Abstract
The cylindrical flow around a cylinder is present in several engineering problems. Moreover, the flow pattern around a rotating cylinder is more complex than that around a cylinder. In this paper, a rotating cylinder at different speed ratios is investigated by means of large-eddy simulations. In particular, the lift coefficient CL, drag coefficient CD, lift-to-drag ratio k, Strouhal number St, the flow field in each section, and the three-dimensional eddy structure are compared at different speed ratios. In addition, the effects of an end disk on the aerodynamic loads and flow field of the rotating cylinder were investigated. The results showed that, in the absence of an end disk, CL increased, CD increased and then decreased, k increased and then decreased, and St increased and then decreased as the speed ratio increased. The turnaround occurs for each parameter at a speed ratio of n = 2, and vortex shedding is suppressed at this speed ratio. Notably, the tip vortex at the free end was not suppressed. The CL, CD, and k values of the cylinder when adding the end disk were greater than those of the normal cylinder. For example, when the speed ratio is 3, the lift coefficient is increased by 27%, the drag coefficient is increased by 24%, and the lift-to-drag ratio is increased by 23% after adding the end plate. In addition, the vortex structure at the free end differed substantially. This study provides a systematic method to evaluate the aerodynamic loads and flow field changes around a cylinder, laying the foundation for solving the problems of cylinder flow and rotating cylinder flow.