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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Methodology for CFD Design Analysis of National Launch System Nozzle Manifold

The current design environment dictates that high technology CFD (Computational Fluid Dynamics) analysis produce quality results in a timely manner if it is to be integrated into the design process. The design methodology outlined describes the CFD analysis of an NLS (National Launch System) nozzle film cooling manifold. The objective of the analysis was to obtain a qualitative estimate for the flow distribution within the manifold. A complex, 3D, multiple zone, structured grid was generated from a 3D CAD file of the geometry. A Euler solution was computed with a fully implicit compressible flow solver. Post processing consisted of full 3D color graphics and mass averaged performance. The result was a qualitative CFD solution that provided the design team with relevant information concerning the flow distribution in and performance characteristics of the film cooling manifold within an effective time frame. Also, this design methodology was the foundation for a quick turnaround CFD analysis of the next iteration in the manifold design.

Haire, Scot L.↗
NASA NTRS1973

Computations of non-reacting and reacting viscous blunt body flows, volume 1

The computer programs developed for computation of viscous shock layer flow distribution surrounding the nose of a shuttle orbiter during reentry are presented. The problem formulation and the numerical procedures used to solve the basic set of equations are described. The results of flow distribution properties at several trajectory points, ranging from the high altitude rarefied region to the low altitude boundary layer region are analyzed.

Li, C. P.↗
NASA NTRS1981

An experimental investigation of a large delta P settling chamber for a supersonic pilot quiet tunnel

The mean streamwise flow distributions and turbulence levels across the chamber were measured with a hot wire anemometer downstream of a series of porous Rigimesh plates which were shown to be an effective means of reducing the chamber acoustic disturbance levels due to upstream pipe and valve systems. Tests made with various types of flow conditioners downstream of the porous plates showed that a series of screens was the most effective means of achieving the objective of a uniform mean flow distribution with reduced vorticity levels downstream of the porous components. Frequency spectra obtained across the series of screens show that they reduce vorticity over a wide frequency range for several different initial upstream vorticity conditions. Improvements in the mechanical installation of the porous plates and damping screens and the use of porous plates with more uniform porosity should reduce the freestream velocity fluctuations to the minimum acoustic levels of about 0.5 percent.

Piatt, M.↗
NASA NTRS1973

Computations of non-reacting and reacting viscous blunt body flows, volume 2

Computer programs for calculating the flow distribution in the nose region of a blunt body at arbitrary speed and altitude are discussed. The programs differ from each other in their ability to consider either thin shock or thick shock conditions and in the use of either ideal, equilibrium air, or nonequilibrium air chemistry. The application of the programs to analyzing the flow distribution around the nose of the shuttle orbiter during reentry is reported.

Li, C. P.↗
NASA NTRS2007

Microfluidic System Simulation Including the Electro-Viscous Effect

This paper describes a practical approach using a general purpose lumped-parameter computer program, GFSSP (Generalized Fluid System Simulation Program) for calculating flow distribution in a network of micro-channels including electro-viscous effects due to the existence of electrical double layer (EDL). In this study, an empirical formulation for calculating an effective viscosity of ionic solutions based on dimensional analysis is described to account for surface charge and bulk fluid conductivity, which give rise to electro-viscous effect in microfluidics network. Two dimensional slit micro flow data was used to determine the model coefficients. Geometry effect is then included through a Poiseuille number correlation in GFSSP. The bi-power model was used to calculate flow distribution of isotropically etched straight channel and T-junction microflows involving ionic solutions. Performance of the proposed model is assessed against experimental test data.

Rojas, Eileen↗
NASA NTRS1968

Improved fluid dynamics similarity, analysis and verification. Part 5: Analytical and experimental studies of thermal stratification phenomena

The stratification behavior of a contained fluid subjected to transient free convection heat transfer was studied. A rectangular vessel was employed with heat transfer from two opposite walls of the vessel to the fluid. The wall temperature was increased suddenly to initiate the process and was then maintained constant throughout the transient stratification period. Thermocouples were positioned on a post at the center of the vessel. They were adjusted so that temperatures could be measured at the fluid surface and at specific depths beneath the surface. The predicted values of the surface temperature and the stratified layer thickness were found to agree reasonably well with the experimental measurements. The experiments also provided information on the transient centerline temperature distribution and the transient flow distribution.

Winter, E. R. F.↗
NASA NTRS1985

Measurement of energy distribution in flowing hydrogen microwave plasmas

An electrothermal propulsion concept utilizing a microwave plasma system as the mechanism to convert electromagnetic energy into kinetic energy of a flowing gas is investigated. A calorimetry system enclosing a microwave plasma system has been developed to accurately measure the energy inputs and outputs of the microwave plasma system. The rate of energy transferred to the gas can be determined to within + or - 1.8 W from an energy balance around the microwave plasma system. The percentage of the power absorbed by the microwave plasma system transferred to the hydrogen gas as it flows through the system is found to increase with the increasing flow rate, to decrease with the increasing pressure, and to be independent of the absorbed power. An upper bound for the hydrogen gas temperature is estimated from the energy content, heat capacity, and flow rate of the gas stream. A lower bound for an overall heat-transfer coefficient is then calculated, characterizing the energy loss from the hydrogen gas stream to the air cooling of the plasma discharge tube wall. The heat-transfer coefficient is found to increase with the increasing flow rate and pressure and to be independent of the absorbed power. This result indicates that a convective-type mechanism is responsible for the energy transfer.

Chapman, R.↗
NASA NTRSDate not supplied

Integrated Computational Fluid Dynamics and Thermal Desktop Thermal Modeling for Assessment of the EMU in Support of ISS EVA 80

Following the reports of water accumulation in the Extravehicular Mobility Unit (EMU) helmet during the ISS US EVA-80, various efforts for mitigation and further understanding of this phenomenon have been undertaken with the goal of prevention and to ensure crew safety in future EVAs. In support of this goal, a combination of Thermal Desktop thermal modeling and Computational Fluid Dynamics (CFD) has been performed in order to characterize the performance of the EMU components, specifically those within the ventilation/cooling water loops. This modeling effort evaluates the dry/wet gas pressure drop and flow distribution through gas and liquid flow paths using CFD, as well as a two-phase flow assessment of condensation production and water separation/removal performance using an integrated Thermal Desktop model of important EMU ventilation loop components. The models assess this overall thermal-fluid performance in comparison with previous existing models, design points, and historical EVA data using their inputs.

Blain Ryan Lancaster↗
NASA NTRSDate not supplied

Integrated Computational Fluid Dynamics and Thermal Desktop Thermal Modeling for Assessment of the EMU in Support of ISS EVA 80

Following the reports of water accumulation in the Extravehicular Mobility Unit (EMU) helmet during the ISS US EVA-80, various efforts for mitigation and further understanding of this phenomenon have been undertaken with the goal of prevention and to ensure crew safety in future EVAs. In support of this goal, a combination of Thermal Desktop thermal modeling and Computational Fluid Dynamics (CFD) has been performed in order to characterize the performance of the EMU components, specifically those within the ventilation/cooling water loops. This modeling effort evaluates the dry/wet gas pressure drop and flow distribution through gas and liquid flow paths using CFD, as well as a two-phase flow assessment of condensation production and water separation/removal performance using an integrated Thermal Desktop model of important EMU ventilation loop components. The models assess this overall thermal-fluid performance in comparison with previous existing models, design points, and historical EVA data using their inputs.

EVA 80↗
NASA NTRS1978

An approach to optimum subsonic inlet design

Inlet operating requirements are compared with estimated inlet separation characteristics to identify the most critical inlet operating condition. This critical condition is taken to be the design point and is defined by the values of inlet mass flow, free-stream velocity and inlet angle of attack. Optimum flow distributions on the inlet surface were determined to be a high, flat top Mach number distribution on the inlet lip to turn the flow quickly into the inlet and a flat bottom skin-friction distribution on the diffuser wall to diffuse the flow rapidly and efficiently to the velocity required at the fan face. These optimum distributions are then modified to achieve other desirable flow characteristics. Example applications are given.

Luidens, R. W.↗
NASA NTRS1979

An approach to optimum subsonic inlet design

The approach consists of comparing inlet operating requirements with estimated inlet separation characteristics to identify the most critical inlet operating condition. This critical condition is taken to be the design point and is defined by the values of inlet mass flow, free stream velocity, and inlet angle of attack. Optimum flow distributions on the inlet surface are determined to be a high, flat top Mach number distribution on the inlet lip to turn the flow quickly into the inlet and a low, flat bottom skin friction distribution on the diffuser wall to diffuse the flow rapidly and efficiently to the velocity required at the fan face. These optimum distributions are then modified to achieve other desirable flow characteristics. Example applications are given. Extension of the method is suggested.

Luidens, R. W.↗