Far-field aerodynamic noise reduction of a circular cylinder by longitudinal grooves: Effect of groove profile, size ratio and number

This paper presents an experimental investigation into the aerodynamic noise characteristics of grooved circular cylinders conducted in an acoustic wind tunnel. It investigates the influence of groove profile—specifically, triangular, circular, and rectangular—as well as groove number and size on the far-field noise generated by the flow. Aerodynamic noise was measured employing far-field microphone arrays. The acoustic results demonstrate that, at a wind speed of 30 m/s, the maximum SPL at the far-field noise monitoring point is reduced by up to 10 dB compared to a smooth circular cylinder when the groove profile is triangular, with 30 grooves and a groove size of h/D = 0.01. At an inlet velocity of 40 m/s, with a circular groove profile, 30 grooves, and a groove size of h/D = 0.01, the far-field noise reduction can reach up to 14 dB relative to the baseline model. Flow characteristics were investigated using particle image velocimetry (PIV) techniques. The PIV results indicate that the noise reduction in the far field is predominantly attributed to the reduced vortex intensity in the flow field. The investigation into the far-field noise characteristics of partially grooved cylinders offers preliminary evidence that the groove structure delays boundary-layer separation around the cylinder, thereby contributing to a reduction in far-field noise. These findings can provide valuable insights for the development of noise control strategies in various engineering applications.