抽蓄电站全过流系统水泵工况停机过渡过程CFD模拟

通过建立某抽蓄电站全过流系统的几何模型,将VOF两相流与单相流流动模型相结合,采用三维非定常流动过渡过程研究方法对泵工况停机过渡过程进行数值计算,获得了机组转速、流量、转轮力矩,以及若干测点压力脉动等参数随时间的变化过程和不同时刻的流场演变规律,并将结果与电站原型试验资料进行了对比.结果表明:机组转速变化规律、蜗壳和尾水管进口压强极值与试验结果基本吻合;抽蓄电站泵工况停机过程中,蜗壳进口和尾水管进口压强变化明显受活动导叶关闭规律的影响,而转轮与活动导叶之间的压强主要受机组转速的影响;随着活动导叶的关闭,当流量小到一定值后,水流主要通过尾水管内侧流向上游,而外侧水流会与转轮同向旋转;导叶全关后,尾水管内的旋涡是导致其能量损耗的主要因素.

CFD simulation of shutdown transient process of pumped storage power station under pump conditions

Three-dimensional unsteady numerical simulations, combined with the normal single-phase model and the VOF model, were executed on the geometrical model of the whole flow system of a pumped storage power station. Through numerical calculation, the changeable flow configuration and variation law of some parameters, such as unit rotating speed, flux, runner moment and pressure of measurement points were obtained and compared with experimental data. Results show that the extreme value of unit rotating speed and measurement points pressure agree fairly well with experimental data. In the shutdown transient process, pressure variation at spiral casing inlet and draft tube inlet is influe-nced by the closure law of guide vanes, while that between runner and guide vanes is mainly affected by runner rotation. As guide vanes close and flux decreases, water flows upstream through the inner side of the draft tube and rotates with the runner. After guide vanes close completely, vortex inside the draft tube is the key factor of its hydraulic energy loss.