Sediment Control At The Lateral Channel Inlet

Environmental and civil engineering projects frequently employ the open channel side intake structure. However, the commonest among the issues faced in most of the lateral intakes include sedimentation and sediment delivery. This involves several problems namely, decreased flow discharge capacity in the irrigation canals and the threat of water blockage during times of low water flow. Besides, this problem with the sediment either lowers the performance levels or causes failure of the facilities that this sub-channel serves. Hence, the engineers focused on designing an intake with the features of high flow discharge and low sediment delivery. This paper attempts to review and summarize the literature relevant to the branching channel flow and submerged vane technique to minimize the sediment-related issues. The present review highlights that most of the earlier research work done dealt with the characteristics of the flow in a right-angle branch channel possessing rigid confines. Also, more investigations are required regarding the implications of the submerged vanes. Besides, no comprehensive studies are available on the saddle point itself, and a high percentage of the studies have been part of earlier investigations that had focused on only briefly outlining this subject.

Experimental Investigation of 900 Intake Flow Patterns with and without Submerged Vanes under Sediment Feeding Conditions

In this study, two experiments were conducted in a 90⁰ water intake to study 3D flow patterns and sediment distribution using submerged vanes under sediment feeding and live-bed conditions. One column three vanes were installed at a 20⁰ angle maintaining for a water discharge ratio of q_r ~ 0.1. Three-dimensional mean and turbulent velocity components of flow in 90⁰ channel intake were measured by Acoustic Doppler Velocimetry (ADV). Flow characteristics of the intake structure area with no vanes are compared with those condition. Results showed that three vanes with single column reduced the amount of sediment by 20% in the intake diversion. In the downstream corner of the intake, high velocities were measured where scouring occurred. The vanes affected the intensity of secondary flow, turbulence energy, flow separation, and moved sediment deposition downstream of the main channel.

Use of bottom slots and submerged vanes for controlling sediment upstream of duckbill weirs

Duckbill weir is one of the water level control structures in irrigation networks, which is of interest to many engineers. Sediments transported in irrigation networks that accumulate upstream of duckbill weirs cause problems in operation, and affect the upstream water level. In this paper, submerged vanes and bottom slots are investigated for flushing the sediment downstream of the said weir. The experiments were conducted in a rectangular flume, 12 m long, and 0.6 m wide. The vanes placed in four sections were perpendicular to the sidewall. Flow-3D software was used for simulation of flow and sedimentation patterns. The results showed that submerged vanes create a secondary flow which is very useful for flushing the sediment, especially in the value of (H is head over the sidewall and P is the weir height). Further, the results showed duckbill weir efficiency (which is defined as the ratio of sediment trap to flow capacity of the weir) is as high as 47% (for values of H/P = 0.1–0.5 and total models). Finally, image processing results showed a maximum relative error of 14.4% for the simulation of the sediment pattern with Flow-3D software.

Velocity rate of screw streams in the site of submerged vanes

Introduction. The formation mechanism of longitudinal screw streams (LSS) along the upstream and downstream face of submerged vanes (SV) is considered. Acting along with the artificial transversal circulation (ATC), these streams protect the water intake from the channel sediments. The intensities and directions of LSS and ATC depend on the regime of flow, the planned-geometric characteristics of the vanes. Recommendations concerning the purpose of SV’s rational characteristics in the aspect of steady formation of all three protective streams in the flow for river damless intakes are contradictory and require clarification. The purpose of the study is to analyze the velocity rate of the LSS in SV site at various planned-geometric characteristics of the vane and hydraulic modes of its operation based on a physical model with an erosion-resistant channel (without water separation), as well as to determine an efficient range of setting angles of the SV’s to the tray board in terms of formation of steady and intensive LSS along the upstream and downstream face of the vane. Materials and methods. Model physical hydraulic studies and theoretical calculations were used. Five hydraulic modes of SV’s operation were studied, with various planned-geometric characteristics, using the physical model with an erosion-resistant channel (without water separation). The obtained experimental data were summarized and analyzed. Results. Results of laboratory hydraulic studies of LSS velocity rate in LSS site were presented. Experimental graphic dependence diagrams were plotted characterizing the intensity and direction of the LSS along upstream and downstream faces of the vane. Conclusions. A determining influence of the setting angle of the vane to the tray board (bank line) on the intensity and direction of the LSS in SV’s site was found out. Experimentally, an efficient SV setting angle was determined in terms of the formation of steady and intensive LSS along the upstream and the downstream vane face with practically usable direction.