Transition and Hot-wire Measurements in Hypersonic Helium Flow

Abstract

Experiments have been performed to determine the influence of freestream disturbances on boundary-layer transition on sharp cones in a hypersonic wind tunnel. A constant current hot-wire anemometer was used to measure freestream and cone shock layer disturbances in two hypersonic helium tunnels. Comparison of these freestream and shock layer hot-wire measurements indicates that the disturbance level in percentage of local mean properties remains essentially unchanged by the cone shock. Transition Reynolds number was found to vary inversely with facility sound disturbance level and also to be strongly dependent on local Mach number.