Study On Numerical Simulation Of Free-surface-pressurized Flow In The Tailwater Tunnel Of Hydropower Station

In company with socio-economic development and advances in science and technology, the demand to electrical energy and water is on the increase. And the number of hydropower stations gets more and more in the worldwide. Due to terrain, geology, disposal or some else causes or for utilize existent tunnel, a great many power stations have long tailwater tunnels. It became more important to realize hydropower stations tailwater tunnel interior waterpower transition process. The article apply numerical simulation means to simulate and calculate hydropower stations tailwater tunnel interior waterpower transition process well and truly.In the numerical simulation, the finite difference scheme broke into the explicit method and implicit method at present. hereinto the implicit method was unconditionally stable in complicated Free-surface-pressurized flow calculation. Moreover characteristic implicit method fit better. The article take a constant water level large reservoir as example, and simulate and calculate tunnel inside leakage flow's free-surface-pressurized flow as strobe unlock. Give a detail introduce on construction of preissmann quatre implicit schemes and implicit schemes's mathematical model, while compare and analyses the result. It has been proven that characteristic implicit schemes are better in astringency, precision and stability.Mounting tail water surge-chamber and tailwater tunnel with sloping ceiling is the common tail water disposal version on hydropower stations. The article apply characteristic implicit schemes to simulate hydropower stations tail water free-surface-pressurized flow transition process. Both boundary treatment and computational process are introduced concretely. Moreover it calculate the gradient of tailwater tunnel with sloping ceiling by numerical calculation, and prove that choosing the gradient doesn't only consider the size of pressure amplitude, but also the quantities of project Tailwater tunnel with sloping ceiling is a sort of new-fashioned Hydropower stations tailwater tunnel somatotype. It can replace the tail water surge-chamber under given conditions, and it suitable for level of tail water amplitude large and tailrace system length between 150m and 600m, especially.