Effect of Gate Openings and Lip Shapes on Upstream Pressure Coefficient of Dam's Vertical Lift Tunnel Gate

The vertical lift gates of the dam tunnel are exposed to the challenges of pressures due to reservoir different high heads and flow conditions, which accordingly, may have affected its performances and safety. In the current paper, the pressure distribution on the upstream face of dam tunnel gates was estimated experimentally using an arbitrary hydraulic model. The measurements were recorded, and the upstream pressure coefficient was assessed by integrating the measured pressure distribution surface area. Several variables that could influence the values and distributions of the upstream pressure coefficient were examined. The six different gate lip inclinations were subjected to the impact of full flow condition and the upstream pressure coefficient are evaluated for different stationary gate openings. The results showed that, for small gate opening ratios (Y/Yo) up to 30 %, the upstream pressure coefficients are high and generally increased as the gate height ratios (Z/Zo) increased. In addition, the use of lip gate shape (θ=45
^o
) causes positive values of pressure coefficient, which reduces the possibility of cavitation phenomena.