Laminar boundary-layer separation and near-wake flow for a smooth blunt body at supersonic and hypersonic speeds.

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At supersonic and hypersonic speeds, the location of the boundary-layer separation point on the surface of a smooth, hlunt body is not fixed a priori, but is determined by the pressure rise communicated upstream through the subcritical base flow. By utilizing the integral or moment method of Reeves and Lees, the separation-interaction region is joined smoothly to the near-wake interaction region passing through a throat downstream of the rear stagnation point. One interesting feature of this problem is that the viscous flow over the blunt body overexpands and goes supercritical. This flow is joined to the near-wake by means of a supercritical-subcritical upstream of separation, and the jump location is determined by the matching conditions. Downstream of the jump, the viscous flow separates in response to the pressure rise, and forms a constant-pressure mixing region leading into the near-wake. As an illustrative example, the method is applied to an adiabatic circular cylinder at MO, = 6, and the results are compared with the experimental measurements of Dew ey and McCarthy. This method can be extended to nonadiabatic bodies, and to slender bodies with smooth bases, provided that the radius of curvature is large compared to the boundarylayer thickness.