Surface Recession Simulations with ESATAN/ABLAT During a Re-Entry Trajectory 2005-01-2856

The ablation process is essentially a method of cooling the vehicle by inducing a controlled loss of mass during entry into a planetary atmosphere. For maximum efficiency, the ablating mass should go through at least one but preferably two phase changes. For inflatable vehicles designed for re-entry, ablating thermal protection systems are often used. Such a system consists of an outer layer of material which melts or decomposes and then vaporizes as it ablates, yielding the cooling advantage of the latent heat of fusion as well the heat of vaporization. Chemical reactions such as oxidation may also be important. Where feasible, ablating systems are designed to provide additional cooling through endothermic reactions. Generally, one is concerned mostly with the heating in the region of the stagnation point, and in this region shock heating accounts for most of the heat deposition. Radiation may also be an important heat transfer process in such scenarios. The hot gas in the post shock region may radiate to the surface of the vehicle, and the surface itself will also radiate to space, providing a cooling mechanism.

The main objective of the present study is to assess the ESATAN/ABLAT capabilities for simulating the surface recession during a realistic re-entry trajectory and on a realistic geometry for the vehicle.

For the ESATAN/ABLAT re-entry simulations, the focus of the present study is to simulate ablation on the nose of an inflatable re-entry vehicle, which would be deployed for re-entry into the Earth’s atmosphere. Additional simulations have been performed for re-entry trajectory into Venus’ atmosphere.