轴流泵装置进水漩涡对压力脉动的影响

Influence of Inlet Vortex on Pressure Pulsation in Axial Flow Pump Unit

轴流泵内压力脉动是引起机组振动和噪声的主要原因之一,为了研究漩涡诱发水泵内压力脉动的机理,采用Fluent软件对轴流泵装置进行非定常计算,得到了大流量工况下(1.2Qd)不同特征断面的频域特性,结合模型试验,利用高速摄像机对漩涡生成到消失全过程进行动态测量,观察到漩涡微观变化过程。结果表明:喇叭管下方漩涡发生位置与低压区位置一致,涡管底端的压力脉动幅值最大,其Cp值约为非中心点处的1.8~2倍,涡管中心处压力脉动次频发生在1倍叶轮转频处,在叶轮进口压力脉动与漩涡压力脉动在1倍叶轮转频处具有同步性,且压力脉动次频均在1倍叶轮转频处。在进水池底部压力脉动激励源为进水漩涡,进水漩涡影响叶轮进口压力分布,诱发叶轮进口压力脉动。通过研究进水漩涡从生成到溃灭的过程及对压力脉动的影响,可为泵站工程实际应用中消涡措施提供理论依据。

The pressure pulsation is one of the main causes of vibration and noise in axial flow pump,in order to study the mechanism of pressure fluctuation induced by vortex,several pressure pulsation monitoring points were stalled at the bottom of the pump sump,the horn mouth,the impeller inlet and outlet,the outlet of the guide vane. The flow rate of 1. 2 Qd（ 1. 2 Qd= 38. 4 L/s） was selected. The dynamic process of vortex generation and disappearance was measured by an advanced high-speed camera,and the microscopic variation of the vortex was observed. The results showed that the vortex tube below the horn position and low position,the maximum amplitude of pressure fluctuation at the bottom of the vortex tube,the Cpvalue was about 1. 8 ~ 2 times of the non center point of pressure fluctuation of Cp value,at the center of tube,the pressure pulsation frequency of the vortex occurred at 1 time of the impeller rotation frequency. The pressure fluctuation at the impeller inlet and the pressure fluctuation at the impeller were synchronized at 1 time of the impeller frequency,and the pressure pulsation frequency was 1 time of the frequency of impeller. The detailed structure of the vortex changes was clearly observed by high-speed cameras. On the whole,the maximum amplitude of pressure fluctuation was at the inlet of impeller,and the maximum amplitude of pressure fluctuation occurred at the center of the vortex belt.The Cpvalue of the pressure fluctuation at the center of the vortex belt was about 1. 8 ~ 2 times of the Cp value of the pressure fluctuation at the non center point. Getting through the water inlet swirl from generation to the collapse process and the influence of pressure fluctuation,can provide a theoretical basis for the pumping station project of vortex elimination measures.