Measurements in a three-dimensional turbulent boundary layer in supersonic flow

Abstract

In this Report the details are given of the results of measurements of mean values in time of pitot pressure and flow direction made in the boundary layer over the insulated side-wall of a specially constructed supersonic nozzle. The external flow first accelerated and then decelerated, and the crosswise pressure gradients were such that the boundary-layer cross-flow was first in one direction and then in the opposite, as happens over wings with swept leading edges. The external Mach number ranged between 1.6 and 2.0. Boundary-layer traverses were made at intervals along external streamlines; from each traverse, profiles of Mach number and streamwise and cross-wise components of velocity were derived. The results were supplemented by measurements of skin friction using surface tubes, and displacement and momentum thicknesses were evaluated. All the results are presented in tabular form, and a discussion is given in which serious limitations in the commonly assumed forms for the cross-flow profiles are pointed out. There is evidence, however, that the streamwise component behaves as it would in an equivalent two-dimensional boundary layer.