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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Technology challenges for the National Aero-Space Plane

The National Aerospace Plane (NASP) will require an exceptionally high degree of integration between propulsion and aerodynamic configuration, in order to achieve the requisite specific impulse and low structural weight. This is to be achieved through the use of forebody shock compression and afterbody exhaust expansion. Attention is presently given to the materials and structural concepts required for the realization of these NASP airframe functions, in view of the exceptionally high aerothermodynamic loads that will be experienced at hypersonic speeds. Active cooling will have to be used in certain critical airframe and propulsion components. CFD characterizations of these processes must be carefully developed and fully validated.

Piland, William M.↗
NASA NTRS1988

The NASA Integrated Test Facility and its impact on flight research

NASA-Ames' Integrated Test Facility (ITF), when completed, will provide ground test facilities for the safe and efficient testing of advanced research aircraft with fully integrated flight control, propulsion systems, structures, and aerodynamic configurations. Flight test risk will be minimized through the reduction of differences between flight and ground test environments; the latter will involve the interfacing of real-time flight simulation with the actual aircraft through a simulation-interface device. The test process and the collection and management of test data will be automated. Attention is given to preliminary ITF results for the X-29 aircraft.

Mackall, D. A.↗
NASA NTRS1988

Phenomenological aspects of infrared imaging in aeronautical research

The various factors leading to obtaining a thermography of an aerodynamic body of interest using an infrared imaging camera are scrutinized. Included is a description of how the various heat transfer mechanisms determine the final surface temperature that may be time dependent even for steady state flows. Some constraining factors of the camera are also discussed. Finally, a method is outlined showing how the infrared imaging of aerodynamic configurations may ultimately evolve as a computational fluid dynamics code validation tool.

Gartenberg, Ehud↗
NASA NTRS1988

The Horizon: A blended wing aircraft configuration design project, volume 3

The results of a study to design a High-Speed Civilian Transport (HSCT) using the blended wing-body configuration are presented. The HSCT is a Mach 2 to 5 transport aircraft designed to compete with current commercial aircraft. The subjects discussed are sizing, configuration, aerodynamics, stability and control, propulsion, performance, structures and pollution effects.

Keidel, Paul↗
NASA NTRS1989

Vector potential methods

Vector potential and related methods, for the simulation of both inviscid and viscous flows over aerodynamic configurations, are briefly reviewed. The advantages and disadvantages of several formulations are discussed and alternate strategies are recommended. Scalar potential, modified potential, alternate formulations of Euler equations, least-squares formulation, variational principles, iterative techniques and related methods, and viscous flow simulation are discussed.

Hafez, M.↗
NASA NTRS1989

Before the high-speed civil transport

Following the cancellation of the U.S. National SST Program in March, 1971, NASA conducted SST propulsion technology and configurational aerodynamics and structures development efforts through what came in the wake of a 1976 conference to be called the Supersonic Cruise Research and Variable Cycle Engine programs. These programs were in turn canceled in 1982. The present historical assessment of major advancements in passenger aircraft technology notes that the flying public has tended to be reluctant in accepting such innovations as swept-wing jet airliners and may be expected to be similarly wary about SST use.

Spearman, M. Leroy↗
NASA NTRS1989

Computation of hypersonic flow fields

The present discussion of the theory, solution methods, and development status of chemically reactive flow CFD codes pertaining to the flow field around a hypersonic vehicle encompasses the formulation of multicomponent viscous equations, grid-generation techniques, and finite-difference algorithms. The Navier-Stokes equations presented focus on such particularities of high speed vehicles as their aerodynamic configuration, lee and wake flow, bow shock, and chemistry and low density effects. Issues for which further development is desirable encompass boundary treatments, grid quality, shock capturing, and the decoupling of chemistry from flow variables.

Li, Chien-Peng↗
NASA NTRS1988

Knowledge-based flow field zoning

Automation flow field zoning in two dimensions is an important step towards easing the three-dimensional grid generation bottleneck in computational fluid dynamics. A knowledge based approach works well, but certain aspects of flow field zoning make the use of such an approach challenging. A knowledge based flow field zoner, called EZGrid, was implemented and tested on representative two-dimensional aerodynamic configurations. Results are shown which illustrate the way in which EZGrid incorporates the effects of physics, shape description, position, and user bias in a flow field zoning.

Andrews, Alison E.↗
NASA NTRS1989

Solar probe mission status

The penetration of coronal regions by a solar probe employing planetary gravity-assist trajectories to attain perihelia of only a few solar radii will allow unique in situ experiments to be conducted. The trajectory design options will fundamentally impact solar probe spacecraft design criteria. The aerogravity-assist method, which requires the bending of a trajectory in the vicinity of a planet by passing through a portion of its atmosphere will yield large changes in direction and velocity. This option would in the case of a solar probe mission involve the use of either the earth or Venus as a target for a specially aerodynamically configured 'waverider' spacecraft with L/D of the order of 10.

Randolph, J. E.↗
NASA NTRS1990

Outer-layer manipulators for turbulent drag reduction

The last ten years have yielded intriguing research results on aerodynamic boundary outer-layer manipulators as local skin friction reduction devices at low Reynolds numbers; net drag reduction device systems for entire aerodynamic configurations are nevertheless noted to remain elusive. Evidence has emerged for dramatic alterations of the structure of a turbulent boundary layer which persist for long distances downstream and reduce wall shear as a results of any one of several theoretically possible mechanisms. Reduced effectiveness at high Reynolds numbers may, however, limit the applicability of outer-layer manipulators to practical aircraft drag reduction.

Anders, J. B., Jr.↗
NASA NTRS1990

Automated domain decomposition for computational fluid dynamics

Automation of flow-field zoning in two-dimensions is an important step towards easing the three-dimensional grid generation bottleneck in computational fluid dynamics. A knowledge-based approach works well, but several aspects of flow-field zoning make the use of such an approach challenging. A proposed model and language to describe the process of zoning a flow field are presented, followed by a discussion of the implementation of EZGrid, a knowledge-based two-dimensional (2-D) flow-field zoner. Results are shown for representative two-dimensional aerodynamic configurations. Finally, an approach to the evaluation of flow-field zonings is described and used to compare the performance of EZGrid with that of a human expert.

Vogel, Alison Andrews↗
NASA NTRS1990

Tethered aerothermodynamic research for hypersonic waveriders

This paper describes the concept of a space-tethered atmospheric system, a hybrid craft consisting of an orbiting spacecraft and a downward-deployed aerodynamically-configured satellite. Such a system could conduct both hypersonic aerothermodynamics research and atmospheric science research in the outer atmosphere (about 150-90 km). Descriptions of specific space-tethered atmospheric systems, scheduled tether flight validation experiments, and a development strategy for a three-phased aerothermodynamics research capability culminating in a 'flying wind tunnel' are provided.

Anderson, John L.↗
NASA NTRS1991

Space-tethered atmospheric systems

This paper describes the concept of a space-tethered atmospheric system, a hybrid craft consisting of an orbiting spacecraft and a downward-deployed aerodynamically-configured satellite. Such a system could conduct hypersonic aerothermodynamics and atmospheric science research in the lower thermosphere (150-90 km). Descriptions of specific tethered atmospheric systems, scheduled tether flight validation experiments, candidate research topics and envisioned capabilities and benefits are provided.

Anderson, J. L.↗
NASA NTRS1991

Technical bases for High Speed Civil Transport environmental acceptability

Uncertainties concerning atmospheric pollution, airport-community noise, and sonic booms, are the concerns of NASA's High-Speed Research Program. Current analytical predictions are of an operational regime centered on Mach 2.4/20-km altitude where the goal of 5-gm equivalent NO2 emissions/kg fuel can result in no more than 1-percent column ozone depletion. Jet-noise suppressors using a mixer-ejector device are seen as capable of furnishing substantial noise reduction. Low-boom aerodynamic configurations are under scrutiny to maximize aircraft economic performance through overland supersonic flight.

Wesoky, Howard L.↗
NASA NTRS1991

Vortex control: Further encounters

The progress of continuing investigations on vortex control techniques is updated. The following topics are briefly discussed: (1) vortex flaps adapted for high-alpha control; (2) alleviation of leading edge extension (LEX) vortex induced twin-tail buffet; (3) controlled decoupling of interactive forebody chine and wing vortices; (4) forebody vortex manipulation by mechanical and pneumatic techniques; and (5) stall-departure alleviation of high aspect-ratio wings. Salient results of exploratory low speed wind tunned experiments are presented. The investigations, primarily aimed at concept validation, were performed on generic configurations utilizing flow visualizations and pressure and balance measurements. Selected results illustrate the efficacy and potential for development of specific vortex control concepts for improved high-alpha configuration aerodynamics.

Rao, Dhanvada M.↗
NASA NTRS1990

Integrated Aerodynamic and Control System Design of Oblique Wing Aircraft

An efficient high speed aircraft design must achieve a high lift to drag ratio at transonic and supersonic speeds. In 1952 Dr. R. T. Jones proved that for any flight Mach number minimum drag at a fixed lift is achieved by an elliptic wing planform with an appropriate oblique sweep angle. Since then, wind tunnel tests and numerical flow models have confirmed that the compressibility drag of oblique wing aircraft is lower than similar symmetrical sweep designs. At oblique sweep angles above thirty degrees the highly asymmetric planform gives rise to aerodynamic and inertia couplings which affect stability and degrade the aircraft's handling qualities. In the case of the NASA-Rockwell Oblique Wing Research Aircraft, attempts to improve the handling qualities by implementing a stability augmentation system have produced unsatisfactory results because of an inherent lack of controllability in the proposed design. The present work focuses on improving the handling qualities of oblique wing aircraft by including aerodynamic configuration parameters as variables in the control system synthesis to provide additional degrees of freedom with which to further decouple the aircraft's response. Handling qualities are measured using a quadratic cost function identical to that considered in optimal control problems, but the controller architecture is not restricted to full state feedback. An optimization procedure is used to simultaneously solve for the aircraft configuration and control gains which maximize a handling qualities measure, while meeting imposed constraints on trim. In some designs wing flexibility is also modeled and reduced order controllers are implemented. Oblique wing aircraft synthesized by this integrated design method show significant improvement in handling qualities when compared to the originally proposed closed loop aircraft. The integrated design synthesis method is then extended to show how handling qualities may be traded for other types of mission performance (drag, weight, etc.). Examples are presented which show how performance can be maximized while maintaining a desired level of handling quality.

Morris, Stephen James↗
NASA NTRS1988

A preliminary component analysis of a Mach-7 hypersonic vehicle

As research continues in the development of an aircraft capable of travelling at hypersonic flight velocities, both the propulsion and thermal management systems stand out as areas requiring innovative technological breakthroughs. For propulsion, the difficulty involves efficiently compressing and combusting hydrogen in a supersonic stream, i.e., developing a viable scramjet with thermal management, the challenge lies in development of materials and active cooling systems capable of handling the enormous heat fluxes associated with hypersonic flight. This paper focuses on these problems and presents component designs for both an active cooling system and an all-external-compression scramjet. These systems are mated to a Mach-6 passenger cruise aircraft whose aerodynamic configuration was derived from an optimization of NASA windtunnel test results. The following outlines the development of the configuration and then focuses in on the design of the two component systems.

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NASA NTRS1988

Design of components for growing higher plants in space

The overall goal of this project is to design unique systems and components for growing higher plants in microgravity during long-term space missions (Mars and beyond). Specific design tasks were chosen to contribute to and supplement NASA's Controlled Ecological Life Support System (CELSS) project. Selected tasks were automated seeding of plants, plant health sensing, and food processing. Prototype systems for planting both germinated and nongerminated seeds were fabricated and tested. Water and air pressure differences and electrostatic fields were used to trap seeds for separation and transport for planting. An absorption spectrometer was developed to measure chlorophyll levels in plants as an early warning of plant health problems. In the area of food processing, a milling system was created using high-speed rotating blades which were aerodynamically configured to produce circulation and retractable to prevent leakage. The project produced significant results having substantial benefit to NASA. It also provided an outstanding learning experience for the students involved.

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