Boundary-Layer Measurements at Supersonic Nozzle Throats

Abstract

Wall static pressure measurements and boundary layer pitot pressure surveys were made near the throat of a flexible wall supersonic wind-tunnel nozzle at three settings having throat radii of curvature from 33 to 59 inches. It is found that the longitudinal static pressure gradient at the nozzle throat calculated from one-dimensional flow theory agreed with the measured wall static pressure gradient. The boundary-layer velocity profiles at the nozzle throat are presented and discussed. The boundary layers were turbulent and 0.046 to 0.107 inch thick. It is found that the boundary-layer momentum thickness at the nozzle throat calculated using the momentum-integral-equation and several approximations agrees with the values determined from the measured boundary layer profiles. Finally, it is noted that in spite of the different static pressure gradients, the boundary-layer velocity profiles for the different nozzle settings are similar, and it is shown analytically that this similarity is to be expected.