PASSIVE CONTROL OF TURBULENT FLOW AROUND A CYLINDER USING COMBINATION OF SPLITTER PLATE AND CONTROL CYLINDER

The turbulent flow around a circular cylinder at the Reynolds number of 13100 is controlled using the combination of downstream splitter plate and upstream control cylinder as a new configuration. For this purpose, first a splitter plate with the length of L is attached to the downstream base of the cylinder and its length is varied to yield the optimum plate length in which the forces are minimum. The Reynolds averaged Navier Stokes equations is solved by a finite volume method together with a K-w SST turbulence model. Results show that the presence of the splitter plate has great impact on the flow characteristics and reduces the time average of the drag coefficient and amplitude of the lift coefficient oscillations. At L/D=1 the drag and lift coefficients of the system is reduced about 48% and 97% respectively. In the next part, a control cylinder with the smaller diameter than the main cylinder is placed at the upstream and the center to center ratio is varied. Results show that the control cylinder reduces the system drag coefficient in all the investigated distances while reduces the lift coefficient just in some bigger distances. At C/D=4 the drag and lift coefficients of the system is reduced about 35% and 11% respectively. In the last part, the simultaneous combination of upstream control cylinder and downstream splitter plate in their optimum configurations is used. Results show that this configuration significantly reduces the drag and lift coefficients of the system compared to the main cylinder. Furthermore, the performance of the new configuration in reducing the drag force is better than those of each of the splitter plate and control cylinder alone. At the condition with C/D=4 and L/D=1 the drag and lift coefficients of the system are reduced about 57% and 63% respectively compared with those of the main cylinder.