A Computational Investigation of Inviscid Hypervelocity Flow of a Dissociating Gas Past a Cone at Incidence

Calculations have been performed for the inviscid hypervelocity flow of nitrogen past a 15 degree semi-angle sharp cone at an incidence of 30 degree, at an enthalphy sufficiently high to produuce dissociation/recombination chemistry downstream of the bow shock wave. A spatially second-order-accurate EFM (Equilibrium Flux Method) scheme for the numerical solution of the inviscid Euler equations was used, combined with the Lighthill-Freeman model of the non-equilibrium ideal dissociating gas. The computations have been sued to gain an understanding fo the interaction between the ags dynamics and the finite-rate chemistry. Inviscid flow has been considered to ensure that the only physical length scales in the flow are those associated with the chemical reactions. It was found that a chemical length scale L_s, based on the local dissociation length behind the shock on the windward plane of symmetry is an important governing parameter of the flow. However, as the flow length-scale becomes large and the flow approached the limiting case of equilibrium chemistry, L_s is not the dominant chemical length-scale, particularly in the leeward flow which contains a shock-vortex structure. A simple modelling technique has been used to determine a more appropriate length scale L_r for the leeward flow, based on the equilibrium conditions behind the leeward cross-flow shock