Experimental Study of Turbulent Fluctuations in Hydraulic Jumps

Abstract

In an open channel, the transformation from a supercritical flow into a subcritical flow is a rapidly varied flow with large turbulent fluctuations, intense air entrainment, and substantial energy dissipation called a hydraulic jump. New experiments were conducted to quantify its fluctuating characteristics in terms of free-surface and two-phase flow properties for a wide range of Froude numbers (3.8<F1<8.5) at relatively large Reynolds numbers (2.1×104<R<1.6×105). The time-averaged free-surface profile presented a self-similar profile. The longitudinal movements of the jump were observed, showing both fast and very slow fluctuations for all Froude numbers. The air–water flow measurements quantified the intense aeration of the roller. Overall the present findings demonstrated the strong interactions between the jump roller turbulence and free-surface fluctuations.