Fluctuation Measurements in a Supersonic Turbulent Boundary Layer

Hot-wire measurements of the fluctuations in turbulent, constant-pressure boundary layers have been made at Mach numbers of 1.72, 3.56, and 4.76 and a Reynolds number based on momentum thickness of about 30 000. The distribution of the static-temperature fluctuation levels through the boundary layer is approximately similar at the various Mach numbers, and the levels are proportional to the mean static-temperature difference across the boundary layer. A decrease of the velocity fluctuation levels is observed as the Mach number is increased. There is a high negative correlation between the velocity and temperature fluctuations at all Mach numbers.