WSEAS Transactions on Fluid Mechanics
Print ISSN: 1790-5087, E-ISSN: 2224-347X
Volume 8, 2013
Chemical Non-Equilibrium Reentry Flows in Two-Dimensions – Part II
Authors: ,
Abstract: This work, second part of this study, presents two numerical tools implemented to simulate inviscid and viscous flows employing the reactive gas formulation of thermal equilibrium and chemical non-equilibrium. The Euler and Navier-Stokes equations, employing a finite volume formulation, on the context of structured and unstructured spatial discretizations, are solved. The aerospace problems involving the hypersonic flow around a blunt body, around a double ellipse, and around a re-entry capsule, in two-dimensions, are simulated. The reactive simulations will involve an air chemical model of five species: N, N2, NO, O and O2. Seventeen chemical reactions, involving dissociation and recombination, will be simulated by the proposed model. The algorithms employed to solve the reactive equations were the Van Leer and the Liou and Steffen Jr., first- and second-order accurate ones. The second-order numerical scheme is obtained by a “MUSCL” (Monotone Upstream-centered Schemes for Conservation Laws) extrapolation process in the structured case. The algorithms are accelerated to the steady state solution using a spatially variable time step procedure, which has demonstrated effective gains in terms of convergence rate, as reported in Maciel. The results have demonstrated that the most correct aerodynamic coefficient of lift to the re-entry problem is obtained by the Van Leer first-order accurate scheme in the viscous, structured simulation. The Van Leer scheme is also the most robust being able to simulate the major part of the studied problems.
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Keywords: Euler and Navier-Stokes equations, Chemical non-equilibrium, Five species model, Hypersonic flow, Van Leer algorithm, Liou and Steffen Jr. algorithm