Performance of Baffle Blocks in Submerged Hydraulic Jumps

Abstract

An experimental study was conducted investigating submerged hydraulic jumps with baffle blocks. An extensive series of tests were completed that covered a range of Froude numbers, submergence factors, and block arrangements. Dimensional analysis was used to interpret the results and study the effect of each parameter. Two flow regimes, the deflected surface jet (DSJ) and reattaching wall jet (RWJ), were observed. The occurrence of a particular regime depends on the block shape and location as well as the Froude number and submergence factor. The DSJ regime was found to dissipate more energy due to the formation of the deflected jet and its impingement on the water surface. The DSJ regime is almost as efficient in dissipating energy as the free hydraulic jump. This flow regime also had a smaller reverse flow region compared to the RWJ regime. Empirical equations were derived for predicting the critical values of the submergence factor at which each flow regime forms. The efficiency of the submerged hydraulic jump with blocks in dissipating energy was compared with that of free without blocks as a function of submergence factor.