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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.
Through theoretical analysis, numerical simulation and experimental comparison, the internal flow under different conditions of a axial flow fan for a helicopter is analyzed.The results show that the theoretical assumption of the relative velocity distribution inside the impeller is suitable for the rated working condition, But does not apply to low flow conditions.When the helicopter flying at high altitude, the fan working flow below the rated conditions, the top of the leaves prone to return flow, increased secondary losses; the same time the flight height is also easy to cause the boundary layer separation, jet - The wake area expands, so that the efficiency of the fan is further reduced. The concentration of low-energy fluid impels the stall of the impeller to occur firstly from the tip of the blade.When designing the axial flow fan for helicopter lubricating oil system, The main aerodynamic parameters influencing the internal flow loss of the impeller under varying working conditions are optimized to improve the stability of the system at high altitude.