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进气道处于起动状态是保证超燃冲压发动机正常工作的前提,进气道帽罩快速开启时的非定常效应可以有效提高进气道的起动能力。采用非定常数值计算深入研究了唇口帽罩不同安装位置开启时的非定常效应对进气道起动过程的影响,分析了不同帽罩安装位置开启时进气道流场的演化过程,并揭示了喉道分离泡的形成机理。研究结果表明,当帽罩上游不存在分离泡时,破膜非定常激波在压缩面反射,与上游复杂波系作用形成沿壁面的低速流,在唇口激波作用下在喉道形成分离泡。帽罩安装靠近唇口可通过缩短激波/边界层作用距离减小低速流动区范围,进气道临界起动内压比随之增大;而当帽罩上游出现大分离泡时,分离泡会先演变为低速流,之后在唇口激波作用下重新聚集形成大尺度分离,进气道临界起动内压比显著降低。
The inlet is in the starting state is to ensure the normal operation of scramjet engine premise, inlet cap quickly open when the unsteady effect can effectively improve the starting ability of the inlet. The unsteady numerical calculation is used to study the influence of the unsteady effect of lip hat and hood on the starting process of the inlet. The evolution process of the inlet flow field when different hoods are installed is analyzed. The throat separation bubble formation mechanism. The results show that the unsteady shock wave of the rupture membrane is reflected on the compression surface when there is no separation bubble in the upper part of the cap, and forms a low velocity flow along the wall surface with the complex wave system in the upstream, and forms a separation in the throat under the action of the lip shock bubble. Cap mounting close to the lip can shorten the shock / boundary layer distance to reduce the scope of low-speed flow area, inlet critical pressure increases as the pressure increases; and when the hat cap large separation bubble, the separation bubble will First evolved into a low-velocity flow, and then re-aggregated to form a large-scale separation under the shock of the lip mouth, and the critical pressure ratio at the inlet port was significantly reduced.