ENERGY DISSIPATION LOSSES IN DIFFERENT GEOMETRIES OF STEPPED SPILLWAY

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Department of Engineering

ABSTRACT
This research study the rate of energy dissipation losses taking place in various types of stepped spillway geometries (end sill at all steps, inclined at all steps, inclined between two steps, end sill between two steps, combination of inclined and end sill on the stepped spillway starting with end sill and combination of inclined and end sill on the stepped spillway starting with inclined ). The models were made from wooden materials each having a chute angle of 45, model height of 24cm, step height 4cm and number of steps 6. Variable flow discharges were applied on each model geometry and the hydraulic parameters were measure and energy dissipation rates were calculated and compared. The result shows that the effect of steps geometry on energy dissipation on stepped chute is significant as the ratio of energy losses to the upstream energy varies from 49% to 70%. The result also indicated that the energy dissipation rate on model C (inclined between two steps) is highest among all the test models. Equations were developed for predicting energy dissipated over the spillway and for calculating the flow rate in stepped chute. Results of the modelled equation were compared with that of experimental studied. The percentage difference between between the values predicted by the modelled equation and that of actual experimental values range 1.10% to 5.12%. this shows that there is a good agreement between the predicted values and experimental values.