Evaluation of lift and drag force of outward dimple cylinder using wind tunnel

Abstract

Cylindrical structures are widely used especially in engineering field. The cylindrical structure produces large drag force due to pressure difference between upstream and downstream direction of the flow. The objective of this study is to fabricate cylindrical model that have 3 different surface characteristics which is smooth surface and outward dimple surface with covered half and full of cylinder surface. The second objective is to determine the drag and lift coefficient of a cylinder for all types of surface. Third objective is to visualize the flow separation of the cylinder for all surface. The experiment is tested in wind tunnel at various speed for lift and drag coefficient from 5.2 m/s to 30.5 m/s. For flow visualization test, the smoke test has been used at constant speed 3.5 m/s. The acting force on the cylinder that have been determined is coefficient of lift C L and coefficient of drag CD. The result is compared with the types of cylinder surface. The result gained showed that the smooth cylinder produce large drag coefficient compared to the dimple cylinder and this results are also agreed with the flow separation test which is the dimple cylinder are resulting in delayed flow separation point.