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尾水管内涡带引起的不稳定流关系到水电站机组的安全。针对一个混流式水轮机的典型部分负荷工况,采用PISO(pressure-implicitwithsplittingofoperators)方法,计算了尾水管内部由于涡带引起的不稳定流场,预测了涡带脉动频率以及尾水管各断面上压力脉动。结果表明,涡带压力脉动频率约为转频的1/3,与实际观察到的脉动频率相符。在此基础上,分析了尾水管直锥段、弯肘段和扩散段内的压力脉动特征以及尾水管内压力脉动对转轮内压力的影响。
The unstable flow caused by the vortex in the tail pipe is related to the safety of hydropower unit. In view of the typical partial load condition of a Francis turbine, the PISO (pressure-implicit with spittingofoperators) method was used to calculate the instability flow field caused by the vortex band in the draft tube. The frequency of the vortex band and the pressure pulsation on each section of the draft tube were predicted. . The results show that the frequency of vortex pressure pulsation is about one third of the frequency of the turntable, which is consistent with the observed pulsation frequency. Based on this, the characteristics of pressure pulsation in the straight conical section, the elbow section and the divergent section of the draft tube and the pressure fluctuation in the draft tube are analyzed.