Aerodynamic Sound Generated by Wake-Body Interaction

Aerodynamic sound generated by two circular cylinders of different diameters in staggered arrangement was studied experimentally as a typical sound caused by the wake-body interaction. The diameter of the upstream cylinder was 0.4 times that of the downstream cylinder. Magnitude of sound associated with the vortex shedding from the upstream cylinder attained maxima and minima at particular longitudinal spacings between the cylinders. The distance between two successive maxima was approximately 4 diameters of the upstream cylinder. This distance was explained in terms of a self-excited flow sustained by a feedback loop. The reduction of sound from the upstream cylinder was achieved by tilting the downstream cylinder which broke the two-dimensionality of the feedback loop.