Converging stepped spillway flow

Abstract

Wall deflection in supercritical flow induces standing waves which significantly influence the flow field close to the wall. This paper analyses the flow in the converging stepped spillway, using two scale-models with different step heights and convergence angles. Results show that the height and the width of the standing wave increase with the increase of the convergence angle. Air concentration decreases while the air-water mixture velocity and residual energy head increase in the vicinity of the converging wall and gradually attain the values for the undisturbed flow outside the standing wave. Compared to the prismatic chutes of equal upstream width, converging spillways are less efficient energy dissipators. Equations for predicting the maximum flow depth and the width-averaged residual energy are proposed.