混流式水轮机部分负荷下尾水管压力脉动试验研究

摘要

The pressure fluctuation in Francis turbine draft tubes during partial load was analyzed based on field test data of the Three Gorges Hydropower Plant. Inapplicability of two current used formulas for calculating the vortex belt frequency of turbine draft tube pressure fluctuation was analyzed. The test results indicated that in lower partial load, under certain water head the main frequency of draft tube pressure fluctuation decrease with the increase of discharge. In higher partial load the main frequency has the distribution of V type with the variation of discharge, which may have the relation with draft tube inherent frequency. In certain guide vane angle, during partial load the main frequency of draft tube pressure fluctuation had no definite relation with water head. Meanwhile, in partial load the draft tube pressure fluctuation may have direct influence to unit stability. The pressure fluctuation in draft tube was the main cause influencing the stability parameter variation.%通过三峡电厂升水位试验数据分析了混流式水轮机部分负荷下尾水管压力脉动主频的变化趋势，指出了目前两种用于计算尾水管涡带频率公式的适用性不足。试验数据表明，定水头下尾水管压力脉动主频在部分负荷低负荷段随着水轮机流量的增大有减小的趋势，在部分负荷高负荷段中呈“V”型分布，这种“V”型分布与尾水管固有频率相关；定导叶开度情况下，部分负荷下尾水管压力脉动主频与水头没有必然联系；试验同时表明，部分负荷下尾水管压力脉动对机组稳定性参数具有直接影响，是引起机组稳定性参数变化的主要原因。