摘要
针对抽水蓄能机组在发电调相转发电工况易引发不稳定现象,对水泵水轮机该工况转换时的排气增压过程进行研究。基于SST k-ω及VOF模型对原型水泵水轮机进行非定常多相流模拟计算,揭示了排气增压过程中机组内气液两相的动态分布,分析了机组有功功率、排气速率和无叶区压力的瞬态变化规律,以及水泵水轮机内部流场演变与外特性的关联特性。研究表明:在排气过程中,机组吸收电网的有功功率与排气速率在初期快速减小后缓慢降低,无叶区压力脉动频率较大且增压效果明显;无叶区因尾水的流入渐渐形成高速水环,气液运动混乱,气体易逆流进入尾水管,是影响机组稳定性的主要因素。研究结果可为保障抽蓄机组调相工况切换时的安全稳定提供一定参考。
The exhaust air pressurization process of a pump-turbine during the shift from this condition is explored to address the issue of instability that is easy to generate in pumped storage units during phase transition from power generation to power generation.Unsteady multiphase flows in a prototype pump-turbine are simulated using the SST k-ωmodel and VOF model.The simulations demonstrate the transient variation trends in the unit's active power,exhaust rate,vaneless zone pressure,and the relationship of the evolution of internal flows in the pump-turbine versus its external characteristics.They also reveal the dynamic distribution of air and liquid phases in the unit in exhaust pressurization process.The study demonstrates that in this process,the unit's active power absorption from the grid and the exhaust rate decreases gradually after their initial rapid decreases,its pressurization effect is evident,and its pressure pulsation frequencies in the vaneless zone are higher.In the vaneless zone,a high-speed water ring forms gradually driven by the inflow coming from tail water,so that air-liquid movements are chaotic and the air is prone to flowing backward into the draft tube,which has a significant impact on the unit's stability.The findings in this study are useful for improving the stability and safety of pumped storage units.
作者
曹中成
周大庆
于安
CAO Zhongcheng;ZHOU Daqing;YU An(School of Electrical and Power Engineering,Hohai University,Nanjing 211100,China)
出处
《水力发电学报》
CSCD
北大核心
2024年第12期98-106,共9页
Journal of Hydroelectric Engineering
基金
国家自然科学基金(51979086,51839008)。
关键词
水泵水轮机
调相工况切换
瞬态气液流动
两相流
流场演变
pump-turbine
switching of condenser mode
transient gas-liquid flow
two-phase flow
flow field evolution
