Comparative Analysis Study Of Gongboxia Level Gyrating Flow Spillway Tunnel Prototype Observation And Inversion Model Experiment Hydraulic Characteristics

The right bank of Gongboxia Hydropower station is the first horizontal swirl spillway hole which is converted by diversion hole, the capacity of vent flow reach to 1000m3/s and water head exceed 100m. The successful application of it provide typical engineering examples to solve high-speed flow problems in the dam construction process and technical and economic issues of diversion tunnel reconstruction.Although many scholars has done a great deal of research on horizontal swirl spillway hole at home and abroad,and Gongboxia level gyrating flow spillway tunnel has passed prototype observation experiment,but considering the promotion application of spillway energy dissipation tunnel in the future,combined with the National Natural Science Foundation Fund and inversion model experiment task of Gongboxia level gyrating flow spillway tunnel, this article revealed Hydraulic characteristics of level gyrating flow spillway tunnel and variation law,and discussed model scale effect.Water level about 2002.00m is turning point from weir flow to submerged flow,overflow discharge of prototype and model is consistent.Pressure variation law of Prototype and model measuring point in import Section and starting rotation device is identical; Affected by differences gas negative values of Swirl hole circulation cavity, prototype and model shaft section ring cavity length is different,so the different of corresponding measuring point pressure variation law in shaft section is great; Dominant frequency of each measuring point Belongs to low-frequency.Circular vent ventilation Volume related to overflow discharge,model scale,jet impact velocity,ring cavity length and so on,and fitting formula with regard to ventilation volume and relative cavity length; Ventilation of starting rotation device ventilation pipe is from Axial flow of swirl hole inner surface takes air leads to vacuum cavity,model existence of scale effect.Water flow aeration effects in shaft section and Swirl hole is good;The more circular vent ventilation Volume,the more section near shaft section ring cavity, the more aeration Volume in shaft near wall,and fitting formula with regard to aeration concentration and elevation changes along the way; The more circulation cavity close to the wall of level of swirl inside the cave,the thinner aquifer, the more aeration Volume.Central district's flow velocity is greater than near wall's in the cross-section shaft; tangential velocity is decreasing along the way in swirl hole,and radial distribution curve gradual smooth, axial velocity is increasing along the way,and has some retention; Spillway export sectional mean velocity of prototype and model is consistent,the value about 14.5m/s.Dissipation effects of level rotary internal enerage dissipation discharage tunnel is good, the calculation energy dissipation rate to spillway export about 84.5%.Cavity center around swirl-hole center counterclockwise rotating,the knee in curve along the way is the location where energy and momentum changed and velocity of flow rapid adjusted;Cavity flow velocity angle along the way show reduce tendency, the value range from 20°to 90°.Gongboxia level gyrating flow spillway tunnel prototype observation water level range is smaller and relatively homogeneous,thus model scale effect about water aeration and ventilation etc. is worth to do further research in the future.