The separation of binary gas mixtures of carbon dioxide and hydrogen in sonic-orifice-generated free jets is investigated over a source Reynolds number range of 100 to 3000 using the well-known electron beam fluorescence technique. The lighter species, hydrogen, is chosen as the minor species in order to examine the extent of the validity of Sherman's first-order diffusive separation theory for large separation. The diffusive separation of mixtures containing approximately 2, 5, and 20 percent hydrogen in carbon dioxide is investigated by experimentally determining the relative number densities of the two species as a function of centerline axial distance within the free jets. Sherman's diffusive separation theory is applied to the jets using axial Mach number profiles which were a combination of experimental and analytical results for gamma = 1.40 expansions. The gamma = 1.40 expansion is shown to approximate the CO2-H2 expansion quite well, and the calculated separation agrees remarkably well with the experimentally determined values.
FLUID MECHANICS AND HEAT TRANSFER
Physics of Fluids (ISSN 0031-9171); 26; Aug. 198