On the influence of porous coating on vibration response and noise reduction of cylinders at high Reynolds numbers

In the present study, the flow simulation based on a two-dimensional finite volume method is coupled with Ffowcs Williams–Hawkings acoustic analogy to investigate the flow noise around a vibrating circular cylinder coated with different models of porous layers over a range of Reynolds numbers, 1700≤Re≤10 270. The flow is incompressible, and the properties of the porous layer are constant (Da=10, ε=0.99). The mass and damping ratios are m*=2.4 and ξ=0, respectively. The effects of the porous models on the vorticity and pressure contours, hydrodynamic coefficients, vibration response, sound pressure level (SPL), and pressure coefficients (Cp) of an elastically mounted cylinder are examined at 2≤Ur≤12. According to the results, the vibration amplitude decreases by more than 60% in model 3 at the initial branch (2≤Ur≤6), while model 2 shows a maximum reduction of 90% at the lower branch (6≤Ur≤12). Compared to the bare cylinder, CD max decreases by more than 50% in model 3. The best CL max reduction is also contributed by model 3 at Ur6 and model 2 at Ur6. Moreover, model 2 shows the highest reduction in the overall sound pressure level for all Reynolds numbers and shows up to 6 dB noise reduction at Re=6847. Models 4, 5, and 6 show the highest peak values of SPL, while models 1 and 2 exhibit the best noise reduction effects with minimum peak values in all Reynolds numbers. Therefore, model 2 is the most efficient structural design for noise reduction and suppression of vortex-induced vibration.