Experimental Study of the Hydraulic Jump Compactness in an Open Trapezoidal Channel

Abstract

In stilling basins there is a change in flow regime from supercritical to subcritical flow; this transition is called a hydraulic jump. To control and stabilize the position of the jump, it is necessary to place a sill across the flow. A bibliographical analysis showed that when the controlled hydraulic jump is entirely formed upstream of the stilling basin, the sill has no effect on the configuration of the jump. However, when the jump length stretches beyond the sill position, this results in jump compactness and leads to several configurations of the latter, until it completely disappears. The main objective of this study is to determine the effect of the hydraulic jump compactness on the main jump features in a trapezoidal horizontal channel. Dimensionless empirical relationships depending on the jump compactness are obtained. Through this study, we aim to show the advantages of the jump compactness on the channel dimension. Indeed, the hydraulic jump is led to its most reduced form, before disappearing, in terms of tail water depth and jump length. Thus, the obtained results are useful for dimensioning the stilling basin.