Numerical investigation of a chemically reacting and rarefied hypersonic flow field

Abstract

Numerical simulations are carried out in the non-continuum flow regime to analyze flow features in the shock layer of a reentry vehicle. A new solver, rarefiedHypersonicFoam, has been developed based on the OpenFOAM platform, which can simulate the intermediate hypersonic reacting flow regime, where chemical non-equilibrium effects are imperative. The solver accommodates features to model air chemistry, multispecies transport, thermodynamic properties of high-temperature air, and non-equilibrium boundary conditions. The solver is validated with ballistic range experimental data for shock standoff distance and heat flux values over a conical reentry vehicle. Results have exhibited good agreement with the experimental data and show significant improvement when compared with the conventional high-speed compressible flow solver. The modified solver is used to analyze hypersonic flow over a bi-conic reentry capsule at different altitudes and velocities in the rarefied hypersonic flow regime. The results show that at lower altitude, chemical reactions absorb a considerable amount of heat compared to higher altitude. The rate of reaction reduces with the decrease in the flow velocity, which results in reduced heat flux values. It is observed that, if only rarefaction effects are considered in the solver, it overpredicts the heat flux values. Therefore, incorporation of chemical reactions while analyzing rarefied hypersonic flow fields is imperative.