The effect of increasing rarefaction on the formation of Edney shock interaction patterns: type-I to type-VI

A shock–shock interaction problem can arise in high-speed vehicles where an oblique shock from one part of the body impinges on a bow shock from a different part of the body. The nature of the interaction can change as the vehicle increases in altitude to a more rarefied environment. In this work, the outcomes of a numerical study investigating the formation of Edney shock patterns from type-I to type-VI as a result of shock–shock interactions at different rarefaction levels are presented. The computations are conducted with a direct simulation Monte Carlo solver for a free-stream flow at a Mach number of 10. In shock–shock interaction problems, both geometrical and rarefaction parameters determine what type of Edney pattern is formed. The region on the shock impinged surface that experiences enhanced thermo-mechanical loads increases when the free-stream flow becomes more rarefied, but the peak values decrease. It is known that these shock interactions can have unsteady behavior in the continuum regime; the current work shows that although increasing rarefaction tends to move the flow toward steady behavior, under some conditions the flow remains unsteady.