Geometry Modification of Stilling Basin USBR VI with Numerical Simulation

Stilling Basin USBR VI is one of the most commonly impact type energy dissipaters. Also this basin is one of the oldest basins that designed for dissipating of outlet flow from the pipes. This basin is a small box-like structure with a hanging wall and an endsill. Hanging wall is to distribute energy of incoming flow to basin width. This basin requires no tailwater for successful performance. Numerical model validation was performed with comparison of recorded pressure on hanging wall and flow depth on endsill in physical model and with comparison of incoming pipe velocity profile with nikuradse physical result in 1932. For basin outlet flow field modification, 4 parameters of mean velocity on endsill, mean velocity in vicinity of endsill, coriolis coefficient and discharge distribution on endsill was selected. These parameters were calculated for more than 100 different models. Finally, with comparison of results of parameters in different models, it is found that gradual variation of width of stilling basin has had the best results after vertical wall for the modification of stilling basin and uniform distributing of flow rate in width direction