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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Stream tube curvature analysis

Program accurately calculates inviscid pressure distribution and flow field, including viscous displacement effects, around arbitrary axisymmetric ducted body at transonic speeds. Computerized flow field analysis predicts transonic flow around long and short high bypass ratio fan duct nacelles with inlet and outlet flows having appropriate aerothermodynamic properties. It makes possible parametric studies for evaluating nacelle design criteria and selecting configurations for further experimental investigations.

Ferguson, D. R.↗
NASA NTRS1979

Design, durability and low cost processing technology for composite fan exit guide vanes

A lightweight composite fan exit guide vane for high bypass ratio gas turbine engine application was investigated. Eight candidate material/design combinations were evaluated by NASTRAN finite element analyses. A total of four combinations were selected for further analytical evaluation, part fabrication by two ventors, and fatigue test in dry and wet condition. A core and shell vane design was chosen in which the unidirectional graphite core fiber was the same for all candidates. The shell material, fiber orientation, and ply configuration were varied. Material tests were performed on raw material and composite specimens to establish specification requirements. Pre-test and post-test microstructural examination and nondestructive analyses were conducted to determine the effect of material variations on fatigue durability and failure mode. Relevant data were acquired with respect to design analysis, materials properties, inspection standards, improved durability, weight benefits, and part price of the composite fan exit guide vane.

Blecherman, S. S.↗
NASA NTRS1979

Experimental study of acoustic loads on an upper-surface-blown STOL airplane configuration

Fluctuating pressure levels were measured on the flap and fuselage of an upper-surface-blown jet-flap airplane configuration in a wind tunnel. The model tested had turbofan engines with a bypass ratio of 3 and a thrust rating of 10 kN. Rectangular nozzles were mounted flush with the upper surface at 35 percent of the wing chord. Test parameters were flap deflection angle, jet impingement angle, angle of attack, free-stream velocity, spanwise location of the engine, and jet dynamic pressure. Load levels were high throughout the jet impingement region, with the highest levels (about 159 dB) occurring on the fuselage and near the knee of the flap. The magnitude of the forward-velocity effect appeared to depend upon the ratio of free-stream and jet velocities. Good agreement was obtained between fluctuating pressure spectra measured at jet dynamic pressures of 7 and 22 kPa when the spectra were scaled by nondimensional functions of dynamic pressure, velocity, and the empirical relationship between dynamic pressure and overall fluctuating pressure level.

Willis, C. M.↗
NASA NTRS1980

QCGAT aircraft/engine design for reduced noise and emissions

The high bypass ratio QCGAT engine played an important role in shaping the aircraft design. The aircraft which evolved is a sleek, advanced design, six-place aircraft with 3538 kg (7,800 lb) maximum gross weight. It offers a 2778 kilometer (1500 nautical mile) range with cruise speed of 0.5 Mach number and will take-off and land on the vast majority of general aviation airfields. Advanced features include broad application of composite materials and a supercritical wing design with winglets. Full-span fowler flaps were introduced to improve landing capability. Engines are fuselage-mounted with inlets over the wing to provide shielding of fan noise by the wing surfaces. The design objectives, noise, and emission considerations, engine cycle and engine description are discussed as well as specific design features.

Lanson, L.↗
NASA NTRS1980

Avco Lycoming QCGAT program design cycle, demonstrated performance and emissions

A high bypass ratio, twin spool turbofan engine of modular design which incorporates a front fan module driven by a modified LTS101 core engine was tested. The engine is housed in a nacelle incorporating full length fan ducting with sound treatment in both the inlet and fan discharge flow paths. Design goals of components and results of component tests are presented together with full engine test results. The rationale behind the combustor design selected for the engine is presented as well as the emissions test results. Total system (engine and nacelle) test results are included.

Fogel, P.↗
NASA NTRS1980

NASA broadened-specification fuels combustion technology program

The broadened-Specification Fuels Combustion Technology program's purpose is to evolve and demonstrate the technology required to enable current and next generation high-thrust, high-bypass-ratio turbofan engines to use fuels with broadened properties and to verify the evolved technology in full scale engine tests. The three phases of the program are combustor concept screening, combustor optimization testing, and engine verification testing. Constraints for designing combustion systems are outlined and problems to be expected in the use of broadened properties fuels are listed.

Fear, J. S.↗
NASA NTRS1980

Analytical investigation of fan tone noise due to ingested atmospheric turbulence

The atmospheric turbulence involved in the fan noise generation is evaluated with an existing model for the atmospheric turbulence and an extended version of an existing model concerned with the effects of a flow contraction on convected turbulence. Fan tone noise due to ingested atmospheric turbulence is evaluated with existing fan noise models. The results indicate that the difference in fan narrowband noise due to atmospheric turbulence between static and flight landing approach conditions is in the order of 30 dB. It is concluded that fan noise due to atmospheric turbulence is insignificant in flight conditions for the fans used in the current high bypass ratio engines. The difference in fan narrowband noise between the two conditions is primarily due to the low intensity of the turbulence involved in fan noise generation in flight conditions. Fan noise due to atmospheric turbulence in static conditions should be reduced below the flight fan broadband noise levels which is best achieved with a reduction in the intensity of the fan inflow turbulence. Such a reduction can be obtained with the use of an inflow control device, low wind velocities, small surface roughness in the test stand environment, and large engine axis height above the ground. Peak sound power levels for fan tone noise due to ingested turbulence occur for transverse integral scales in the order of 25% of the rotor blade spacing in the fan tip region.

Ganz, U. W.↗
NASA NTRS1980

Experimental evaluation of exhaust mixers for an Energy Efficient Engine

Static scale model tests were conducted to evaluate exhaust system mixers for a high bypass ratio engine as part of the NASA sponsored Energy Efficient program. Gross thrust coefficients were measured for a series of mixer configurations which included variations in the number of mixer lobes, tailpipe length, mixer penetration, and length. All of these parameters have a significant impact on exhaust system performance. In addition, flow visualization pictures and pressure/temperature traverses were obtained for selected configurations. Parametric performance trends are discussed and the results considered relative to the Energy Efficient Engine program goals.

Kozlowski, H.↗
NASA NTRS1979

TF34 engine compression system computer study

The stability of the fan and the compressor components was examined individually using linearized and time dependent, one dimensional stability analysis techniques. The stability of the fan core integrated compression system was investigated using a two dimensional compression system model. The analytical equations on which this model was based satisfied the mass, axial momentum, radial momentum, and energy conservation equations for flow through a finite control volume. The results gave an accurate simulation of the flow through the compression system. The speed lines of the components were reproduced; the points of instability were accurately predicted; the locations where the instability was initiated in the fan and the core were indicated; and the variation of the bypass ratio during flow throttling was calculated. The validity of the analytical techniques was then established by comparing these results with test data and with results obtained from the steady state cycle deck.

Hosny, W. M.↗
NASA NTRS1981

JT8D engine performance retention

The attractive performance retention characteristics of the JT8D engine are described. Because of its moderate bypass ratio and turbine temperature, and stiff structural design, the performance retention versus flight cycles of the JT8D engine sets a standard that is difficult for other engines to equal. In addition, the significant benefits of refurbishment of the JT8D engine are presented. Cold section refurbishment offers thrust specific fuel consumption improvements of up to 2 percent and payback in less than a year, making a very attractive investment option for the airlines.

James, A. D.↗
NASA NTRS1980

Design, durability and low cost processing technology for composite fan exit guide vanes

A program was conducted to design, fabricate and test a durable, low cost, lightweight composite fan exit guide vane for high bypass ratio gas turbine engine application. Eight candidate material/design combinations were evaluated by NASTRAN finite element analysis. Four of these candidate systems were selected for composite vane fabrication by two vendors. A core and shell vane design was chosen in which the unidirectional graphite core fiber was the same for all candidates. The shell material, fiber orientation and ply configuration were varied. Material tests were performed on raw material and composite specimens to establish specification requirements. Composite vanes were nondestructively inspected and subsequently fatigue tested in both dry and 'wet' conditions. The program provided relevant data with respect to design analysis, materials properties, inspection standards, improved durability, weight benefits and part price of the composite fan exit guide vane.

Blecherman, S. S.↗
NASA NTRS1981

Advanced supersonic transport propulsion and configuration technology improvements

This paper presents the results of recent Douglas Aircraft Company integration studies for an advanced supersonic transport. The studies include technology improvements such as superplastic formed and diffusion-bonded titanium sandwich primary structure, composite secondary structure, bicone engine inlet, improved mechanical suppressors based on flight test data, improved aerodynamic efficiency based on wind tunnel test data, and updated performance for both variable-cycle and low-bypass-ratio engines. Technology development requirements for an economically viable and environmentally acceptable advanced supersonic transport are defined through these studies. A new Douglas Aircraft Company baseline supersonic transport designed to carry 350 passengers is defined for cost comparisons.

Rowe, W. T.↗
NASA NTRS1981

Ground effects on aircraft noise for a wide-body commercial airplane

Ground effects on noise from a high-bypass ratio engined aircraft are investigated. A 747 is flown at altitudes from 30 to 960 m past a 20-microphone array, and ground effects are calculated from noise measurements as a function of elevation angle and slant range. Results are given in terms of EPNL units and are compared with previous results of a turbojet-powered T-38 and SAE-recommended empirical lateral attenuation prediction procedures. Theoretical predictions are made based on a method developed by Pao et al. (1978) and are compared with both 747 and T-38 results, demonstrating good agreement although a consistent underprediction of peak measured attenuation is observed. Measured ground effects are found largest at 200 Hz, and no definite shielding differences are apparent for a directivity angle of 122.5 deg. Less lateral attenuation of effective perceived noise is measured for both aircraft and is attributed to the dominance of low-frequency noise in the source spectrum.

Willshire, W. L., Jr.↗
NASA NTRS1982

Computer modeling of fan-exit-splitter spacing effects on F100 response to distortion

The distortion response of the F100(3) engine was effected by the fan exit splitter configuration. The sensitivity for a proximate splitter fan is calculated to be slightly greater than a remote splitter configuration with identical airfoils. Predicted response was based upon a multiple segment parallel compressor Model modified to include a bypass ratio representation that effects the performance characteristics of the last rotor and intermediate case struts. The predicted distortion response required an accurate definition of row pre- and post-stall undistorted operation.

Shaw, M.↗
NASA NTRS1981

Ground test of a large scale 'D' vented thrust deflecting nozzle

Future V/STOL aircraft will require efficient techniques for changing the thrust vector from the vertical direction for VTOL operation to the horizontal direction for conventional flight. Most V/STOL concepts utilize thrust vectoring nozzles to provide this variation in the thrust vector direction. An experimental test program was initiated to demonstrate the capabilities of a large scale 'D' vented thrust deflecting system coupled with a high bypass ratio turbofan engine. Data were obtained for a 'D' vented nozzle mounted behind a YTF-34-F5 turbofan engine. Preliminary data are presented for a variety of test conditions. Attention is given to aspects of 'D' vented nozzle design, the test apparatus, engine-nozzle compatibility, exit area variation, longitudinal vectoring performance, nozzle temperature distribution, and large scale - small scale comparisons.

Rosenberg, E. W.↗
NASA NTRS1983

Installation of electric generators on turbine engines

The installation of generators on turbine aircraft is discussed. Emphasis is placed on the use of the samarium cobalt generator. Potential advantages of an electric secondary power system at the engine level are listed. The integrated generator and the externally mounted generator are discussed. It is concluded that the integrated generator is best used in turbojet and low bypass ratio engines where there is no easy way of placing generators externally without influencing frontal areas.

Demel, H. F.↗
NASA NTRS1984

Hot-flow tests of a series of 10-percent-scale turbofan forced mixing nozzles

An approximately 1/10-scale model of a mixed-flow exhaust system was tested in a static facility with fully simulated hot-flow cruise and takeoff conditions. Nine mixer geometries with 12 to 24 lobes were tested. The areas of the core and fan stream were held constant to maintain a bypass ratio of approximately 5. The research results presented in this report were obtained as part of a program directed toward developing an improved mixer design methodology by using a combined analytical and experimental approach. The effects of lobe spacing, lobe penetration, lobe-to-centerbody gap, lobe contour, and scalloping of the radial side walls were investigated. Test measurements included total pressure and temperature surveys, flow angularity surveys, and wall and centerbody surface static pressure measurements. Contour plots at various stations in the mixing region are presented to show the mixing effectiveness for the various lobe geometries.

Head, V. L.↗
NASA NTRS1982

Nacelle Aerodynamic and Inertial Loads (NAIL) project

A flight test survey of pressures measured on wing, pylon, and nacelle surfaces and of the operating loads on Boeing 747/Pratt & Whitney JT9D-7A nacelles was made to provide information on airflow patterns surrounding the propulsion system installations and to clarify processes responsible for inservice deterioration of fuel economy. Airloads at takeoff rotation were found to be larger than at any other normal service condition because of the combined effects of high angle of attack and high engine airflow. Inertial loads were smaller than previous estimates indicated. A procedure is given for estimating inlet airloads at low speeds and high angles of attack for any underwing high bypass ratio turbofan installation approximately resembling the one tested. Flight procedure modifications are suggested that may result in better fuel economy retention in service. Pressures were recorded on the core cowls and pylons of both engine installations and on adjacent wing surfaces for use in development of computer codes for analysis of installed propulsion system aerodynamic drag interference effects.

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