蜗壳断面形状及叶轮位置对蜗壳式轴流泵性能的影响

根据速度系数法设计了1种对称的“马蹄形”断面蜗壳和2种非对称的 “圆形”断面蜗壳与相同的轴流泵叶轮组合,并基于标准k-ε模型封闭的雷诺平均方程,应用 ANSYS CFX 14.5 软件,对设计的3个蜗壳式轴流泵内部的三维流动开展数值模拟.当采用“马蹄形”蜗壳时,设计流量点的扬程和效率最低,蜗壳内部压力分布不如非对称的圆形断面蜗壳均匀.选择水力效率相对较高的蜗壳,将4种轴向位置不同的叶轮与该蜗壳组合,并进行三维流动数值模拟,结果表明:叶轮出口与蜗壳进口中间平面距离40 mm时,轴流泵效率最高,叶轮出口与蜗壳进口中间平面距离80 mm时,轴流泵效率最低.此时,过流段和蜗壳内有明显回流和旋涡.轴流式叶轮与蜗壳的相对位置对蜗壳轴流泵的扬程-流量曲线和效率-流量曲线都有明显的影响.

Effects of volute cross-section shape and impeller position on volute type axial flow pump performance

In view of this situation that the study on the volute type axial flow pump volute design optimization, the external features and internal flow field distribution is less, the 3D flow in the volute type axial flow pump was numerically simulated by using ANSYS CFX 14.5 software, based on Reynolds-averaged equations closed by the standard k-ε model. Three kinds of new volutes combined with impellers were simulated. The head and efficiency at the design flow rate are the lowest in case of horseshoe-section volute. The 3D flow numerical simulation between the impeller at 4 different axial positions and the volute in terms of relatively higher hydraulic efficiency was carried out. The results show that when the exit of the impeller and the volute inlet middle plane are 40 mm apart, axial flow pump efficiency is the highest. When the impeller exit and the volute inlet middle plane are 80 mm apart, axial flow pump efficiency is the lowest. In this case, between the impeller and volute and in the volute exist substantial reflux and whirlpool. The relative position of axial flow impeller and volute have ob-viously affects the flow-head curve and the flow-efficiency curve.