Abstract
A high head gated outlet at a tunnel may cause cavitation and gate's vibration in case of subatomospheric pressures occurs at a high velocity flow entraining the air. To avoid severe subatomospheric pressures, the adequate amount of the air have to be supplied to the outlet through the air vent located downstream of the gate. In order to estimate the amount of air supply, and to make clear the characteristics of the air-entrained flows, we implemented the field measurements of air demand at Agigawa Dam and carry out the hydraulic model tests. Based on the results of these tests, we developed the simulation model for air supply estimation.
