Flow characterization and numerical modeling of the DLR High-Enthalpy Shock Tunnel Göttingen (HEG)

Kurzfassung

The present manuscript supports a lecture given in the scope of the VKI Lecture Series STO-AVT-325 - Flow Characterization and Modeling of Hypersonic Wind Tunnels. It provides basic information on the High Enthalpy Shock Tunnel Göttingen, its operation conditions and the approach followed to determine the free-stream conditions. The described approach couples experimental data and CFD to determine e.g. the chemical and thermal equilibrium state of the flow. Furthermore, the manuscript comprises free-stream disturbance measurements by means of a slender wedge probe. Comparative tunnel noise measurements at Mach 3, 6 and 7.4 in two Ludwieg tube facilities and the HEG shock tunnel are discussed. Surface pressure fluctuations were evaluated over a wide range of frequencies and test conditions including harsh test environments not accessible to measurement techniques such as pitot probes and hot-wire anemometry. A good agreement was found between the wedge probe readings and normalized pitot pressure fluctuations converted into normalized static pressure fluctuations. Quantitative results of the tunnel noise are provided in frequency ranges relevant for hypersonic boundary layer transition. Results of complementary numerical simulations of the leading-edge receptivity to fast and slow acoustic waves at the wedge probe at conditions corresponding to the experimental free-stream conditions are provided.