蜗壳式混流泵压力脉动特性研究

基于雷诺时均方程和RNG k-ε湍流模型,应用SIMPLE算法,对混流泵内部流场进行非定常数值模拟,分析不同工况监测点上压力脉动的时域特性和频域特性。取定常计算的外特性与实验值对比,对比结果为不同工况的扬程偏差均小于5%,证明该数值模型能准确地描述泵内流场特征。结果表明:叶片进口处水流冲击产生的回流和漩涡是引起叶轮内压力脉动的主要动力源,叶轮与蜗壳间的动静相干作用是产生蜗壳内压力脉动的主要动力,并且在向下游传播过程中,压力脉动逐渐减弱,叶频占主导地位,在小流量工况运行时,主频有向叶轮转频迁移的趋势,大流量工况下最大压力脉动发生在转轮中间位置;叶轮内的压力脉动要远远高于蜗壳,这是引起机组振动和噪声的主要来源。

Study on pressure fluctuation characteristics of interior flow in mixed-flow pump with volute

The unsteady flow in a mixed -flow pump was simulated based on Reynolds time -averaged equation and RNAS solver embedded with RNG turbulence model and SIMPLE algorithm , and the pressure fluctuation characteristics in time -domain and frequency-domain at different monitoring points under different flow rate were analyzed .A comparison between external characteristics of steady flow with test date verified that the interior flow simulated by the numerical model was relatively accurate with lifting error less than 5%.The numerical results show that reflux and whirlpool , generated by flow rush at blade entrance , is the main power source of pressure fluctuation at the impeller , and rotor-stator interaction is the main power of pressure fluctua-tion in spiral case;the pressure pulsation decays in the downstream propagation process , and the impeller blade frequency gradu-ally dominates;the main frequency is tend to move to rotating frequency of impeller under low flow rate , and the maximum pres-sure fluctuation appears in the middle part of impeller under high flow rate .Pressure fluctuation in impeller is much higher than that in the volute , which is the main source of unit vibration and noise .