引射混合器数值模拟及性能预测方法研究

通过引射混合器主次流不同压比下混合管内流场的模拟计算,确定了该几何构形下发生壅塞时的主次流压比.对高压比下次流壅塞现象的研究表明,壅塞以后继续增大压比,当主流出口静压远大于混合管静压时,混合管内气流只经历一次膨胀和再压缩的过程.同时激波位置固定,不再随压比的继续增大发生变化.基于准一维控制体模型、Fabri壅塞假设模型和连续方程,提出了能有效预测引射器最高性能的饱和超音速模型,推出了此模型下引射系数与总压比和面积比之间的关系.由此得到直接反映引射器性能的特性曲线和修正曲线.最后把解析结果与数值计算的结果进行对比,验证了该模型的有效性.

A study of numerical simulation of mixer-ejector and the method of performance prediction

The pressure ratio between the primary flow and the secondary flow is first ascertained when the choking happens under the geometrical configuration,through numerical simulation of the flow field in the mixing duct under different pressure ratios of the mixer-ejector.The analysis of the secondary flow choking under high pressure ratio shows that,the flow in the mixing duct undergoes only one cycle of expansion and recompression before the flow mixes with the ambient pressure at the exit of the mixing duct when the pressure is high enough.Meanwhile,the position of shocks and expansions stays unaltered,not changing with the pressure ratio.A saturated supersonic model is proposed which effectively predicts the maximum performance of the mixer-ejector in terms of the quasi-1D control volume model,Fabri Choking model,as well as the continuity equation,and then derivates the relationship among the bypass ratio,total pressure ratio and area ratio.Performance curve and modifed curve that directly embodies the maximum performance are obtained based on this model.Finally,a comparison between numerical simulation and calculation effectively confirms the reliability of this model.