Numerical Simulation Supersonic Free Shear Layers


Book Description

The objective of the current research is to study the mixing and stability characteristics of three dimensional supersonic free shear flows through a direct numerical solution of 3-D compressible flow equations. Supersonic shear flows are of interest to SCRAMJET engine designers. The successful operation of these engines requires rapid and efficient (i.e. minimum total pressure loss) mixing of supersonic airstreams and subsonic/sonic fuel streams. (jhd).







Numerical Simulation Supersonic Free Shear Layers


Book Description

The objective of the current research is to study the mixing and stability characteristics of three dimensional supersonic free shear flows through a direct numerical solution of 3-D compressible flow equations. Supersonic shear flows are of interest to SCRAMJET engine designers. The successful operation of these engines requires rapid and efficient (i.e. minimum total pressure loss) mixing of supersonic airstreams and subsonic/sonic fuel streams. (jhd).




Numerical Simulations of the Structure of Supersonic Shear Layers


Book Description

Time-dependent two-dimensional numerical calculations were performed to study the mixing characteristics of unforced, planar, confined shear layers formed by two parallel streams of air that come into contact after passing over a splitter plate. The evolution of the shear layer was examined by systematically varying the velocities, densities, and the static pressures of the two streams that come into contact at the trailing edge of the plate. At least one of the streams was always supersonic. For the range of the parameters studied, the supersonic shear layers show some organization, albeit less coherent than their subsonic counterparts. The most amplified frequency, obtained by Fourier analysis of the velocity and pressure fluctuations, depends on the effective inlet momentum thickness. Convective Mach numbers of the streams corresponding to each side of the shear layer were found to be quite different. The simulations indicate that the single convective Mach number as derived from an isentropic model is not sufficient to characterize the mixing behavior when the velocity, pressure, and density ratios are changed independently. Keywords: Numerical simulations; Supersonic shear layers. (jhd).




Numerical Simulations of the Structure of Supersonic Shear Layers


Book Description

Time-dependent two-dimensional numerical calculations were performed to study the mixing characteristics of unforced, planar, confined shear layers formed by two parallel streams of air that come into contact after passing over a splitter plate. The evolution of the shear layer was examined by systematically varying the velocities, densities, and the static pressures of the two streams that come into contact at the trailing edge of the plate. At least one of the streams was always supersonic. For the range of the parameters studied, the supersonic shear layers show some organization, albeit less coherent than their subsonic counterparts. The most amplified frequency, obtained by Fourier analysis of the velocity and pressure fluctuations, depends on the effective inlet momentum thickness. Convective Mach numbers of the streams corresponding to each side of the shear layer were found to be quite different. The simulations indicate that the single convective Mach number as derived from an isentropic model is not sufficient to characterize the mixing behavior when the velocity, pressure, and density ratios are changed independently. Keywords: Numerical simulations; Supersonic shear layers. (jhd).




A Two-Dimensional Numerical Simulation of a Supersonic, Chemically Reacting Mixing Layer


Book Description

Research has been undertaken to achieve an improved understanding of physical phenomena present when a supersonic flow undergoes chemical reaction. A detailed understanding of supersonic reacting flows is necessary to successfully develop advanced propulsion systems now planned for use late in this century and beyond. In order to explore such flows, a study was begun to create appropriate physical models for describing supersonic combustion, and to develop accurate and efficient numerical techniques for solving the governing equations that result from these models. From this work, two computer programs were written to study reacting flows. Both programs were constructed to consider the multicomponent diffusion and convection of important chemical species, the finite rate reaction of these species, and the resulting interaction of the fluid mechanics and the chemistry. The first program employed a finite difference scheme for integrating the governing equations, whereas the second used a hybrid Chebyshev pseudospectral technique for improved accuracy. Drummond, J. Philip Langley Research Center BOUNDARY LAYERS; CHEMICAL REACTIONS; FLUID MECHANICS; MIXING; MIXING LAYERS (FLUIDS); NUMERICAL ANALYSIS; SIMULATION; SUPERSONIC FLOW; CHEBYSHEV APPROXIMATION; COMPUTER PROGRAMS; FINITE DIFFERENCE THEORY; HYPERSONIC AIRCRAFT; SUPERSONIC COMBUSTION RAMJET ENGINES...