STUDY OF THE BEHAVIOUR OF HYDRAULICS JUMP OVER ROUGH HORIZONTAL BED USING DIFFERENT SIZES OF WOODEN BLOCKS

Abstract

ABSTRACT A hydraulic jump is a phenomenon of hydraulics which is frequently observed in open channel flow such as rivers and spillways. The hydraulic jump depends on the initial fluid speed. If the initial speed of the fluid is below the critical speed, then no jump is possible. This project discusses about the behaviour of hydraulic jump on rough horizontal bed and its implementation in field. In the previous studies various types of roughness were used. For the present study to create roughness on bed by using, different sizes of wooden blocks with different spacing between them are used and seen its effect on hydraulic jump properties such as sequent depth ratio, roller length & the loss of energy etc. For this a large no. of experimental series were carried out with different cases. It was found that the rough bed dissipates more energy with a decrease in length of jump as compared to a smooth bed. To see the effect of roughness some relationships were also plotted. It was also found that sequent depth ratio is function of Froude no. Here with an increase in discharge the sequent depth ratio decreases. By plotted another relation between Froude No. and sequent depth, it was found that with increase in Froude No., the sequent depth ratio also increases rapidly. The ratio of spacing and height should be in proportionate manner; otherwise it will not serve as a rough bed. Because the increased height of roughness works as an obstruction not as a roughness. If the ratio of height decreases with their spacing, then it works as a smooth bed not rough bed. For this study some empirical equations & results were used which are helpful in estimation of Froude no. and other properties of hydraulic jump.