximum temperature is lower than in the diffusion flame. Hence the corresponding pollution index is also lower.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 74-160 , Selected Papers on Advanced Design of Air Vehicles; p 79-88|AIAA Aerospace Sci. Meeting; Jan 30, 1974 - Feb 01, 1974; Washington, DC; United States
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    NASA TECHNICAL REPORTS
  • 113
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    Acoustic performance of inlet multiple-pure-tone suppressors installed on NASA Quiet Engine 'C' (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The purpose of the experimental program reported herein was to define the length of multiple pure tone (MPT) treatment required to reasonably suppress the MPT's produced by a supersonic tip speed fan and also determine what other suppression, broadband, and blade passing frequency (BPF), might be accomplished. The experimental results are presented in terms of both far-field and duct acoustic data. Front quadrant sound power level reduction in the far field is shown to agree with duct measurements over the range of treatment lengths. Detailed one-third octave and narrow band spectra at the maximum forward noise angle are presented. Some detailed analyses of one-third-octave band amplitudes are shown as a function of far-field angle. An approximate spinning mode duct propagation analysis is then introduced which predicts the acoustic suppression by the treatment on the multiple pure tones.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-1333 , Aeroacoustics Conference; Oct 03, 1977 - Oct 05, 1977; Atlanta, GA
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  • 114
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    Coherence between internal and external noise generated by gas turbine combustors (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Experiments and analysis on a gas turbine combustor unit are reported with a view in mind to separate propagated acoustic power from non-propagating 'pseudo-sound'. Analytically, it is suggested that a transition frequency will exist below which the interior pressure fluctuations are non-propagating, whereas above this frequency, of the order of 100 Hz, the noise is dominated by propagating acoustic waves. Coherence measurements are reported which show this concept to be borne out experimentally. Coherence between interior and exterior microphones is measured over a wide range of experimental conditions for a gas turbine combustor exhausting directly to the atmosphere. The purpose is to show that below a certain frequency, measurements of interior noise are not indicative of combustion noise ultimately propagating from an engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-20 , Aerospace Sciences Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles, CA
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  • 115
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    State-of-the-art of turbofan engine noise control (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The technology of turbofan engine noise reduction is surveyed. Specific topics discussed include: (1) new fans for low noise; (2) fan and core noise suppression; (3) turbomachinery noise sources; and (4) a new program for improving static noise testing of fans and engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73734 , E-9254 , NOISE-CON 77; Oct 17, 1977 - Oct 19, 1977; Hampton, VA; United States
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  • 116
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    Measurement of far field combustion noise from a turbofan engine using coherence functions (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Coherence measurements between fluctuating pressure in the combustor of a YF-102 turbofan engine and far-field acoustic pressure were made. The results indicated that a coherent relationship between the combustor pressure and far-field existed only at frequencies below 250 Hz, with the peak occurring near 125 Hz. The coherence functions and the far-field spectra were used to compute the combustor-associated far-field noise in terms of spectra, directivity, and acoustic power, over a range of engine operating conditions. The acoustic results so measured were compared with results obtained by conventional methods, as well as with various semiempirical predictions schemes. Examination of the directivity patterns indicated a peak in the combustion noise near 120 deg (relative to the inlet axis).
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73748 , E-9320 , AIAA PAPER 77-1277 , Aeroacoustics Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
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  • 117
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    Steady-state unbalance response of a three-disk flexible rotor on flexible, damped supports (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Experimental data are presented for the unbalance response of a flexible, ball bearing supported rotor to speeds above the third lateral bending critical. Values of squeeze film damping coefficients obtained from measured data are compared to theoretical values obtained from short bearing approximation over a frequency range from 5000 to 31 000 cycles/min. Experimental response for an undamped rotor is compared to that of one having oil squeeze film dampers at the bearings. Unbalance applied varied from 0.62 to 15.1 gm-cm.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73666 , E-9091-1 , Vibrations Conf.; Sep 26, 1977 - Sep 29, 1977; Chicago
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    NASA TECHNICAL REPORTS
  • 118
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    Multimodal far-field acoustic radiation pattern: An approximate equation (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The far-field sound radiation theory for a circular duct was studied for both single mode and multimodal inputs. The investigation was intended to develop a method to determine the acoustic power produced by turbofans as a function of mode cut-off ratio. With reasonable simplifying assumptions the single mode radiation pattern was shown to be reducible to a function of mode cut-off ratio only. With modal cut-off ratio as the dominant variable, multimodal radiation patterns can be reduced to a simple explicit expression. This approximate expression provides excellent agreement with an exact calculation of the sound radiation pattern using equal acoustic power per mode.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73721 , Aeroacoustics Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
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    NASA TECHNICAL REPORTS
  • 119
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    Output feedback regulator design for jet engine control systems (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design procedure based on the output feedback regulator formulation is described and applied to turbofan engine model. Full order model dynamics, were incorporated in the example design. The effect of actuator dynamics on closed loop performance was investigaged. Also, the importance of turbine inlet temperature as an element of the dynamic feedback was studied. Step responses were given to indicate the improvement in system performance with this control. Calculation times for all experiments are given in CPU seconds for comparison purposes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73776 , Intern. Forum on Alternatives for Linear Multivariable Control; Oct 13, 1977 - Oct 14, 1977; Chicago
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  • 120
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    Progress in advanced high temperature turbine materials, coatings, and technology (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Material categories as well as coatings and recent turbine cooling developments are reviewed. Current state of the art is identified, and as assessment, when appropriate, of progress, problems, and future directions is provided.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73628 , Panel on Propulsion and Energetics; Sep 19, 1977 - Sep 23, 1977; Ankara
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  • 121
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    Advanced turboprop technology development (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The efficiency of high-speed turboprop propulsion systems is considered with emphasis on fuel savings. Specific topics discussed include: (1) high efficiency and low noise of propeller design; (2) fuselage noise attenuation; (3) propeller and gear box maintenance; and (4) engine-airframe integration.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73729 , E-9290 , Aircraft Systems and Technol. Meeting; Aug 22, 1977 - Aug 24, 1977; Seattle
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  • 122
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    Design of turbofan engine controls using output feedback regulator theory (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design procedure based on output feedback regulator (OFR) theory is applied to the F100 turbofan engine. Results for the OFR design are compared to a design based on linear quadratic regulator (LQR) theory. The OFR feedback control is designed in the full order state space and thus eliminates any need for model reduction techniques. Using the performance measure and control structure of the LQR design, an equivalent OFR feedback control is obtained. The flexibility of the OFR as a control design procedure is demonstrated, and differing feedback control structures are evaluated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73622 , E-9113 , Joint Automatic Control Conf.; Jun 22, 1977 - Jun 24, 1977; San Francisco
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  • 123
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    The application of the Routh approximation method to turbofan engine models (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Routh approximation technique is applied in the frequency domain to a 16th order state variable turbofan engine model. The results obtained motivate the extension of the frequency domain formulation of the Routh method to the time domain to handle the state variable formulation directly. The time domain formulation is derived, and a characterization, which specifies all possible Routh similarity transformations, is given. The characterization is computed by the solution of two eigenvalue eigenvector problems. The application of the time domain Routh technique to the state variable engine model is described, and some results are given.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73623 , E-9114 , Joint Autom. Control Conf.; Jun 22, 1977 - Jun 24, 1977; San Francisco
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  • 124
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    NASA Quiet Clean General Aviation Turbofan (QCGAT) program status (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The suitability of large engine technology to reduce noise, emissions, and fuel consumption of small turbine engines and develop new technology where required is determined. The design, fabrication, assembly, test, and delivery of the experimental engines to NASA are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73564 , E-9008 , Intern. Gas Turbine Conf.; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA; United States
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  • 125
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    Effect of endwall cooling on secondary flows in turbine stator vanes (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effect of endwall cooling on the secondary flow behavior and the aerodynamic performance of a core turbine stator vane was determined. The investigation was conducted in a cold-air, full-annular cascade, where three-dimensional effects were obtained. Two endwall cooling configurations were tested. In the first configuration, the cooling holes were oriented so that the coolant was injected in line with the inviscid streamline direction. In the second configuration, the coolant was injected at an angle of 15 deg to the inviscid streamline direction and oriented towards the vane pressure stator. In both cases the stator vanes were solid and uncooled so that the effect of endwall cooling was obtained directly. Total-pressure surveys were taken downstream of the stator vanes over a range of cooling flows at the design, mean-radius, critical velocity ratio of 0.778. Changes in the total-pressure contours downstream of the vanes were used to obtain the effect of endwall cooling on the secondary flows in the stator.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73568 , AGARD 49th Propulsion and Energetics Panel Conf.; Mar 28, 1977 - Apr 04, 1977; The Hague
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    NASA TECHNICAL REPORTS
  • 126
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    Core noise measurements on a YF-102 turbofan engine (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Core noise from a YF-102 high bypass ratio turbofan engine was investigated through the use of simultaneous measurements of internal fluctuating pressures and far field noise. Acoustic waveguide probes, located in the engine at the compressor exit, in the combustor, at the turbine exit, and in the core nozzle, were employed to measure internal fluctuating pressures. Spectra showed that the internal signals were free of tones, except at high frequency where machinery noise was present. Data obtained over a wide range of engine conditions suggest that below 60% of maximum fan speed the low frequency core noise contributes significantly to the far field noise.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73587 , E-9050 , Aerospace Sci. Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles
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    NASA TECHNICAL REPORTS
  • 127
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    Analysis and design of a high tip speed, low noise aircraft fan incorporating swept leading edge rotor and stator blades (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135092 , BBN-3332
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    NASA TECHNICAL REPORTS
  • 128
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    Application of polynomial techniques to multivariable control of jet engines (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper describes a complete case study of the application of the theory of minimal design to multivariable control of jet engines. The minimal-design problem is approached from the viewpoint of polynomial modules, and computational experience with PL/I and FORMAC-PL/I software is discussed. The complete minimal-design solution exhibits flexibilities not apparent in early industry studies, and a matrix approach to pole assignment can be used to advantage in this situation.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: International Symposium on Multivariable technological systems; Jul 04, 1977 - Jul 08, 1977; New Brunswick; Canada
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    NASA TECHNICAL REPORTS
  • 129
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    Direct-connect test of a hydrogen-fueled three-strut injector for an integrated modular scramjet engine (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The study aims at illustrating the effects of strut and injector interactions and strut wakes not totally simulated in previous, less complex, direct-connect hardware. In addition, the influence of the relative location of the injectors on opposite sides of each strut and the effect of injector spacing are evaluated. It is shown that better mixing efficiency is attained by locating the fuel injectors on opposite sides of a strut so that the jets come together, rather than being staggered, in the strut wake. It is not possible to determine the combustion efficiency by means of a one-dimensional analysis of the wall pressure.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Combustion Meeting; Aug 15, 1977 - Aug 17, 1977; Colorado Springs, CO
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  • 130
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    An empirical model for inverted-velocity-profile jet noise prediction (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An empirical model for predicting the noise from inverted-velocity-profile coaxial or coannular jets is presented and compared with small-scale static and simulated flight data. The model considered the combined contributions of as many as four uncorrelated constituent sources: the premerged-jet/ambient mixing region, the merged-jet/ambient mixing region, outer-stream shock/turbulence interaction, and inner-stream shock/turbulence interaction. The noise from the merged region occurs at relatively low frequency and is modeled as the contribution of a circular jet at merged conditions and total exhaust area, with the high frequencies attenuated. The noise from the premerged region occurs at high frequency and is modeled as the contribution of an equivalent plug nozzle at outer stream conditions, with the low frequencies attenuated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73838 , E-9425 , Meeting of the Acoustical Soc. of Am.; Dec 13, 1977 - Dec 16, 1977; Miami, FL; United States
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  • 131
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    The promise of eutectics for aircraft turbines (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The current status of the first generation eutectics, gamma/gamma transition - delta and NiTaC-13, is described in detail. Several second generation systems, such as gamma/gamma transition - alpha and NiTaC 3-116A, gamma - beta, and COTAC 74 are also reviewed with particular emphasis on their critical physical and mechanical properties, future research directions, and potential applications. Results of recent cost-benefit analyses of eutectic turbine blades are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73714 , E-9258 , Mater. Show and Conf.; Oct 25, 1977 - Oct 27, 1977; Chicago
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  • 132
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    Direct-connect tests of hydrogen-fueled supersonic combustors (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Direct-connect tests of hydrogen-fueled supersonic combustors were performed using arc-heated air at combustor inlet Mach numbers of 2.9 to 3.2. Various axisymmetric combustor geometries of 5.89 and 6.96 cm (inner diameter) inlet were investigated; the fuel was injected from the wall either from a ring of equally spaced holes normal to the air stream, or from a circumferential slot oriented 45 deg downstream. The hole-type injectors consistently gave better results. The effects of various parameters are examined, and the performance comparison procedure is described. A theoretical model of the supersonic combustion process which includes a precombustion shock-compression is used to explain the character of the observed pressure distributions and to assess the effects of the measured heat transfer rates, deduced wall shear, and combustor geometry on performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: International Symposium on Combustion; Aug 15, 1976 - Aug 20, 1976; Cambridge, MA
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  • 133
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    Composite hubs for low cost turbine engines (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A detailed stress analysis is performed using NASTRAN to demonstrate theoretically the adequacy of composite hubs for low cost turbine engine applications. The results show that composite hubs are adequate for this application from the steady state stress viewpoint.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Annual Conference on Discover reinforced plastics; Feb 08, 1977 - Feb 11, 1977; Washington, DC
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  • 134
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    Static performance of vectoring/reversing non-axisymmetric nozzles (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: An experimental program sponsored by the Air Force Flight Dynamics Laboratory is currently in progress to determine the internal and installed performance characteristics of five different thrust vectoring/reversing non-axisymmetric nozzle concepts for tactical fighter aircraft applications. Internal performance characteristics for the five non-axisymmetric nozzles and an advanced technology axisymmetric baseline nozzle were determined in static tests conducted in January 1977 at the NASA-Langley Research Center. The non-axisymmetric nozzle models were tested at thrust deflection angles of up to 30 degrees from horizontal at throat areas associated with both dry and afterburning power. In addition, dry power reverse thrust geometries were tested for three of the concepts. The best designs demonstrated internal performance levels essentially equivalent to the baseline axisymmetric nozzle at unvectored conditions. The best designs also gave minimum performance losses due to vectoring, and reverse thrust levels up to 50% of maximum dry power forward thrust. The installed performance characteristics will be established based on wind tunnel testing to be conducted at Arnold Engineering Development Center in the fall of 1977.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-840 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 135
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    Measured effects of coolant injection on the performance of a film cooled turbine (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Tests have been conducted on a 20-inch diameter single-stage air-cooled turbine designed to evaluate the effects of film cooling air on turbine aerodynamic performance. The present paper reports the results of five test configurations, including two different cooling designs and three combinations of cooled and solid airfoils. A comparison is made of the experimental results with a previously published analytical method of evaluating coolant injection effects on turbine performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-946 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 136
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    Aero-acoustic performance comparison of core engine noise suppressors on NASA quiet engine 'C' (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The purpose of the experimental program reported herein was to evaluate and compare the relative aero-acoustic effectiveness of two core engine suppressors, a contractor-designed suppressor delivered with the Quiet Engine, and a NASA-designed suppressor, designed and built subsequently. The NASA suppressor was tested with and without a splitter making a total of three configurations being reported in addition to the baseline hardwall case. The aerodynamic results are presented in terms of tailpipe pressure loss, corrected net thrust, and corrected specific fuel consumption as functions of engine power setting. The acoustic results are divided into duct and far-field acoustic data. The NASA-designed core suppressor did the better job of suppressing aft end noise, but the splitter associated with it caused a significant engine performance penalty. The NASA core suppressor without the splitter suppressed most of the core noise without any engine performance penalty.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-922 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 137
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    Atmospheric effects on inlets for supersonic cruise aircraft (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Time response effects of atmospheric-type disturbances on inlets and some implications regarding inlet controls are considered. A study involving the simulation of a mixed-compression inlet is described. The study employs a linear dynamic analysis, modified for a significant nonlinearity. Transient disturbances in ambient temperature and pressure and wind gusts are considered independently at the inlet cruise Mach number of 2.5. The presented results show the maximum amplitude of a triangular-wave disturbance, that does not cause inlet unstart, as a function of disturbance pulse width.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-874 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 138
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    Comparison of Estimated with Measured Maximum Instantaneous Distortion Using Flight Data from an Axisymmetric Mixed Compression Inlet (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: YF-12C flight-measured inlet dynamic distortion data are compared with predictions made on the basis of the method reported by Melick et al. (1976). The YF-12C aircraft is a twin engine aircraft capable of speeds above 3. The inlets have a translating spike to control the inlet throat area. A bypass system is used to control the terminal shock of the inlet for operation in the mixed compression mode. The dynamic data were obtained with the aid of 24 high frequency response total pressure sensors. The model of Melick et al. is discussed along with the computer program used to implement the model. It is found that the predictions of maximum instantaneous distortion are within 20 percent of the measured values, which had been obtained at Mach numbers of 1.8, 2.1, 2.5, and 3.0.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-876 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; United States
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  • 139
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    Comparison of axisymmetric and nonaxisymmetric nozzles installed on the F-15 configuration (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: An investigation has been conducted in the Langley 16-foot transonic tunnel to determine nozzle/afterbody performance of nonaxisymmetric nozzles installed in a 1/12-scale F-15 propulsion model. Tests were performed at Mach numbers from 0.60 to 1.20 at angles-of-attack from -2 to +9 deg and jet-total-pressure ratios from 1.0 (jet-off) to 5.0, depending on Mach number. The baseline F-15 afterbody was tested with axisymmetric nozzles, and two different two-dimensional wedge nozzle afterbody designs. Results of this investigation indicate that one of the two-dimensional afterbody designs had lower drag than the baseline at a Mach number of 1.20, and about the same drag for subsonic Mach numbers at scheduled nozzle pressure ratios. Thrust vectoring of the two-dimensional wedge nozzles produced significant induced lift on the afterbody and horizontal tails, while thrust reversing had little effect on horizontal tail effectiveness.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-842 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 140
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    Evaluation of an F100 multivariable control using a real-time engine simulation (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The control evaluated has been designed for the F100-PW-100 turbofan engine. The F100 engine represents the current state-of-the-art in aircraft gas turbine technology. The control makes use of a multivariable, linear quadratic regulator. The evaluation procedure employed utilized a real-time hybrid computer simulation of the F100 engine and an implementation of the control logic on the NASA LeRC digital computer/controller. The results of the evaluation indicated that the control logic and its implementation will be capable of controlling the engine throughout its operating range.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-835 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 141
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    Experimental investigations of thrust vectoring systems for VTOL aircraft (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: This paper presents a summary of two technology programs sponsored by NASA to investigate the characteristics of two thrust vectoring schemes for V/STOL aircraft. The operational capability of the VTOL aircraft is dependent on maximum utilization of the installed thrust in both the cruise and powered lift modes of flight. An effective thrust vectoring system on the cruise propulsion unit is therefore essential to provide maximum payload in hover and STOL plus minimum specific fuel consumption in loiter and cruise. Introducing a high by-pass ratio fan system, augmenting the gas generator thrust, as the propulsion system for VTOL aircraft places increased significance on the performance of the relatively short coupled thrust vectoring systems. The two programs discussed herein include both large-scale and small-scale tests of a vectoring hood system with a vented, internal-lip and swivel nozzle systems. These tests indicated that a satisfactory thrust vectoring system can be developed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-805 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 142
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    Fan inlet for a V/STOL airplane (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: An inlet was designed for a tilt nacelle lift/cruise fan. A complete set of low speed data was obtained with a 38-cm diameter cold-flow model, and a partial set of data was obtained with a 140-cm-diameter inlet coupled to a high bypass turbofan. The results indicate that a fixed-geometry inlet is a viable concept for the proposed application. Analyses of the data demonstrate that at high angles of incidence and at low airflow rates inlet-flow separation is strongly sensitive to Reynolds number and, consequently, the large-scale inlet has a significantly greater range of separation-free operation.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-802 , Propulsion Conference; Jul 11, 1977 - Jul 13, 1977; Orlando, FL; US
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  • 143
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    Design and performance of energy efficient propellers for Mach 0.8 cruise (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: It is believed that a fuel saving of 14 to 40 percent may be realized by the use of an advanced high-speed turboprop. This turboprop must be capable of high efficiency at Mach 0.8 cruise above 9.144 km altitude if it is to compete with turbofan powered commercial aircraft. Several advanced aerodynamic concepts were investigated in recent wind tunnel tests under NASA sponsorship on two propeller models. These concepts included aerodynamically integrated propeller/nacelles, area-ruling, blade sweep, reduced blade thickness and power (disk) loadings several times higher than conventional designs. The aerodynamic design methodology for these models is discussed in this paper. In addition, some of the preliminary test results are presented which indicate that propeller net efficiencies near 80 percent were obtained for high disk loading propellers operating at Mach 0.8.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 770458 , Business Aircraft Meeting; Mar 29, 1977 - Apr 01, 1977; Wichita, KS
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  • 144
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    Propeller design by numerical optimization (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A computer program designed to optimize propeller characteristics was developed by combining two main programs: the first is the optimization program based on the gradient algorithm; the second is based on a propeller blade element theory and uses an aerodynamics subprogram to approximate the lift and drag characteristics of the NACA 16-series airfoil section. To evaluate the propeller program alone (with its aerodynamics subprogram), propeller characteristics were computed and compared to those from wind tunnel investigations conducted on three different NACA propellers. Although the thrust and power coefficients which were computed using the blade element theory were generally higher than the experimental results for two of the three propellers, the corresponding efficiencies showed good agreement for all three propellers. The propeller optimization program was then used to study the NACA 4-(5)(08)-03 propeller at various Mach numbers from 0.175 to 0.60. Improvements in propeller efficiency and thrust were obtained through the use of the propeller optimization program.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 770451 , Business Aircraft Meeting; Mar 29, 1977 - Apr 01, 1977; Wichita, KS
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  • 145
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    A two-dimensional cascade solution using minimized surface singularity density distributions - with application to film cooled turbine blades (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An investigation of the effects of coolant injection on the aerodynamic performance of cooled turbine blades is presented. The coolant injection is modeled in the inviscid irrotational adiabatic flow analysis through the cascade using the distributed singularities approach. The resulting integral equations are solved using a minimized surface singularity density criteria. The aerodynamic performance was evaluated using this solution in conjunction with an existing mixing theory analysis. The results of the present analysis are compared with experimental measurements in cold flow tests.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-715 , Conference on Fluid and Plasmadynamics; Jun 27, 1977 - Jun 29, 1977; Albuquerque, NM
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  • 146
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    V/STOL shaft propulsion system analytical performance model (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Several classes of system performance simulations of V/STOL propulsion systems are presented. A digital simulation approach for a typical system (a propulsion system made up of three engines, shafts and gearbox, and remote lift fan) is given with a description of the general philosophy, solution options and model flexibility.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-582 , V/STOL Conference; Jun 06, 1977 - Jun 08, 1977; Palo Alto, CA
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  • 147
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    Altitude engine test of a turbofan exhaust gas mixer to conserve fuel (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A comparison of the specific fuel consumption was made with and without an internal mixer installed in a low bypass ratio, confluent flow turbofan engine. Tests were conducted at several Mach numbers and altitudes for core to fan stream total temperature ratios of 2.0 and 2.5 and mixing lengths of L/D = 0.95 and 1.74. For these test conditions, the specific fuel consumption improvement varied from 2.5 to 4.0 percent.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 77-GT-97 , Gas Turbine Conference and Products Show; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA
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  • 148
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    Static and flyover noise measurements of an inverted profile exhaust jet (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Tests using a TF30 mixed flow afterburning turbofan engine in an F-111 airplane were conducted to study the noise characteristics of an inverted velocity profile jet. Full-authority digital engine control allowed the inverted profile jet to be compared to a uniform jet of equal thrust statically and in flight. An exhaust velocity survey showed that the ratio of the outer to inner stream velocities was 1.37; therefore, only small noise reductions were expected. At static conditions, the inverted profile jet was approximately 3 decibels quieter than the uniform jet at peak noise angles. During a flyover it was approximately 1 decibel quieter.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 77-GT-81 , Gas Turbine Conference and Products Show; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA
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  • 149
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    Fan inlet disturbances and their effect on static acoustic data (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: There is evidence that measurements of fan-rotor inlet noise taken during static test situations are at variance with aircraft engine flight data. In particular, static tests generally yield a significantly higher tone at blade passing frequency than that measured during flight. An experimental program was carried out to investigate this discrepancy. Inlet ground vortices and large-scale inlet turbulence were generated intentionally in an anechoic test chamber. Far-field acoustic measurements and inlet flow field hot film mappings of a fan rotor were then carried out to study the influence of such inlet disturbances at a static test facility. Experimental results indicate that the acoustic effect of such disturbances appears to be less severe for supersonic than for subsonic tip speeds. Further, a reverse flow that occurs on the exterior cowl in static test facilities appears to be an additional prime candidate for creating inlet disturbances and causing variance between flight and static acoustic data.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 77-GT-63 , Gas Turbine Conference and Products Show; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA
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  • 150
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    Computation of the temperature distribution in cooled radial inflow turbine guide vanes (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A two-dimensional finite-difference numerical technique is presented to determine the temperature distribution of an internally-cooled blade of radial turbine guide vanes. A simple convection cooling is assumed inside the guide vane. Such an arrangement results in relatively small cooling effectiveness at the leading edge and at the trailing edge. Heat transfer augmentation in these critical areas may be achieved by using impingement jets and film cooling. A computer program is written in Fortran IV for IBM 370/165 computer.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 77-GT-83 , Gas Turbine Conference and Products Show; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA
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  • 151
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    Optical detection of blade flutter (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The paper examines the capabilities of photoelectric scanning (PES) and stroboscopic imagery (SI) as optical monitoring tools for detection of the onset of flutter in the fan blades of an aircraft gas turbine engine. Both optical techniques give visual data in real time as well as video-tape records. PES is shown to be an ideal flutter monitor, since a single cathode ray tube displays the behavior of all the blades in a stage simultaneously. Operation of the SI system continuously while searching for a flutter condition imposes severe demands on the flash tube and affects its reliability, thus limiting its use as a flutter monitor. A better method of operation is to search for flutter with the PES and limit the use of SI to those times when the PES indicates interesting blade activity.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 77-GT-66 , Gas Turbine Conference and Products Show; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA
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  • 152
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    Jet noise source modification due to forward flight (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The effects of forward flight on the turbulence characteristics of a jet in a co-flowing stream have been determined for a 2.22 inch circular jet in a 36 inch free jet wind tunnel. The nozzle exit velocity was 400 ft/sec, and the tunnel velocity was set at 0, 40, 120 and 200 ft/sec. Measurements of flow properties including mean velocity, turbulence intensity and spectra, convection velocity, integral length scale, and convected integral time scale were carried out using two linearized hot wires. Results were used to predict changes due to flight in the jet acoustic sources. The noise reductions for a cold jet with a velocity of 1000 ft/sec, due to the change in acoustic sources in flight, agreed well at all angles with measured noise reductions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-58 , Aerospace Sciences Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles, CA
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  • 153
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    Heat transfer in cooled guide vanes (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A numerical study to determine the temperature distribution in the guide vanes of a radial inflow turbine is presented. A computer program has been developed to calculate the temperature distribution when the vanes are cooled internally using a combination of impingement and film cooling techniques. The study is based on the use of the finite difference method in a two dimensional heat conduction problem. The results are then compared to determine the best cooling configuration for a certain coolant to primary mass flow ratio.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-200 , Aerospace Sciences Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles, CA
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  • 154
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    An investigation of combustion and entropy noise (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The relative importance of entropy and direct combustion noise in turbopropulsion systems and the parameters upon which these noise sources depend were studied. Theory and experiment were employed to determine that at least with the apparatus used here, entropy noise can dominate combustion noise if there is a sufficient pressure gradient terminating the combustor. Measurements included combustor interior fluctuating pressure, near and far field fluctuating pressure, and combustor exit plane fluctuating temperatures, as well as mean pressures and temperatures. Analysis techniques included spectral, cross-correlation, cross power spectra, and ordinary and partial coherence analysis. Also conducted were combustor liner modification experiments to investigate the origin of the frequency content of combustion noise. Techniques were developed to extract nonpropagational pseudo-sound and the heat release fluctuation spectra from the data.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135220
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  • 155
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    Improved high pressure turbine shroud (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A new high pressure turbine shroud material has been developed from the consolidation of prealloyed powders of Ni, Cr, Al and Y. The new material, a filler for cast turbine shroud body segments, is called Genaseal. The development followed the identification of oxidation resistance as the primary cause of prior shroud deterioration, since conversion to oxides reduces erosion resistance and increases spalling under thermal cycled engine conditions. The NICrAlY composition was selected in preference to NIAL and FeCRALY alloys, and was formulated to a prescribed density range that offers suitable erosion resistance, thermal conductivity and elastic modulus for improved behavior as a shroud.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135181 , R77AEG481
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  • 156
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    Minimum-time acceleration of aircraft turbofan engines (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Minimum-time accelerations of the F100 turbofan engine are presented. A piecewise-linear engine model, having three state variables and four control variables, is used to obtain the minimum-time solutions. The linear model which applies at a given time in the trajectory is determined by calculating a normalized distance from the current state to the equilibrium state associated with each linear model. The linear model associated with the closest equilibrium point is then used. The control histories for the minimum-time solutions are used as input to a nonlinear simulation of the F100 engine to verify the accuracy of the piecewise linear solutions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73624 , E-9115 , Joint Automatic Control Conf.; Jun 22, 1977 - Jun 24, 1977; San Francisco
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  • 157
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    Analysis of control concepts for gas and shaft-coupled V/STOL aircraft lift fan systems (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: For lift-fan powered V/STOL aircraft, two unconventional propulsion system types were proposed. The first type uses fans connected by hot gas ducting, and the second type uses fans connected by cross shafting. An analytical study identified the basic steady-state and dynamic characteristics for each type of system. For the gas-coupled system, the control concepts analyzed were variable-area fan turbines and throttling valves in the ducting. For the shaft-coupled system, the control concepts analyzed were variable-pitch fans and variable fan inlet guide vanes. All of these concepts are capable of meeting V/STOL aircraft control moment and transient response requirements when appropriate propulsion controls are used.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73611 , E-9094 , V/STOL Conf.; Jun 06, 1977 - Jun 08, 1977; Palo Alto, CA; United States
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  • 158
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    An Investigation of the Aerodynamics and Cooling of a Horizontally-Opposed Engine Installation (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A research program to investigate the aerodynamics of reciprocating aircraft engine cooling installations is discussed. Current results from a flight test program are presented concerning installation flow measurement methods. The influence of different inlet designs on installation cooling effectiveness and efficiency are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-152734 , SAE Business Aircraft Meeting, Century 2; Mar 29, 1977 - Apr 01, 1977; Wichita, KS; United States
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  • 159
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    Optical Detection of Blade Flutter (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Dynamic strain gages mounted on rotor blades are used as the primary instrumentation for detecting the onset of flutter and defining the vibratory mode and frequency. Optical devices are evaluated for performing the same measurements as well as providing supplementary information on the vibratory characteristics. Two separate methods are studied: stroboscopic imagery of the blade tip and photoelectric scanning of blade tip motion. Both methods give visual data in real time as well as video tape records. The optical systems are described, and representative results are presented. The potential of this instrumentation in flutter research is discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73573 , E-9022 , Intern. Turbine Conf.; Mar 27, 1977 - Mar 31, 1977; Philadelphia
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  • 160
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    Design and performance of energy efficient propellers for Mach 0.8 cruise (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The increased emphasis on fuel conservation in the world has stimulated a series of studies of both conventional and unconventional propulsion systems for commercial aircraft. Preliminary results from these studies indicate that a fuel saving of 14 to 40 percent may be realized by the use of an advanced high-speed turboprop. This turboprop must be capable of high efficiency at Mach 0.8 cruise above 9.144 km altitude if it is to compete with turbofan powered commercial aircraft. Several advanced aerodynamic concepts were investigated in recent wind tunnel tests under NASA sponsorship on two propeller models. These concepts included aerodynamically integrated propeller/nacelles, area ruling, blade sweep, reduced blade thickness and power (disk) loadings several times higher than conventional designs. The aerodynamic design methodology for these models is discussed. In addition, some of the preliminary test results are presented which indicate that propeller net efficiencies near 80 percent were obtained for high disk loading propellers operating at Mach 0.8.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73612 , E-9095 , SAE-PAPER-770458 , 1977 Natl. Business Aircraft Meeting and Exposition; Mar 29, 1977 - Apr 01, 1977; Wichita
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  • 161
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    Preliminary design study of advanced multistage axial flow core compressors (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A preliminary design study was conducted to identify an advanced core compressor for use in new high-bypass-ratio turbofan engines to be introduced into commercial service in the 1980's. An evaluation of anticipated compressor and related component 1985 state-of-the-art technology was conducted. A parametric screening study covering a large number of compressor designs was conducted to determine the influence of the major compressor design features on efficiency, weight, cost, blade life, aircraft direct operating cost, and fuel usage. The trends observed in the parametric screening study were used to develop three high-efficiency, high-economic-payoff compressor designs. These three compressors were studied in greater detail to better evaluate their aerodynamic and mechanical feasibility.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135133 , R77AEG222
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  • 162
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    Composite hubs for low cost gas turbine engines (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A detailed stress analysis was performed using NASTRAN to demonstrate theoretically the adequacy of composite hubs for low cost turbine engine applications. Composite hubs are adequate for this application from the steady state stress view point.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73578 , E-9038 , Annual Conf. of the Reinforced Plastics of Composites Inst.; Feb 08, 1977 - Feb 11, 1977; Washington, DC; United States
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  • 163
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    Flap noise and aerodynamic results for model QCSEE over-the-wing configurations (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Noise spectra in three dimensions and aerodynamic data were measured for a model of the NASA quiet clean short-haul experimental engine (QCSEE) over-the-wing configuration. The effects of flap length, nozzle exhaust velocity, and nozzle geometry were determined using a single nozzle and wing-flap segment. The scaled-up model data is representative of full scale flap noise with the QCSEE engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73588 , E-9051 , Aerospace Sci. Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles
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  • 164
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    Prediction of Laminar and Turbulent Boundary Layer Flow Separation in V/STOL Engine Inlets (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A description is presented of the development of the boundary layer on the lip and diffuser surface of a subsonic inlet at arbitrary operating conditions of mass flow rate, free stream velocity and incidence angle. Both laminar separation on the lip and turbulent separation in the diffuser are discussed. The agreement of the theoretical results with model experimental data illustrates the capability of the theory to predict separation. The effects of throat Mach number, inlet size, and surface roughness on boundary layer development and separation are illustrated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73575 , E-9028 , Aerospace Sci. Conf.; Jan 24, 1977 - Jan 26, 1977; Los Angeles
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  • 165
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    Computer program for the analysis of the cross flow in a radial inflow turbine scroll (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A computer program was used to solve the governing of the potential flow in the cross sectional planes of a radial inflow turbine scroll. A list of the main program, the subroutines, and typical output example are included.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135321
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  • 166
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    Cost benefit study of advanced materials technology for aircraft turbine engines (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The cost/benefits of eight advanced materials technologies were evaluated for two aircraft missions. The overall study was based on a time frame of commercial engine use of the advanced material technologies by 1985. The material technologies evaluated were eutectic turbine blades, titanium aluminide components, ceramic vanes, shrouds and combustor liners, tungsten composite FeCrAly blades, gamma prime oxide dispersion strengthened (ODS) alloy blades, and no coat ODS alloy combustor liners. They were evaluated in two conventional takeoff and landing missions, one transcontinental and one intercontinental.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135235
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  • 167
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    Advanced supersonic propulsion study, phase 4 (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Installation characteristics for a Variable Stream Control Engine (VSCE) were studied for three advanced supersonic airplane designs. Sensitivity of the VSCE concept to change in technology projections was evaluated in terms of impact on overall installed performance. Based on these sensitivity results, critical technology requirements were reviewed, resulting in the reaffirmation of the following requirements: low-noise nozzle system; a high performance, low emissions duct burner and main burner; hot section technology; variable geometry components; and propulsion integration features, including an integrated electronic control system.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135273 , PWA-5547-4
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  • 168
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    Rotor burst protection program: Experimentation to provide guidelines for the design of turbine rotor burst fragment containment rings (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Empirical guidelines for the design of minimum weight turbine rotor disk fragment containment rings made from a monolithic metal were generated by experimentally establishing the relationship between a variable that provides a measure of containment ring capability and several other variables that both characterized the configurational aspects of the rotor fragments and containment ring, and had been found from exploratory testing to have had significant influence on the containment process. Test methodology and data analysis techniques are described. Results are presented in graphs and tables.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 107-149
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  • 169
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    An investigation of temperature distribution in cooled guide vanes (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A numerical study to determine the temperature distribution in the guide vane blades of a radial inflow turbine is presented. A computer program was developed which permits the temperature distribution to be calculated when the blade is cooled internally using a combination of impingement and film cooling techniques. The study is based on the use of the finite difference method in a two dimensional heat conduction problem. The results are then compared to determine the best cooling configuration for a certain coolant to primary mass flow ratio.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-152048
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  • 170
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    Identification of Spey engine dynamics in the augmentor wing jet STOL research aircraft from flight data (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The development and validation of a spey engine model is described. An analysis of the dynamical interactions involved in the propulsion unit is presented. The model was reduced to contain only significant effects, and was used, in conjunction with flight data obtained from an augmentor wing jet STOL research aircraft, to develop initial estimates of parameters in the system. The theoretical background employed in estimating the parameters is outlined. The software package developed for processing the flight data is described. Results are summarized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-152054
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  • 171
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    Noise characteristics of upper surface blown configurations. Experimental program and results (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental data base was developed from the model upper surface blowing (USB) propulsive lift system hardware. While the emphasis was on far field noise data, a considerable amount of relevant flow field data were also obtained. The data were derived from experiments in four different facilities resulting in: (1) small scale static flow field data; (2) small scale static noise data; (3) small scale simulated forward speed noise and load data; and (4) limited larger-scale static noise flow field and load data. All of the small scale tests used the same USB flap parts. Operational and geometrical variables covered in the test program included jet velocity, nozzle shape, nozzle area, nozzle impingement angle, nozzle vertical and horizontal location, flap length, flap deflection angle, and flap radius of curvature.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-145143 , LG77ER0198
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  • 172
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    Attenuation of upstream-generated low frequency noise by gas turbines (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The acoustic transfer functions of low frequency (below 3500 Hz) noise through aircraft turbines were investigated. Model test results were compared with theoretical predictions in order to assess the validity of the theory. Component tests were conducted on both high pressure and low pressure model turbines. The influence of inlet temperature and turbine speed attenuation was evaluated, while the effects of turbine pressure ratio, blade-row choking, and additional downstream stages were determined. Preliminary identification of pertinent aeroacoustic correlating parameters was made.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135219 , R77AEG482
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  • 173
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    Experimental investigation of a swept-strut fuel-injector concept for scramjet application (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Results are presented of an experiment to investigate the behavior at Mach 4 flight conditions of the swept-strut fuel-injector concept employed in the Langley integrated modular scramjet engine design. Autoignition of the hydrogen fuel was not achieved at stagnation temperatures corresponding to a flight Mach number of 4; however, once ignition was achieved, stable combustion was maintained. Pressure disturbances upstream of the injector location, which were caused by fuel injection and combustion, were generally not observed; this indicates the absence of serious adverse combustor-inlet interactions. Mixing performance and reaction performance determined from probe surveys and wall pressure data indicate that high combustion efficiency should be obtained with the combustor length provided in the scramjet engine design. No adverse interaction between the perpendicular and parallel fuel-injection modes was observed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TN-D-8454 , L-11050
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  • 174
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    Dual cycle aircraft turbine engine (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method and apparatus are presented for improving operating efficiency over broad ranges of flight conditions and for reducing jet engine noise output in takeoff and landing by controlling the airflow entering and exiting the engines. A turbojet engine apparatus is described which operates efficiently at both subsonic and supersonic speeds and a method is described which enables a turbofan with an associated satellite turbojet or turbofan to operate more efficiently at both subsonic and supersonic speeds. In both cases, takeoff and landing noise is reduced substantially. The apparatus consists essentially of arranging for two separate portions of an engine to act upon one airstream or, alternately, to operate on independent airstreams.
    Keywords: AIRCRAFT PROPULSION AND POWER
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  • 175
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    Analysis and documentation of QCSEE (Quiet Clean Short-haul Experimental Engine) over-the-wing exhaust system development (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A static scale model test program was conducted in the static test area of the NASA-Langley 9.14- by 18.29 m(30- by 60-ft) Full-Scale Wind Tunnel Facility to develop an over-the-wing (OTW) nozzle and reverser configuration for the Quiet Clean Short-Haul Experimental Engine (QCSEE). Three nozzles and one basic reverser configuration were tested over the QCSEE takeoff and approach power nozzle pressure ratio range between 1.1 and 1.3. The models were scaled to 8.53% of QCSEE engine size and tested behind two 13.97-cm (5.5-in.) diameter tip-turbine-driven fan simulators coupled in tandem. An OTW nozzle and reverser configuration was identified which satisfies the QCSEE experimental engine requirements in terms of nozzle cycle area variation capability and reverse thrust level, and provides good jet flow spreading over a wing upper surface for achievement of high propulsive lift performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-2792 , R76AEG407
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  • 176
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    Preliminary study of a hydrogen peroxide rocket for use in moving source jet noise tests (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A preliminary investigation was made of using a hydrogen peroxide rocket to obtain pure moving source jet noise data. The thermodynamic cycle of the rocket was analyzed. It was found that the thermodynamic exhaust properties of the rocket could be made to match those of typical advanced commercial supersonic transport engines. The rocket thruster was then considered in combination with a streamlined ground car for moving source jet noise experiments. When a nonthrottlable hydrogen peroxide rocket was used to accelerate the vehicle, propellant masses and/or acceleration distances became too large. However, when a throttlable rocket or an auxiliary system was used to accelerate the vehicle, reasonable propellant masses could be obtained.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73678 , E-9210
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  • 177
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    Blade retainer assembly (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A retaining assembly is provided for locking radially extending blades in a rotor disc associated with a gas turbine engine. The assembly includes a pair of spaced apart lugs axially extending from one side of the disc to form an access gap for insertion of a blade tang into a dovetail slot in the rotor disc. A pair of axially aligned inwardly facing recesses are disposed in the lugs. A retaining member resides in the recesses and extends across the gap to preclude egress of the blade tang from the dovetail slot. The retaining member includes at least one axially extending protrusion adapted to radially overlap and abuttingly engage a radially inwardly facing abutment surface on the lugs.
    Keywords: AIRCRAFT PROPULSION AND POWER
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  • 178
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    Preliminary design of propulsion system for V/STOL research and technology aircraft (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The V/STOL Research and Technology Aircraft (RTA)propulsion system design effort is limited to components of the lift/cruise engines, turboshaft engine modifications, lift fan assembly, and propulsion system performance generation. The uninstalled total net thrust with all engines and fans operating at intermediate power was 37,114 pounds. Uninstalled system total net thrust was 27,102 pounds when one lift/cruise is inoperative. Components have lives above the 500 hours of the RTA duty cycle. The L/C engine used in a fixed nacelle has the cross shaft forward of the reduction gear whereas the cross shaft is aft of the reduction gear in a tilt nacelle L/C engine. The lift/cruise gearbox contains components and technologies from other DDA engines. The rotor has a 62-inch diameter and contains 22 composite blades that have a hub/tip ratio of 0.454. The blade pitch change mechanism contains hydraulic and mechanical redundancy. The lift fan assembly is completely self-contained including oil cooling in 10 exit vanes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135207 , DDA-EDR-9082
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  • 179
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    Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow base line and suppressor nozzles. Summary report (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A test program was conducted in the Boeing large anechoic test chamber and the NASA-Ames 40- by 80-foot wind tunnel to study the near- and far-field jet noise characteristics of six baseline and suppressor nozzles. Static and wind-on noise source locations were determined. A technique for extrapolating near field jet noise measurements into the far field was established. It was determined if flight effects measured in the near field are the same as those in the far field. The flight effects on the jet noise levels of the baseline and suppressor nozzles were determined. Test models included a 15.24-cm round convergent nozzle, an annular nozzle with and without ejector, a 20-lobe nozzle with and without ejector, and a 57-tube nozzle with lined ejector. The static free-field test in the anechoic chamber covered nozzle pressure ratios from 1.44 to 2.25 and jet velocities from 412 to 594 m/s at a total temperature of 844 K. The wind tunnel flight effects test repeated these nozzle test conditions with ambient velocities of 0 to 92 m/s.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-2841 , D6-44121-3
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  • 180
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    Static, noise, and transition tests of a combined-surface-blowing V/STOL lift/propulsion system (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Efficient thrust vectoring and high levels of circulatory lift were obtained in tests of a half model V/STOL airplane by using a type of externally blown jet flap in which the jet exhaust from wing-mounted cruise fans is directed over both upper and lower surfaces of a flapped wing. Approximately 90% thrust recovery with 87 deg of thrust vectoring was achieved under static conditions using 89 deg of trailing edge flap deflection. The approximately 10% loss appears to be associated primarily with pressure losses due to the flap brackets or slot entries. The jet induced lift was shown to be 55% of the theoretical value for a fullspan jet-flapped wing, even though only 27.5% of the wingspan was immersed in the jet. Steady rate of descent capability in excess of 1,000 feet per minute is predicted. The possibility of significant aerodynamic-noise cancelling when blowing over both surfaces at high velocities is indicated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-151954 , D210-11175-1
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  • 181
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    Boron/aluminum fan blades for SCAR engines (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Processing procedures were developed to enhance boron/aluminum bond behavior and foreign object damage (FOD) tolerance. Design and analysis indicated that the J101 Stage 1 fan blade meets the required frequencies without a midspan shroud. The fabricability of full size J101 blades was assessed, while six blades were fabricated and finished machined.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135184
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  • 182
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    Experimental apparatus for investigation of fan aeroelastic instabilities in turbomachinery (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The application, installation, and monitoring of dynamic strain gage instrumentation on the rotating fan blades for subsonic stalled flutter mode of the first fan rotor are described. The engine installation, the modifications to the engine controls to obtain off schedule operation of the fan, engine aerodynamic instrumentation, and general data acquisition systems are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3508 , E-9088
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  • 183
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    A method to estimate weight and dimensions of aircraft gas turbine engines. Volume 3: Programmer's manual (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: For abstract, see N77-25171.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135172 , D6-44258-VOL-3
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  • 184
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    A method to estimate weight and dimensions of aircraft gas turbine engines. Volume 2: User's manual (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: For abstract, see N77-25171.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135171 , D6-44258-VOL-2
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  • 185
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    A method to estimate weight and dimensions of aircraft gas turbine engines. Volume 1: Method of analysis (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Weight and envelope dimensions of aircraft gas turbine engines are estimated within plus or minus 5% to 10% using a computer method based on correlations of component weight and design features of 29 data base engines. Rotating components are estimated by a preliminary design procedure where blade geometry, operating conditions, material properties, shaft speed, hub-tip ratio, etc., are the primary independent variables used. The development and justification of the method selected, the various methods of analysis, the use of the program, and a description of the input/output data are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135170 , D6-44258-VOL-1
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  • 186
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    Noise of fan designed to reduce stator lift fluctuations (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An existing fan stage was redesigned to reduce stator lift fluctuations and was acoustically tested at three nozzle sizes for reduced noise generation. The lift fluctuations on the stator were reduced by increasing the stator cord, adjusting incidence angles, and adjusting the rotor velocity diagrams. Broadband noise levels were signficantly reduced in the middle to high frequencies. Blade passage tone sound power was not lessened, but decreases in the harmonics were observed. Aerodynamic improvements in both performance and efficiency were obtained.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3538 , E-8986
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  • 187
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    Performance of high-area-ratio annular dump diffuser using suction-stabilized-vortex flow control (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A short annular dump diffuser having a geometry conductive to formation of suction stabilized toroidal vortices in the region of abrupt area change was tested. The overall diffuser area ratio was 4.0 and the length to inlet height ratio was 2.0. Performance data were obtained at near ambient temperature and pressure for inlet Mach numbers of 0.18 and 0.30 with suction rates ranging from 0 to 18 percent of total inlet mass flowrate. Results show that the exit velocity profile could be readily biased toward either wall by adjustment of inner and outer wall suction rates. Symmetric exit velocity profiles were inherently unstable with a tendency to revert to a hub or tip bias. Diffuser effectiveness was increased from about 38 percent without suction to over 85 percent at a total suction rate of 10 to 12 percent. At the same time diffuser total pressure loss was reduced from 3.1 percent to 1.1 percent at an inlet Mach number of 0.3.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3535 , E-9011
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  • 188
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    Analytical prediction of the performance and stability of a J85-13 compressor with distorted inlet flow (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The parallel compressor concept was studied using a compressor model based on the overall clean-inlet performance map obtained from experimental tests in an altitude chamber using a General Electric J85-13 turbojet engine. The model, which includes a static-pressure balance calculation at compressor discharge, was exercised at conditions corresponding to 10 different screen-induced distortion patterns included in the experimental data base. The spoiled area of these patterns ranged from 30 deg to 180 deg, and the distortion screen density, or the area blocked by the screen wire per unit area of screen, varied from 26 to 69 percent. The study indicates that at the higher corrected speeds, the analytical surge lines obtained are good representations of the corresponding experimental surge lines and are independent of distortion angle or distortion angle or distortion level.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3515 , E-8887
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  • 189
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    Inlet Reynolds number and temperature effects on the steady-state performance of a TFE731-2 turbofan engine (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Effects of varying engine inlet Reynolds number index (0.75, 0.50, 0.25, and 0.12) and temperature (289 and 244 K) on a TFE731-2 turbofan engine were evaluated. Results were classified as either compression system effects or effects on overall performance. Standard performance maps are used to present compression system performance. Overall performance parameters are presented as a function of low rotor speed corrected to engine inlet temperature.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3537 , E-8941
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    NASA TECHNICAL REPORTS
  • 190
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    Interior and exterior fuselage noise measured on NASA's C-8a augmentor wing jet-STOL research aircraft (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Interior and exterior fuselage noise levels were measured on NASA's C-8A Augmentor Wing Jet-STOL Research Aircraft in order to provide design information for the Quiet Short-Haul Research Aircraft (QSRA), which will use a modified C-8A fuselage. The noise field was mapped by 11 microphones located internally and externally in three areas: mid-fuselage, aft fuselage, and on the flight deck. Noise levels were recorded at four power settings varying from takeoff to flight idle and were plotted in one-third octave band spectra. The overall sound pressure levels of the external noise field were compared to previous tests and found to correlate well with engine primary thrust levels. Fuselage values were 145 + or - 3 dB over the aircraft's normal STOL operating range.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73235 , A-7012
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 191
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    Preliminary studies of autoignition and flashback in a premixing-prevaporizing flame tube using Jet-A fuel at lean equivalence ratios (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Lean equivalence ratios from 0.3 to 0.7 were observed. Combustor inlet air pressures were varied from 0.54 to 2.5 MPa, combustor inlet air temperatures from 550 to 700 K, and reference velocities from 8 to 35 meters per second. Autoignition delay times ranged from 15 to 100 milliseconds and varied inversely with pressure. The Arrhenius activation energy was 41,840 joules per mole. Temperature rise data were obtained in a long premixing-prevaporizing tube at a pressure of 0.56 MPa. Preflame temperature rise data were a function of equivalence ratio, inlet air temperature, and tube residence time. Significant temperature rise occurred above temperatures of 760 K, with autoignition occurring at 775 K for equivalence ratios greater than 0.47. The reactions were similar to cool-flame phenomena. Flashback velocities were measured at temperatures of 610 and 700 K, pressure of 0.56 MPa, and equivalence ratios from 0.6 to 1. Flashback velocities varied from 30 to 65 meters per second.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3526 , E-9039
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 192
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    Application of differential similarity to finding nondimensional groups important in tests of cooled engine components (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The method of differential similarity is applied to the partial differential equations and boundary conditions which govern the temperature, velocity, and pressure fields in the flowing gases and the solid stationary components in air-cooled engines. This procedure yields the nondimensional groups which must have the same value in both the test rig and the engine to produce similarity between the test results and the engine performance. These results guide the experimentalist in the design and selection of test equipment that properly scales quantities to actual engine conditions. They also provide a firm fundamental foundation for substantiation of previous similarity analyses which employed heuristic, physical reasoning arguments to arrive at the nondimensional groups.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3484 , E-8943
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 193
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    Definition of propulsion system for V/STOL research and technology aircraft (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Wind tunnel test support, aircraft contractor support, a propulsion system computer card deck, preliminary design studies, and propulsion system development plan are reported. The Propulsion system consists of two lift/cruise turbofan engines, one turboshaft engine and one lift fan connected together with shafting into a combiner gearbox. Distortion parameter levels from 40 x 80 test data were within the established XT701-AD-700 limits. The three engine-three fan system card deck calculates either vertical or conventional flight performance, installed or uninstalled. Design study results for XT701 engine modifications, bevel gear cross shaft location, fixed and tilt fan frames and propulsion system controls are described. Optional water-alcohol injection increased total net thrust 10.3% on a 90 F day. Engines have sufficient turbine life for 500 hours of the RTA duty cycle.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135161 , EDR-9020
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 194
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    Numerical solution for the temperature distribution in a cooled guide vane blade of a radial gas turbine (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A two dimensional finite difference numerical technique is presented to determine the temperature distribution of an internal cooled blade of radial turbine guide vanes. A simple convection cooling is assumed inside the guide vane blade. Such cooling has relatively small cooling effectiveness at the leading edge and at the trailing edge. Heat transfer augmentation in these critical areas may be achieved by using impingement jets and film cooling. A computer program is written in FORTRAN IV for IBM 370/165 computer.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-137943
    Format: application/pdf
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  • 195
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    A numerical study of the temperature field in a cooled radial turbine rotor (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The three dimensional temperature distribution in the cooled rotor of a radial inflow turbine is determined numerically using the finite element method. Through this approach, the complicated geometries of the hot rotor and coolant passage surfaces are handled easily, and the temperatures are determined without loss of accuracy at these convective boundaries. Different cooling techniques with given coolant to primary flow ratios are investigated, and the corresponding rotor temperature fields are presented for comparison.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-137951
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    NASA TECHNICAL REPORTS
  • 196
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    A study of the optimization method used in the NAVY/NASA gas turbine engine computer code (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Sources of numerical noise affecting the convergence properties of the Powell's Principal Axis Method of Optimization in the NAVY/NASA gas turbine engine computer code were investigated. The principal noise source discovered resulted from loose input tolerances used in terminating iterations performed in subroutine CALCFX to satisfy specified control functions. A minor source of noise was found to be introduced by an insufficient number of digits in stored coefficients used by subroutine THERM in polynomial expressions of thermodynamic properties. Tabular results of several computer runs are presented to show the effects on program performance of selective corrective actions taken to reduce noise.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135180 , AMA-77-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 197
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    Analytical screening of low emissions, high performance duct burners for supersonic cruise aircraft engines (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analytical screening study was conducted to identify duct burner concepts capable of providing low emissions and high performance in advanced supersonic engines. Duct burner configurations ranging from current augmenter technology to advanced concepts such as premix-prevaporized burners were defined. Aerothermal and mechanical design studies provided the basis for screening these configurations using the criteria of emissions, performance, engine compatibility, cost, weight and relative risk. Technology levels derived from recently defined experimental low emissions main burners are required to achieve both low emissions and high performance goals. A configuration based on the Vorbix (Vortex burning and mixing) combustor concept was analytically determined to meet the performance goals and is consistent with the fan duct envelope of a variable cycle engine. The duct burner configuration has a moderate risk level compatible with the schedule of anticipated experimental programs.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135157 , PWA-5489
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 198
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    Ultra high tip speed (670.6 m/sec) fan stage with composite rotor: Aerodynamic and mechanical design (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A highly loaded, single-stage compressor having a tip speed of 670.6 m/sec was designed for the purpose of investigating very high tip speeds and high aerodynamic loadings to obtain high stage pressure ratios at acceptable levels of efficiency. The design pressure ratio is 2.8 at an adiabatic efficiency of 84.4%. Corrected design flow is 83.4 kg/sec; corrected design speed is 15,200 rpm; and rotor inlet tip diameter is 0.853 m. The rotor uses multiple-circular-arc airfoils from 0 to 15% span, precompression airfoils assuming single, strong oblique shocks from 21 to 43% span, and precompression airfoils assuming multiple oblique shocks from 52% span to the tip. Because of the high tip speeds, the rotor blades are designed to be fabricated of composite materials. Two composite materials were investigated: Courtaulds HTS graphite fiber in a Kerimid 601 polyimide matrix and the same fibers in a PMR polyimide matrix. In addition to providing a description of the aerodynamic and mechanical design of the 670.0 m/sec fan, discussion is presented of the results of structural tests of blades fabricated with both types of matrices.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135122 , PWA-5487
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  • 199
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    Detailed design of a quiet high flow fan (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A single stage fan was designed to demonstrate the noise abatement properties of near-sonic inlet flow and long-chord stator vanes for the reduction of both upstream and downstream propagated fan source noise. It is designed to produce a pressure ratio of 1.653:1 with an adiabatic efficiency of 83.9%. The fan has a 508 mm inlet diameter with a hub/tip ratio of 0.426 and a design tip speed of 533.4 m/sec. The design inlet specific flow rate is 219.71 kg/sec sq m and there are 10 tandem stator vanes with a combined aspect ratio of 0.54.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135126 , EDR-9071
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 200
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    Analysis of turbofan propulsion system weight and dimensions (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Weight and dimensional relationships that are used in aircraft preliminary design studies are analyzed. These relationships are relatively simple to prove useful to the preliminary designer, but they are sufficiently detailed to provide meaningful design tradeoffs. All weight and dimensional relationships are developed from data bases of existing and conceptual turbofan engines. The total propulsion system is considered including both engine and nacelle, and all estimating relations stem from physical principles, not statistical correlations.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73199 , A-6890
    Format: application/pdf
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