جستجوی مقالات مرتبط با کلیدواژه « ورتکس » در نشریات گروه « آب و خاک »

The formation of vortices behind the gates of diversion dams is an operational challenge. Such vortices lead to vibration and corrosion in the gate, reducing the lifetime and raising the operational cost of the dam. This study investigated these vortices and their formation. It was found that the gate or cutoff wall was not the only explanation for the vortices; the closed side gates also contribute to vortex formation. Furthermore, an increase in the gate width reduced vorticity; the vortex size experienced a 200% reduction as the gate size increased by 200%. The cutoff wall diameter was another determinant. An increase in the cutoff wall diameter raised vorticity. The vortices increased by 50% as the wall diameter increased by 150%.

In many cases some series of obstacles are placed in the path of water، the water passes through them and at the obstacles downstream the vortex flows are created. By overlapping the created vortices by the obstacles، transverse waves that their propagation direction is perpendicular to the direction of the water flow are formed. These waves cause reduction of the suspended sediment transfer toward the downstream of the obstacles. In this study، the effects of the perpendicular waves in flow modes 1 and 2 on the suspended sediment concentration at the downstream of the obstacles were studied، in a laboratory flume. In each experiment for comparing the results، the suspended sediment concentrations were measured in two conditions (with and without the presence of transverse waves) at the 2 end points of the flume. The results show that at equal amplitudes of the waves، modes 1 and 2، the ability of transverse wave mode 1 in the rejection of suspended sediment toward the upstream and reducing its concentration in the downstream of the obstacles is greater than that of the Wave mode 2.