No abstract

Abstract. The influence of the nitrogen dissociation on the interactions due to the interference of two planar shock waves in a hypersonic high enthalpy flow is theoretically investigated for infinite reaction rates. The two limiting cases of infinitely slow and infinitely fast reactions are modelled as a perfect gas and an ideal dissociating gas in chemical equilibrium.To investigate the influence of finite reaction rates on the interactions of shock waves, experiments are performed in the "high enthalpy shock tunnel G6ttingen" (HEG) with a wind tunnel model consisting of a wedge type shock generator and a transversally mounted cylinder. The pressure and heat transfer loads resulting from the shock wave interferences are measured and the flow field is visualized by means of interferograms. The experimental results are compared with the results of a numerical simulation for a dissociating nitrogen flow and with the experimental results for a perfect gas flow.

For the optical flow visualisation in the new High Enthalpy shock tunnel of the German Aerospace Research Establishment (DLR) in GOttingen (HEG) a fully automated holographic interferometer has been installed and improved. The interferometer applies the phase shift technique, which enables computerized evaluation of the holograms, to create high quality interferograms. Because of the high resolution of the images, optical enlargement and Hologram-Schlieren is made possible. With use of the simple Gladstone-Dale equation it is possible to calculate complete flow field gradients.