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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Evaluation of Propulsion Systems for Mach 2.4 and 3.2 High Speed Civil Transports

Advanced technology high speed civil transport (HSCT) engine cycles equipped with low emissions combustors and low noise exhaust nozzles were investigated. The objectives were as follows: (1) evaluate a range of cycle variables for engine types appropriate for Mach 2.4 and 3.2 HSCT; (2) select the most promising propulsion systems; and (3) identify and define the critical/key technology development and demonstration programs needed to be conducted prior to initiation of the product engine development and certification program. Two types of variable engines were studied: turbine bypass engines (TBE) and variable stream control engines (VSCE). This study identified payoffs in terms of aircraft gross weight, airline economics, stratospheric cruise emissions, and airport noise improvements. Comparison between the the TBE and VSCE showed the TBE to be clearly superior for Mach 2.4 and 3.2 cruise cruise operation. Critical technology areas were also identified which included the following: (1) Low emissions combustor; (2) Low noise exhaust system; (3) High temperature materials and coatings; (4) Advanced turbine cooling and aerodynamics; (5) Integrated propulsion system (inlet/engine/nozzle) and airframe controls; (6) Advanced fan/compressor aerodynamics; and (7) Magnetic bearings.

Turbine Bypass Engine (TBE)↗
NASA NTRS1986

Flight effects on noise from coaxial dual flow. II - Heated jets

This paper is a continuation of the study described in Part I and deals with the flight effects on noise from heated jets. The present work shows that coaxial exhaust flows with inverted profiles are much quieter than flows with conventional profiles. Among all possible coaxial configurations with only one of the streams heated conventional profile, inverted profile, and the variable stream control engine (VSCE) cycle - and holding constant mass flow and thrust, a VSCE cycle is the best possible engine cycle as it provides over 18-dB reduction in sound pressure level (as compared to noise from a conventional profile cycle) at all angles, both statically and in flight. The study also indicates that, if both the coaxial streams are heated unequally, a duct-burning profile, combined with the variable stream control engine (DB-VSCE) concept, gives rise to a powerful coaxial device which generates the least noise, both statically and in flight. This concept will be of paramount importance as one of the most variable nozzle designs of the future.

Dash, R.↗
NASA NTRS1956

Preliminary Report on Experimental Investigation of Engine Dynamics and Controls for a 48-inch Ram-jet Engine

Engine dynamics and controls data are presented for a ram-jet engine which was operated in a free-jet facility at a Mach number of 2.76 and altitudes from 68,000 to 82,000 feet. The predominant engine dynamic characteristics was dead time, with values ranging from 0.018 to 0.053 sec. The control systems were designed to hold a constant ratio of a diffuser static pressure to an inlet-cone reference static pressure. Response times and percent overshoot to fuel-flow disturbances that would have caused subcritical operation without control are included for a wide range of control settings. For all settings, the control response was fast enough (0.08 to 0.5 sec) to prevent subcritical operation.

Vasu, George↗
NASA NTRS1984

Application of advanced control techniques to aircraft propulsion systems

Two programs are described which involve the application of advanced control techniques to the design of engine control algorithms. Multivariable control theory is used in the F100 MVCS (multivariable control synthesis) program to design controls which coordinate the control inputs for improved engine performance. A systematic method for handling a complex control design task is given. Methods of analytical redundancy are aimed at increasing the control system reliability. The F100 DIA (detection, isolation, and accommodation) program, which investigates the uses of software to replace or augment hardware redundancy for certain critical engine sensor, is described.

Lehtinen, B.↗
NASA NTRS1976

A digital computer propulsion control facility: Description of capabilities and summary of experimental program results

Flight weight digital computers are being used today to carry out many of the propulsion system control functions previously delegated exclusively to hydromechanical controllers. An operational digital computer facility for propulsion control mode studies has been used successfully in several experimental programs. This paper describes the system and some of the results concerned with engine control, inlet control, and inlet engine integrated control. Analytical designs for the digital propulsion control modes include both classical and modern/optimal techniques.

Zeller, J. R.↗
NASA NTRS1972

Modification of a fuel-cell engine for control by a digital computer

A manually operated fuel-cell system was modified to be monitored and controlled by a digital computer. The purpose was to have a test item with which to study possible system-computer interface problems. The modification consisted of installing solenoid valves, circuitry, transducers, and limit switches on the system. These modifications permit computer control of load current, reactant purge, water removal, and electrolyte concentration and computer initiation of system shutdown.

Hagedorn, N. H.↗
NASA NTRS1972

Characterization of the space shuttle reaction control system engine

A computer program was developed and written in FORTRAN 5 which predicts the transient and steady state performance and heat transfer characteristics of a pulsing GO2/GH2 rocket engine. This program predicts the dynamic flow and ignition characteristics which, when combined in a quasi-steady state manner with the combustion and mixing analysis program, will provide the thrust and specific impulse of the engine as a function of time. The program also predicts the transient and steady state heat transfer characteristics of the engine using various cooling concepts. The computer program, test case, and documentation are presented. The program is applicable to any system capable of utilizing the FORTRAN 4 or FORTRAN 5 language.

Wilson, M. S.↗
NASA NTRS1973

Control optimization, stabilization and computer algorithms for aircraft applications

Computationally useful algorithms are considered that can aid the control engineer in designing systems control in linear time invariant dynamics for aircraft applications. Structural aspects of system identification, matrix parameterization, and the effect of feedback on identifiability of systems. Adaptive and stochastic control model constructions are projected, and a method for approximate identification of aircraft characteristics and subsequent generation of control signals is outlined.

Mitter, S. K.↗
NASA NTRS1978

The stirling engine for vehicle propulsion

The performance data of experimental Stirling engines are considered along with questions of exhaust-gas composition, engine noise, engine volume and weight, engine control, and the engine-starting process. The Stirling engine can use practically any liquid or gaseous fuel for its operation. It is found that technically a use of the Stirling engine in motor vehicles is feasible. Economic questions related to an introduction of the Stirling engine are discussed along with possible new developments which could improve the economic situation in favor of a use of Stirling engine.

Kuhlman, P.↗
NASA NTRS1983

A case study of a system engineered for control by humans

Alternatives to the traditional concepts for real time health and safety operations were examined. The pitfalls of the conventional contingency planning for health and safety are highlighted. The Solar Maximum Mission (SMM) contingency planning and operations provides the evolution from the conventional people intensive health and safety operation, toward a night watchman mode of operations. The SMM spacecraft health and safety operations were budget constrained to the point that one operator was responsible for the health and safety of the entire spacecraft one week after launch. The spacecraft was a protoflight with brand new subsystem configurations, software and procedures. To manage the risks associated with this one man SMM health and safety operation, the real time contingency planning and operations centered around unambiguously identifying a system level problem, and reactively safing components susceptible to unrecoverable damage. The methodology applied to both analyzing and implementing this approach of SMM is shown.

Rothenberg, J.↗
NASA NTRS1983

Inlet, engine, airframe controls integration development for supercruising aircraft

In connection with a consideration of advanced military aircraft systems, attention is given to research for improving the technology of the design of supersonic cruise aircraft. Syberg et al. (1981) have shown that an analytic design method is now available to accurately predict the flow characteristics of axisymmetric supersonic inlets, including off-design angle of attack operation. On the basis of information regarding the inlet flow characteristics, the control system designer can begin the inlet design and development, before wind tunnel testing has begun. The present investigation is concerned with details and status of inlet control technology. A detailed representation of a supersonic propulsion system is developed. This development demonstrates the feasibility of the selected hybrid computational concept.

Houchard, J. H.↗
NASA NTRS1984

In-flight thrust determination on a real-time basis

A real time computer program was implemented on a F-15 jet fighter to monitor in-flight engine performance of a Digital Electronic Engine Controlled (DEES) F-100 engine. The application of two gas generator methods to calculate in-flight thrust real time is described. A comparison was made between the actual results and those predicted by an engine model simulation. The percent difference between the two methods was compared to the predicted uncertainty based on instrumentation and model uncertainty and agreed closely with the results found during altitude facility testing. Data was obtained from acceleration runs of various altitudes at maximum power settings with and without afterburner. Real time in-flight thrust measurement was a major advancement to flight test productivity and was accomplished with no loss in accuracy over previous post flight methods.

Ray, R. J.↗
NASA NTRS1987

Advanced detection, isolation and accommodation of sensor failures: Real-time evaluation

The objective of the Advanced Detection, Isolation, and Accommodation (ADIA) Program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines by using analytical redundacy to detect sensor failures. The results of a real time hybrid computer evaluation of the ADIA algorithm are presented. Minimum detectable levels of sensor failures for an F100 engine control system are determined. Also included are details about the microprocessor implementation of the algorithm as well as a description of the algorithm itself.

Merrill, Walter C.↗
NASA NTRS1987

The value of early flight evaluation of propulsion concepts using the NASA F-15 research airplane

The value of early flight evaluation of propulsion and propulsion control concepts was demonstrated on the NASA F-15 airplane in programs such as highly integrated digital electronic control (HIDEC), the F100 engine model derivative (EMD), and digital electronic engine control (DEEC). (In each case, the value of flight demonstration was conclusively demonstrated). This paper described these programs, and discusses the results that were not expected, based on ground test or analytical prediction. The role of flight demonstration in facilitating transfer of technology from the laboratory to operational airplanes is discussed.

Burcham, Frank W., Jr.↗
NASA NTRS1987

The value of early flight evaluation of propulsion concepts using the NASA F-15 research airplane

The value of early flight evaluation of propulsion and propulsion control concepts was demonstrated on the NASA F-15 airplane in programs such as highly integrated digital electronic control (HIDEC), the F100 engine model derivative (EMD), and digital electronic engine control (DEEC). (In each case, the value of flight demonstration was conclusively demonstrated.) This paper describes these programs, and discusses the results that were not expected, based on ground test or analytical prediction. The role of flight demonstration in facilitating transfer of technology from the laboratory to operational airplanes is discussed.

Burcham, Frank W., Jr.↗
NASA NTRS1988

Advanced detection, isolation, and accommodation of sensor failures - Real-time evaluation

The objective of the Advanced Detection, Isolation, and Accommodation (ADIA) program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines by using analytical redundancy to detect sensor failures. The results of a real-time hybrid computer evaluation of the ADIA algorithm are presented. Minimum detectable levels of sensor failures for an F100 engine control system are determined. Also included are details about the microprocessor implementation of the algorithm as well as a description of the algorithm itself.

Merrill, Walter C.↗