周向弯曲叶片叶顶泄漏流随流量变化特性数值研究

对带有周向前弯和周向后弯叶片的低压轴流风机,叶顶泄漏流动随流量变化特性进行了数值研究和实验校核,探讨了随流量减小,周向弯曲对叶顶泄漏涡的起源和发展规律的影响.性能计算结果与试验测量较为吻合,计算结果表明:随着流量减小,泄漏涡起源向前缘方向迁移,周向弯曲使泄漏流与主流掺混加剧;周向前弯叶片泄漏涡的起源距叶片前缘最远,涡强度最弱,移动最缓慢;周向前弯稳定叶顶流动,降低端壁损失,扩大稳定工作范围. 

Numerical analysis on tip leakage flow of circumferential skewed blades according to flow rates

In this paper, the tip leakage flow fields at the off-designation condition in a lower pressure axial flow fan with three kinds of circumferential skewed blades, including the traditional radial blade, the forward-skewed blade and the backward-skewed blade were investigated by numerical method. Based on the simulated results of the velocity and pressure fields, the characteristics of tip leakage flow and tip leakage vortex according to flow rates were studied, and effects of the circumferential skewed blades were described and analyzed. The results show that at the off-designation condition the mixing process between the tip leakage vortex and main flow is stronger in the forward-skewed blade than in the backward-skewed blade; the tip leakage vortex of the circumferential forward blades is closer to the leading edge of the blade and move slowly with the flow rate decreased, and resist the end-wall losses; the circumferential forward blades maintain the tip leakage flow , and is benefit to range of steady operation condition; the tip leakage vortex being the strong and decaying slower results in the lower flux capability of the cascade, the end-wall losses increase.