小湾水电站大型导流洞改建泄洪洞研究

针对小湾水电站高水头、大流量的泄洪特点，通过大量的优化试验研究，将旋流竖井式泄洪洞技术应用于小湾水电站导流改建工程，并提出适合工程特点的体形布置形式，解决了下游高水位淹没泄洪洞出口的技术难题。研究表明，这种旋流竖井式泄洪的消能效率可达90％左右，涡室与竖井的水流流态比较平顺，压力分布分理，导流洞内水流速度低于20m/s，不失为高水头、大流量条件下导流洞改建为泄洪洞的有效方式之一。

Study on the rebuild of large-sized diversion tunnel into flood-releasing tunnel in the Xiaowan Hydropower Station

According to the characteristics of the releasing flood with high head and large discharge in the Xiaowan Hydropower Station and on the basis of optimal tests and studies, the authors apply the rotation flow vertical shaft flood releasing tunnel technology to the reconstruction of diversion tunnel of Xiaowan Hydropower Station. They also put forward a configuration layout that is suitable to the characteristics of Xiaowan Hydropower Project. Therefore the technical problem that the outlet of flood releasing tunnel is submerged by the high downstream water level has been solved. The study shows that the energy dissipation rate of such rotation flow vertical shaft flood releasing tunnel could reach up to 90% and the flow pattern and pressure distribution between the spiral housing and the vertical shaft is comparatively smooth. The flow velocity in the diversion tunnel is less than 20 m/s. Therefore it is one of effective ways to change diversion tunnel into flood releasing tunnel under the conditions of high water head and large discharge.