波转子非定常泄漏流动机理

针对制约波转子性能的泄漏问题,通过提取波转子中与泄漏相关的主要流动现象并建立波转子单通道泄漏模型,对非定常泄漏流动机制进行了详细的数值研究,对本文给出的非定常泄漏损失预测模型进行了数值验证。结果表明:转子通道中存在不同程度的压力波动,波动幅值与间隙宽度有关;连续反射膨胀波、周期性出现的弓形激波及其反射激波是压力波动的根本原因;间隙内部泄漏过程存在3个主要的流动阶段;泄漏过程中通道激波传播速度不变、波后时均压力不变;在一定间隙宽度范围内,激波马赫数、激波静增压比与无量纲间隙宽度均呈线性关系,当间隙宽度从0增大到0.08时,激波马赫数衰减7.3%,激波静增压比衰减10.1%;泄漏流动通过泄漏产生的主膨胀波对激波传播过程施加影响,通道激波衰减本质上是理想激波与主膨胀波叠加效应的结果;泄漏损失预测模型与数值结果吻合良好。

Mechanism of nonsteady leakage flow of wave rotors

The problem of leakage flow can restrict the performance of a wave rotor.This paper extracts main flow phenomena related to leakage in a wave rotor,and establishes a two-dimensional single passage leakage model.The mechanism of nonsteady leakage flow is analyzed numerically,and the prediction model for loss of unsteady leakage flow is further verified.The results show that there exists pressure oscillation of varying extent in rotor passage,and the oscillation amplitude is related to the gap width.The continuous reflected expansion wave,periodic emerging bow shock and its reflected shock are reasons for pressure oscillation.There exist three main flow stages in the leakage gap during leakage flow process and during which the propagation speed of passage shock and post-shock time-averaging pressure stay unchanged.Within a certain range of gap width,shock Mach number and shock static pressure ratio are both linearly dependent on the nondimensional leakage gap width.When the gap width is increased from 0 to 0.08,the shock Mach number decreases by 7.3 ％,and the shock static pressure ratio decreases by 10.1％.The propagation of channel shock wave is influenced by leakage flow process via main expansion wave,and shock wave attenuation is essentially the result of superposition of ideal shock wave and expansion wave.The results obtained with leakage loss prediction model is found to be consistent with CFD results.