Computational Fluid Dynamic Solutions of Optimized Heat Shields Designed for Earth Entry

Computational fluid dynamic solutions are obtained for heat shields optimized aerothermodynamically using Newtonian impact theory. Aerodynamically, the low-order approach matches computational simulations within 10%. Benchmark Apollo 4 solutions show that predicted heat fluxes under-predict convective heating by 30% and over-predict radiative heating by 16% compared to computational results. Parametric studies display a power law reliance of convective heat flux on edge radius. A slender heat shield optimized for a single design point produces heat fluxes 1.8 times what was predicted using the Newtonian approach. Here, maximum heating decreases with the inverse cube of the base sharpness. Coupled vehicle/trajectory optimized designs are examined for lunar return (11 km/s) and Mars return (12.5 km/s) and show possible discrepancies for eccentric shapes using low-order empirical correlations. Ultimately, gains suggested by the low-order approach using complex geometries are not reflected in high-fidelity simulations. In some respects, the simpler shape is the ideal on