Aeolian tone radiated from a circular cylinder with solid spiral fin in cross flow

Abstract

This study focuses on the characteristics of the Aeolian tone and Karman vortex shedding from a circular cylinder with a solid spiral fin. The fin pitch ratios range from 0.11 to 0.80. We measured the turbulence intensity, the spectrum of velocity fluctuation, the coherence of the Karman vortex in the spanwise direction, and the sound pressure level (SPL) of aerodynamic sound. The Aeolian tone induced by Karman vortex shedding was observed in the case of a solid spiral finned tube. For a small fin pitch, the peak level of the SPL spectrum, periodicity of vortex shedding, and coherent spanwise scale of Karman vortex all increased. However, the locations of the maximum turbulence intensity in the wake of a finned tube was found not move downstream when the fin pitch was decreased. The vortex shedding frequency could be estimated by the equivalent diameter of finned tube, as well as the bare tube, in a manner similar to the Strouhal number.

Keywords

• karman vortex
• aeolian tone
• spanwise correlation length
• solid spiral fin
• strouhal number