Structure Optimizing And Project Augmentation For Internal Dissipation Discharge Tunnel With Swirling Flow Reconstructed From Diversion Tunnel Of Gongboxia Power Station

Large scale diversion tunnel is often adopted when building a hydraulic power station between high mountains or in canyons on a great river. However the diversion tunnel is generally discarded after used, because the construction period of hydraulic power station is pressing , the lining standard of tunnel needs being improved and the up and down steam water level is difficult to be joined. But the general used ski-jump energy dissipation scheme often causes a series of insurmountable difficulties, such as fogging, cavitations demolition, and bank scouring . In order to solve above mentioned two kind problems ,in recent years , many test researches and designing schemes have been done aimed at internal dissipater with swirling flow .Firstly in the paper the research of hydraulic characters and the optimize of structure have being carried out on the four bigger design schemes of permanent internal dissipation discharge tunnel reconstructed from the right bank's diversion tunnel of Gongboxia Power Station with a method of theoretical analysis combined with test comparisons. On this basis , two form swirling flow internal dissipation schemes, vertical and horizontal axis are recommended to the construction unit of the station as the schemes to be selected next. Secondly, according to the experts' opinions of General Institute of Hydraulic and Water Power Design and the ideas presented by the construction unit and the design branches , author of the paper accomplished the research of hydraulic characters and the optimize of structure on the submerged flow scheme and free flow scheme of horizontal swirling flow dissipation, and brought forward the recommend scheme of these two flow patterns respectively . Finally , author analyzed and compared these two schemes on the aspects of technology and economy according to the wholly structure optimizing process and outcome, and recommended the final scheme of the right bank's diversion tunnel of Gongboxia Power Station reconstructed into a horizontal swirling flow internal dissipater tunnel.The horizontal swirling flow internal dissipater tunnel being built in Gongboxia Power Station will be the first one reconstructed from a diversion tunnel whose dischargereaches to 1000m Vs and water head is more than 100m in china . Its scheme's argumentation ,test research and future apply will have important meanings to the design .research and engineering application of internal dissipation discharge tunnel with swirling flow, will powerfully promote engineering application of this new kind of dissipation mode , which may solve some high velocity problems in high dam construction and provide a engineering example for technological and economical augmentation in a diversion tunnel reconstruction. It is of theoretical and practical importance to promote hydraulic structure researches and development.