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.