Replacing open channel with pipe channel and flap gate to avoid foam formation at outfall of Angamos Power Plant, Chile

摘要

Pipe flow is designed to avoid sea foam formation at a power plant outfall at Angamos,Chile, instead of present open channel.A flap gate is designed at the end of the pipe to control variable high pressure caused by large head difference between sea level and ground level of the power plant constructed by POSCO in 2003.Present open channel is 14 m long over sloped ground from the plant.The foam is formed by air entrainment from free surface with high disturbance.Flap gate counter-weight is a function of the flap gate gap, and should be well chosen to have adequate opening water head, and allow both normal and emergency-operational flow fluxes.Natural oscillation frequency of the flap gate due to interaction with water pressure and frequency of fluid eddy shedding should not amplify unexpected motion.Laboratory experiments were carried out to find out optimal shape and weight of flap gate for this pipe flow.Long pipeline was represented as a vertical column considering experimental space.Selected counter-weight shows reasonable gap under high pressures, and no unwanted vibration was observed.