Action of gas-permeable materials of varied porosity on the supersonic separated flow over a forward-facing step

摘要

Results of an experimental and numerical study of a supersonic flow over a model forward-facing step with a gas-permeable insert of variable porosity installed upstream of the step are reported. The free-stream Mach number was M = 2.0, 2.5, and 3.0, and the Reynolds number, Re = 5·10~5. The gas-permeable insert was either a section of a perforated plate or a section of a highly porous permeable cellular material. The flow visualization performed using the shadow method, PIV, and a soot-oil film has shown that the characteristic size of the vortical flow region exhibited a profound decrease on increasing the insert porosity. In numerical calculations performed at high values of that porosity, data on the displacement of the recirculation flow region into the porous material were obtained.