叶轮不同叶片对离心泵内流道流场的影响

Influence of different impellers on the flow field in the centrifugal pump

对离心泵进行三维建模,并对内部流场进行数值模拟.采用"仿真-实验"法验证了六叶片离心泵流场仿真的合理性,研究了叶轮上不同叶片数对内流道流场的影响.数值模拟原理为大涡模拟,通过网格直接模拟大尺度的紊流运动,同时,利用次网格尺度模型来模拟小尺度紊流运动对大尺度紊流运动所造成的影响.大涡模拟可以获得雷诺时均模拟法无法获得的流场细微图像.模拟结果表明:离心泵叶片数量过多,会使叶片表面摩擦力做功加大,使得离心泵出口处的总功减少,从而降低离心泵的扬程和效率.经过模拟实验研究分析发现,当叶片数为5时,离心泵流场的综合性能最好,运行效率最高,湍流强度低,流场稳定性最好.

In this paper,the centrifugal pump is modeled and its internal flow field is numerically simulated.The“simulation-experiment”method was used to verify the rationality of the flow field simulation of the six-blade centrifugal pump.Then,the influence of different blades number of the impeller on the flow field was studied in detail.The method of numerical simulation is large eddy simulation in this paper.For its simulation principle,the large-scale turbulent motion is directly simulated by the grid,and the sub-grid scale model is used to simulate the influence of small-scale turbulent motion on large-scale turbulent motion.The large eddy simulation can obtain a better image of the flow field that cannot be obtained by the Reynolds Time-average simulation method.The simulation results show that the excessive blades number of centrifugal pump will make the friction of the blade surface too large,which will reduce the total power at the outlet of the centrifugal pump,thus reducing the lift and efficiency of the centrifugal pump.Through simulation experiments,it’s found that when the number of blades is 5,the flow field of centrifugal pump has the best comprehensive performance,the highest operating efficiency,lower turbulence intensity and best flow field stability.