Abstract
Aeolian tone from a semi-circular cylinder in a uniform flow is studied experimentally for various angles of attack. It is found that the peak sound spectrum of the Aeolian tone from the semi-circular cylinder is smaller than that from the circular cylinder and the lowest sound is observed around the zero angle of attack. This is due to the reduction in the fluctuating lift force on the semi-circular cylinder compared to that of the circular cylinder. This result suggests the validity of the analogy between the sound pressure level and the fluctuating lift force on a semi-circular cylinder in a stream. The flow visualization study also supports these results.
Highlights
Aeolian tone generated from a bluff body in a stream has been a topic of interest for many years, because it is closely related to the environmental noise problem induced by the stream
These studies are concerned with the aerodynamic characteristics of the circular cylinder in a uniform flow, which is closely related to the generation mechanism of Aeolian tone
The Strouhal number stays around 0.2 in the range of angle of attack θ = −90 to −45 degrees and the result agrees with that of the circular cylinder. These results indicate that the variation of the Strouhal number with the angle of attack is caused by the wake-width variation, which will be seen in the flow visualization pictures in Figure 8, while the high Strouhal number at 15 degrees and the low Strouhal number at −15 degrees is due to the change of the separation point along the surface. 3.2
Summary
Aeolian tone generated from a bluff body in a stream has been a topic of interest for many years, because it is closely related to the environmental noise problem induced by the stream. Examples of such flow noise can be found in wind turbines, vehicles, cables, buildings, and so on. The Aeolian tone from the circular cylinder has been studied by many researchers, which is summarized in review papers [1] [2] These studies are concerned with the aerodynamic characteristics of the circular cylinder in a uniform flow, which is closely related to the generation mechanism of Aeolian tone. The experimental results on the unsteady fluid forces of the circular cylinder indicate that the fluctuating lift coefficient is dependent on the Reynolds number of the flow and is highly correlated with the Aeolian tone from the circular cylinder [3]
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