Shock/Shock Interaction Experiments in the High Enthalpy Shock Tunnel Göttingen

Abstract

Shock/shock-interaction studies have been conducted in the High Enthalpy Shock Tunnel Göttingen /HEG). A cylinder of radius 45mm with a span of 500mm and a 10 degree wedge are used. Two different freestream conditions with burst pressures of around 50 and 100 MPa are available. Freestream total enthalpies are around 20 MJ/kg and Mach numbers are approximately 9 for both conditions; air is used as the test gas. The cylinder is equipped with 17 pressure transducers and 17 thermocouples. For all tests holographic interferograms are obtained and, for some tests Schlieren pictures are also available. The experimental results are presented and compared to computations. Additionally the ideal dissociating gas model of Lighthill has been used to predict pressure and heat transfer rates on the body surface. A comparison between experimental, numerical and theoretical pressure and heat transfer loads is presented. Fairly good agreement is achieved. The influence of the chemical dissociation reactions are mainly seen to reduce the length scales of the flow. The experiments as well as the calculations of the Edney type IV interaction show unsteady flow behaviour. An approximate Strouhal number of Sh = 0.79 for the experiment and Sh = 1.02 for the calculation is determined.