Experimental study on cylinder wake control using forced rotation

Abstract

The study focused on the flow over a rotating circular cylinder in the context of flow control. Particle Image Velocimetry was employed to examine flow characteristics at 2.5 × 103 ≤ Re ≤ 10 × 103. The rotation rates (α) were considered up to 1.57. The mean drag coefficients (CD‾) and Strouhal numbers (St) were examined. The vortex formation length was obtained as approximately 2.1 times the cylinder diameter for α = 1.57. For the stationary cylinder, the length was 1.2 times the diameter from Re = 2.5 × 103 to Re = 10 × 103. Forced rotation enhanced the momentum for the boundary layer and postponed the flow separation on the upper side of the body, leading to flow attachment at α = 1.57. The values decreased from CD‾ = 1.029 to CD‾ = 0.907 as α increased from 0 to 0.39 due to the shrinkage of the wake at Re = 10 × 103. Drag reduction was 3.5 % for α = 0.13, 5.7 % for α = 0.26, and 11.8 % for α = 0.39 thanks to active flow control. The St was attained as 0.17 ≤ St ≤ 0.21 for Re varied, while it remained relatively stable for different α values at the same Re. © 2024 Elsevier Ltd