Abstract:

 By theoretical analysis, numerical calculation and engineering example, it is proved that stage-discharge relation of downriver decrease surge-chamber ground swell, and makes little difference to other guaranteed regulations because of buffer action of surge-chamber. Boundary condition of constant water level is safe because stage-discharge relation reduces stable sectional area of tailrace surge tank, and improves governing quality. But which is unsafe in power station without tail surge tank because fluctuation of tail water directly influence pressure in the draft tube and make it worse.