Discharge coefficient and energy dissipation on stepped weir

Abstract

High volumes of kinetic energy are generated as water is transported to the dam downstream. Stepped weir are some of the best in lowering the kinetic energy of a flow traveling downstream. In stepped weirs, the steps’ design can impact how much of the flow’s kinetic energy is transferred downstream. Because these weirs could dissipate more power, recently, pooled designs have been more common than smooth ones. Therefore, this work investigated the impact of sills at the ends-edge of the steps and discharge values on flow patterns, particularly energy dissipation. Seventy-five experiments were conducted and five models were used with a slope angle of 35° with different step dimensions, different numbers of steps (14, 10, 7, 5, and 3), and other discharges. Three-step configurations were used: flat, fully pooled, and zigzag pooled steps. The results indicated that increasing the number of steps increased the energy dissipation rate. In addition, an increase in the discharge leads to an increase in the discharge coefficient and thus decreases the energy dissipation rate. A coefficient of determination R2{R}^{2} gives a good agreement for the discharge coefficient (0.73).

Keywords

• stepped weir
• energy dissipation
• discharge coefficient
• end-sill