Abstract
Based on the theories of vortex sound generation and acoustic analogy, the characteristics of flow and aerodynamic noise produced from a circular cylinder attached by a splitter plate with different lengths have been investigated at a Reynolds number of 6 × 104. The accuracy of the numerical simulations is verified through the predicted spectra of far-field aerodynamic noise which match well with measured data in an anechoic wind tunnel for the circular cylinder. Results show that the attached splitter plate elongates and weakens the interaction of the two separated shear layers at the top and bottom of the circular cylinder, strengthening the dissipation of vortex motion and mitigating the regular vortex shedding in the wake. Those flow phenomena reduce the aerodynamic force fluctuations and the mean drag produced by the circular cylinder. Consequently, the strengths of quadrupole sound sources in the wake and surface dipole sources are inhibited. Meanwhile the tonal peak corresponding to the vortex shedding and the overall far-field noise are reduced effectively. Thereby a good aerodynamic noise reduction effect is achieved for a circular cylinder by attaching a splitter plate. It is also found that when the attached splitter plate length is larger than the cylinder diameter, more noise is produced from the splitter plate itself. Splitter plates with length of less than the cylinder diameter are most effective in reducing the aerodynamic noise generated from the circular cylinder.
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