ADVANCED MODEL OF NITRIC-OXIDE FORMATION IN HYPERSONIC FLOWS

A model for nitric oxide (NO) formation in low-density hypersonic flow s is presented. The thermal nonequilibrium reaction rates, reactant en ergy removal rates, and product energy disposal rates are based on a q uasiclassical trajectory analysis of the Zeldovich reactions, At hyper sonic now conditions, the newly obtained reaction rate for the second Zeldovich reaction is approximately an order of magnitude larger than the commonly used rate. The rate of this reaction is a weak function o f the reactant internal energy, but it produces vibrationally excited NO molecules that result in an elevated NO vibrational temperature, A flowfield model that includes these effects is proposed, and a computa tional fluid dynamics method is used to simulate the BSUV1 and BSUV2 f light experiments. The new model generally improves the agreement with the spectrally resolved radiation data; however, it appears that ther e are additional mechanisms that preferentially remove the highly exci ted NO molecules.