轴向偏转型自循环机匣处理对高速压气机扩稳效果的影响机理

本文提出了一种新的轴向偏转型自循环机匣处理结构,偏转角度为叶片顶部弦长与压气机轴向的夹角,设计了正偏和反偏2种方案,然后,以一个高速轴流压气机转子为研究对象进行数值模拟,结果表明：相对于实壁机匣,压气机在正偏、反偏自循环机匣处理时的综合稳定裕度分别增加11.52%、10.15%,峰值效率仅分别下降了0.32%、0.59%。分析原因是正偏型自循环机匣处理时,喷射的高速气流将叶顶泄漏流沿叶顶弦长方向吹向下游,改善了叶顶流场,起到了扩稳效果,同时,喷射流与压气机叶顶主流方向一致,提高了进口速度,减小了掺混损失,因此,效率下降很小。反偏型自循环机匣处理时,喷射的高速气流将叶顶泄漏流吹向转子叶片吸力面,抑制和削弱了叶顶泄漏流,也起到了扩稳效果,但由于喷射流与叶顶泄漏流、压气机主流都存在夹角,因此,造成了较大的掺混损失,效率比正偏型自循环机匣处理时下降略多。

Influence Mechanism of Axial Deflection Self-Circulating Casing Treatment on Stability Enhancement of High-Speed Compressor

In this paper, a new self-circulating casing treatment structure with axial deflection is proposed. The deflection angle is the angle between the chord length at the top of the blade and the axial direction of the compressor. Two schemes of forward and reverse bias are designed. Then, a high-speed axial compressor rotor is taken as the research object for numerical simulation. The results show that the comprehensive stability margin of the compressor increases by 11.52% and 10.15% respectively, and the peak efficiency decreases by 0.32% and 59% respectively, compared with the solid wall case. The reason for the analysis is that when the positive bias self-circulating casing is treated, the high-speed jet flow will blow the tip leakage flow downstream along the chord length of the top of the blade, which improves the tip flow field and enlarges the stability. At the same time, the jet flow is in line with the main flow direction of the compressor tip, improves the inlet speed and reduces the mixing loss. Therefore, The compressor rotor efficiency decreases slightly. When the reverse-biased self-circulating casing is treated, the high-speed jet airflow will blow the tip leakage flow to the suction surface of the rotor blade, which restrains and weakens the tip leakage flow and also enhances the stability. However, due to the angle between the jet flow and the tip leakage flow and the mainstream of the compressor, the mixing loss is greater and the efficiency degradation is a little more than that of positive bias self-circulating casing treatment.