轴流压气机转子叶尖泄漏流行为的数值研究

Numerical investigation on behavior of tip leakage flow in axial compressor rotor

为了加深对某高速小尺寸轴流压气机转子的叶尖泄漏流行为的理解,采用定常数值计算的方法对其内部流场进行了全三维的数值模拟。计算结果表明:峰值效率工况下,叶尖泄漏涡集中且稳定,而近失速工况下,叶尖泄漏涡在通道中发生破碎,破碎后泄漏流的速度剧减,形成巨大的低能团,严重堵塞顶部通道。低能流体团压缩叶尖泄漏流的流动空间,迫使叶尖泄漏流溢出叶片前缘平面,导致转子突尖型失速先兆发生。进一步详细分析叶尖泄漏流的结构发现,叶尖泄漏流与来流的交界面随流量减小而向上游移动,并受叶尖泄漏涡破碎、前部弦长范围叶尖间隙两侧压差增加及逆压梯度增强的共同影响。

With the aim to advance the understanding of the behavior of tip leakage flow of a small-scale high-speed axial flow compressor rotor,three-dimensional steady flow simulations were conducted to obtain the internal flow fields.The computational results show that tip leakage vortex keeps concentrated and stable at peak efficiency condition,while the breakdown of the tip leakage vortex occurs inside the passage at near stall condition followed by a rapid deceleration of the leakage flow,leading to the formation of a large-size low-energy fluid mass.Thus,the top of the passage is severely blocked.Low-energy fluid mass occupies the flow area of tip leakage flow,forcing tip leakage flow to overflow ahead of the blade leading edge plane,which is responsible for the spike-type stall inception of rotor.By further analyzing the structure of tip leakage flow in detail,it was found that the interface between tip leakage flow and the incoming flow moving upstream as the mass flow decreases is affec-ted by the breakdown of tip leakage vortex,the increased pressure difference between the pressure side and suction side of the tip clearance block among the front range of blade′s tip chord and the increased adverse pressure gradient.