High Frequency Free-Stream Disturbance Measurements in Hypersonic Wind Tunnels by Means of a Slender Wedge Probe

Experimental investigations of the free-stream disturbance spectrum by means of a slender wedge probe were conducted in the DLR High Enthalpy Shock Tunnel Gottingen (HEG) at Mach 7.4, the DNW Ludwieg tube (RWG) at Mach 3 and Mach 6 as well as in the TU Braunschweig Ludwieg tube (HLB) at Mach 6. The identical measurement chain, including the probe, the amplifier and the type of transducer were used in all facilities. A wide range of fast response pressure, temperature and heat flux transducers were used to measure the corresponding fluctuations on the probe surface behind the oblique shock. Quantitative results were obtained as function of frequency taking into account the limitations imposed by each transducer. The wedge probe was shown to be a robust and easy to implement probe particularly suited for use in harsh test environments which do not allow the application of hot wire techniques or flush mounted transducers in a Pitot probe configuration.