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  • AIRCRAFT PROPULSION AND POWER  (270)
  • 1975-1979  (270)
  • 1977  (270)
  • 1
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    New materials for high temperature turbines; ONERA's DS composites confronted with blade problems (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: ONERA's refractory DS composites were cited as materials required for use in advanced aircraft turbines, operating at high temperatures. These materials were found to be reliable in the construction of turbine blades. Requirements for a blade material in aircraft turbines operating at higher temperatures were compared with the actual performance as found in COTAC DS composite testing. The structure and properties of the more fully developed 74 and 741 types were specified. High temperature structural stability, impact of thermal and mechanical fatigue, oxidation resistance and coating capability were thoroughly evaluated. The problem of cooling passages in DS eutectic blades is also outlined.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75216 , High Temp. Probl. in Gas Turbine Eng.; 19-23 Sept. 1977; Ankara
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    NASA TECHNICAL REPORTS
  • 2
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    High temperature corrosion-resistant protective coatings in stationary gas turbines (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Methods currently used to deposit protective coatings in gas turbines are reviewed, and the structure of the respective coatings is examined. The corrosion behavior of such coatings is discussed on the basis of experimental data. General trends in the preparation of protective coatings are noted.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75181 , Tagung in Verbundwerkstoffe; Mar 28, 1974 - Mar 29, 1974; Constance; Germany
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  • 3
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    Aerodynamic investigation of an air-cooled axial-flow turbine. Part 2: Rotor blade tip-clearance effects on overall turbine performance and internal gas flow conditions: Experimental results and prediction methods (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: Total turbine blade performance was investigated while changing the blade tip clearance in three ways. The internal flow at the moving blade outlet point was measured. Experimental results were compared with various theoretical methods. Increased blade clearance leads to decreased turbine efficiency.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75138
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  • 4
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    Eight-bladed propeller design could bring back turboprop airplanes (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: P77-10204 , NASA-NEWS-RELEASE-77-206
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  • 5
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    Protection of cooled blades of complex internal structure (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: The problem of general protection of cooled blades of complex internal structure was solved by a method called SF technique which makes possible the protection of both external and internal surfaces, as well as those of the orifices of cooling air, whatever their diameter. The SF method is most often applied in the case of pack process, at controlled or high activity; it can be of use on previously uncoated parts, but also on pieces already coated by a thermochemical, chemical or PVD method. The respective thickness of external and internal coatings may be precisely predetermined, no parasitic particle being liable to remain inside the parts after application of the protecting treatment. Results obtained to date by application of this method are illustrated by the presentation and examination of a various selection of advanced turbo engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75217 , AGARD-CP-229 , Conf. on High Temp. Probl. in Gas Turbine Engines; Sep 19, 1977 - Sep 23, 1977; Ankara
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  • 6
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    Effect of Flame Stabilizer Design on Performance and Exhaust Pollutants of a Two-Row Swirl-Can Combustor Operated to Near-Stoichiometric Conditions (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-14
    Description: Emissions and performance characteristics were determined for two full annulus modular combustors operated to near stoichiometric fuel air ratios. The tests were conducted to obtain stoichiometric data at inlet air temperatures from 756 to 894 K and to determine the effects of a flat plate circular flame stabilizer with upstream fuel injection and a contraswirl flame stabilizer with downstream fuel injection. Levels of unburned hydrocarbons were below 0.50 gram per kilogram of fuel for both combustors and thus there was no detectable difference in the two methods of fuel injection. The contraswirl flame stabilizer did not produce the level of mixing obtained with a flat plate circular flame stabilizer. It did produce higher levels of oxides of nitrogen, which peaked at a fuel air ratio of 0.037. For the flat plate circular flame stabilizer, oxides of nitrogen emission levels were still increasing with fuel air ratio to the maximum tested value of 0.045.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3495 , E-8317
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  • 7
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    Reducing secondary losses by blowing cold air in a turbine (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: Local blowing on the profile suction side of the turbine guide wheel blades can be effective in preventing the propagation of secondary flows that is, the transport of casing and hub boundary layers by pressure gradients. Some preliminary results on how the blowing should be accomplished in order to influence the secondary flows in the desired manner are given. The effectiveness of blowing is demonstrated. Blowing is also seen to be more effective than using boundary layer slots as far as diminishing losses in the rim zones is concerned.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75185 , PAPER-76-164 , DGLR Jahrestagung; Sep 14, 1976 - Sep 16, 1976; Munich
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  • 8
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    Effects of film injection on performance of a cooled turbine (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: Some of the most dramatic increases in the performance of turbojet and turbofan aircraft engines have been obtained as a result of increased thermodynamic cycle temperatures made possible by the use of film cooling techniques. The realization of the potential performance gains, however, is only possible if the quantity of cooling air and the aerodynamic mixing losses resulting from the injection of coolant in the form of film on the flowpath surfaces are minimized. Such a minimization requires a more complete understanding of the relationship between cooling and aerodynamics. A review is conducted of tests which have been conducted to determine the effects of coolant injection on turbine performance. The results obtained in the tests are compared with an analytical technique developed for predicting coolant injection effects. Particular attention is given to the effects of turbine cooling on overall cycle thermodynamic efficiency, taking into account incremental changes in turbine thermodynamic efficiency for various incremental changes in coolant flow rate.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Propulsion and Energetics Panel Meeting; Sept. 19-23, 1977; Ankara; Turkey
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  • 9
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    State-of-the-art of turbofan engine noise control (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A description is presented of some of the recent advances in the technology of turbofan engine noise reduction, taking into account turbomachinery noise sources, new fans for low noise, fan and core noise suppression, and a new program for improving static noise testing of fans and engines. The problem of jet noise has been substantially reduced in connection with the lower jet velocities employed in the case of the high bypass turbofan engines. The dominant noise sources are now related to the turbomachinery with the fan stage, the compressor, and the turbine. Since the fan stage is the primary source of turbomachinery noise, it has been considered in a major part of the investigations designed to reduce turbofan engine noise.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: In: NOISE-CON 77; National Conference on Noise Control Engineering; Oct 17, 1977 - Oct 19, 1977; Hampton, VA
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  • 10
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    Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Winter Annual Meeting; Nov 27, 1977 - Dec 02, 1977; Atlanta, GA
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  • 11
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    General aviation energy-conservation research programs at NASA-Lewis Research Center (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A review is presented of non-turbine general aviation engine programs underway at the NASA-Lewis Research Center in Cleveland, Ohio. The program encompasses conventional, lightweight diesel and rotary engines. Its three major thrusts are, in order of priority: (1) reduced SFCs; (2) improved fuels tolerance; and (3) reducing emissions. 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 1980s, for engines whose total fuel costs are as much as 30% lower than today's conventional engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Conference on Energy Conservation in General Aviation; Oct 10, 1977 - Oct 11, 1977; Kalamazoo, MI
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  • 12
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    Output feedback regulator design for jet engine control systems (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A multivariable control design procedure based on the output feedback regulator formulation is described and applied to an F100 turbofan engine model. Full order model dynamics, are incorporated in the example design. The effect of actuator dynamics on closed loop performance is investigated. Also, the importance of turbine inlet temperature as an element of the dynamic feedback is studied. Step responses are 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: National Electronics Conference; Oct 13, 1977 - Oct 14, 1977; Chicago, IL
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  • 13
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    Effectiveness of an inlet flow turbulence control device to simulate flight fan noise in an anechoic chamber (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A hemispherical inlet flow control device was tested on a 50.8 cm. (20-inch) diameter fan stage in the NASA-Lewis Anechoic Chamber. The control device used honeycomb and wire mesh to reduce turbulence intensities entering the fan. Far field acoustic power level results showed about a 5 dB reduction in blade passing tone and about 10 dB reduction in multiple pure tone sound power at 90% design fan speed with the inlet device in place. Hot film cross probes were inserted in the inlet to obtain data for two components of the turbulence at 65 and 90% design fan speed. Without the flow control device the axial intensities were below 1.0%, while the circumferential intensities were almost twice this value. The inflow control device significantly reduced the circumferential turbulence intensities and also reduced the axial length scale.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
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  • 14
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    Combustor fluctuating pressure measurements in-engine and in a component test facility - A preliminary comparison (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Combustor internal fluctuating pressure and far-field noise generated in a YF-102 turbofan engine are investigated; combustor internal measurements are also made in a duct-component test facility operating over a range of conditions encompassing those characteristic of the aircraft engine. Although directly measured spectra for the engine and the duct-component test facility show discrepancies, the results of coherence function, transfer function and phase relationship comparisons suggest that the internal dynamics of the combustor as an acoustic source may be preserved in a component test facility.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
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  • 15
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    An empirical model for inverted-velocity-profile jet noise prediction (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: It is known that the noise generated by inverted-velocity-profile coaxial (without center plug) and coannular (with center plug) nozzles should be modeled as the combined contributions of various source regions and noise generation mechanisms. In this paper, an empirical noise-prediction model is described which considers the noise generated by two jet-mixing regions and two potential regions of shock/turbulence interaction. Results calculated from the empirical model are compared with model-scale experimental data for static and simulated flight conditions. These comparisons are made for cases where both streams are subsonic, where the outer stream is supersonic with the inner stream subsonic, and where both streams are supersonic. The cases considered cover a range of inner-to-outer-stream area ratios and include both coaxial and coannular nozzles. It is shown that the model gives reasonable predictions of absolute noise spectra and even better predictions of incremental changes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
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    NASA TECHNICAL REPORTS
  • 16
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    Noise of deflectors used for flow attachment with STOL-OTW configurations (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Future STOL aircraft may utilize engine-over-the-wing (OTW) installations in which the exhaust nozzles are located above and separated from the upper surface of the wing. An external jet-flow deflector can be used with such installations to provide flow attachment to the wing/flap surfaces for lift augmentation. In the present work, the deflector noise in the flyover plane measured with several model-scale nozzle/deflector/wing configurations is examined. The deflector-associated noise is correlated in terms of velocity and geometry parameters. The data also indicate that the effective overall sound pressure level of the deflector-associated noise peaks in the forward quadrant near 40 deg from the inlet axis.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Meeting of the Acoustical Society of America; Dec 13, 1977 - Dec 16, 1977; Miami Beach, FL
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  • 17
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    Failure detection and correction for turbofan engines (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: In this paper, a failure detection and correction strategy for turbofan engines is discussed. This strategy allows continuing control of the engines in the event of a sensor failure. An extended Kalman filter is used to provide the best estimate of the state of the engine based on currently available sensor outputs. Should a sensor failure occur the control is based on the best estimate rather than the sensor output. The extended Kalman filter consists of essentially two parts, a nonlinear model of the engine and up-date logic which causes the model to track the actual engine. Details on the model and up-date logic are presented. To allow implementation, approximations are made to the feedback gain matrix which result in a single feedback matrix which is suitable for use over the entire flight envelope. The effect of these approximations on stability and response is discussed. Results from a detailed nonlinear simulation indicate that good control can be maintained even under multiple failures.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA; US
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    NASA TECHNICAL REPORTS
  • 18
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    Design of turbofan engine controls using output feedback regulator theory (1977)
    In:  Other Sources
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    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. This LQR design was obtained as part of the F100 Multivariable Control Synthesis (MVCS) program. In the MVCS program the LQR feedback control was designed in a reduced dimension state space and then applied to the original system. However, 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 MVCS program 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: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
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  • 19
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    Optimal controls for an advanced turbofan engine (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Linear optimal control theory is applied to the control synthesis of a high bypass ratio, variable pitch, turbofan engine. The basic control philosophy is to use only a low order dynamic model of the plant coupled with the concept of integral-output states so as to maintain control simplicity yet guarantee integral control of thrust, turbine temperature and other important engine outputs. Linear simulation results indicate that the control system developed provides rapid control of small thrust perturbations and quickly eliminates the effect of unmodelled thrust and temperature disturbances. Large thrust accelerations are obtained in about one half second while the control maintains negligible overshoot in temperature and stall margins.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Joint Automatic Control Conference; Jun 22, 1977 - Jun 24, 1977; San Francisco, CA
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  • 20
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    The application of the Routh approximation method to turbofan engine models (1977)
    In:  Other Sources
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    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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  • 21
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    Minimum-time acceleration of aircraft turbofan engines (1977)
    In:  Other Sources
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    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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  • 22
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    Frequency domain compensation of a DYNGEN turbofan engine model (1977)
    In:  Other Sources
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    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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  • 23
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    Preliminary QCSEE program - Test results (1977)
    In:  Other Sources
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    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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  • 24
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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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  • 25
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    Preliminary QCSEE program test results (1977)
    In:  CASI
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    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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    NASA TECHNICAL REPORTS
  • 26
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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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    NASA TECHNICAL REPORTS
  • 27
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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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    NASA TECHNICAL REPORTS
  • 28
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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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    NASA TECHNICAL REPORTS
  • 29
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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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  • 30
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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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    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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  • 32
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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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  • 33
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    Coherence between internal and external noise generated by gas turbine combustors (1977)
    In:  Other Sources
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    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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  • 34
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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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  • 35
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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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  • 36
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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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  • 37
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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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  • 38
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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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  • 39
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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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  • 40
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    Advanced turboprop technology development (1977)
    In:  CASI
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    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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  • 41
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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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  • 42
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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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  • 43
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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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  • 44
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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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  • 45
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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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  • 46
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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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  • 47
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    Application of polynomial techniques to multivariable control of jet engines (1977)
    In:  Other Sources
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    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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  • 48
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    Direct-connect test of a hydrogen-fueled three-strut injector for an integrated modular scramjet engine (1977)
    In:  Other Sources
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    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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  • 49
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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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  • 50
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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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  • 51
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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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  • 52
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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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  • 53
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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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  • 54
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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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  • 55
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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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  • 56
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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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  • 57
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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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  • 58
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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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  • 59
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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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    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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  • 61
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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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  • 62
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    Design and performance of energy efficient propellers for Mach 0.8 cruise (1977)
    In:  Other Sources
    Details
    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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  • 63
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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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  • 64
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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
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    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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  • 65
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    V/STOL shaft propulsion system analytical performance model (1977)
    In:  Other Sources
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    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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  • 66
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    Altitude engine test of a turbofan exhaust gas mixer to conserve fuel (1977)
    In:  Other Sources
    Details
    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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  • 67
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    Static and flyover noise measurements of an inverted profile exhaust jet (1977)
    In:  Other Sources
    Details
    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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  • 68
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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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  • 69
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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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  • 70
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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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  • 71
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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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  • 72
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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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  • 73
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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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  • 74
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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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  • 75
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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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  • 76
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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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  • 77
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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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  • 78
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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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  • 79
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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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  • 80
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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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  • 81
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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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  • 82
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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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  • 83
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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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  • 84
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    Hierarchy of simulation models for a turbofan gas engine (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Steady-state and transient performance of an F-100-like turbofan gas engine are modeled by a computer program, DYNGEN, developed by NASA. The model employs block data maps and includes about 25 states. Low-order nonlinear analytical and linear techniques are described in terms of their application to the model. Experimental comparisons illustrating the accuracy of each model are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Annual Pittsburgh Conference; Apr 21, 1977 - Apr 22, 1977; Pittsburgh, PA
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  • 85
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    Sound separation probes for flowing duct noise measurements (1977)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: In order to understand the propagation of broadband sound from a device such as a jet engine, it is necessary to make fluctuating pressure measurements in the ducted airstream. However, in a flowing duct, fluctuating pressure energy can be due to both turbulence and sound travelling in the duct. By using the principal that sound waves and turbulent flow pressure perturbations travel at different velocities, a probe has been developed that provides the data necessary to separate the energy due to sound from that due to turbulence. A mini-computer based FFT analysis of the probe measurements provides the overall level of the broadband sound in the duct as well as the spectral distribution of the sound energy.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: International Instrumentation Symposium; May 01, 1977 - May 05, 1977; Las Vegas, NV
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  • 86
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    Core compressor exit stage study. Volume 1: Blading design (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A baseline compressor test stage was designed as well as a candidate rotor and two candidate stators that have the potential of reducing endwall losses relative to the baseline stage. These test stages are typical of those required in the rear stages of advanced, highly-loaded core compressors. The baseline Stage A is a low-speed model of Stage 7 of the 10 stage AMAC compressor. Candidate Rotor B uses a type of meanline in the tip region that unloads the leading edge and loads the trailing edge relative to the baseline Rotor A design. Candidate Stator B embodies twist gradients in the endwall region. Candidate Stator C embodies airfoil sections near the endwalls that have reduced trailing edge loading relative to Stator A. Tests will be conducted using four identical stages of blading so that the designs described will operate in a true multistage environment.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135391 , DOC-R77AEG400-VOL-1
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  • 87
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    Wide range operation of advanced low NOx combustors for supersonic high-altitude aircraft gas turbines (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An initial rig program tested the Jet Induced Circulation (JIC) and Vortex Air Blast (VAB) systems in small can combustor configurations for NOx emissions at a simulated high altitude, supersonic cruise condition. The VAB combustor demonstrated the capability of meeting the NOx goal of 1.0 g NO2/kg fuel at the cruise condition. In addition, the program served to demonstrate the limited low-emissions range available from the lean, premixed combustor. A follow-on effort was concerned with the problem of operating these lean, premixed combustors with acceptable emissions at simulated engine idle conditions. Various techniques have been demonstrated that allow satisfactory operation on both the JIC and VAB combustors at idle with CO emissions below 20 g/kg fuel. The VAB combustor was limited by flashback/autoignition phenomena at the cruise conditions to a pressure of 8 atmospheres. The JIC combustor was operated up to the full design cruise pressure of 14 atmospheres without encountering an autoignition limitation although the NOx levels, in the 2-3 g NO2/kg fuel range, exceeded the program goal.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135297 , RDR-1817-22
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  • 88
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    Ceramics in gas turbine: Powder and process characterization (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Some of the intrinsic properties of various forms of Si3N4 and SiC are listed and limitations of such materials' availability are pointed out. The essential features/parameters to characterize a batch of powder are discussed including the standard techniques for such characterization. In process characterization, parameters in sintering, reaction sintering, and hot pressing processes are discussed including the factors responsible for strength limitations in ceramic bodies. Significant improvements in material properties can be achieved by reducing or eliminating the strength limiting factors with consistent powder and process characterization along with process control.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73875 , E-9475 , Conf. on Composites and Advanced Maters.; Jan 17, 1977 - Jan 19, 1977; Cocoa Beach, FL; United States
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  • 89
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    Linear aerospike engine study (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Parametric data on split-combustor linear engine propulsion systems are presented for use in mixed-mode single-stage-to-orbit (SSTO) vehicle studies. Preliminary design data for two selected engine systems are included. The split combustor was investigated for mixed-mode operations with oxygen/hydrogen propellants used in the inner combustor in Mode 2, and in conjunction with either oxygen/RP-1, oxygen/RJ-5, O2/CH4, or O2/H2 propellants in the outer combustor for Mode 1. Both gas generator and staged combustion power cycles were analyzed for providing power to the turbopumps of the inner and outer combustors. Numerous cooling circuits and cooling fluids (propellants) were analyzed and hydrogen was selected as the preferred coolant for both combustors and the linear aerospike nozzle. The maximum operating chamber pressure was determined to be limited by the availability of hydrogen coolant pressure drop in the coolant circuit.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135231 , RI/RD77-170
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  • 90
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    Cost analysis of advanced turbine blade manufacturing processes (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A rigorous analysis was conducted to estimate relative manufacturing costs for high technology gas turbine blades prepared by three candidate materials process systems. The manufacturing costs for the same turbine blade configuration of directionally solidified eutectic alloy, an oxide dispersion strengthened superalloy, and a fiber reinforced superalloy were compared on a relative basis to the costs of the same blade currently in production utilizing the directional solidification process. An analytical process cost model was developed to quantitatively perform the cost comparisons. The impact of individual process yield factors on costs was also assessed as well as effects of process parameters, raw materials, labor rates and consumable items.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135203 , TRW-1ER-7930
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  • 91
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    Summary of forward velocity effects on fan noise (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The available experimental data comparing the in-flight and static behavior of fan noise are reviewed. These results are then compared with recent data obtained for a fan stage tested with forward velocity in the NASA Lewis 9x15 low speed wind tunnel. Tentative conclusions are presented, based on the author's judgments, about the significance and nature of the changes in noise observed when a forward velocity is imposed. Finally, the implications of the emerging picture of in-flight fan source noise for suppressor design are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 77-1319 , Aeroacoustics Conference; Oct 03, 1977 - Oct 05, 1977; Atlanta, GA
    Format: text
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  • 92
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    Effect of endwall cooling on secondary flows in turbine stator vanes (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An experimental investigation was performed to determine the effect of endwall cooling on the secondary flow behavior and the aerodynamic performance of a core-turbine stator vane. The investigation was conducted in a cold-air, full-annular cascade, where three-dimensional effects could be obtained. In one configuration, the cooling holes were oriented so that the coolant was injected in line with the inviscid streamline direction. In another configuration, the coolant was injected at an angle of 15 deg to the inviscid streamline direction and oriented toward the vane pressure surface. Total-pressure surveys were taken downstream of the stator vanes over a range of cooling flows. 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. Comparisons are made between the two cooled-endwall configurations and with the results obtained previously for solid (uncooled) endwalls.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Propulsion and Energetics Panel Conference; Mar 28, 1977 - Apr 04, 1977; The Hague; Netherlands
    Format: text
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  • 93
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    Cooling considerations for design of a radial inflow turbine (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A numerical study to determine the temperature distribution in the rotor of a radial inflow turbine is presented. Internal cooling passages are modeled in the present formulation in order to carry out solid and coolant temperature computations simultaneously resulting in a considerable computer time savings. The stresses due to centrifugal and thermal loadings are determined in an actual rotor and the effect of cooling design on its mechanical integrity is discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 77-GT-82 , Gas Turbine Conference and Products Show; Mar 27, 1977 - Mar 31, 1977; Philadelphia, PA
    Format: text
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  • 94
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    Opportunities for ceramics in the ERDA/NASA Continuous Combustion Propulsion Systems Program (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The ERDA/NASA Continuous Combustion Highway Vehicles Program is concerned with the development of improved automotive powerplants. Specific program goals are related to an achievement of an improved fuel economy, low emissions, multifuel capability, and marketability. An employment of high temperature ceramic materials is considered in connection with the development of improved gas turbine and Stirling engines. The ceramic materials technology project is discussed, taking into account the characterization of ceramic materials, improved ceramic materials, and questions of component design, fabrication, and testing.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Workshop on Ceramics for Energy Conversion Systems; Jan 24, 1977 - Jan 27, 1977; Orlando, FL
    Format: text
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  • 95
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    Core noise measurements on a YF-102 turbofan engine (1977)
    In:  Other Sources
    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: AIAA PAPER 77-21 , Aerospace Sciences Meeting; Jan 24, 1977 - Jan 26, 1977; Los Angeles, CA
    Format: text
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  • 96
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    Pollution reduction technology program for small jet aircraft engines, phase 1 (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A series of combustor pressure rig screening tests was conducted on three combustor concepts applied to the TFE731-2 turbofan engine combustion system for the purpose of evaluating their relative emissions reduction potential consistent with prescribed performance, durability, and envelope contraints. The three concepts and their modifications represented increasing potential for reducing emission levels with the penalty of increased hardware complexity and operational risk. Concept 1 entailed advanced modifications to the present production TFE731-2 combustion system. Concept 2 was based on the incorporation of an axial air-assisted airblast fuel injection system. Concept 3 was a staged premix/prevaporizing combustion system. Significant emissions reductions were achieved in all three concepts, consistent with acceptable combustion system performance. Concepts 2 and 3 were identified as having the greatest achievable emissions reduction potential, and were selected to undergo refinement to prepare for ultimate incorporation within an engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135214 , AIRESEARCH-21-2498
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  • 97
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    Over-the-wing model thrust reverser noise tests (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Static acoustic tests were conducted on a 1/12 scale model over-the-wing target type thrust reverser. The model configuration simulates a design that is applicable to the over-the-wing short-haul advanced technology engine. Aerodynamic screening tests of a variety of reverser designs identified configurations that satisfied a reverse thrust requirement of 35 percent of forward thrust at a nozzle pressure ratio of 1.29. The variations in the reverser configuration included, blocker door angle, blocker door lip angle and shape, and side skirt shape. Acoustic data are presented and compared for the various configurations. The model data scaled to a single full size engine show that peak free field perceived noise (PN) levels at a 152.4 meter sideline distance range from 98 to 104 PNdb.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73495 , E-9328 , Aeroacoustics Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
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  • 98
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    High stiffness seals for rotor critical speed control (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An annular seal is analyzed in which the inlet clearance is larger than the outlet clearance; the flow path may be either stepped or tapered. This design produces radial stiffness 1.7 to 14 times that of a constant clearance seal having the same minimum clearance. When sealing high pressure fluids, such a seal improves rotor stability and can be used to shift troublesome critical speeds to a more suitable location.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-73654 , E-9171 , Vibrations Conf.; Sep 26, 1977 - Sep 29, 1977; Chicago
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  • 99
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    Acoustic performance of inlet multiple-pure-tone suppressors installed on NASA quiet engine C (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The length of multiple-pure-tone (MPT) treatment required to reasonably suppress the MPT's produced by a supersonic tip speed fan was defined. Other suppression, broadband, and blade passing frequency, which might be accomplished were also determined. The experimental results are presented in terms of both far-field and duct acoustic data.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73713 , Aeroacoustics Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
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  • 100
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    Interaction of rotor tip flow irregularities with stator vanes as a noise source (1977)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The role of the interaction of rotor tip flow irregularities (vortices and velocity defects) with downstream stator vanes is discussed as a possible fan noise mechanism. This is accomplished by: (1) indicating some of the mothods of formation of these flow irregularities; (2) observing how they would behave with respect to known noise behavior; and (3) attempting to compare the strength of the rotor tip flow irregularity mechanism with the strength of the more common rotor wake-stator mechanism. The rotor tip flow irregularity-stator interaction is indicated as being a probable inflight noise source.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-73706 , Aeroacoustics Conf.; Oct 03, 1977 - Oct 05, 1977; Atlanta
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