EXPERIMENTAL INVESTIGATION OF HYDRAULIC JUMP CHARACTERISTICS IN CONTRACTIONS AND EXPANSIONS

Hydraulic jump is one of the most important phenomena in a rapid changing flow. It occurs when flow change from supercritical into subcritical and there is an increase in the depth over a small distance. In the present study, the characteristics of hydraulic jumps in contractions and expansions with curved walls were investigated for five Froude numbers in the range 5.8<Fr1<9.1. The values of the depths and instantaneous velocities were measured at different locations in the hydraulic jumps throughout the transition. The results of the study indicated that energy dissipation in the contraction compared with the expansion decreased on average by 8.74%. On the other hand, the values of the second depth and the jump length increased by 1.8 and 2.5 cm in average. Also, the findings of the study revealed that as the longitudinal distance from the beginning of jump increased, the maximum amount of Reynolds intensions increased in the contraction and decreased in the expansion.