Numerical Simulations of Hypersonic Flows over the Fire II Capsule: Impact of Mesh Resolution and Boundary Conditions on Convective Heat Transfer

Abstract

Numerical computation of a mixture of oxygen and nitrogen are presented for the Fire II capsule under hypersonic flow conditions including thermodynamic non-equilibrium. Mesh refinement studies in the regions adjacent to the observed thermodynamic and chemical non-equilibrium flow conditions are performed based on the Re_cell parameter. Two wall boundary conditions, catalytic and non-catalytic, are tested and their results are compared to experimental data available in terms of convective heat flux. The finite volume method is used to solve the Navier-Stokes equations including Park's two-temperature model. Results are presented in terms of thermodynamic non-equilibrium level of the gas mixture along the flow stagnation line, and good agreement is observed between simulations and experimental data in terms of heat flux at the stagnation point of the flow. The species dissociation profiles lead to changes with respect to thermal non-equilibrium, presented in terms of temperature modes. Under such conditions, it is possible to observe the occurrence of thermodynamic non-equilibrium through the magnitude difference of the translational-rotational and vibrational-electronic temperature modes inside the shock layer forming upstream of the capsule.