Noise generation by two staggered circular cylinders of equal diameter in cross-flow

Abstract

The complex flow field around two staggered cylinders is of importance in many different engineering applications. Although it has received much attention in numerical and experimental research, only a very limited number of studies on the corresponding generation of aerodynamic noise has been published. In the study described in the present paper, the far-field noise generation of a tandem cylinder configuration under incident flow has been measured in a small open jet wind tunnel for two different cylinder spacings at moderate Reynolds numbers between 3,300 and 11,500. The angle of incidence has been varied between 0° and 90°. In addition, the influence of a turbulent inflow has been investigated, obtained by mounting passive turbulence grids to the nozzle of the wind tunnel. The resulting sound pressure level spectra show very characteristic tonal features. For the wide spacing, a bistable behavior can be observed, where the vortex shedding peak splits into two (or more) peaks at certain angles of incidence. For the moderate spacing, a distinct vortex shedding peak can only be observed in a range of angles from approximately 20° to 80°, while at high frequencies a complicated structure consisting of multiple tones can be observed. Additional flow measurements or simulations are necessary to fully understand the extensive results presented in this paper.