Hydraulic performance of labyrinth side weirs using vanes or piles

In the present study, methods for improving the hydraulic performance of labyrinth side weirs in a rectangular channel are reported based on model experimentation. For this purpose different arrangements and configurations of groups of guide vane plates and piles in the side weir flow field were tested. Experiments were conducted on labyrinth side weirs of different lengths and sill heights fitted in the test section of a rectangular glass-walled channel. Depths of flow were measured in both longitudinal and crosswise directions at regular intervals and their profiles were studied. It was found that the discharge coefficient of the labyrinth side weirs under these conditions gave considerably higher values compared with that of classical simple labyrinth side weirs. Presented in the form of graphs and simplified equations, these new methods enable the designers to improve the hydraulic performance of a given labyrinth side weir. Useful guidance on the layout and construction of vanes and piles across the labyrinth side weir is illustrated and detailed information is given for proper design of these tools. Finally, reliable equations for the discharge coefficient of labyrinth side weirs with regard to the influential parameters of the guide vane plates and piles are presented. The derived expressions are in good agreement with the experimental results.