Investigation of Wall Catalytic Effects on the Aeroheation of Hypersonic Ablative Noses by Space Marching Method

The most accurate method for calculating the aeroheating is numerical solution method. Using finite volume method to solve the Navier-Stokes equations in time is very time consuming. So by using the finite difference algorithm, transfer equations to curvature coordinate by the mapping function, and combination of the viscous shock layer and similarity of boundary layer, the CTCA Code was developed. Determine the species mass concentration at the wall boundary due to chemical reactions of surface ablation and air dissociation/ionization, is one of the main inputs to solve the flow field around the hypersonic noses. Species mass concentration at the wall boundary due to chemical reactions is dependent on the catalytic wall type or time duration of flow stop at the specified point of wall. For fully catalytic walls, the time duration of flow stop is greater than the time required to equivalence chemical reactions and the wall boundary conditions are determined by using the chemical equilibrium assumption. Also in the non-catalytic walls, the time duration of flow stop is less than the time required to equivalence chemical reactions and they are determined by using the chemical frozen assumption. The severity of wall catalyst is dependent on the recombination average rate of species and this parameter is one of the inputs to solve the problem. Therefore in this study, the wall catalytic effects on the aeroheating of ablative noses were investigated by the space marching method. The result of current research and other similar researches showed that, the fully catalytic at stagnation points and the non-catalytic at body are reasonable assumptions.