Numerical investigation on flow and noise of cylinder-airfoil configuration by longitudinal groove on the up-stream cylinder

To reduce the interaction noise of the cylinder-airfoil configuration, longitudinal grooves are applied to the upstream cylinder. In this work, the noise and flow characteristics are numerically investigated, with a focus on three key factors: groove profile, groove size ratio, and groove number. It is found that when the groove profile is circular, the groove size ratio is 0.01, and the groove number is 60, the far-field noise is reduced by approximately 14 dB—the maximum reduction observed. Shallow grooves exhibit a better noise reduction effect than deep ones. The investigation of transient flow fields shows that shedding vortices have a significant impact on far-field noise levels. The groove structure, especially the circular groove profile, can break down large-scale vortices into smaller ones, which contributes to noise reduction. This investigation provides new insights and methods for noise control in wind turbines and landing gear systems.