Analytical and experimental heat transfer and flow-field prediction on a rectangular reentry module

Abstract

A General Purpose Heat Source (GPHS) has been designed for the purpose of supplying power to a radioisotope thermal generator intended for interplanetary missions. The baseline configuration, nominally 2 in. x 4 in. x 4 in. with sharp edges and corners, is required to survive accidental earth reentry as well as terminal impact velocities. Several problems have been identified relative to survival criteria during reentry. This paper is concerned with the flow field and reentry heating for a broad face-on or side-on reentry orientation. Moreover, the analysis considers convective heat transfer in the absence of roughness or ablation effects during the supersonic/hypersonic regime of reentry. The anaytical results are compared with wind tunnel data. From these studies it was concluded that heat transfer distributions for non-circular shapes ca be obtained for reentry conditions using wind tunnel data for the surface distributions and a stagnation value based on a reference sphere condition. The distributions obtained at a fixed Mach number (M > 1) appear valid over an extended range of Mach numbers. The above required definition of a proper velocity gradient, and definition of an area aspect ratio. Flowfield predictions (inviscid) using the CM2DT program provide a proper definition of pressure and shock characteristics for non-similar (viscous) solutions. (LCL)