某厂顶溢流式电站拦污栅破坏原因分析

某厂顶溢流式电站在遭遇20 a一遇的洪水后,灯泡贯流式机组进水口设置的拦污栅发生了脱槽破坏。为了探寻拦污栅破坏原因,利用数值模拟的方法,对电站引水渠内的纵向水流流态进行了模拟,根据模拟结果分析了拦污栅的受力情况。结果表明:在电站厂顶过流时,电站前池存在强大的横轴漩涡及负压,受纵向水流长时间冲击以及水流脉动的影响,拦污栅强度丧失,发生变形,最终脱槽破坏。希望设计人员在设计同类型电站拦污栅时,考虑纵向水流的冲击力,避免同类事件发生。

Causes of Damage of the Trash Rack of a Hydropower Station with Roof Overflow

The trash rack at the inlet of generating unit of a powerhouse with roof overflow is destroyed off the gate slot suffering from a 20-year event flood. To find out the causes of damage, we simulated the longitudinal flow pattern in the water diversion canal, and analyzed the forces on trash rack according to simulation result. Results suggest that strong transverse vortex and negative pressure in the fore-bay were induced by roof overflow. Affected by long-time longitudinal flow impact and flow pulsation, the trash rack gradually lost strength and experienced deformation, and was ultimately destroyed off the gate slot. We suggest that the impact of longitudinal flow should be considered in the design of trash rack of the same type power station to avoid similar accidents.