Expansion Effects on Supersonic Turbulent Boundary Layers

摘要: Abstract : The effects of various expansion regions on the large scale structure a Mach 3 fully-developed-turbulent boundary layer are investigated. Five cases studied: 7 deg and 14 centered expansions, gradual flat plate. Multi-point surface pressure measurements, filtered Rayleigh scattering visualizations, double-pulse visualizations were employed. Plan view images plate reveal presence structures very streamwise, limited spanwise, extent. These found well above inner layer, nominally at n/delta = 0.5-1.0. also in expanded layers. Across expansion, outer undergo an increase angle. small turbulent motions incoming quenched by while respond more gradually. Convection velocities from correlations reasonable but unreasonably high appear reasonable. discrepancy between two results suggests relationship convecting field is severely altered expansions.