Study On The Influence Of Different Drop Bucket Size On The Gas Content Reduction

The high mountain canyon area in China has a large number of distribution, its special topography, which determines the uniqueness of the layout of the water conservancy and hydropower engineering project. Due to the transmission, flood discharge structure of the gap between the lower reaches, outlet flow with the flow velocity, resulting in pressure can be reduced, even the negative pressure, the easy to cause the building cavitation damage.Flow surface cavitation destroy not only the discharge structure of exports, will lead to serious damage to the main project etc.. It has been studied that the effective way to prevent the generation of holes by using the air flow in the low pressure area.The for spillway tunnel flow of brake possible cavitation phenomenon, through physical model test study on test 0×0mm, 4×4mm, 8×8mm, 12×12 mm, 16×16 mm and different drop sill section size under the condition of pressure and velocity distribution.Results show that with step-down size from 0×0mm by gradually increase to 12×12mm,the measuring point hole number increases gradually; fell ridge dimensions continue to increase to 16×16 mm, changes in pressure and velocity is not obvious, the changes in the number of holes tends to be stable, the volume is becoming saturated. Therefore, under the condition of model test, the reduction effect of the mixed gas is obvious when the size of the section of the falling sill is 12×12mm or 16×16mm.In this paper, the numerical simulation of the flow of the gate is carried out, and the pressure and flow velocity distribution of the model dimension drop sill is 0×0mm,12×12mm, 16×16mm are calculated. According to the results of numerical simulation, the in falling sill size to 0×0mm, most notably in slope break period of negative pressure, and falling sill size in for 12×12 mm, 16×16 mm, in three sections at the negative pressure has been increased. The flow rate is reduced, but fell ridge dimensions for 12×12 mm, 16×16mm, pressure and flow rate had no obvious changes. The results of numerical simulation are consistent with the experimental results of the physical model. On this basis, the results will be used for a reservoir of Hongdong project, the size of the bucket is 400×400mm to500×500mm, can effectively reduce the number of holes in the water flow, and reduce the possibility of cavitation damage.