直升机用轴流风机内部流动分析

通过理论分析、数值仿真与试验比较相结合的方法,对某型直升机用轴流风机不同工况下的内部流动进行了分析.结果表明,叶轮内部相对速度分布的理论假设适用于额定工况,但不适用于小流量工况.当直升机高空飞行时,风机工作流量低于额定工况,叶顶处容易出现回流,二次流损失加剧;同时飞行高度增加还易导致边界层分离、射流-尾迹区域扩大,从而使风机效率进一步降低;低能流体的集中,促使叶轮失速往往首先从叶顶处出现.在设计直升机滑油系统用轴流风机时,应注意对其变工况性能进行研究,对影响变工况下叶轮内部流动损失的主要气动参数进行优化设计,以提高系统高空工作的稳定性.

Off-design performance study of axial flow fan in helicopter

This paper analyses inner flow of an axial flow fan in helicopter at different work conditions by the ways of theoretical analysis, numerical simulation and experiment. The results show that theoretical hypothesis of relative velocity in the impeller is applicable for rated condition but not for surge condition. When the helicopter flies at high altitude and the fan works at low flow rate condition, stall will appear firstly in blade tip region and secondary flow loss increases; increment of helicopter flight altitude also causes boundary layer separation and widening of jet-wake area, thus the fan efficiency decreases; stalling will first appear in tip clearance area with low speed flow gathering there. So it is important that research on off-design performance should be performed to optimize main aerodynamic parameters influencing fan loss and to improve the stability of altitude performance when designing axial flow fan for lubrication system of helicopter.