对转压气机外伸激波对叶顶泄漏流影响

摘要:为了揭示对转压气机下游转子外伸激波对上游转子泄漏流的影响规律,针对上游转子叶顶间隙分别为0.2、0.5、0.8 mm的对转压气机开展了非定常数值模拟研究。研究发现:受下游转子外伸激波掠扫影响,上游转子尾缘附近压力面会形成弱压缩波,且随上游转子泄漏流增强而逐渐减弱;而该外伸激波在上游转子尾缘附近吸力面,会形成与型线切向相垂直的较强压缩波,且其位置基本不受叶顶间隙大小影响;外伸激波使上游转子尾缘附近吸、压力面压差增大,叶顶泄漏流增强,进而导致其损失增大;随着叶顶间隙增大,上游转子叶尖区弦长前半段压力波动的频率,由通道激波转为叶顶泄漏流主导,且呈现减小的趋势,而弦长后半段压力波动的频率主要由外伸激波主导,且基本不变。 

Impact of bow shock on tip leakage flow in counter-rotating compressor

In order to reveal the impact of the bow shock of downstream rotor on the tip leakage flow of upstream rotor in a counter-rotating compressor, the unsteady numerical simulation of a counter-rotating compressor was conducted with tip clearance of 0.2, 0.5 and 0.8 mm of the upstream rotor, respectively. Results showed that impacted by the sweep of the downstream rotor bow shock, a weak compression wave was formed on the pressure surface near the tail edge of the upstream rotor, which could be weakened gradually with the increase of the leakage flow of the upstream rotor. On the suction surface near the trailing edge of the upstream rotor, a strong compression wave perpendicular to the tangential direction of the blade profile was formed causing the downstream rotor bow shock, and its position was basically not affected by the sizes of tip clearance. Also, the pressure difference between the suction and the pressure surfaces near the tail edge of the upstream rotor increased by the bow shock, which led to the augment of the tip leakage flow, and then the flow loss. With the increase of tip clearance, the motivator of the main frequency of the pressure fluctuation, which was located among the blade tip half-chord region belonging to the leading edge of the upstream rotor, was changed from the channel shock to the tip leakage flow and the main frequency decreased gradually. While the blade tip half-chord region was located at the trailing edge, the pressure fluctuation was mainly dominated by the downstream rotor bow shock, and its main frequency was consistent with the bow shock sweeping.