Reentry Thermal Analysis of a Generic Crew Exploration Vehicle Windward Wall Structures

摘要

Reentry heat transfer analysis was performed on the windward wall structures of a generic composite Crew Exploration Vehicle (CEV) capsule, seen in figure 1, protected by the Apollo thermal protection system (TPS) (ablative material). The Apollo low Earth orbit reentry trajectory was used to calculate the input reentry heating rates. In the thermal analysis computer program used, the TPS ablation effect was not included; however, the results from the non-ablation heat transfer analyses were used to develop an approximate virtual ablation method to estimate the ablation heat loads and the TPS secession thicknesses. Depending on the severity of the heating-rate time history, the virtual ablation period was found to last for 93-117 s, and the ablation heat load was estimated to be in the range of 85-87 percent of the total heat load for the ablation period. The TPS recession thickness was estimated to be in the range of 0.08-0.11 in. The TPS thickness range of 0.717-0.733 in was found to be adequate to keep the composite sub-structural temperatures at the limit of 300 F.