海水淡化高转速泵作透平的压力脉动分析北大核心CSCD

离心泵反转作透平是海水淡化能量回收一体机的核心动力部件之一,运行时的压力脉动是机组产生振动和噪声的主要因素之一。本文以高转速离心泵反转作透平为研究对象,采用SAS-SST-CC湍流模型,对其进行整机流道三维非定常流动数值计算,通过流场分析及压力脉动频谱分析,探讨该透平在运行时的非定常流动特性。非定常数值计算结果显示,蜗壳内多测点的压力脉动主频均为叶片通过频率,说明蜗壳内压力脉动主要由转轮和蜗壳隔舌间的动静干涉引起;旋转转轮域内8个叶片间流道中各布置了6个测点,各相似位置测点间的压力脉动峰峰值最大相差10.3%,说明对称的旋转转轮内的流动分布严重不均,这些旋转测点的脉动频率主要为叶频8倍频附近的主频或次主频,说明转轮与蜗壳间的动静干涉、叶片流道间的漩涡是引起转轮内压力脉动的主要因素,且局部漩涡引起的压力脉动强于转轮动静干涉造成的。结果表明,转轮内压力脉动比蜗壳内明显剧烈,旋转转轮内的压力脉动是机组振动主要水力原因。

Analysis of pressure pulsation in high rotating speed pump as turbine in seawater desalination

A centrifugal pump used as a turbine is a core power component of the seawater desalination energy recovery machine; its pressure pulsation during operation is a major factor causing vibration and noise. This paper presents full-passage numerical simulations of the three-dimensional unsteady flows in a high rotating speed centrifugal pump as a turbine using a SAS-SST-CC turbulence model. We discuss the unsteady flow characteristics through flow field analysis and pressure fluctuation spectrum analysis. The results show the dominant frequencies of pressure pulsation at multiple measuring points in the volute are the same as the blade passing frequency, indicating the pulsation comes largely from the dynamic and static interference between the runner and volute tongue. Among the six measuring points located in each of the 8 blade channels of the runner, the maximum difference in the peak-to-peak amplitudes at the corresponding positions is 10.3%, revealing a significant uneven feature of flow distribution in the runner. The pulsation frequencies at these rotating measuring points are largely the dominant frequency or secondary dominant frequency near the frequency of 8 times the blade frequency, indicating the dynamic and static interference between the runner and volute is significant. Vortices in the blade channels are the main factor causing pressure pulsation in the runner, and these local vortices cause pressure pulsation stronger than those from the dynamic and static interference of the runner. The results show that pressure pulsation in the runner is more severe than that in the volute, and the former is the main hydraulic cause of unit vibration.