An Exploratory Study of Transition on a Slender Cone in Hypervelocity Flow

Results are presented from an experimental exploratory study of laminar, transitional and turbulent boundary layers on a slender, sharp cone at zero incidence in hypervelocity flow. The study was conducted in the hypervelocity shock tunnel T5, whose high operating pressure permits achieving the necessary high Reynolds numbers at high total enthalpy. Surface heat transfer rate and resonantly enhanced flow visualization were used to determine transition location and flow structure. Results indicate that the transition mechanism at the conditions tested is via the Tollmien-Schlichting instability. No detailed information about the noise spectrum in the facility is available. A strong, gas-dependent increase of the transition Reynolds number evaluated at the reference temperature on specific total enthalpy was observed. This effect increases monotonically with the dissociation energy of the gas.