Effect Of Channel Width on Energy Dissipation Efficiency of Stepped Spillway

Abstract:

Experimental investigation on flat stepped spillway were conducted with two different width 0.52m and 0.28m on 26.67⁰ slope under nappe flow regimes. The study assessed the rate of energy dissipation at the toe of the spillway for unit discharge, q, ranging from 0.00954m²/s to 0.078854 m²/s for Froude number (F_r) between 0.5 to 0.85. The stepped chute comprised 10 identical steps having 0.10-m step heights and 0.2-m length. It is observed that the rate of energy dissipation at the step edge was relatively observed to be higher in the wider channel. The energy dissipation rate decreased from 3.81% to 26.135% by decreasing the channel width by 46.15% under same unit discharges. It signifies that the width of channel has certain influence on energy dissipation efficiency of spillway under same slope. Therefore, wider channel should be taken for design of stepped spillway under nappe flow regime. The variation in energy dissipation is due to the variation in mean air concentration between two widths. For further validation of these experimental observations, computational fluid dynamics (CFD) models were also used with k-ɛ turbulence model and0.010 m mesh size. 

Keywords: stepped spillway, energy dissipation, channel width, CFD