New Stilling Basins Designs for Deep Rectangular Outlets

The experimental study reported here is intended to evolve new designs of stilling basins for deep and narrow openings used as outlets. Several appurtenances such as grid, Impact wall, stepped wall, weir wall, sloping end sill and wedge shaped blocks are used to study their influence on the hydraulic performance of the stilling basins with an aim to propose efficient stilling basin models. All the models were tested at inflow Froude number Fr = 4.89 keeping a constant run time and same erodible bed material for each stilling basin model for comparison of the performance. The performance of each model was evaluated by observing the maximum depth of scour and its location after the end sill. A non-dimensional number named as Scour Index has been evolved for comparing the performance of the different stilling basin models. The use of wedge shaped blocks as a splitter block and baffle blocks reduced the depth of scour indicating a significant dissipation of energy and good flow conditions, downstream of the stilling basin.