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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Turbulent heat transfer prediction method for application to scramjet engines

An integral method for predicting boundary layer development in turbulent flow regions on two-dimensional or axisymmetric bodies was developed. The method has the capability of approximating nonequilibrium velocity profiles as well as the local surface friction in the presence of a pressure gradient. An approach was developed for the problem of predicting the heat transfer in a turbulent boundary layer in the presence of a high pressure gradient. The solution was derived with particular emphasis on its applicability to supersonic combustion; thus, the effects of real gas flows were included. The resulting integrodifferential boundary layer method permits the estimation of cooling reguirements for scramjet engines. Theoretical heat transfer results are compared with experimental combustor and noncombustor heat transfer data. The heat transfer method was used in the development of engine design concepts which will produce an engine with reduced cooling requirements. The Langley scramjet engine module was designed by utilizing these design concepts and this engine design is discussed along with its corresponding cooling requirements. The heat transfer method was also used to develop a combustor cooling correlation for a combustor whose local properties are computed one dimensionally by assuming a linear area variation and a given heat release schedule.

Pinckney, S. Z.↗
NASA NTRS1974

Engineering education and a lifetime of learning

The result of an eleven-week study by the National Aeronautics and Space Administration (NASA) and the American Society of Engineering Education is presented. The study was the ninth of a series of programs. The purposes of the programs were: (1) to introduce engineering school faculty members to system design and to a particular approach to teaching system design, (2) to introduce engineering faculty to NASA and to a specific NASA center, and (3) to produce a study of use to NASA and to the participants. The story was concerned with engineering education in the U.S., and concentrated upon undergraduate education and teaching, although this bias was not meant to imply that research and graduate study are less important to engineering education.

Eisley, J.↗
NASA NTRS1975

Application of real-time engine simulations to the development of propulsion system controls

The development of digital controls for turbojet and turbofan engines is presented by the use of real-time computer simulations of the engines. The engine simulation provides a test-bed for evaluating new control laws and for checking and debugging control software and hardware prior to engine testing. The development and use of real-time, hybrid computer simulations of the Pratt and Whitney TF30-P-3 and F100-PW-100 augmented turbofans are described in support of a number of controls research programs at the Lewis Research Center. The role of engine simulations in solving the propulsion systems integration problem is also discussed.

Szuch, J. R.↗
NASA NTRS1975

Orbital maneuvering engine feed system coupled stability investigation

A digital computer model used to analyze and predict engine feed system coupled instabilities over a frequency range of 10 to 1000 Hz was developed and verified. The analytical approach to modeling the feed system hydrodynamics, combustion dynamics, chamber dynamics, and overall engineering model structure is described and the governing equations in each of the technical areas are presented. This is followed by a description of the generalized computer model, including formulation of the discrete subprograms and their integration into an overall engineering model structure. The operation and capabilities of the engineering model were verified by comparing the model's theoretical predictions with experimental data from an OMS-type engine with a known feed system/engine chugging history.

Kahn, D. R.↗
NASA NTRS1975

Wind tunnel investigation of a large-scale upper surface blown-flap model having four engines

Investigations were conducted in the Ames 40- by 80-Foot Wind Tunnel to determine the aerodynamic characteristics of a large-scale subsonic jet transport model with an upper surface blown flap system. The model had a 25 deg swept wing of aspect ratio 7.28 and four turbofan engines. The lift of the flap system was augmented by turning the turbofan exhaust over the Coanda surface. Results were obtained for several flap deflections with several wing leading-edge configurations at jet momentum coefficients from 0 to 4.0. Three-component longitudinal data are presented with four engines operating. In addition, longitudinal and lateral data are presented with an engine out. The maximum lift and stall angle of the four engine model were lower than those obtained with a two engine model that was previously investigated. The addition of the outboard nacelles had an adverse effect on these values. Efforts to improve these values were successful. A maximum lift of 8.8 at an angle-of-attack of 27 deg was obtained with a jet thrust coefficient of 2 for the landing flap configuration.

Aoyagi, K.↗
NASA NTRS1975

Application of real-time engine simulations to the development of propulsion system controls

The development of digital controls for turbojet and turbofan engines can be facilitated by the use of real-time computer simulations of the engines. The engine simulation provides a 'test-bed' for evaluating new control laws and for checking and 'debugging' control software and hardware prior to engine testing. This paper describes the development and use of real-time, hybrid computer simulations of the Pratt & Whitney TF30-P-3 and F100-PW-100 augmented turbofans in support of a number of controls research programs at the Lewis Research Center. The role of engine simulations in solving the propulsion systems integration problem is also discussed.

Szuch, J. R.↗
NASA NTRS1975

DC-9 flight demonstration program with refanned JT8D engines. Volume 1: Summary

The design, analysis, fabrication, and ground and flight testing of DC-9 airframe/nacelle hardware with prototype JT8D-109 engines are discussed. The installation of the JT8D-109 engine on the DC-9 Refan airplane required new or modified hardware for the pylon, nacelle, and fuselage. The acoustic material used in the nose cowl was bonded aluminum honeycomb sandwich and the exhaust duct acoustic material was Inconel 625 Stresskin. The sea level static, standard day bare engine takeoff thrust, the cruise TSFC and the maximum available cruise thrust for the JT8D-109 engine were compared with those of the JT8D-9 engine. The range capabilities of the DC-9 Refan and the production DC-9 airplane were also compared. The Refan airplane demonstrated flight characteristics similar to the production DC-9-30 and satisfied airworthiness requirements. Flyover noise levels were determined for the DC-9 Refan and the DC-9 C-9A airplane for takeoff and landing conditions. Cost estimates were also made.

Source record↗
NASA NTRS1975

Design and evaluation of a sensor fail-operational control system for a digitally controlled turbofan engine

A self-learning, sensor fail-operational, control system for the TF30-P-3 afterburning turbofan engine was designed and evaluated. The sensor fail-operational control system includes a digital computer program designed to operate in conjunction with the standard TF30-P-3 bill-of-materials control. Four engine measurements and two compressor face measurements are tested. If any engine measurements are found to have failed, they are replaced by values synthesized from computer-stored information. The control system was evaluated by using a realtime, nonlinear, hybrid computer engine simulation at sea level static condition, at a typical cruise condition, and at several extreme flight conditions. Results indicate that the addition of such a system can improve the reliability of an engine digital control system.

Hrach, F. J.↗
NASA NTRS1976

Stimulation of a turbofan engine for evaluation of multivariable optimal control concepts

The development of control systems for jet engines requires a real-time computer simulation. The simulation provides an effective tool for evaluating control concepts and problem areas prior to actual engine testing. The development and use of a real-time simulation of the Pratt and Whitney F100-PW100 turbofan engine is described. The simulation was used in a multi-variable optimal controls research program using linear quadratic regulator theory. The simulation is used to generate linear engine models at selected operating points and evaluate the control algorithm. To reduce the complexity of the design, it is desirable to reduce the order of the linear model. A technique to reduce the order of the model; is discussed. Selected results between high and low order models are compared. The LQR control algorithms can be programmed on digital computer. This computer will control the engine simulation over the desired flight envelope.

Seldner, K.↗
NASA NTRS1976

Research requirements for emergency power to permit hover-one-engine-inoperative helicopter operation

The research and technology demonstration requirements to achieve emergency-power capability for a civil helicopter are documented. The goal for emergency power is the ability to hover with one engine inoperative, transition to minimum-power forward flight, and continue to a safe landing where emergency power may or may not be required. The best method to obtain emergency power is to augment the basic engine power by increasing the engine's speed and turbine-inlet temperature, combined with water-alcohol injection at the engine inlet. Other methods, including turbine boost power and flywheel energy, offer potential for obtaining emergency power for minimum time durations. Costs and schedules are estimated for a research and development program to bring emergency power through a hardware-demonstration test. Interaction of engine emergency-power capability with other helicopter systems is examined.

Yost, J. H.↗
NASA NTRS1977

Analysis of liquid-propellant rocket engines designed by F. A. Tsander

The development of the oxygen-gasoline OR-2 engines and the oxygen-alcohol GIRD-10 rocket engine is described. A result of Tsander's rocket research was an engineering method for propellant calculation of oxygen-propellant rocket engines that determined the basic parameters of the engine and the structural elements.

Dushkin, L. S.↗
NASA NTRS1977

Combustor fluctuating pressure measurements in engine and in a component test facility: A preliminary comparison

In a program to investigate combustor noise, measurements were made with a YF-102 engine of combustor internal fluctuating pressure and far field noise. The relationship of far field noise to engine internal measurement was ascertained. The relationships between combustor internal measurements obtained in an engine and those obtained in a component test facility were established by using a YF-102 combustor, instrumented identically with that used in the engine tests. The combustor was operated in a component test facility over a range of conditions encompassing engine operation. A comparison of the directly measured spectra at corresponding locations in the two tests showed significant differences. The results of two point signal analyses within each combustor, were similar for both tests, indicating that the internal dynamics of the combustor as an acoustic source are preserved in a component test facility.

Reshotko, M.↗
NASA NTRS1978

Automotive Stirling engine development program

The Ford/DOE automotive Stirling engine development program is directed towards establishing the technological and developmental base that would enable a decision on whether an engineering program should be directed at Stirling engine production. The fuel economy assessment aims to achieve, with a high degree of confidence, the ERDA proposal estimate of 20.6 MPG (gasoline) for a 4500 lb 1WC Stirling engine passenger car. The current M-H fuel economy projection for the 170 HP Stirling engine is 15.7 MPG. The confidence level for this projection is 32%. A confidence level of 29% is projected for a 22.1 MPG estimate. If all of the planned analyses and test work is accomplished at the end of the one year effort, and the projected improvements are substantiated, the confidence levels would rise to 59% for the 20.6 MPG projection and 54% for the 22.1 MPG projection. Progress achieved thus far during the fuel economy assessment is discussed.

Kitzner, E. W.↗
NASA NTRS1978

General aviation internal-combustion engine research programs at NASA-Lewis Research Center

An update is presented of non-turbine general aviation engine programs. The program encompasses conventional, lightweight diesel and rotary engines. It's three major thrusts are: (1) reduced SFC's; (2) improved fuels tolerance; and (3) reduced 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 1980's, for engines whose life cycle fuel costs are 30 to 50% lower than today's conventional engines.

Willis, E. A.↗
NASA NTRS1978

Flight effects on noise by the JT8D engine with inverted primary/fan flow as measured in the NASA-Ames 40 by 80 foot wind tunnel

A JT8D-17R engine with inverted primary and fan flows was tested under static conditions as well as in the NASA Ames 40 by 80 Foot Wind Tunnel to determine static and flight noise characteristics, and flow profile of a large scale engine. Test and analysis techniques developed by a previous model and JT8D engine test program were used to determine the in-flight noise. The engine with inverted flow was tested with a conical nozzle and with a plug nozzle, 20 lobe nozzle, and an acoustic shield. Wind tunnel results show that forward velocity causes significant reduction in peak PNL suppression relative to uninverted flow. The loss of EPNL suppression is relatively modest. The in-flight peak PNL suppression of the inverter with conical nozzle was 2.5 PNdb relative to a static value of 5.5 PNdb. The corresponding EPNL suppression was 4.0 EPNdb for flight and 5.0 EPNdb for static operation. The highest in-flight EPNL suppression was 7.5 EPNdb obtained by the inverter with 20 lobe nozzle and acoustic shield. When compared with the JT8D engine with internal mixer, the inverted flow configuration provides more EPNL suppression under both static and flight conditions.

Strout, F. G.↗
NASA NTRS1978

Design approaches to more energy efficient engines

The status of NASA's Energy Efficient Engine Project, a comparative government-industry effort aimed at advancing the technology base for the next generation of large turbofan engines for civil aircraft transports is summarized. Results of recently completed studies are reviewed. These studies involved selection of engine cycles and configurations that offer potential for at least 12% lower fuel consumption than current engines and also are economically attractive and environmentally acceptable. Emphasis is on the advancements required in component technologies and systems design concepts to permit future development of these more energy efficient engines.

Saunders, N. T.↗
NASA NTRS1978

Applications of hybrid and digital computation methods in aerospace-related sciences and engineering

The computing equipment in the engineering systems simulation laboratory of the Houston University Cullen College of Engineering is described and its advantages are summarized. The application of computer techniques in aerospace-related research psychology and in chemical, civil, electrical, industrial, and mechanical engineering is described in abstracts of 84 individual projects and in reprints of published reports. Research supports programs in acoustics, energy technology, systems engineering, and environment management as well as aerospace engineering.

Huang, C. J.↗
NASA NTRS1977

Failure detection and correction for turbofan engines

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.

Corley, R. C.↗