抽水蓄能电站泵工况断电飞逸过渡过程三维耦合数值研究

3-D combined simulation of power-off runaway transient process of pumped storage power station under pump condition

该文建立了某抽水蓄能电站包括引水系统、调压井、水泵水轮机组与尾水系统等部件的全过流系统几何模型。采用联合VOF两相流模型和单相流模型的三维耦合湍流计算方法对其泵工况断电飞逸过渡过程进行了数值研究,获得并分析了若干参数随时间的变化规律和不同时刻流场的演变过程,与电站原型试验资料进行了对比。结果表明:历程线模拟结果与试验结果吻合良好,基于耦合算法的三维湍流过渡过程研究方法具有较高精度。电站内外特性变化剧烈,相互影响,依次经历水泵、制动、水轮机和飞逸工况。转轮内大量的涡流在尾水管形成了强烈的顺时针螺旋形涡带,是飞逸工况机组低频压力脉动的主要原因。

Power-off runaway transient characteristics of pumped storage power station at pump mode were studied by three dimensional unsteady numerical method combined with normal single-phase model and VOF model, and simulations were executed on geometrical model of the whole flow system including diversion tunnel, surge tank, pump turbine unit, tailrace tunnel and reservoirs. Through numerical calculation, the changeable flow configuration and variation law of some parameters were obtained and compared with experimental date. Numerical results show that the simulation results agree well with that of test, which proves the combined three dimensional unsteady numerical methods performs well. The unit will undergo pump condition, braking condition, turbine condition and runaway condition with external characteristic varying significantly during power-off runaway transient process. Internal flow configuration is closely related to external characteristic and affects each other. There are lots of vortexes inside runner at runaway condition, which cause violent clockwise spiral vortex rope in draft tube. That is the key factor of low frequency pressure fluctuation of PSP station at runaway condition.