NONEQUILIBRIUM HYPERSONIC INVISCID STEADY FLOWS

A numerical method for the solution of nonequilibrium flows about blunt bodies is presented. The method is based on the splitting in two parts of the reactive Euler equations: the gasdynamic operator (mass and momentum equations) and the chemical operator (energy and species conservation equations). The gasdynamic operator is discretized on a body- and shock-fitted grid, and integrated in diagonalized form by means of a semi-implicit technique. The chemical operator is integrated along the streamlines by means of an implicit technique with variable step size. A detailed chemical nonequilibrium model is adopted, while vibrational energy is assumed in equilibrium. The shock is modeled with a shock-fitting technique. Nonequilibrium flows about cylinders are computed in order to demonstrate the capability of the present method, both to achieve high resolution in chemical relaxation layers and to overcome the stiffness in nearequilibrium conditions without resulting in cumbersome calculations. Numerical results are presented and compared with experimental data.