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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Gas compression apparatus

Apparatus for transferring gas from a first container to a second container of higher pressure was devised. A free-piston compressor having a driving piston and cylinder, and a smaller diameter driven piston and cylinder, comprise the apparatus. A rod member connecting the driving and driven pistons functions for mutual reciprocation in the respective cylinders. A conduit may be provided for supplying gas to the driven cylinder from the first container. Also provided is apparatus for introducing gas to the driving piston, to compress gas by the driven piston for transfer to the second higher pressure container. The system is useful in transferring spacecraft cabin oxygen into higher pressure containers for use in extravehicular activities.

Terp, L. S.↗
NASA NTRS1985

Explosive decomposition of hydrazine due to rapid gas compression

Results from tests which attempt to determine conditions which cause explosive decomposition of hydrazine from rapid gas compression are described. Hydrazine was initiated by pressure in combination with shock waves from the pressurant gas. A new test method was developed at the White Sands Test Facility which subjects a gas bubble in contact with liquid hydrazine to pure adiabatic compression. Results from this new test method are compared to those from the U-tube method.

Briles, O.↗
NASA NTRS1969

Compressed Gas Handbook

High pressure compressible flow systems in space vehicle ground support equipment

Cota, R. A.↗
NASA NTRS1947

Application of the Analogy Between Water Flow with a Free Surface and Two-dimensional Compressible Gas Flow

The theory of hydraulic analogy, that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow and the limitations and conditions of the analogy are discussed. A test run was made using the hydraulic analogy as applied to the flow about circular cylinders at various diameters at subsonic velocities extending to the super critical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and airflow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.

Orlin, W James↗
NASA NTRS1947

Application of the Analogy Between Water Flow with a Free Surface and Two-Dimensional Compressible Gas Flow

The theory of the hydraulic analogy -- that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow -- and the limitations and conditions of the analogy are discussed. A test was run using the hydraulic analogy as applied to the flow about circular cylinders of various diameters at subsonic velocities extending into the supercritical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and air flow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.

Orlin, W James↗
NASA NTRS1942

Heat Transfer in the Turbulent Boundary Layer of a Compressible Gas at High Speeds

The Reynolds law of heat transfer from a wall to a turbulent stream is extended to the case of flow of a compressible gas at high speeds. The analysis is based on the modern theory of the turbulent boundary layer with laminar sublayer. The investigation is carried out for the case of a plate situated in a parallel stream. The results are obtained independently of the velocity distribution in the turbulent boundar layer.

Frankl, F.↗
NASA NTRS1992

Computing interface motion in compressible gas dynamics

An analysis is conducted of the coupling of Osher and Sethian's (1988) 'Hamilton-Jacobi' level set formulation of the equations of motion for propagating interfaces to a system of conservation laws for compressible gas dynamics, giving attention to both the conservative and nonconservative differencing of the level set function. The capabilities of the method are illustrated in view of the results of numerical convergence studies of the compressible Rayleigh-Taylor and Kelvin-Helmholtz instabilities for air-air and air-helium boundaries.

Mulder, W.↗
NASA NTRS1951

Sideslip in a viscous compressible gas

By an analysis of the Navier-Stokes equations it is shown that the aerodynamic coefficients of an infinite rectangular swept wing in an isothermal or adiabatic flow of a compressible gas can be determined from the aerodynamic coefficients of the unswept wing. When the flow is neither isothermal nor adiabatic, a three-dimensional boundary layer theory is developed and applied to the special case of a swept flat plate.

THEORIES - WINGS, SWEEPBACK & SWEEPFORWARD↗
NASA NTRS2007

Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas

Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. To use conservations laws, smooth pre-distributions of the Dirac delta measure are applied whose supports are contained within the shock thickness. Furthermore, smooth pre-distributions of the Heaviside function are applied which vary from zero to one across the shock wave. It is shown that if the equations of motion are expressed in nonconservative form then the relationships between the jump functions for the flow parameters may be found unambiguously. The analysis yields the classical Rankine-Hugoniot jump conditions for an inviscid shock wave. Moreover, non-monotonic entropy jump conditions are obtained for both inviscid and viscous flows. The report shows that products of generalized functions may be defined consistently using nonstandard analysis; however, physically meaningful products of generalized functions must be determined from the physics of the problem and not the mathematical form of the governing equations.

Baty, Roy S.↗
NASA NTRS1951

Behavior of fast moving flow of compressible gas in cylindrical pipe in presence of cooling

For compressible flow with friction in a cylindrical pipe the momentum, continuity, and heat-transfer equations are examined to determine whether an increase in Mach number ("thermal" Laval nozzle) is obtainable through heat conduction from the gas through the pipe walls. The analysis is based on the assumption that the wall temperature is negligibly small in comparison with the stagnation temperature of the gas. The analysis leads to a negative result. When the gas cooling is increased by also considering radiation to the wall, a limited region at high temperatures is obtained where Mach number increases were theoretically possible. Obtaining this condition practically is considered impossible.

FLOW, SUPERSONIC↗
NASA NTRSDate not supplied

A New Approach for a Wider Class of Entropy Split Methods for Compressible Gas Dynamics and MHD

The high order entropy split methods of Sjögreen & Yee [1, 2] by entropy splitting of the compressible Euler (inviscid) flux derivatives for a thermally-perfect gas are based on Harten’s entropy function [3, 4, 5]. Their derivation takes advantage of the homogeneity property of Euler flux, symmetrizable Euler flux derivatives and energy-norm stability in conjunction with high order classical spatial central, DRP (dispersion relation-preserving) [6, 7, 8] or Padé (compact) spatial discretizations [9] with summation-by-parts (SBP) operators [10]. Our entropy split methods have been proven entropy conserving and stable [1, 11, 12]. Our proofs do not rely on a two-point numerical flux, but rather only a linear difference operator is required to derive these methods. To extend the entropy split method for the MHD, we used the Godunov symmetrizable non-conservative MHD form [12, 13, 14]. These high order entropy split methods not only preserve certain physical properties of the chosen governing equations but are also known to either improve numerical stability, and/or minimize aliasing errors in long time integration of turbulent flow computations without the aid of added numerical dissipation. In our previous published work, extensive error norm comparison with grid refinement was performed to show the high accuracy performance of these methods. These studies also showed how well the entropy split methods conserve the entropy, momentum and mass, and preserve the kinetic energy for long time integration of the various flows [1, 2, 12, 13, 14]. The objective of the present work is to use a new approach to obtain a wider class of entropy split methods consisting of a two-point numerical flux portion and a non-conservative portion in such a way that the homogeneity property of the compressible Euler flux is not required. For high order classical spatial central, DRP (dispersion relation-preserving) or Padé (compact) spatial discretizations, this new approach can be proven to be entropy conservative with conservative spatial dsicretizations while at the same time allowing a wider class of symmetrizable inviscid flux derivatives. We also use this generalization to derive an entropy split scheme that is entropy conserving for the equations of MHD without the homogeneity property using the Godunov symmetrizable ideal MHD formulation [15].

High Order Physical Preserving Methods↗
NASA NTRS1971

Compressed gas handbook

Handbook includes thermodynamic and related fluid flow data required to analyze high pressure compressible and incompressible fluid systems. Some theory and applications include thermodynamic fundamentals, gas behavior, adiabatic and isentropic flow, shock waves, flow measurement, and adiabatic and isothermal friction flow in pipes.

Cota, R. A.↗
NASA NTRS1944

The Theory of a Free Jet of a Compressible Gas

In the present report the theory of free turbulence propagation and the boundary layer theory are developed for a plane-parallel free stream of a compressible fluid. In constructing the theory use was made of the turbulence hypothesis by Taylor (transport of vorticity) which gives best agreement with test results for problems involving heat transfer in free jets.

Abramovich, G. N.↗
NASA NTRS1983

Use of a generalized Stokes number to determine the aerodynamic capture efficiency of non-Stokesian particles from a compressible gas flow

The aerodynamic capture efficiency of small but nondiffusing particles suspended in a high-speed stream flowing past a target is known to be influenced by parameters governing small particle inertia, departures from the Stokes drag law, and carrier fluid compressibility. By defining an effective Stokes number in terms of the actual (prevailing) particle stopping distance, local fluid viscosity, and inviscid fluid velocity gradient at the target nose, it is shown that these effects are well correlated in terms of a 'standard' (cylindrical collector, Stokes drag, incompressible flow, sq rt Re much greater than 1) capture efficiency curve. Thus, a correlation follows that simplifies aerosol capture calculations in the parameter range already included in previous numerical solutions, allows rational engineering predictions of deposition in situations not previously specifically calculated, and should facilitate the presentation of performance data for gas cleaning equipment and aerosol instruments.

Israel, R.↗