Numerical Investigation of the Flow Characteristics in the vicinity of Pressure Conduit’s Gates

Bottom outlet is one of the related hydraulic structures of dams used to control initial water volume in reservoir and to help the spillways discharge capacity in floodwaters. Designed elements of bottom outlet such as control gates must be able to properly act to regulate downstream flow in entirely closed and semi-open situation. Bottom outlets which work with high heads, may create intense change in velocity and pressure field near the control systems (gates) by high velocity that probably causes cavitation phenomenon and unusual vibration on the structure’s wall and conduit to happen. In the present research, characteristics of the flow, such as momentary and average flow s pressure and velocity near the service gate, cavitation index and gate vibration frequency in reservoir normal head (100 m) at various service gate openings were extracted and analyzed using numerical model of Seymareh dam’s bottom outlet with FLOW 3D software and RNG(K-ε) turbulence model. The results of this research will help to appropriately understand the hydraulic phenomena occurred around outlet gates.