Hypervelocity Boundary Layer Studies for Inward Turning Inlets

Abstract

Inward turning hypersonic vehicle inlets have the theoretical potential to achieve higher efficiency than conventional two-dimensional geometries. However, the design of axisymmetric, streamtraced inlets depends on the capability to model boundary layer behavior over surfaces with concave curvature. In this work, we carry out a fundamental study of boundary layers flows, which are known to be significantly influenced by three-dimensional effects, at high stagnation-enthalpy, hypersonic conditions over surfaces with different concave geometry. Surface heat transfer and boundary layer visual thickness data over models with cubic, quadratic and blended concave surface curvature are compared with a flat plate baseline case. For all models, concave surface curvature produces an increase in the heat flux over flat plate laminar values. We demonstrate that reasonable estimates of the laminar heat flux augmentation due to concave surface curvature may be obtained from the local turning angle at the conditions of these experiments.