Page - 192 - in Book of Full Papers - Symposium Hydro Engineering

Figure 12 Total, orifice and floor efficiencies in the discharge of 37 l/s (a) S4 mode, (b) S6 mode, (c) S8 mode Figure 13 Total, orifice and floor efficiencies in the discharge of 45 l/s (a) S4 mode, (b) S6 mode, (c) S8 mode Efficiency in each part of the vortex settling basin is the weight ratio of the sediment accumulated in that section. Thus, an increase in the orifice efficiency compared to the no- vane mode is desirable but increase in the floor efficiency is not desirable because it means the accumulation of more sediments in this area and the lack of sediment washing of the floor. Thus, as shown in diagrams, R3, R4 and R3 4 arrangements have better efficiency because they reduce the share of sediments settled on the vortex settling basin floor and increase the share of sediments exited from the flushing orifice. In these modes, the floor efficiency reduced and the orifice efficiency increased. According to no-vane tests, the desirability of such arrangements were somewhat predictable so that most sediments settled on the vortex settling basin floor in no-vane modes are in areas R3 and R4 (Figure 9). So the insertion of vanes in the two areas will increase sediment washing from the floor. As shown in Figure 14, among R3, R4 and R3 4 arrangements, R3 4 has the lowest efficiency in sediment washing. Curvature submerge vanes in some arrangements decreased sediment washing from the floor. This reduction can be attributed to the impact of vanes in avoiding secondary flows which occur in the vortex settling basin floor towards the orifice. (a) (b) Figure 14: Percent of the floor sediment washing compared to no-van mode (a) discharge of 37 l/s ,(b) discharge of 45 l/s This study examined the effect of radial sections in curvature submerge vanes. The vanes were inserted in three modes, with radial sections with angles of 90, 60 and 45 called S4, S6 and S8, respectively. Figures 12 and 13 show the results of changing the number of radial sections of vanes inserted in the floor on the efficiency of each part of the basin. It is 192