Publications Details

Supersonic Expansion Corner Effects on Downstream Shock/Boundary-Layer Interactions

Swain, William E.; Nicholson, Gary L.; Pandey, Anshuman; Beresh, Steven J.

This experimental work investigates the flow field associated with a tandem expansion-compression geometry in the Sandia Trisonic Wind Tunnel. PIV measurements of the boundary layer before the expansion characterized properties of the incoming boundary layer. Schlieren and oil-flow experiments were conducted at Mach 1.5 and 2 for a range of stagnation pressures. Further PIV experiments were conducted across the expansion and compression corners to observe the post-expansion changes in the boundary layer and its influence on the shock/boundary-layer interaction at the compression corner. Velocity profiles qualitatively matched well with RANS simulations and showed rapid growth of the boundary layer following the expansion, tapering off to a slower rate of growth with distance. Turbulence intensity, exemplified by the streamwise component of turbulent normal stress, diminished substantially after the expansion corner leading to the belief that relaminarization processes were occurring. Comparison with analysis from the literature suggests that the distortion of the boundary layer due to expansion leads to a separation length 30% larger than for an equilibrium turbulent boundary layer.