离心泵作透平最佳工况点下的瞬态流动特性分析

为揭示离心泵作透平在最佳工况点下主要过流部件的瞬态流动特性，采用修正的PANS模型对一台比转速为90的离心泵作透平的瞬态流动特性进行数值模拟，通过试验验证数值计算的准确性；根据叶片的进、出口速度三角形计算理论最佳工况点，并对最佳工况下叶栅内部的流动规律进行预测；对蜗壳、叶轮在最佳工况点下的内部瞬态流动特性进行分析。结果表明，叶轮理论进、出口最佳工况点分别为55 m³/h、108 m³/h，实际最佳工况点为80 m³/h；叶片与蜗壳隔舌的动静干涉会促进隔舌前缘旋涡的脱落，当叶轮前缘与隔舌前缘平齐时，蜗壳内压力脉动强度最低；叶栅内旋涡的脱落频率约为2f_n，涡量的演变主要由其输运方程中的拉伸项及科氏力项共同主导；吸力面附近涡量的演变对叶轮前、中部流道内的压力脉动影响较大，而叶片尾缘涡量的演变对叶轮出口处的压力脉动影响较大。研究结果可为提高离心泵作透平在余能回收系统中的运行稳定性提供参考。

Analysis of the Unsteady Flow Characteristics of Chemical Centrifugal Pump as Turbine at the Best Efficiency Point Condition

Considering that the self-developed deep-sea electric pump operates under off-design conditions, its internal unsteady fluid radial force may cause vibration of the pump and even bring harm to the whole mining system. At present, it is impossible to calculate the radial force directly through theoretical formula. Therefore, the experimental and numerical simulation methods are used to study the regular and the production mechanism. Firstly, the accuracy of the numerical simulation method is verified by hydraulic performance test of the electric pump, and then the pressure distribution in the six-stage deep-sea electric pump and the radial force distribution of the fluid in the pump and its generating mechanism are studied. Finally, the radial force distribution law of two-stage deep-sea electric pump under different flow rates is compared and analyzed. The results show that the radial force in impeller at all stages varies periodically, and the stronger the regularity is at the last stage; the change period of radial force in impeller at all stages is related to the number of impeller blades. When other parameters remain unchanged, the smaller the flow rate is, the greater the radial force is, and the stronger the fluctuation is.