Planar measurements of supersonic boundary layers with curvature driven pressure gradients

Experimental analyses were performed to quantify the response of supersonic (M = 2.86) high Reynolds number (Re 60,000) turbulent boundary layers to streamline curvature driven pressure gradient distortions. The pressure gradients included a zero, a weak favorable, a strong favorable and a strong adverse. To quantify the flow structure, the following measurements were accomplished: highly resolved planar measurements of mean and fluctuating velocity components with particle image velocimetry, surface pressure contours via pressure sensitive paint, pitot pressure profiles and schlieren photography. In addition to quantifying the mean and turbulent shear stress fields, the PIV data were also processed to provide the production of the axial, transverse and shear stresses. In the favorable pressure gradient regions of the wind tunnel models, a reduction in the turbulence levels (up to 40%) was seen. Corresponding reductions of 50% and 45% in the axial and shear stress production, respectively, were also observed. The reductions in the turbulent stresses, and the production thereof, were due to the manipulation of velocity gradients by the streamline curvature driven gradients. In the adverse pressure gradient region, the trend was reversed.

Planar measurements of supersonic boundary layers with curvature driven pressure gradients Conference Paper