Turbulent Boundary-Layer Characteristics at Supersonic Speeds-Theory and Experiment

Abstract

Turbulent boundary-layer characteristics at supersonic speeds have been experimentally determined from Pitot pressure surveys made at several stations along a flat plate, and the data are compared with theoretical results. The theory is based on the assumption that von Karman's differential equation for the velocity distribution in the incompressible boundary layer applies for compressible flow when the variation in density through the boundary layer is taken into account. Taking the case of a thermally insulated flat plate and neglecting radiation effects, a relation between mean turbulent skin-friction coefficient and Reynolds Number is derived, and the relation appears to be valid throughout the test range of Mach Numbers and Reynolds Numbers. The check between theory and experiment is limited by the maximum test values of Mach Number and Reynolds Number, which are approximately 2.2 and 19 X 10, respectively. The theory is expected to be valid at Reynolds Numbers higher than 19 X 10 for Mach Numbers within the test range. However, the validity of the theory for Mach Numbers greatly in excess of 2.2 should be checked by further experiments.