Unsteady pressure measurements by means of PSP in cryogenic conditions
The capability of the Pressure-Sensitive Paint (PSP) method for application in unsteady flow in cryogenic wind tunnels was investigated. The experiments were conducted in the Cryogenic Ludwieg-Tube Goettingen (KRG). The suction side of the 2-D airfoil model LV2F was coated with PtTFPP/PTMSP and tested in a nitrogen atmosphere. The measurements were performed at test conditions in the temperature range from 120 to 283 K, at Mach numbers M = 0.72, 0.74, 0.76, and 0.78 and chord Reynolds number up to Re = 14.6 x 10^6. PSP and conventional pressure data were acquired for all different test cases. The oxygen concentration of the flow was set to about 1000 ppm by preconditioning supplying dry air. As a result, the intensity-based PSP method successfully visualized the pressure distribution on the LV2F model under cryogenic conditions and clearly shock oscillations could be detected by means of PSP.