Investigation On Start Process Of Hypersonic Inlets And Flow Mechanism In Isolators

The paper focused on start process and flowfields in unstart status of hypersonic inlets,and the analysis and comparison of large-scale separation zones are the key point of this paper.The start process of a two-dimensional hypersonic inlet together with the movement,balance,and self-sustaining mechanism of large-scale separation zones was investigated and analyzed.The role and effect of a large-scale separation zone in the start process of a two-dimensional hypersonic inlet was investigated through numerical simulation on a simplified inlet model.The self-sustaining mechanism was systematically summarized.Contraction ratio,length of the internal duct and thickness of the incoming flow were chosen as the research parameters to further analyse the high pressure of the leeward side of a separation zone as well as the balance and self-sustaining mechanism of a separation zone.A self-sustaining index _iS was proposed to quantificationally evaluate the self-sustaining ablity of a large-scale separation zone._iS can be useful for identifying the critical point of the timing that a separation loses its balance.The three-dimensional effect of the flow in start process was investigated.Three dimensional computation and two-dimensional computation were compared,and the effect of aspect ratio and configuration of the sidewall on start characteristics was investigated.Crossflow was emphasized to analyse the flowfield and movements of separation zones in three-dimensional condition.Designing and flow mechanism of rectangular-to-circular isolator and S-shape turning isolator was investigated,and the flowfield,backpressure performance and the forward spreading process of high backpressure were analyzed and summarized.