Energy-Dissipating Bypass for Hydroelectric Powerhouse

A hydraulic energy-dissipating bypass system for continuous flow operation in a hydroelectric power plant is described. Difficulties with cavitation, flow separation, vibration, and mechanical failures are encountered in many existing bypass systems. These difficulties increase with the pressure head. This paper describes the design principles and features of a high-head bypass system that successfully eliminates these difficulties and discharges a steady, uniform, low velocity flow at its outlet. The bypass system consists of a needle valve, an air entrainment system or energy-absorber cone, and an energy-absorbing stilling chamber with attached outlet duct. Modifications to the system are described including the installation of baffle blocks in the outlet duct. Full-scale tests verifying system performance by pressure and flow velocity measurements are described.