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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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NASA NTRS1992

NASA-UVA light aerospace alloy and structures technology program (LA(sup 2)ST)

The general objective of the Light Aerospace Alloy and Structures Technology (LA(sup 2)ST) Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and thermal gradient structures in collaboration with Langley researchers. Specific technical objectives are established for each research project. We aim to produce relevant data and basic understanding of material behavior and microstructure, new monolithic and composite alloys, advanced processing methods, new solid and fluid mechanics analyses, measurement advances, and critically, a pool of educated graduate students for aerospace technologies. Four research areas are being actively investigated, including: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals and Composites; (2) Aerospace Materials Science; (3) Mechanics of Materials and Composites for Aerospace Structures; and (4) Thermal Gradient Structures.

Gangloff, Richard P.↗
NASA NTRS1991

FAST: A multi-processed environment for visualization of computational fluid dynamics

Three-dimensional, unsteady, multi-zoned fluid dynamics simulations over full scale aircraft are typical of the problems being investigated at NASA Ames' Numerical Aerodynamic Simulation (NAS) facility on CRAY2 and CRAY-YMP supercomputers. With multiple processor workstations available in the 10-30 Mflop range, we feel that these new developments in scientific computing warrant a new approach to the design and implementation of analysis tools. These larger, more complex problems create a need for new visualization techniques not possible with the existing software or systems available as of this writing. The visualization techniques will change as the supercomputing environment, and hence the scientific methods employed, evolves even further. The Flow Analysis Software Toolkit (FAST), an implementation of a software system for fluid mechanics analysis, is discussed.

Bancroft, Gordon V.↗
NASA NTRS1990

Aeropropulsion 1987

Papers from the Aeropropulsion '87 Conference, held at the NASA Lewis Research Center (LeRC), are presented. Unclassified presentations by LeRC and NASA Headquarters senior management and many LeRC technical authors covered the philosophy and major directions of the LeRC aeropropulsion program, and presented a broad spectrum of recent research results in materials, structures, internal fluid mechanics, instrumentation and controls, and both subsonic and high-speed propulsion technology.

Source record↗
NASA NTRS1992

Development of a quiet supersonic wind tunnel with a cryogenic adaptive nozzle

The main objective of this work was the development of an interim quiet (low-disturbance) supersonic wind tunnel for the NASA-Ames Fluid Mechanics Laboratory (FML). This is a result of the need to bring the full-scale tunnel on-line as rapidly as possible to impact the NASA High Speed Research Program (HSRP). The development of a cryogenic adaptive nozzle and other sophisticated features of the tunnel will now happen later, after the full scale wind tunnel is in operation.

Wolf, Stephen W. D.↗
NASA NTRS1992

The FML compressor as a drive system for the LFSWT: A narrative

During 1988, a feasibility study was performed to decide how best to build a Laminar Flow Supersonic Wind Tunnel (LFSWT) at the NASA-Ames Fluid Mechanics Laboratory (FML) for boundary layer transition research. A full report was received in June 1988. The report was based on the following guidelines: continuous operation at Mach numbers within the range from 1.8-4.0 was required to impact the NASA 'HiStar' project; low disturbance flow is essential for transition research; minimum test section height is 8 inches; tunnel must fit in an FML test cell; tunnel design should be simple; and construction costs should be minimized. The study considered three drive system options: (1) use surplus JPL compressors and support equipment; (2) use of the FML compressor with ambient injectors; and (3) use of the FML compressor with injectors driven by the NASA-Ames 3000 psia air supply.

Laub, James↗
NASA NTRS1992

Dynamic simulation of compressor and gas turbine performance

Dynamic simulation of compressor and gas turbine performance is useful in a variety of design, analysis, and test applications. Mathematical models employing estimated or experimentally-derived component characteristics have been widely used, especially for near-design-point studies of acceleration and deceleration transients and control strategies. With recent progress in simulation methods and computational power, it has become possible to build models with detail at the stage level, and with fundamental fluid mechanics input. Such models are more useful because of the ability to study the details of inter-component flow property behavior during machine transients, even including stall and surge. Dynamic performance simulation models are discussed with emphasis on the fundamental principles of the models and the methods used to represent component and stage flow characteristics. Results of several simulations of the dynamic behavior of multistage compressors are shown with comparisons to experimental data. Possibilities for advanced computational techniques for near-real-time simulations of compressors and gas turbines are reviewed.

Walter F O'Brien↗
NASA NTRS1991

A survey of spacecraft thermal design solutions

A review of activities at the NASA/Marshall Space Flight Center in the heat transfer and thermodynamics disciplines as well as attendant fluid mechanics, transport phenomena, and computer science applications is presented. Attention is focused on recent activities including the Hubble Space Telescope, and large space instruments, particularly telescope thermal control systems such as those flown aboard Spacelab 2 and the Astro missions. Emphasis is placed on defining the thermal control features, unique design schemes, and performance of selected programs. Results obtained both by ground testing and analytical means, as well as flight and postflight data are presented.

Humphries, R.↗
NASA NTRS1992

Vortex rings

The vortex-ring problem in fluid mechanics is examined generally in terms of formation, the steady state, the duration of the rings, and vortex interactions. The formation is studied by examining the generation of laminar and turbulent vortex rings and their resulting structures with attention given to the three stages of laminar ring development. Inviscid dynamics is addressed to show how core dynamics affects overall ring motion, and laminar vortex structures are described in two dimensions. Viscous and inviscid structures are related in terms of 'leapfrogging', head-on collisions, and collisions with a no-slip wall. Linear instability theory is shown to successfully describe observational data, although late stages in the breakdown are not completely understood. This study of vortex rings has important implications for key aerodynamic issues including sound generation, transport and mixing, and vortex interactions.

Shariff, Karim↗
NASA NTRS1991

On the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF

Fluid mechanics scaling is briefly reviewed and testing ship models at high Reynolds numbers in the National Transonic Facility is discussed. Particular attention is given to the 1986 body of revolution experiment, the expanded model capabilities for a future body of revolution experiment, major features of a future flat plate experiment, the proposed liquid helium tunnel from the user's point of view, and a comparison of the NTF and the Conceptual Helium Tunnel.

Coder, David W.↗
NASA NTRS1991

Water tunnels

Some of the uses of water tunnels are demonstrated through the description of the NASA Ames-Dryden Flow Visualization Facility. It is concluded that water tunnels are capable of providing a quick and inexpensive means of flow visualization and can aid in the understanding of complex fluid mechanics phenomena.

Bjarke, Lisa J.↗
NASA NTRS1992

Decoupled predictions of radiative heating in air using a particle simulation method

A particle simulation technique with decoupled radiation is used to estimate the radiative emission along the stagnation streamline and the radiative heating at the stagnation point of a blunt-nosed vehicle entering the earth's atmosphere at hypersonic speed. The direct simulation Monte Carlo (DSMC) method is used to compute the fluid mechanics of the weakly ionized flow. The radiative emission is computed using the NEQAIR computer code with the radiation decoupled from the flowfield solution. It is concluded that the new models make it possible to decrease the predicted total radiative heating at the stagnation point of the vehicle by a factor of 15. A comparison of the DSMC approach with a continuum flow model shows that the total predicted radiative heating estimates agree within a factor of 2.

Boyd, Iain D.↗
NASA NTRS1992

Evaluation of thermochemical models for particle and continuum simulations of hypersonic flow

Computations are presented for one-dimensional, strong shock waves that are typical of those that form in front of a reentering spacecraft. The fluid mechanics and thermochemistry are modeled using two different approaches. The first employs traditional continuum techniques in solving the Navier-Stokes equations. The second approach employs a particle simulation technique (the direct simulation Monte Carlo method, DSMC). The thermochemical models employed in these two techniques are quite different. The present investigation presents an evaluation of thermochemical models for nitrogen under hypersonic flow conditions. Four separate cases are considered that are dominated in turn by vibrational relaxation, weak dissociation, strong dissociation and weak ionization. In near-continuum, hypersonic flow, the nonequilibrium thermochemical models employed in continuum and particle simulations produce nearly identical solutions. Further, the two approaches are evaluated successfully against available experimental data for weakly and strongly dissociating flows.

Boyd, Iain D.↗
NASA NTRS1992

A general explicit or semi-explicit algorithm for compressible and incompressible flows

A unified finite element algorithm is developed which is applicable to a wide range of problems of fluid mechanics without recourse to artificial, empirically determined factors. In its explicit form, the algorithm is similar to the Taylor-Galerkin scheme and is easily adopted to standard codes. The scheme proposed here possesses sufficient natural balancing diffusion and thus reduces and sometimes eliminates the need for special 'shock capturing' diffusion. The efficiency of the algorithm is demonstrated using several examples ranging from incompressible through transonic regions to supersonic flows.

Zienkiewicz, O. C.↗
NASA NTRS1992

Flow induction by pressure forces

A dual experimental/computational approach to the fluid mechanics of complex interactions that take place in a rotary-jet ejector is presented. The long-range goal is to perform both detailed flow mapping and finite element computational analysis. The described work represents an initial finding on the experimental mapping program. Test results on the hubless rotary-jet are discussed.

Garris, C. A.↗
NASA NTRS1992

A discrete vortex model for predicting wing rock of slender wings

The fluid mechanism responsible for generating wing rock of slender sharp-edged delta wings was investigated using an unsteady discrete vortex model developed for that purpose, which is based on results of experimental investigations. Combined experimental and computational results indicate that wing rock is sustained by a lag in the position of the leading edge vortices normal to the surface. Results of comutations also indicate that certain complex aerodynamic problems may be governed primarily by unsteady inviscid phenomena.

Arena, Andrew S., Jr.↗
NASA NTRS1992

An experimental technique for performing 3-D LDA measurements inside whirling annular seals

During the last several years, the Fluid Mechanics Division of the Turbomachinery Laboratory at Texas A&M University has developed a rather unique facility with the experimental capability for measuring the flow field inside journal bearings, labyrinth seals, and annular seals. The facility consists of a specially designed 3-D LDA system which is capable of measuring the instantaneous velocity vector within 0.2 mm of a wall while the laser beams are aligned almost perpendicular to the wall. This capability was required to measure the flow field inside journal bearings, labyrinth seals, and annular seals. A detailed description of this facility along with some representative results obtained for a whirling annular seal are presented.

Morrison, Gerald L.↗
NASA NTRS1992

A fundamental study of suction for Laminar Flow Control (LFC)

This report covers the period forming the first year of the project. The aim is to experimentally investigate the effects of suction as a technique for Laminar Flow Control. Experiments are to be performed which require substantial modifications to be made to the experimental facility. Considerable effort has been spent developing new high performance constant temperature hot-wire anemometers for general purpose use in the Fluid Mechanics Laboratory. Twenty instruments have been delivered. An important feature of the facility is that it is totally automated under computer control. Unprecedently large quantities of data can be acquired and the results examined using the visualization tools developed specifically for studying the results of numerical simulations on graphics works stations. The experiment must be run for periods of up to a month at a time since the data is collected on a point-by-point basis. Several techniques were implemented to reduce the experimental run-time by a significant factor. Extra probes have been constructed and modifications have been made to the traverse hardware and to the real-time experimental code to enable multiple probes to be used. This will reduce the experimental run-time by the appropriate factor. Hot-wire calibration drift has been a frustrating problem owing to the large range of ambient temperatures experienced in the laboratory. The solution has been to repeat the calibrations at frequent intervals. However the calibration process has consumed up to 40 percent of the run-time. A new method of correcting the drift is very nearly finalized and when implemented it will also lead to a significant reduction in the experimental run-time.

Watmuff, Jonathan H.↗