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Kinetic Phenomena in Spherical Expanding Flows of Binary Gas Mixtures

2003; American Institute of Aeronautics and Astronautics; Volume: 17; Issue: 4 Linguagem: Inglês

10.2514/2.6798

1533-6808

Vladimir V. Riabov,

Optical properties and cooling technologies in crystalline materials

Diffusion and kinetic effects in the spherical expanding e ows of argon‐ helium mixtures have been studied using the direct simulation Monte Carlo technique at the Knudsen numbers from 0.0015 to 0.03 and pressure ratios from 100 to 10,000. Similarity analysis was used to analyze the e ow structure in supersonic e ow region, spherical shock wave, and subsonic area behind it. Both kinetic and diffusion effects ine uence the shock-wave thickness, parallel and transverse species temperatures, diffusion velocities, the effectiveness of species separation, and ambient gas penetration. In the supersonic region the effect of “ freezing” the parallel temperature has been found in all considered cases. The temperature freezing comes e rst for heavier molecules of argon. The transverse temperature for both species follows the temperature in the isentropic expansion. Accumulation of the hot light (helium) component occurs in the leading front of the spherical shock wave. The multitemperature regime of the e ow inside the shock wave is found and studied using the similarity factor, which is based on theratio of stagnation pressures calculated at critical-source-e ow and background conditions. Nomenclature C = constant; Eq. (5) F = transformed mole-fraction function; Eq. (15) f = mole fraction of heavier component H = transformed temperature function; Eq. (15) Kna = Knudsen number based on the length scale parameter at ine nity L Kn¤ = Knudsen number based on the critical radius of a spherical source r¤ K2 = similarity parameter, Re¤.pa=p0¤/ 1=2