低速轴流压气机周向单槽机匣处理扩稳实验研究

周向槽机匣处理作为一种有效的扩稳措施得到了广泛应用,但是缺乏对其机理的深入理解和认识。为此,在一台低速单转子轴流压气机上考察了周向单槽机匣处理随轴向位置变化的扩稳效果。实验中获得了单槽不同轴向位置的扩稳规律,在该台压气机上得出了扩稳效果最好的槽位于40%~60%轴向弦长,而当单槽位于27%轴向弦长附近时,其扩稳效果最差。在此基础上,选取了最优扩稳槽位和最差扩稳槽位进行详细的壁面非定常流场测量和尾迹测量,对比分析了光壁条件与各单槽处理机匣对叶顶间隙泄漏流和转子尾迹的影响。结果表明,采用扩稳效果最优槽位之后,周向单槽能推迟叶顶间隙泄漏流与主流交界面前移,以及减弱叶顶间隙泄漏流非定常性,且能明显增强尾迹区1BPF(叶片通过频率)的能量,同时减弱0.5BPF的能量,达到扩稳的目的。而对于扩稳效果最差槽位而言,叶顶间隙泄漏流与主流交界面直到失速前也无法跨过单槽从叶片前缘溢出,周向单槽改变了叶顶间隙内部诱发突尖失速先兆的扰动传播方式;另外,其对转子尾迹区0.5BPF和1BPF的影响也比较小,从而使得其扩稳效果减弱。

Experimental investigation of stability enhancement with single circumferential groove casing treatment on a low speed axial compressor

Circumferential casing grooves are known to increase the stable operating range of axial compressors; however, the mechanism by which the stability enhancement occurs is poorly understood. In this paper, experimental investigations are performed on a low speed axial compressor to study the stability enhancement effect of single circumferential casing groove with different axial locations. The complete change rule of stability enmancement improvement is obtained when the groove moves from the leading edge towards trailing edge. It is found that the optimum grooves locate at the location of 40% to 60% of axial chord of the blade tip, and the worst grooves locate near the location of 27% of axial chord of the blade tip. On this basis, dynamic measurements are performed on the casing and at the rotor wake to analyze the effect on the tip leakage flow and rotor wake with different groove locations compared with smooth casing. These results reveal that the optimum groove can delay the forward movement of the interface and it can also enhance the power of frequency band of blade passing frequency (BPF) and weaken the power of 0.5BPF. But for the worst groove, the interface cannot cross the groove to spill out at the leading edge, even until the stall; it will affect the circumferential propagation of the disturbance which induced the stall inception. Its effect on the power of 1BPF and 0.5BPF at the rotor wake is very slightly.