Type III and type IV shock/shock interferences: theoretical and experimental aspects

In the present paper we analyse type III and type IV shock–shock interactions. The main emphasis of the paper is first to review the various shock–shock interference patterns that may occur, and the theoretical approaches: (1) to determine and to characterize the conditions for the transition from one type to another; and (2) to estimate the aerothermal loads for the most critical interactions. The paper then presents an experimental investigation focused on type III and type IV interferences, the goal being the assessment of the influence of the impinging shock strength. The results indicate that the most critical conditions occur when the supersonic jet (typical of type IV interaction) is nearly perpendicular to the body surface. The jet is found to exhibit a change from perpendicular to curved in the case of strong shock wave strength. The analysis also shows that shock/shock interactions may experience a hysteresis phenomenon which is typical of steady shock wave reflections.