Improving the Reservoir's Pressurized Flushing Efficiency by Connecting PBC Structure to the Dam Bottom Outlet

Reservoir sedimentation is always known as a serious problem for sustainable use of reservoirs and the main factor of reservoirs storage loss. One of the most common engineering techniques for preserving the reservoirs storage capacity is the periodical desilting of reservoirs by hydraulic flushing. Review of the literature shows that the pressurized flushing operation is currently accomplished with low efficiency. In this paper, the effect of PBC structure on the sediment removal efficiency during pressurized flushing operation was experimentally investigated. In this way, PBC structure with four relative length and four relative diameters were used in the reservoir. Non-cohesive sand particles with D50=0.36 mm were used as the deposited sediments in the reservoir. The results showed that by using the PBC structure with LPBC/Doutlet = 5.26andDPBC/Doutlet = 1.32, the flushing efficiency became 4.57 times more than that of reference test. By increasing the relative length of PBC structure, the maximum relative length and width of flushing cone increased, respectively, compared to the reference test while the variation of the maximum relative depth was negligible. In addition, all the geometric parameters of flushing cone hadtheir maximum values atDPBC/Doutlet = 1.32.