Passive Control of Vortex Shedding via Screen Shroud

Abstract

Abstract.The turbulent wake of screen-shrouded cylinders were experimentally investigated using flow visualization. Screen cylinders made from screen mesh of various porosity (37%, 49%, 61% and 67%) were used as the shrouds. The main purpose of the study is to examine the effect of screen porosity, β and screen diameter ratio, d w /D (wire diameter to cylinder diameter ratio) on the vortex development behind the shrouded cylinders, particularly in supressing the vortex shedding from a circular cylinder. The diameter ratio between the screen shroud and the plain cylinder, D/d was 2.0. The flow Reynolds number based on the shroud diameter, Re D was about 1000. Results showed that the inclusion of the screen shrouds has significant impact on the wake of the circular cylinder. With larger value of the non-dimensional parameter βd w /D, vortex was impaired and the formation length was longer in the shrouded cylinder wake. The vortex generation mechanism was also discussed.