非轴对称端壁对轴流风机二次流动的影响

Effect of non-axisymmetric endwall on secondary flow in axial fan

为了研究非轴对称端壁对低速风机二次流动的影响机理,本文在某单级低速轴流风机的静子轮毂采用了非轴对称端壁(CEW)造型,并利用三维数值模拟软件进行了数值分析。结果表明:100%设计转速下工作点的等熵效率和总压升系数均有所提高,且在小流量点的提升幅度大于大流量点;其中风机峰值效率点的等熵效率提升了1.27%,总压升系数提高了2.97%;非轴对称端壁通过型面变化来改变局部的压力梯度,其中近吸力面凹槽使得流向逆压梯度(APG)减弱,而近叶栅通道出口的端壁凸包可以提高其前方压力,抑制横向流动的发展,这两种型面均有利于抑制角区分离。对该非轴对称端壁凹槽结构的径向深度幅值进行了对比分析,发现其存在一个约为静子根部弦长5.73%的最佳深度。

Computational results to assess the effectiveness of non-axisymmetric endwall contouring in a low-speed axial fan were presented.The endwall was designed by geometric scaling of a prior optimized endwall.Results showed that the isentropic efficiency and total pressure rise coefficient at 100% design speed increased,and the performance of the contoured endwall(CEW)at near stall condition was better than that at the near choke point.Besides,the CEW got 1.27%isentropic efficiency and 2.97%total pressure rise coefficient increased at peak efficiency point.According to the mechanism of the improvement of CEW,the adverse pressure gradient(APG)had been reduced through the groove configuration near the leading edge of the suction surface.Moreover,there was an optimum depth for the groove configuration of this axial fan,which was equal to about 5.73%chord length at stator hub.