Thermochemical Non-Equilibrium Entry Flows in Mars in Two-Dimensions - Part I

摘要

This work, first part of this study, describes a numerical tool to perform thermochemical non-equilibrium simulations of reactive flow in two-dimensions. The Van Leer and Liou and Steffen Jr. schemes, in their first- and second-order versions, are implemented to accomplish the numerical simulations. The Euler and Navier-Stokes equations, on a finite volume context and employing structured and unstructured spatial discretizations, are applied to solve the "hot gas" hypersonic flows around a blunt body, around a double ellipse, and around an entry capsule, in two-dimensions. The second-order version of the Van Leer and Liou and Steffen Jr. schemes are obtained from a "MUSCL" extrapolation procedure in a context of structured spatial discretization. In the unstructured context, only first-order solutions are obtained. The convergence process is accelerated to the steady state condition through a spatially variable time step procedure, which has proved effective gains in terms of computational acceleration. The reactive simulations involve a Mars atmosphere chemical model of nine species: N, O, N_2, O_2, NO, CO_2, C, CO, and CN, based on the work of Kay and Netterfield. Fifty-three chemical reactions, involving dissociation and recombination, are simulated by the proposed model. The Arrhenius formula is employed to determine the reaction rates and the law of mass action is used to determine the source terms of each gas species equation. The results have indicated the Van Leer TVD scheme as the most accurate one, both inviscid and viscous cases. In this paper is presented the blunt body results. In Part II is presented the results with the double ellipse and the entry capsule.