Near wake flow field measurements.

In the present paper, measurements of the stagnation-temperature field behind a 10° halfangle wedge and a 10° half-angle cone have been made in the Avco RAD hypersonic shock tunnel at Mach 16 and stagnation temperature of 2400 °K using a constant-temperature hotwire anemometer. The effect of Reynolds number and wall-to-stagnation-temperature ratios were investigated. Reynolds numbers of 5.7 X 10/ft and 4.8 X 10/ft and ratios of wall-tostagnation temperature of 0.0325, 0.125, and 0.155 were used. Experimental results showing wake centerline stagnation temperatures and some transverse stagnation-temperature profiles are presented. For both the cone and wedge, a region of constant temperature exists for a distance of 0.3 to 0.75 base diameters from the model base. This region of constant temperature is then followed by a region of increasing temperature typical of far wakes. For the models tested, the stagnation temperature in the near wake was found to decrease with increasing Reynolds number and to approach a limiting value as the ratio of wall-to-stagnation temperature approaches zero. These limiting values are a function of Reynolds number. Schlieren photographs show that the time for wake formation is of the order of 1 msec.