Rarefaction effects on Edney interactions and flow physics for high–enthalpy Mach 10 flows

Purpose The present work aims to investigate the impact of rarefaction and freestream enthalpy on Edney Type shock interactions. Design/methodology/approach The evolution of shock interaction is examined under high-enthalpy conditions, using a low-enthalpy experiment at Kn=0.0067 as a baseline. Investigations targeted the slip flow regime across a Knudsen number span of 0.0067–0.0536, evaluating two scenarios: fixed geometric and fixed oblique shock angle configurations. In the first case, both the bow shock and oblique shock angle vary with increasing rarefaction. In contrast, second configuration maintains a constant oblique shock angle, isolating rarefaction effects on the bow shock and downstream flow. A two-temperature unsteady Navier–Stokes solver was used to simulate thermochemical non-equilibrium effects numerically. Findings In the fixed geometric configuration, the clockwise rotation of the interaction causes a transition from Edney Type IV to Type V and attenuates the supersonic jet, thereby reducing peak aerothermal loads. In contrast, preserving the oblique shock angle maintains the Type IV topology, sustaining higher localized thermal loads. A counter-clockwise jet rotation emerges with increasing rarefaction. Across both configurations, increased rarefaction limits vibrational excitation and prevents temperatures from reaching dissociation thresholds, thereby reducing molecular dissociation at higher Knudsen numbers. Originality/value This study introduces a fixed geometric and fixed oblique shock angle configurations to analyze rarefied shock interactions. By eliminating the effects of rarefaction on the oblique shock angle, this approach provides a new perspective on the structural changes of shock interactions within the slip flow regime.