环型超声速空气引射器零二次流流场数值研究

Numerical study on the flowfields of the zero second-flow annular supersonic air ejectors

关键词:  引射式冲压发动机  引射喷管  压力自动调节系统  高空试车台  数值仿真

Key words:  Ejector ramjet engine  Shrouded nozzle  Automatic pressure regulating system  Altitude test stand  Numerical simulation

摘要:

采用二维轴对称雷诺平均方程和标准k ε双方程湍流模型 ,数值研究了环型超声速引射器零二次流的流场结构及盲腔压强的变化。空间上采用二阶迎风格式进行耦合求解 ,时间上采用显示的Runge Kutta方法进行迭代推进。结果表明 ,引射器几何参数不变的情况下 ,启动后的盲腔压强与引射气流总压之比为一常数 ;喷管马赫数不变情况下 ,喷管出口面积与混合室入口面积比越小 ,盲腔压强越低 ,扩压器性能越好 ,启动要求的总压越低。对超声速空气引射器的设计具有指导意义。

Abstract:

The zero second flow field and the pressure of the blind cavity in the annular supersonic air ejector were numerically investigated using two dimensional axial symmetry average Reynolds equations and the standard two equation k ε turblent models. Two order upstream scheme and explicit Runge Kutte algorithm were used to solve these equations. The results show that the ratio of the blind cavity pressure to the eject flow total pressure remains almost constant when the geometry parameters of the ejector is fixed. In the condition that the nozzle Mach number keeping constant, the area ratio of the nozzle exit to the mixing chamber entrance is smaller the lower the pressure of the blind cavity. The better the performance of the diffuser and the lower the total pressure needed for starting. The conclusions can be a guide to supersonic air ejector design.