周向弯曲叶片内部三维流动扩稳机理的实验研究

对带有周向前弯和周向后弯叶片的低压轴流风机,采用双丝热线技术实验研究了周向弯曲叶片出口三维流动随流量降低变化规律。基于测量结果,详细阐述了周向弯曲叶片流道内三维流动结构的演化发展过程,分析非设计工况下叶片弯掠对流动的影响规律,结合径向平衡方程讨论了周向弯曲叶片对变工况边界层迁移的控制。结果表明：小流量工况下,周向弯曲叶片显著改变了流道内流动结构,且明显改善上下端壁区域的流通性,对于扩大稳定工作范围有着积极的作用;由于旋转离心力的增大,Fr对于径向压力梯度影响也发生变化,从而改变边界层的迁移方向和速度。

Experimental investigation of extending stall-free mechanism of three-dimensional flow in circumferential skewed axial fans

In this paper, the three-dimensional flow field at downstream of lower pressure axi al fans with circumferential forward-skewed, backward-skewed blades are successfully measured using a hot-wire CTA system at off-design conditions. An X hot-wire probe is used to obtain three dimensional velocity. Based on measurement results, the evolution of three-dimensional flow in these fans according to flow rate, and the effect of circumferential skewed blades on transporting of boundary layer at off-design conditions are discussed. The measurement results show that as flow rate decreases, three-dimensional flow structure is changed by circumferential skewed blades; the obvious suppression of passage flow is found near shroud and hub region, which is benefitial to improve stable operation range of circumferential skewed rotors; as centrifugal force increases, blade radial force Fr of circumferential forward-skewed blade has a positive effect on pressure gratitude, and seems to be efficient to control the velocity and direction of boundary layer movement.