Evolution of a wave packet to turbulent spot in a boundary layer at high speeds

Hypersonic boundary layer stability and transition were studied experimentally for the test case of 7 degree half-angle cone with various nose bluntness. The experiments were performed for M = 6. Wall pressure pulsations were recorded synchronously with the high-speed schlieren. The combined data processing algorithm for coupling of unsteady pressure sensors with high-speed schlieren images was proposed. Analysis of the wall pressure pulsations evolution reveals that the turbulent spot may arise in different ways. It was found that for the blunted model, the role of the second mode in origination of the turbulent spot is more evident.