Time resolved holographic interferometry for short duration hypersonic high enthalpy test facilities
The High Enthalpy Shock Tunnel Göttingen (HEG) of the German Aerospace Cen- ter (DLR) is one of the major European hypersonic test facilities. The HEG can operate over a wide range of test conditions, from low altitude high density Mach 6 flows through the simulation of Mach 8 flow at approximately 30 km altitude up to high enthalpy re-entry conditions. Full utilization of such ground based high enthalpy impulse facilities, with typical test times in the order of one to several milliseconds, requires detailed knowledge of the flow in the test section, and its starting processes. Further, the temporal development of the model flow must be known in order to assure that a steady flow has developed during the test time. For that reason a high speed flow visualization (HSFV) system has been implemented at HEG using the schlieren and shadowgraph technique. This paper describes a feasibility study undertaken to extend the optical measurement capabilities of the HEG by combining the HSFV system with the phase step holographic interferometry (HI) system used so far in single shot mode.
KeywordsTest Section Light Path Reference Beam Holographic Interferometry Object Beam
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