The use of shrouded cylinder and splitter plate on controlling the vortex shedding in the annular region

The purpose of this work was to control flow structures in the area between the inner and outer cylinders, fluctuations of velocity components and the vibration generated by this flow structure on the cylinder. This study has three main components. The first component was the inner cylinder which has Di = 50mm diameter which kept constant for all experiments. The second component was the perforated outer cylinder which has three different porosities such as, βc =0.3, 0.5, 0.7. The third component was the splitter plate which has also three different porosities, βp =0.3, 0.5, 0.7. The splitter plate had five different plate angles as α = 60°, 90°, 120°, 150°, 180° taking the flow direction as a reference line. The Reynolds number was kept constant at Re = 5x103 based on the inner cylinder diameter. Quantitative and qualitative outcomes were obtained by dye visualization and PIV measurements to define the best combination of cylinders and splitter plate for controlling flow structure. The results showed that βc =0.3 outer cylinder causes a significant decrease in the TKEmax value and also the number of vortices in the annular region decreased to one instead of two because this outer cylinder caused a reduction in the amount of flow which goes into this inner region. In general, the outer cylinder with low porosities such as βc = 0.3 and βc = 0.5 cylinders were found to be better for diminishing the TKEmax than βc = 0.7 outer cylinders. The results indicated that the time average vorticity magnitudes increase by increasing porosity ratios of the splitter plate and the outer cylinder. It was concluded that α = 150° was the most effective plate angle for control flow structure when used with the βc =0.5 cylinder and βp =0.5 plate.