Accession Number : AD0263527

Title :   EXPERIMENTAL STUDY OF HELIUM AND ARGON DIFFUSION IN THE WAKE OF A CIRCULAR CYLINDER AT MACH NUMBER 5.8

Corporate Author : CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS

Personal Author(s) : KINGSLAND,LOUIS JR.

Report Date : 01 JUN 1961

Pagination or Media Count : 1

Abstract : Experimental measurements of the diffusion of helium and argon in the wake of a porous cylinder were made in the hypersonic wind tunnel at Mach 5.8. The cylinder was mounted perpendicular to the flow and small quantities of tracer gas were pumped through the model walls into the flow. The thermal conductivity method of gas analysis was used to determine the concentration of sample gases extracted from points in the wake. The transverse and axial distribution of concentration appeared to follow theoretical estimates of similarity behavior. Injection of tracer gas was found to have a measurable effect on stagnation pressure and this effect was taken into account during computations. Numerical values of diffusion coefficients along the wake centerline were computed from the experimental data and then compared with theoretical values for laminar flow. Close agreement between experimental and theoretical values when the Reynolds number reached 18,000 verified that the inne wake was laminar as far downstream as measurements could be made (15 diameters). At a Reynolds number value of 72,000, the data showed that mixing processes were 3 times more rapid for helium, and 10 times more rapid for argon, than those expected in laminar flow. (Author)

Descriptors :   *ATMOSPHERE ENTRY, *CYLINDRICAL BODIES, *HYPERSONIC CHARACTERISTICS, *HYPERSONIC FLOW, *HYPERSONIC WIND TUNNELS, AERODYNAMIC CHARACTERISTICS, ARGON, DIFFUSION, HELIUM, INSTRUMENTATION, TEST METHODS, THEORY, THERMAL CONDUCTIVITY, TURBULENCE, WAKE.

Distribution Statement : APPROVED FOR PUBLIC RELEASE