Two-dimensional simulation of ablation due to aerodynamic heating in the SARA sub-obital platform
Humberto A. Machado
Space and sub-orbital vehicles reach high velocities within atmosphere, about 100 km over Earth’s surface. Such high velocities result in aerodynamic heating and air temperature surpasses 2000oC at the stagnation point. Besides the effects of high temperatures on the mechanical behavior of the structure and on-board devices, it is mandatory to preserve the payload, by using an efficient TPS (Thermal Protection System). Along the years ablative materials have been effectively used as TPS of space vehicles. In order to obtain the temperature profile and the heat load, the energy conservation equation has to be solved together with the moving boundary problem concerned to the ablation process. The coupling between the heat transfer processes in the surface and within the layers represents an additional difficulty. A common approach is to consider the heat conduction as one-dimensional, in the normal direction relative to the local surface. However, such hypothesis becomes inaccurate as temperature gradients in the tangential direction, change of material or a great thickness variation occur. In this work, the computational simulation of the ablative process in the vicinity of the stagnation point during the flight of SARA Sub-orbital Platform via an interface tracking method is presented, taking into account the effects of the two-dimensional conduction in the wall layers. Such procedure will allow a more accurate dimensioning of the TPS, contributing for project optimization.
Keywords: Ablation, TPS, Aerodynamic heating, Computational simulation, Moving boundary, SARA sub-orbital platform.