Experimental and numerical simulation of shock train characteristics in an isolator with incident shocks

Abstract

To better comprehend the steady-state structure and dynamic characteristics of shock train flow fields under interactions with incident shocks, wind tunnel experiments investigating the shock train flow fields in a supersonic isolator with incident shocks were conducted. High-speed schlieren visualization with multiple knife edges, surface tuft visualization, and high-frequency wall pressure measurements were used to analyze the shock train flow fields in the primary and corner regions. The understanding of the flow mechanism was enhanced based on additional three-dimensional steady numerical simulations. Flow field asymmetry was observed when the shock train interacted with parallel incident shocks. The shock train leading edge comprised a longer shock, which traversed the entire channel, and a shorter shock, with flow separation extending downstream of the longer shock. The flow downstream of the shorter shock passed through a small separation bubble before reattachment. The flow field was symmetrical when the shock train interacted with crossed incident shocks. Stronger oscillations were observed in the symmetric shock train owing to the adverse pressure gradient created by the incident shock and the inconsistent flow parameters downstream of the shock. The downstream propagation of the pressure fluctuation caused by the oscillation of the shock train leading edge was revealed based on coherence and phase analyses. The flow separation initiated further upstream in the corner region than in the primary region of the shock train flow field, and the separation flow covered a larger proportion of the flow field. These differences were enhanced by increasing the incoming Mach number.