An experimental study of the geometric performance of the hydrosuction dredging system

Abstract

Sedimentation in dam reservoirs causes problems such as reducing storage volume and useful life of reservoirs, reducing the volume of flood control, sluices, tunnels, and turbines clogged, and other related issues. Despite the development of several methods to solve this problem, the sedimentation rate of the world’s dam reservoirs indicates the existence of this problem. The Hydrosuction Sediment Removal System discharges sediments inside the dam reservoir using the energy caused by the difference in water level in the reservoir and the output point of the system. This study is aimed to investigate the effect of geometric properties of the hydrosuction system (effective head, suction pipe diameter, and suction pipe inlet angle) on its performance and to understand the flow characteristics and behaviors in the hydrosuction dredging operation. Quantitative comparison of the results revealed that, with the increase in the suction pipe diameter from 478 to 956, the growth of the effective head from 21 × 103 to 34 × 103, and the increase in the suction pipe inlet angle from 30o to 90o, the maximum diameter and depth of the scour hole increased by 103% and 275%, 22% and 49%, and 38% and 50%, respectively. At the beginning of the desilting process by the hydrosuction system, seepage flow through deposits removed sediment particles and, along with the scour hole dimensions development, it reduced the effect of this flow type. Irregular vortexes were observed in the final stages of the desilting process. These vortexes caused limited development in the scour hole.