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Effect of approach channel shape on theformation of vortices at single-horizontal intakes

Sönmez, Can Metin
In an experimental setup of a water intake structure composed of a reservoir-pipe system, the formation of air-entraining vortices under symmetric flow conditions were investigated for different approach channel shapes. In the first set of the experiments the approach channel walls were kept parallel to each other and be perpendicular to the head-wall of the intake structure. In the following sets of the experiments these walls were located at different angles to the head-wall. A series of experiments were conducted on the model with varying approach channel shapes and a wide range of discharges to determine the critical submergences required for the formation of vortices. Consequently, the effect of the approach channel shape on the formation of air-entraining vortices were investigated. Experimental results show that critical submergence is mainly affected by Froude number and approach flow channel shapes. Moreover, a dimensionless equation, related with hydraulic and geometrical parameters, was obtained by using dimensional analysis for the critical submergence. Furthermore, empirical equations were derived to calculate critical submergence by using regression analysis. After that, simplified empirical equation was obtained by eliminating some of the dimensionless parameters. Furthermore, data obtained from the experiments and from the empirical equations are compared with each other’s.