Nonequilibrium Rotational Temperature Measurements over Flat Plates in Hypersonic Rarefied Gas Flow

An experimental study of the interaction between a shock wave and a boundary layer over a flat plate with a sharp leading edge in hypersonic rarefied gas flow is presented. Experiments in a low-density wind tunnel using an electron beam probe were conducted at the Shock Wave Laboratory, RWTH Aachen. Germany. Rotational temperatures for stagnation temperatures of T-0 = 1000 K and Kn=0.028 based on a reference length of 0.05 to were calculated using Robben and Talbot's method. The rotational temperature profiles at X=3 mm for LE=45 and 90 are 100 K larger than those for LE=30. This means that a bow shock wave in front of the leading edge affects the rotational temperature profiles over the plate. The rotational energy distributions differ from the Maxwell-Boltzmann distributions and they are non-equilibrium distributions. The rotational temperature profiles for alpha=12 deg are also 100 K larger than those for alpha=0 deg. The feature of the rotational temperature over the plate for alpha=12 deg is similar to that for LE=45 and 90 deg.