INVESTIGATION OF EFFECTS OF DISTRIBUTED SURFACE ROUGHNESS ON A TURBULENT BOUNDARY LAYER OVER A BODY OF REVOLUTION AT A MACH NUMBER OF 2.01

摘要

The results indicate that the effects of distributed surface rough¬ness on a turbulent boundary layer at a Mach number of 2.01 are generally similar to those found at a Mach number of 1.6l and at subsonic speeds. That is, for a given roughness height, some critical Reynolds number exists at which the skin friction begins to depart from the classical turbulent skin-friction law because of the form drag of the individual roughness particles. The results further indicate that (in the Reynolds number range of these tests) increasing the Mach number from 1.6l to 2.01 increases the allowable roughness for a turbulent boundary layer by about 40percent. This increase is in good agreement with that predicted on the basis of a constant ratio of allowable roughness height to laminar-sublayer thickness or to a constant value of the Reynolds number based on allowable roughness height, shearing-stress velocity, and local con¬ditions at the surface.