DescriptionThe flow surrounding a wall mounted hemisphere in supersonic flow at Mach 3.4 was investigated experimentally using stereoscopic particle image velocimetry in the Rutgers University Emil Buhler supersonic wind tunnel. The aim of this investigation was to quantify the basic flow structures associated with a three-dimensional shock boundary layer interaction caused by a hemispherical disturbance. The flow velocity upstream and downstream of a 38 mm radius hemisphere was measured at the spanwise centerline. The flow velocity upstream of a 25 mm radius hemisphere was measured at three spanwise locations: centerline, 1.5 mm off center, and 3.0 mm off center. The velocity fields indicate a significant spanwise velocity component in the hemisphere wake in the separated shear layer. From the velocity fields, turbulent kinetic energy and Reynolds stresses were derived. These quantities indicate a significantly turbulent flow in the wake in the separated shear layer and show evidence of three-dimensional flow structures both upstream and downstream of the hemisphere.
Velocity field measurements upstream of the separation shock wave were used to calculate an estimate for the undisturbed turbulent boundary layer on the ceiling of the Rutgers University Emil Buhler supersonic wind tunnel. Ten streamwise locations were sampled across two spanwise planes and the final boundary layer thickness estimate was δ_99=16.52 mm ± 1.26 mm.