Abstract
In the present paper, the effect of solid fin around a bare tube on the aerodynamic sound was experimentally investigated. This fin was mounted spirally around a bare tube and had the same geometry as those actually used in boiler tubes. We measured the sound pressure level of the aerodynamic noise generated from finned tubes with various fin pitches. An Aeolian tone induced by Karman vortex shedding was observed in the case of a finned tube. A decrease in the pitch of the fin effectively caused an increase in the equivalent diameter, which acted as the characteristic length of a cylinder with fin. When the pitch of the fins decreased, the peak level of the sound pressure spectrum decreased. However, the peak level at the fin pitch ratio of 0.11 became larger than the case of bare tube.
