EFFECT OF RIGID AND FLEXIBLE SPLITTER PLATE ATTACHED TO SQUARE CYLINDER ON STROUHAL NUMBER AT MODERATE REYNOLDS NUMBER
The present work focusses on the experimental investigation on Strouhal number modification by a passive flow control technique over a square cylinder placed in test section of a sub-sonic wind tunnel. Rigid and flexible splitter plate attached downstream of the cylinder have been used as a passive flow control technique for flow over the cylinder at Re = 400. Lengths of the splitter plates were varied from 0.5D to 8D to manipulate the wake behind the cylinder. Hot Wire Anemometer (CTA) measurement technique has been used to characterize the flow in the wake of the cylinder at four different downstream locations at different point across the wake. Single wire probe has been used to measure the near wake and far wake mean and root mean square velocities of the cylinder as well as vortex shedding frequencies for all cases. The study infers that the splitter plate fixed downstream to square cylinder modifies the wake structure of the cylinder and consequently suppresses the vortex shedding phenomenon as an efficient passive control technique. The reduction in the shedding frequency of the flow over the cylinder has been achieved in both rigid and flexible splitter plate case. Flexible splitter plate suppresses the vortex shedding phenomenon more effectively than the rigid plate for all splitter plate lengths. The maximum suppression of Strouhal number by rigid plate is found approximately 65 % whereas, in flexible splitter plate case it is found nearly 75 % with respect to Strouhal number of bare cylinder without splitter plate at Re = 400.