Effects of Dam Tunnel Longitudinal Slope, Flow Rates and Gate Lip Geometry on Top Pressure Coefficient

Hydrostatics and Hydrodynamics forces are generated and applied on the vertical lift tunnel gates due to the influence of wide range of heads and operation conditions. Many hydraulic and geometrical parameters control the initiation of these forces, especially, when the flow passing over and below the gate and consequently two forces are created along the top and bottom surfaces of the gate. The difference between these two forces generates the downpull force which in turn determines the stability of the gate and its sound performance and operation. In current study the focusing is applied on the top pressure coefficient and regarding factors those affect its values and distribution. A hydraulic model was build up and the effect of three flow rates, seven lip gate geometries and four tunnel longitudinal slopes on the behavior of top pressure coefficient are examined. The results show that the top pressure coefficient is effectively affected by change of discharge, gate lip angles, and slopes of tunnel and less effect are observed with change of gate openings ratios.