Cylinder Experiments in the High Enthalpy Tunnel HEG

Abstract

Fourteen cylinder experiments in the HEG under high enthalpy conditions habe been carried out for four different free-stream conditions in air and one free-stream condition in nitrogen. Schlieren, interferogram and luminosity pictures were obtained. Interferograms have been used to determine the density distribution on the stagnation streamline. The density profile on the stagnation streamline has been compared to results from Navier-Stokes calculations. The sshock wave stand-off distance has been determined using these optical measurements and compared to the shock wave stand-off distance for the ideal gas case. The distance was found to be between the frozen and the equilibrium limit, even though data varies from measurement to measurement technique. At the wall of the cylinder 18 pressure and 17 thermocouple sensors have been installed at five degree steps from -40 to 40 degree relative to the free-stream flow direction.