Simulation of Flow Separation and Reattachment on a Re-entry Capsule Afterbody Frustum

In this paper the flowfield around an Apollo-shaped capsule at non-zero angle of attack is numerically investigated. The focus is on the afterbody flowfield, especially the windward side. Experiments have shown that there is local flow separation and reattachment on the windward meridian at selected angles of attack. Local flow reattachment on the afterbody can lead to high surface heating. Further, the size of the windward separation bubble is found to decrease with increasing angle of attack. Simulations are performed at a fixed Mach number and varying angles of attack. The solutions reproduce all the experimentally observed flow features, including a localized separation bubble on the windward meridian. The simulations also predict the variation of the windward reattachment location with angle of attack correctly. The numerical solutions are further used to study the unsteady nature of the flow, the three-dimensional flow pattern in the near wake and its e ffect on the surface heat transfer rate.