Species Separation by Stagnation of Argon-Helium Mixtures in Supersonic Flow.

Abstract : Measurements were made of the gas composition in the stagnation region of hemispherical probes immersed in supersonic flows of argon-helium mixtures. Substantial enrichment of heavy species was found at densities high enough that impact pressure measurements indicated no viscous enhancement. As densities (Reynolds numbers) were further decreased, enrichment of heavy species increased. A correlation is presented which describes the enrichment in terms of probe Knudsen number, free stream Mach number and free stream composition. (Author)