Visualization of a hypersonic boundary layer on a transition cone

A series of experiments is performed in the High Enthalpy shock tunnel Göttingen (HEG) to investigate instability development and transition in the hypersonic boundary layer of a slender, zero-incidence cone. Two schlieren-based-techniques - pulsed-laser schlieren and schlieren deflectometry - are employed over a range of conditions, both lowand high-enthalpy. Pulsed-laser schlieren, a development of an earlier technique, provides a detailed picture of instability growth and breakdown, both in an average sense and for individual wave packets. Measurements on a smooth cone surface and a naturally porous, ceramic surface are compared. The deflectometry technique allows approximate amplification rates to be determined. Finally, fast-response temperature sensitive paint measurements are performed to obtain quantitative heat-transfer information on the unsteady transitional region of the cone