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摘要
This paper describes recent applications of particle image velocimetry(PIV) in Mach 4.0 flows in MMH(Multi-Mach number High-speed) intermittent wind tunnel of SJTU. To achieve this challenging progress in supersonic flow regime, appropriate seeding particles were selected and seeding dispersion of tracer particles was carefully developed to meet the requirements of high-speed and short-duration flow. In this paper, the measured velocity flowfield at Ma=4.0 was firstly discussed. The results showed that the flowfield at the nozzle exit was parallel to the nozzle axis and homogeneous as expected from supersonic nozzle theory. A ramp was further introduced into Mach 4.0 flow to study the typical shock wave flowfield with large velocity gradient and seed particle performance across an oblique shock. The PIV measured results were also in good agreement with calculated velocities from oblique shock theory. The flowfield over a corner was tested and the PIV results showed that the complex flow structures were clearly visible as schileren. Therefore, PIV has proved to be an effective technique for supersonic flow as well as for subsonic flow regimes.
