大型立式轴流泵装置流道内部流动特性分析

Characteristics of Flow in Large Vertical Axial Flow Pumping System

基于三维不可压缩流体的雷诺平均N-S方程和RNGk-ε湍流模型,采用CFX软件计算了额定转速下180-340 L/s流量范围内6个工况点的立式轴流泵装置内部流动,分析了进水流道和出水流道的流动特性,重点研究进口流动细部结构,同时预测了泵装置的水力性能。计算结果表明：叶轮旋转对进水流道出口轴向流速分布和切向流速分布的影响较小。导叶出口环量对出水流道的流场影响较大,导致隔墩两侧流量分配不均,大流量时隔墩两侧水流流态比较平顺,而小流量时隔墩右侧流道内出现螺旋状水流,两侧水流严重不均衡。通过计算预测了泵装置水力性能,并与泵装置模型性能试验结果进行了对比,表明最优工况时数值模拟与试验结果吻合较理想,可以满足工程实际的需要。

The internal flow field in a vertical axial flow pumping system was simulated by CFX software using the Reynolds averaged N-S equations and RNG k-ε turbulence model.Focusing on details of the inlet flow field,the flow characteristics in the inlet and outlet passages of pumping system were analyzed based on the calculation of different operating conditions with the flow rates range 180~340 L/s at the rated rotating speed.The results show that rotating of impeller has effects on the distribution of axial and tangential velocity components at the pump inlet,but the numerical values are relatively small.Outlet circulation of guide vane has great influence on flow pattern in the outlet passage.The flow distribution for both sides of the dividing pier is not symmetric,especially for small flow rate condition,the helical flow occurs at the right side of dividing pier.A good agreement is achieved in the performances of the pumping system between the predicted data and experimental data at the best efficiency point,which can meet the requirement of practical application.