大型低扬程立式蜗壳混流泵装置模型试验研究及分析

Experimental study on large-scale volute mixed-flow model pump system of low head

针对某低扬程立式蜗壳混流泵站更新改造的需要,在CFD分析的基础上开展该泵站模型装置试验研究工作,并提出了泵站更新改造的流程分析图。对泵装置模型进行了能量性能、空化性能、飞逸转速和水力脉动的测试。试验结果表明,在设计流量282 L/s和扬程4.7 m工况下初步优化后的泵装置在叶片安放角-1.3°时泵装置效率提高了4%,达到了工程改造的预期目标。采用中高频动态传感器HM90对不同工况的泵装置水力脉动信号进行了采集和分析,得出叶轮进口和进水流道"ω"后壁处的脉动受工况的改变影响较小,叶轮进口流态受叶轮旋转的影响较小,叶轮进口的主频与转频相同,蜗壳压水室的脉动主频与转频成倍数关系。在保证叶轮中心线有足够淹没深度的情况下,泵站能安全可靠运行,该结论为立式蜗壳混流泵机组的稳定运行提供了科学依据,可为同类泵站的改造提供借鉴。

To renovate a large-scale volute mixed-flow pump station, an experimental study on hydraulic behaviors of its model pump was made in combination with CFD flow analysis, and a chart of its renovation procedure was put forward. For this model pump system, the energy performance, cavitation, runaway speed and pressure pulsations were measured at a speed of 1450 r/min. The test results show that under the design flow of 282 L/s and the design lift of 4.7m, the efficiency of the system can be improved by 4% through a preliminary optimization with a blade angle -1.3°, which meets the design goal. Three HM90 dynamic transducers of medium-high frequency and a data sampling and processing system EN900 were used for measurement of pressure pulsations. This reveals that the pressure pulsations at the impeller intake and the inlet＇ s co-shape rear wall are nearly independent of the operating conditions, and that the dominant frequency in the intake is roughly equal to the rotation frequency, while in the double helix volute passage it becomes a multiple of that frequency. Thus, by enough submergence of the impeller centerline, stable operation of the pump station can be ensured. This study lends a theoretical basis for stable operation and renovation of mixed- flow pump stations.