Abstract:

This paper presents the results of an experimental investigation of the sound produced by flow interaction with a wall-mounted finite length cylinder of circular or square cross-section. Acoustic measurements have been taken in an anechoic wind tunnel at a range of flow speeds and for a wide variety of aspect ratios (cylinder length to diameter ratio). Unsteady velocity data have also been measured in the cylinder wake using hot-wire anemometry and these data are related to far-field noise measurements to determine the flow mechanisms responsible for noise generation. Cylinder aspect ratio was found to be an important parameter that controls vortex shedding behaviour and hence tonal noise generation. Multiple peaks in the noise spectra can be attributed to different vortex cells in the near wake, the number and strength of which are controlled by aspect ratio influencing flow over the tip or cylinder-wall junction.