Experimental Assessment of the Aerodynamic Noise Generated by a Porous Coated Staggered Tandem Cylinder Configuration

The flow around two staggered circular tandem cylinders has been subject of numerous studies, most of them considering the flow structures around the cylinders, while only few focus on the corresponding noise generation. Porous cylinder coatings are one possible approach to reduce the aerodynamic noise from such configurations. The study presented in the current paper focuses on acoustic measurements on tandem cylinder configurations using a porous coating on either the upstream cylinder or the downstream cylinder at various inflow angles, thus mapping the additional effect of cross wind situations. In the experimental investigation on the reference configuration without coating, complex flow structures and interaction between the upstream and downstream cylinder were observed especially at medium angles of incidence. This resulted in a bifurcation of the main tonal peak in the frequency spectrum. When a porous coating is applied to the upstream cylinder, the flow onto the downstream cylinder is influenced, leading to noise reduction at low angles of incidence. At higher angles, the tandem cylinder configuration behaves like two single cylinders, thus diminishing the noise mitigation potential of the porous coated upstream cylinder.