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对某气动阀式脉冲爆震发动机(PDE)亚声速进气道进行了试验和数值仿真研究,分析了该进气道在冷流条件和点火条件下的流场结构和工作特性。结果表明,在冷流条件下,通道内整流锥上游的流动较顺畅,无可见分离存在。但在点火条件下,爆震波的干扰使得进气道出口的压强呈周期性振荡,其峰值压力达300kPa以上。由于气动阀并没有起到有效的隔离作用,爆震波在进气道出口平面形成的压力扰动会逐渐向上游传播,并在2ms内越过气动阀,导致进气道进口出现了高速整体倒流,其倒流时间占据了约半个周期,且瞬时倒流马赫数最大可达到0.8。本文还对冷流条件和点火条件下的进气道流场进行了数值模拟,仿真较好地模拟出了该进气道的试验条件,且进气道内流动与试验基本一致。非定常仿真结果进一步表明了该进气道在爆震高压扰动下会出现整体高速倒流的现象。由于进气道进口的瞬时倒流形成了较大的反向冲量,对爆震发动机的推力特性极为不利,故必须在下一步的研究中对气动阀进行改进。
The experimental and numerical simulation of the subwoofer inlet of a pneumatic valve pulse detonation engine (PDE) was carried out. The flow field and operating characteristics of the inlet under cold flow and ignition conditions were analyzed. The results show that under the condition of cold flow, the flow in the upstream of the coning cone in the channel is smoother and there is no visible separation. However, under the conditions of ignition, the pressure of the outlet of the intake port oscillates periodically with the interference of the detonation wave, and the peak pressure is more than 300 kPa. As the pneumatic valve does not play an effective role in isolation, the pressure disturbance formed by the detonation wave at the air outlet exit plane gradually propagates upstream and passes the air valve within 2 ms, resulting in a high-speed overall reverse flow at the air intake Backflow time occupies about half a cycle, and the instantaneous backflow Mach number up to 0.8. In this paper, numerical simulation was also carried out on the inlet flow field under the condition of cold flow and ignition, the simulation of the inlet flow conditions was simulated well, and the flow in the inlet was basically the same as the experiment. The result of unsteady simulation further shows that the inlet will have an overall high-speed reverse flow under high-pressure knocking. Because of the instantaneous backflow of the inlet, a large inverse impulse is formed, which is extremely unfavorable to the thrust characteristics of the detonation engine. Therefore, the pneumatic valve must be improved in the next study.