Characterization of a turbulent separating/ reattaching flow using optical pressure and velocity measurements

The turbulent wake flow behind a generic spacecraft was investigated experimentally in the trisonic wind tunnel Munich at subsonic Mach numbers M8 = [0.3; 0.7].The flow/structure interaction which raised critical safety aspects on the real spacecraft in the past was studied. The characterization of the coherent flow structures was performed by means of transient optical and classical measurement techniques. The topology and dynamics of the wake flow and the pressure field were investigated with the 2C2D-PIV and the instationary PSP. The reattachment position as well as the local dynamic behavior of strong flow structures were successfully characterized and the presence of dominant vortex shedding at expected frequencies around fshed ~ [400; 900] Hz was confirmed. It was the first time that the fluid/structure interaction and the position of strongest stresses could be characterized experimentally with very high spatial and temporal resolution.A PSP system had to be established in order to perform the desired experiments. Therefore, basic components (e.g. calibration chamber, excitation, evaluation tool) had to be developed and the performance of the entire system had to be validated.