突扩跌坎掺气设施深化研究

Further Study on Aerators with Sudden Lateral Enlargement and Bottom Drop

高速水流下的空化空蚀和高水头下的闸门止水问题是高水头泄水建筑物运行所遇到的2大问题。为深入研究突扩跌坎掺气设施,进一步了解其水力特性和空化特性,以某水利枢纽孔板泄洪洞中闸室通气系统和突扩跌坎掺气设施为具体研究对象,通过建立比尺1∶20的局部水工模型,分析研究了通气孔风速、流态、压力、掺气浓度等水力特征参数,并将试验结果与原型观测结果进行了对比。结果表明:该工程布置的掺气效果良好,试验所得通气管内风速随闸门开度变化的趋势、水流掺气浓度、压力及其脉动在数值上与原型观测结果均一致,说明工程原型观测与模型试验对比验证是成功的。理论研究和实际运用均表明,结合闸门止水和掺气减蚀要求的突扩跌坎布置,是符合实际需求且安全可行的,同时也是解决高水头条件下闸门止水和掺气减蚀的有效措施,具有广泛的推广应用价值。

Cavitation and cavitation erosion under high flow velocity and gate seal under high water head are two problems that high-head outlet structure is facing with in operation. To further understand the hydraulic and cavita- tion characteristics of aerators with sudden lateral enlargement and bottom drop, we took a hydraulic project＇ s flood discharge tunnel with orifices as research object and through a local hydraulic model with scale of 1：20, we ana- lyzed the physical hydraulic parameters （wind velocity of ventilation hole, flow pattern, pressure, air concentra- tion） of the middle lock chamber＇ s ventilation system and the aerator with sudden lateral enlargement and bottom drop. Furthermore we compared the test results with＇prototype observation results. Results showed that this project had good aeration effect. The test values of wind speed change with gate opening in ventilation pipe, flow aeration concentration, pressure and its fluctuation were consistent with prototype result. Prototype observation and practical operation both validate that the sudden enlargement layout meets practical demand, so it is safe and feasible. It is also an effective measure to solve gate seal and air entrainment to alleviate cavitation under high water head.