Effect of cavity pressure on shock train behavior and panel aeroelasticity in an isolator

Abstract

The flow characteristics of shock train in the isolator play an important role in the overall performance of the scramjet. Although several studies have concentrated on understanding this phenomenon in rigid isolators, few works have focused on methods to control it. The current study proposes a new concept shock train control strategy based on the aeroelastic effect of the flexible panel. An in-house developed code was used to solve the compressible Navier–Stokes equations and the geometric nonlinear equations of the panel, where the conventional serial staggered algorithm was adopted for the two-way fluid–structure interaction. Then, we numerically investigated the effect of cavity pressure on the dynamic behavior of the panel, location, and structure of the shock train, separation zone, and performance of the isolator. The results show that the dynamic response of the panel subjected to the different cavity pressure can be characterized into three states: static stability state, high-frequency second-order limit cycle flutter state, and multi-frequency periodic flutter state. The panel flutter mainly presents an approximately second-mode pattern for the limit cycle flutter state and a first-order vibration mode for the periodic flutter state. With increasing cavity pressure, the average value of shock-train head location moves downstream significantly, while the general trend of separation zone length on top and bottom walls becomes smaller. The flexible panel with the high-frequency second-order limit cycle flutter state can increase the total pressure recovery coefficient with the smaller side load and outlet flow distortion, reduce the averaged separation length, and make the shock-train head move downstream. This is due to the isentropic compression and expansion waves induced by the vibration and deformation of the flexible panel.