Research On Joint Energy Dissipation Of Differential Lip Bucket And Flaring Pier

Because of the large river fall, narrow riverbed and poor bedrock of downstream,centripetal effects of flood discharge usually occurred in many hydropower stations whichbuilt between two mountains, so that the anti-erosion capability of downstream river bed isseverely threatened. At the same time, both sides of the mountain are scoured severely byreflux which is formed by water tongue launched into water. Which kind of energy dissipationshould be taken to solve such problems effectively has been a subject of concern toresearchers.Numerous studies had found that in the ski-jump energy dissipation, the flaring piercould change the direction of the water tongue, so as to solve the erosion problem caused byconcentrated falling in to water; heterotypic differential lip bucket could make water interface staggered up and down while leaving bucke, increase the contact area of water interface andair, enhance turbulence, aeration and diffusion, improve the effect of energy dissipation, andreduce the erosion depth. However, less research on combination of these two kinds of energydissipation had been done. Based on the model test of Shilong Hydropower Project, researchhydraulic characteristics of WES weir using joint energy dissipation of differential lip bucketand flaring pier were carried out.In view of the back flow problem at left and right side of the mountain, down-stream ofthe flip bucket in original scheme, caused by the jet angle of flip bucket was smaller, and theogee section was shorter, which couldn’t make flow deflect fully to downstream, instead,being pushed downstream, through increasing the angle and the ogee section, setting upflaring pier and heterotypic differential lip bucket to adjust water tongue, flow in modifiedscheme could be deflected fully to the air, dissipated as much as possible and dispersedly fallinto the water, thereby the downstream flow velocity and the erosion on both sides of themountain could be reduced. The results showed that:（1）Setting the heterotypic differential lip bucket for spillway can make water tongue ofoutflow spread evenly along the arc layer by layer and cover the downstream river. It can alsoextend the range of outflow into the water. Based on this，it can not only resolve thecentripetal problem，but also reduce the discharge per unit width. At the same time，it can alsomake the slope from the bottom of scour pit to the bottom of differential lip bucket meet the regulatory requirements.（2）In order to prevent the mountain from the reflux caused by lateral diffusion of thedivergence of the right water tongue, flaring pier was set on the sidewall located at the rightside of the flip bucket to reduce the divergence angle of water tongue, thereby the scope andintensity of reflux were reduced, so was the scour of the right bank.（3）Because of the narrow riverbed of downstream and the mountain of right side closeto the flip bucket, the scope and intensity of the splash were wide when releasing flood waters,and there are still some scouring on the right side of the mountain. Therefore, adequateprotection of the deeper local scour on the right side of the mountain should be taken, in orderto reduce the scour and eliminate security risks.