OVERLAY METHOD FOR CALCULATING EXCITED-STATE SPECIES PROPERTIES IN HYPERSONIC FLOWS

In many hypersonic flows, the excited states of some chemical species are the dominant radiators. Often, those electronically excited partic les are present in small concentrations and the chemical kinetics mech anisms for their formation are very complicated and costly to implemen t in a fully coupled computational fluid dynamics method. An efficient computational method is presented for the calculation of chemical spe cies present in trace amounts, including excited state species, The us efulness of this overlay method is demonstrated with several examples: OH(A) formation from water vapor in a hypersonic shocklayer, state-sp ecific CO vibrational relaxation and CO(a) formation in a rocket motor nozzle, and CO(a) kinetics in an expanding flow. The overlay calculat ions allow a careful sensitivity analysis of the kinetics modeling and permit comparison with radiance data obtained in flight.