Seite - 182 - in Book of Full Papers - Symposium Hydro Engineering

changing the basin size and shape, these researchers tried to increase its efficiency. Ogihara and Sakaguchi (1984) suggested a plan that differed from other plans in the weir outlet flow. In this basin, they used a Bell-mouth weir within the basin for smooth water transmission. Mashauri (1986) proposed a plan in which inlet and outlet flows were separated by a horizontal vane. Paul (1991) proposed a plan in which a Soleus-shaped vane (deflector) was installed at a distance of one-third of the flow depth in the basin inlet channel. Saneie (1999) studied hydraulic parameters of vortex flow within vortex settling basins. Ziaei (2000) proposed a new model of vortex settling basins that is actually a combination of two inlets for clockwise and anti-clockwise flows. Athar et al. (2002) proposed two other models for vortex settling basins. Using experimental models and changing the orifice radius, Chyan and Quang (2010) determined the discharge coefficient Cd for the orifice. In their experiments, Niknia, et al. (2011) investigated the flow structure under the deflector and compared it with the flow structure without deflector for counterclockwise inlet flow to vortex basins. One problem of vortex settling basins is the settlement of part of sediments in the basin floor. More studies are necessary to provide a method to remove or reduce these sediments. At Istanbul University of Technology (IUT), researchers such Cecen and Akmandor (1973), Curi et al. (1979) and Cecen and Bayazit (1975) found that the existence of a radial gradient in the floor towards the orifice can lead to better performance of the basin and reduced sediments settled on the floor. Salakhov (1975) proposed two percent increase in the gradient of the basin floor. Paul et al. (1991) and Ziaei (2000) suggested that the sediments deposited on the floor can be washed by installing two inlets for the flow and changing the flow from clockwise to counterclockwise and vice versa. To increase the residence time on the floor and increase the sediment washing efficiency in the basin floor, Nguyen (2011) used deflector in different arrangements and by combining one, two and three deflectors. The present study proposes a plan to solve the problem of sediments being deposited in such basins and investigates the efficiency of vortex settling basins. This plan consists of a batch of curved submerge vanes with different arrangements in vortex settling basins. In fact, the aim of installing curvature submerge vanes in the basin floor is to modify the vortex flow shape and strengthen vortex flow to direct sediments towards the flushing orifice. These submerge vanes were first used to deal with the external erosion of rivers. Moreover, the application of these structures has been developed to control sediments in intakes due to their successful results. 182