A method for measuring recompression shock unsteadiness applied to two supersonic wakes

The recompression shock system in blunt-base cylinder wakes at 0° and 10° angles-of-attack to an M=2.46 freestream is visualized by planar laser scattering, allowing the instantaneous position of the shock to be determined over a wide region of the flow. The recompression shock at α=0° is highly branched and appears to be quite weak. The shock appears to be stronger at α=10°, with far less branching. Correlation analysis for the α=10° wake indicates that fluctuations in the shock position tend to be correlated over relatively long streamwise distances. Analysis of the shock angle for the angle-of-attack wake shows a significant variation in the local angle of the shock, with trends similar to those seen for the unsteadiness in the shock position.