SIMULATION OF NONEQUILIBRIUM HYPERSONIC FLOWS

Simulation of hypersonic reacting flows is a challenging task, due not only to the large variety of applications (e.g. reentry problems of s pace vehicles or supersonic combustion etc.) but also to the fact that a large amount of computational and numerical efforts have to be made in order to overcome the difficulties in,the numerical solution of th e governing Navier Stokes equations. Whereas very often mathematical m odelling is simplified by neglecting second-order effects like molecul ar transport, thus solving the Euler equations, several interesting ph enomena such as gas surface interactions require the solution of the f ull set of Navier-Stokes equations. The algorithm presented here is ba sed on a fully conservative formulation of the conservation equations and uses a first-order flux-splitting scheme. The large system of ordi nary differential and algebraic equations resulting from the spatial d iscretization is solved by a time-accurate implicit extrapolation meth od. In comparing two different nonequilibrium reaction schemes we show that finite rate chemistry has a strong influence on the computed flo wfield, e.g. the maximum temperature in the shock wave or the species concentrations.