Flow control in the near wake of a circular cylinder by splitter plate and perforated cylinder combination

In this study, it is aimed to flow control in the near wake of a circular cylinder by splitter plate and perforated cylinder combination in deep water. The cylinder diameter was kept to constant during the experiments as D=50 mm and corresponding Reynolds number based on the cylinder diameter Re=5×103. Experiments were performed in three stages. In the first stage, the effect of perforated cylinder on the flow control was investigated using the PIV measurement technique and also force measurement was performed in the air tunnel in order to calculate the drag and the lift coefficients of the cylinder for β=0.3, 0.4, 0.5, 0.6 and 0.7 at D/Ds=0.4, 0.5 and 0.6. In the second stage, the flow structure in the further downstream of the perforated cylinder was investigated using dye visualization technique. Finally, the effect of the splitter plate and perforated cylinder combination in the near wake was investigated on the flow control with respect to total drag and lift coefficients. The results depicted that the porosity, β and the diameter ratio, D/Ds have substantial effects on the flow control and the drag reduction of the cylinder. The flow control was achieved in the near wake region for β=0.5 and 0.6 at D/Ds=0.4 and 0.5. Also, the drag coefficient of cylinder was reduced by 65% for β=0.5 at D/Ds=0.4. It was observed that using of the splitter plate remarkably affected the flow structure and increased the total lift coefficient.