SELF-SIMILAR HYPERVELOCITY SHOCK INTERACTIONS WITH OBLIQUE CONTACT DISCONTINUITIES

The two-dimensional inviscid refraction of a shock wave at an oblique contact discontinuity is self-similar; i.e. it depends only upon the v ariables xi = x/t, eta = y/t. We transform the compressible Euler equa tions into the self-similar (xi,eta) coordinates and solve the resulti ng boundary-value problem by an implicit equilibrium flux method. We p resent results for strong shock (M greater than or equal to 10 where M is the incident shock Mach number) interactions with an oblique conta ct discontinuity separating an inert gas from a gas which exhibits hig h-temperature gas chemistry effects. To model high-temperature effects we employ Lighthill's ideal dissociating gas (IDG) model. Comparison between the frozen and equilibrium limits, both of which are self-simi lar, indicate large changes in peak density and temperatures. Signific ant differences in the overall flow pattern between the frozen and equ ilibrium limits are observed for interfaces with low negative Atwood r atio and high positive Atwood ratio. Results from a local analysis are presented when the shock refraction is regular. The critical angle at which the transition from regular to irregular refraction occurs is s lightly larger for the equilibrium chemistry case.