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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Dynamics of a supersonic inlet-engine combination subjected to disturbances in fuel flow and inlet overboard bypass airflow

An axisymmetric mixed-compression supersonic inlet and a single-spool turbojet engine were dynamically tested at Mach 2.5. The propulsion system was subjected to sweep-frequency sinusoidal disturbances of either inlet overboard bypass airflow. The disturbances were at a logarithmic sweep rate of 1 decade per minute. Dynamic responses were taken of signals throughout the propulsion system. Selected signals were reduced relative to the prime propulsion system parameters. The experimental data are presented in Bode plots. Most of the plots are for a frequency range of 1.0 to 50 hertz.

Wallhagen, R. E.↗
NASA NTRS1972

Tabulated pressure measurements on a large subsonic transport model airplane with high bypass ratio, powered, fan jet engines

An experimental wind-tunnel investigation to determine the aerodynamic interference and the jet-wake interference associated with the wing, pylon, and high-bypass-ratio, powered, fan-jet model engines has been conducted on a typical high-wing logistics transport airplane configuration. Pressures were measured on the wing and pylons and on the surfaces of the engine fan cowl, turbine cowl, and plug. Combinations of wing, pylons, engines, and flow-through nacelles were tested, and the pressure coefficients are presented in tabular form. Tests were conducted at Mach numbers from 0.700 to 0.825 and angles of attack from -2 to 4 deg.

Flechner, S. G.↗
NASA NTRS1972

Bypass control valve seal and bearing life cycle test report

The operating characteristics of a bypass control valve seal and bearing life cycle tests are reported. Data from the initial assembly, leak, torque, and deflection tests are included along with the cycle life test results and conclusions. The equipment involved was to be used in the nuclear engine for the rocket vehicles program.

Lundback, A. V.↗
NASA NTRS1974

Developmental design, fabrication, and test of acoustic suppressors for fans of high bypass turbofan engines

An analysis procedure was developed for design of acoustically treated nacelles for high bypass turbofan engines. The plan was applied to the conceptual design of a nacelle for the quiet engine typical of a 707/DC-8 airplane installation. The resultant design was modified to a test nacelle design for the NASA Lewis quiet fan. The acoustic design goal was a 10 db reduction in effective perceived fan noise levels during takoff and approach. Detailed nacelle designs were subsequently developed for both the quiet engine and the quiet fan. The acoustic design goal for each nacelle was 15 db reductions in perceived fan noise levels from the inlet and fan duct. Acoustically treated nacelles were fabricated for the quiet engine and quiet fan for testing. Performance of selected inlet and fan duct lining configurations was experimentally evaluated in a flow duct. Results of the tests show that the linings perform as designed.

Tucker, R. H.↗
NASA NTRS1974

Skylab communications carrier 16536G and filter bypass adapter assembly 12535G

Communications equipment for use with the Skylab project is examined to show compliance with contract requirements. The items of equipment considered are: (1) communications carrier assemblies, (2) filter bypass adapter assemblies, and (3) sub-assemblies, parts, and repairs. Additional information is provided concerning contract requirements, test requirements, and failure investigation actions.

Source record↗
NASA NTRS1974

Distributed porous throat stability bypass to increase the stable airflow range of a Mach 2.5 inlet with 60 percent internal contraction

The results of an experimental investigation to increase the stable airflow operating range of a supersonic, mixed-compression inlet with 60-percent internal contraction are presented. Various distributed-porous, throat stability-bypass entrance configurations were tested. In terms of diffuser-exit corrected airflow, a large inlet stable airflow range of about 25 percent was obtained with the optimum configuration if a constant pressure was maintained in the by-pass plenum. The location of the centerbody bleed region had a decided effect on the overall inlet performance. Limited unstart angle-of-attack data are presented.

Shaw, R. J.↗
NASA NTRS1975

A throat-bypass stability system for a YF-12 aircraft research inlet using self-acting mechanical valves

Results of a wind tunnel investigation are presented. The inlet was modified so that airflow can be removed through a porous cowl-bleed region in the vicinity of the throat. Bleed plenum exit flow area is controlled by relief type mechanical valves. Unlike valves in previous systems, these are made for use in a high Mach flight environment and include refinements so that the system could be tested on a NASA YF-12 aircraft. The valves were designed to provide their own reference pressure. The results show that the system can absorb internal-airflow-transients that are too fast for a conventional bypass door control system and that the two systems complement each other quite well. Increased tolerance to angle of attack and Mach number changes is indicated. The valves should provide sufficient time for the inlet control system to make geometry changes required to keep the inlet started.

Cole, G. L.↗
NASA NTRS1975

A throat-bypass stability system for a YF-12 aircraft research inlet using self-acting mechanical valves

Results of a wind tunnel investigation are presented. The inlet was modified so that airflow can be removed through a porous cowl-bleed region in the vicinity of the throat. Bleed plenum exit flow area is controlled by relief type mechanical valves. Unlike valves in previous systems, these are made for use in a high Mach flight environment and include refinements so that the system could be tested on a NASA YF-12 aircraft. The valves were designed to provide their own reference pressure; hence, do not respond to slowly varying disturbances. However, the results show that the system can absorb internal-airflow-transients that are too fast for a conventional bypass door control system and that the two systems complement each other quite well. Increased tolerance to angle of attack and Mach number changes is indicated. The valves should provide sufficient time for the inlet control system to make geometry changes required to keep the inlet started.

Cole, G. L.↗
NASA NTRS1979

Multiplexed battery-bypass control system

Cell-bypass control system senses low capacity cells before they overcharge or discharge. Relay automatically removes defective cell (when it is detected) from battery circuit. System shows promise for improving batteries in computer standby power systems, electric vehicles, and energy storage systems.

Bennett, J. C.↗
NASA NTRS1979

Compact bypass-flow filter

Annular filter consisting of stacked rings separates particulates from bypass fluid passing through it in radial direction without slowing down main flow across unimpeded flow of fluid through its center. Applications include fluidized bed reactors, equipment for catalyst operations, and water purification.

Swift, W. G.↗
NASA NTRS1978

Low speed test of a high-bypass-ratio propulsion system with an asymmetric inlet designed for a tilt-nacelle V/STOL airplane

A large scale model of a lift/cruise fan inlet designed for a tilt nacelle V/STOL airplane was tested with a high bypass ratio turbofan. Testing was conducted at low freestream velocities with inlet angles of attack ranging from 0 deg to 120 deg. The operating limits for the nacelle were found to be related to inlet boundary layer separation. Small separations originating in the inlet diffuser cause little or no performance degradation. However, at sufficiently severe freestream conditions the separation changes abruptly to a lip separation. This change is associated with a significant reduction in nacelle net thrust as well as a sharp increase in fan blade vibratory stresses. Consequently, the onset of lip separation is regarded as the nacelle operating limit. The test verified that the asymmetric inlet design will provide high performance and stable operation at the design forward speed and angle of attack conditions. At some of these, however, operation near the lower end of the design inlet airflow range is not feasible due to the occurrence of lip separation.

Syberg, J.↗
NASA NTRS1980

Investigation of performance deterioration of the CF6/JT9D, high-bypass ratio turbofan engines

The aircraft energy efficiency program within NASA is developing technology required to improve the fuel efficiency of commercial subsonic transport aricraft. One segment of this program includes engine diagnostics which is directed toward determining the sources and causes of performance deterioration in the Pratt and Whitney Aircraft JT9D and General Electric CF6 high-bypass ratio turbofan engines and developing technology for minimizing the performance losses. Results of engine performance deterioration investigations based on historical data, special engine tests, and specific tests to define the influence of flight loads and component clearances on performance are presented. The results of analysis of several damage mechanisms that contribute to performance deterioration such as blade tip rubs, airfoil surface roughness and erosion, and thermal distortion are also included. The significance of these damage mechanisms on component and overall engine performance is discussed.

Ziemianski, J. A.↗
NASA NTRS1980

Conceptual study of an advanced supersonic technology transport (AST-107) for transpacific range using low-bypass-ratio turbofan engines

An advanced supersonic technology configuration concept designated the AST-107, using a low bypass ratio turbofan engine, is described and analyzed. The aircraft had provisions for 273 passengers arranged five abreast. The cruise Mach number was 2.62. The mission range for the AST-107 was 8.48 Mm (4576 n.mi.) and an average lift drag ratio of 9.15 during cruise was achieved. The available lateral control was not sufficient for the required 15.4 m/s (30 kt) crosswind landing condition, and a crosswind landing gear or a significant reduction in dihedral effect would be necessary to meet this requirement. The lowest computed noise levels, including a mechanical suppressor noise reduction of 3 EPNdB at the flyover and sideline monitoring stations, were 110.3 EPNdB (sideline noise), 113.1 EPNdB (centerline noise) and 110.5 EPNdB (approach noise).

Morris, S. J., Jr.↗
NASA NTRS1981

Turbine bypass engine: A new supersonic cruise propulsion concept

Engine performance and mission studies were carried out for a single-spool Turbine Bypass Engine concept. Comparisons were made between the TBE, a conventional single-spool turbojet, and the Pratt & Whitney Variable Stream Control Engine. The airplane assumed for the study was a Mach 2.32 commercial supersonic transport. The nominal mission was a 4000-nautical miles total range with a 300-nautical miles subsonic cruise leg. The figure of merit was the minimum takeoff gross weight for the mission. Comparisons of the three engines were also made for the 4000-nautical miles total range with longer subsonic cruise legs.

Franciscus, L. C.↗
NASA NTRS1981

Mixing effectiveness test of an exhaust gas mixer in a high bypass turbofan at altitude

Thermal mixing effectiveness characteristics of an eighteen lobe, scalloped and unscalloped, partial, forced mixer were measured in a high-bypass turbofan engine. Data were also obtained without the mixer installed, i.e., free mixing. Tests were conducted at four combinations of simulated flight conditions from 0.3 to 0.8 Mach number and from 6,096 meters (20,000 ft) to 13,715 m (45,000 ft) altitude, mixing chamber lengths of L/D=0.52 and 0.65 were tested. For this range of test conditions and mixer configurations, the forced mixing effectiveness varied from 59 to 68 percent. Values of mixing effectiveness and total pressure loss were calculated from temperature and pressure data obtained at the mixer inlet and exhaust nozzle exit.

Cullom, R. R.↗
NASA NTRS1980

Performance deterioration of commercial high-bypass ratio turbofan engines

NASA programs for improving aircraft engine fuel efficiency include the Engine Component Improvement Project of which the Engine Diagnostics section is to identify performance deterioration factors for the JT9D and CF6 high-bypass ratio turbofan engines and to develop technology for fuel consumption reduction. The program tests and inspects engines, examines deteriorated elements, formulates deterioration trends and models, identifies specific causative events or modules and determines mechanisms. Results show that short-term performance deterioration is less than 1% of cruise specific fuel consumption and is caused by flight loads or thermal damage due to rubbing of turbine blade tips against shrouds. Long-term deterioration is 2.5-3% of cruise specific fuel consumption after 2500-3000 flights and mechanisms are thermal damage to blade tips with rubbing and damaged airfoils and parts.

Mehalic, C. M.↗
NASA NTRS1981

Composite fan exit guide vanes for high bypass ratio gas turbine engines

Various composite materials were identified for reduced weight applications as fan exit guide vanes in high bypass ratio gas turbine engines. Candidate materials, airfoil geometry and ply orientation were evaluated using NASTRAN finite element analysis. A vane core and shell design approach utilizing several different fiber orientation concepts was selected and variations in bending and torsional stiffness were documented. Material suppliers and airfoil fabricators were selected to provide panels and airfoils which were inspected, environmentally conditioned and tested. Static and dynamic airfoil tests established durability characteristics for a range of composite material/design approaches.

Blecherman, S. S.↗
NASA NTRS1981

Turbine bypass engine - A new supersonic cruise propulsion concept

Engine performance and mission studies were carried out for a single-spool turbine bypass engine (TBE) concept. Comparisons were made between the TBE, a conventional single-spool turbojet, and the Pratt and Whitney Variable Stream Control Engine (VSCE). The airplane assumed for the study was a Mach 2.32 commercial supersonic transport. The nominal mission was a 4000 n mi total range with a 300 n mi subsonic cruise leg. The figure of merit was the minimum takeoff gross weight for the mission. Comparisons of the three engines were also made for the 4000 n mi total range with longer subsonic cruise legs.

Franciscus, L. C.↗