CONTROL OF THE CONTROL OF THE UNSTEADY FLOW STRUCTURE BEHIND CYLINDER WITH PASSIVE CONTROL METHOD

In this study, it is aimed to control flow structure downstream of inner cylinder with seven different diameters (di= 30, 40, 50, 60, 70, 80, 90mm) by a surrounding outer cylinder that have =0.5 porosity. the diameter of outer cylinder was chosen as 100mm. the perforation hole diameters of the cylinder were 10mm. the water height was kept constant during experiments as hw=400mm .the depth-averaged free stream velocity was u=100m/s which corresponded to a reynolds number red=10000 based on outer cylinder diameter. flow characteristics downstream of cylinder was investigated by using particle image velocimetry (piv) technique. piv experiments were performed at the mid-section of water 200mm. it has been observed that the perforated outer cylinder decreased vortex shedding downstream of inner cylinder with different diameters (di=30, 40, 50, 60, 70, 80, 90mm). for high diameter ratios di/do≥0.7 perforated outer cylinder lost its effect on the flow control.