Experimental Investigation of Energy Dissipation and Hydraulic Jump Length in Rough bed Condition With Cubic Blocks Downstream Sluice gate

Energy dissipation structures are device to control of hydraulic jump, in addition to dissipation of water energy. In this research, experimental investigation the effect of cubic roughness was done with staggered and strip arrangements in different angles and rows on jump length and energy dissipation. For this purpose, in laboratory model used from flume with length of 12, width of 0.5 and height 0.7 meters and rough beds placed in downstream of sharp sluice gate. Experiments was performed for Froude number between 4.5 to 9. The results showed staggered arrangement produced better performance compare to strip arrangement in terms of decreasing relative length, moreover, value showed 49 percent, so that percent of decreasing hydraulic jump length for tested rough beds in compare with smooth bed calculated in range of 46 to 54 percent for staggered arrangement and 37 to 46 percent in strip arrangement. Jump relative length (Lj/ y*2) increases for staggered arrangement with increasing Froude number and for strip arrangement the variation of Lj/ y*2 in high Froude number are independent of Froude numbers. The percent of increasing hydraulic jump energy dissipation rate was in range of 19 to 31 for staggered arrangement and 20 to 34 percent in strip arrangement.