采用全流道三维非定常流动数值模拟方法,研究了混流式水轮机在部分负荷工况运行时,尾水管涡带在尾水管内引起的压力脉动现象。计算工况为典型的部分负荷工况,单位转速为70.52r/min,单位流量为0.679m3/s。计算结果表明在4个计算点都得到了涡带低频压力脉动:频率为0.333Hz,是转频1.25Hz的1/3.75,相近工况(n11=71.25r/min,Q11=0.689m3/s)模型试验测得涡带频率为5.31Hz,是转频18.62Hz的1/3.51,从涡带频率看计算结果与试验测量结果一致。研究成果表明数值模拟方法是可行的,可以在设计阶段预测尾水管内涡带压力脉动的特性。
The 3-D global flow passage numerical simulation was carried out to study the low frequency pressure fluctuation occurred to the draft tube of a Francis turbine due to the unsteady vortex rope. The operation situation of typical partial load of the turbine with unit rotation speed 70.52 rpm and unit discharge 0.679m~3/s was calculated. The calculation results were compared with model test data. It is found that the frequency of calculated fluctuation pressure due to vortex rope at four positions of the draf...