Experimental analysis of hydraulic jump at high froude numbers

Abstract

The hydraulic jump is a rapid transition state from supercritical to subcritical ow that occurs commonly in rivers, prismatic channels and downstream of spillways. In this study, the characteristics of the hydraulic jump in a stilling basin downstream of the spillway chute channel with the slopes of α = 12 o and 30 o were investigated experimentally for different Froude numbers of incoming ow, Fr 1 = 7, 7.5, 8, 9, 10 and 12, and relative heights of sill in the range of 4 < h s /h 1 (S) < 13 (S relative height). In the experiments, in which velocity eld measured by laser Doppler Anemometry, it was particularly focused on the effects of both different structural con guration and ow conditions on the hydraulic jump and energy dissipation ratio. Experimental measurements showed that the length of hydraulic jump and the roller zone increases with the decrease of the sill height for α = 12 o and 30 o . In addition, the length of the hydraulic jump and roller zone increased with decreasing Froude numbers. The turbulence intensity in the jump region was determined to be greater than the turbulence intensity in the region near the bottom of stilling basin. The turbulence intensity, in general, tended to decrease with decreasing Froude number.