Research On 3D Numerical Simulation Of Hydraulic Characteristics Of High-speed Flood Discharge Flow

Flood discharge flow is often a category of high-speed flow. Because of its high velocity, large discharge amount, high energy dissipation and concentrated energy, flood discharge structures are often damaged. Many domestic and foreign scholars carry out extensive research on high-speed flood discharge tunnels(FDTs). This paper, based on predecessors' achievements, conducts a 3D numerical simulation of hydraulic characteristics of FDT in a key water-control project in Xinjiang using FLUENT software and carries out an optimized simulation research on the shape of its aeration facility.To obtain hydraulic characteristics of high-speed flood discharge flow, this paper adopts a two-phase model of water and gas based on VOF method and carry out a 3D numerical calculation of hydraulic characteristics in FDTs in the original scheme, using a SIMPLE algorithm combining standard k-? turbulent model, finite volume method and staggered mesh. The results of numerical simulation of flow regime,water surface profile, top clearance and flow velocity are compared with the measured values of physical modeling experiment. They fit well, suggesting that the mathematical model and empirical parameters adopted in this paper are basically correct. Simulation results show that both sectional dimension and top elevation of the original scheme meet requirements of flood discharge. But the aeration cavity of the aeration tank in the original scheme is relatively small and the shape of cavity is poor. It cannot achieve the purpose of aeration and corrosion reduction. So a numerical simulation of two working conditions, a total of five schemes before and after the aeration facility is set up is carried out. Part of hydraulic characteristics and aeration effect at the aeration tank is analyzed and compared in detail. A recommended shape of aeration facility is finally obtained. Under designed and verified working conditions of FDTs in the recommended scheme, wall heights of the structure are up to design requirements. Water flow at the aeration tank is smooth, without tumble or other bad flow regimes. Mixed gases form a complete cavity in the downstream of the bucket fa?ade, suggesting that this scheme can aerate effectively. Finally, this paper calculates cavitation amount of the recommended scheme and finds that the drain slot section is easily damaged by cavitation. We need to take requisite measures to prevent damages of cavitation.