半高导叶对离心泵径向力影响数值模拟研究

Numerical study of the influence of half diffuser on the radial force in a centrifugal pump

半高导叶广泛应用于压缩机与涡轮机械中,能有效改善其气动性能,而在离心泵中应用较少,对其性能的影响机理不明确。采用SST k-ω湍流模型对半高导叶离心泵内部流场进行非稳态数值分析,重点研究半高导叶对离心泵压力脉动及径向力性能的影响规律。结果表明:当H/b=0.4～0.6时,离心泵的水力性能最优、高效区较宽;随着流量增加;当H/b=1.0时,离心泵叶轮出口各流道压力对称性在逐渐变好,作用于叶轮上径向力在逐渐降低;当H/b=0～0.8时,离心泵中叶轮出口各流道压力对称性在逐渐变差,径向力在逐渐增加;在各流量工况下,当H/b=0～0.8时离心泵径向力瞬时平均值高于H/b=1.0,但其径向力波峰与波谷差值较小,且作用于叶轮上径向力矢量分布更均匀,叶轮出口液流角波动较稳定。分析结果为离心泵半高导叶设计提供理论依据与参考。

Half guide vanes have been widely used in compressor and turbine machinery to improve the aerodynamic performance,but are seldom used in centrifugal pumps and the influence mechanism of the performance of pump is not yet very clear.The SST k-ωturbulence model was adopted to analyze the unsteady state of internal flow field of a half guide vane centrifugal pump.The influence of half guide vanes on the pressure fluctuation and radial force performance of centrifugal pump was discussed by numerical simulations and experiments.The results show that when the H/b=0.4~0.6,the centrifugal pump has the best hydraulic performance and wider efficiency range.With the increase of the flow rate,the pressure symmetry of the flow path in the impeller of the ordinary guide vane centrifugal pump gradually becomes better,and the radial force acting on the impeller gradually decreases,while the pressure symmetry of the flow path in the impeller of the half guide vane centrifugal pump is gradually deteriorated and the radial force is gradually increased.In each flow conditions,the instantaneous average radial force of the half guide vane centrifugal pump is greater than that of the ordinary guide vane centrifugal pump,but the difference between its radial force crest and trough is small,that is,the half guide vanes can effectively reduce the alternating stress in the impeller.The radial force distribution on the impeller of the half guide vans centrifugal pump is more uniform,and in each flow condition,the fluctuation of the impeller outlet flow angle is somewhat less.The results provide a theoretical basis and reference to the design of centrifugal pumps with half guide vanes.