The leading-edge interaction noise due to the cylinder wake impingement gradually loses its dominance with the increase of the cylinder vertical distance. The results show that compared to the single flat plate, the trailing-edge noise associated with the vortex shedding from the flat plate is significantly reduced when the vertical gap H/D≤1, i.e., when the cylinder is close to the flat-plate surface, and the corresponding vortex shedding frequency also decreases visibly. Noise characteristics were measured using far/near-field microphone arrays. The cylinder-plate model configuration varies by changing the cylinder diameter (D) and the vertical gap (H) between the cylinder and the flat-plate surface. This paper experimentally studies the interaction characteristics between an upstream cylinder and a downstream finite-chord-length flat plate with a blunt trailing edge in an acoustic wind tunnel. The findings from this study are beneficial for engineers in designing low-noise components in several aeronautical and industrial applications. Flow visualization using particle image velocimetry was conducted to analyze the noise change mechanism. In addition, the noise source distribution of different frequencies also changes with the variation of rod–airfoil configurations. Of the angles, the most effective way is the change of the sweep angle β, which can achieve a noise reduction of 8 dB when β reaches 20 deg, but the attack angle α has more influence in reducing the vortex shedding frequency. The interaction noise level decreases with the increase of the eccentricity of the elliptical rod.
#Airfoil cross section install
Test range, both the elliptical rod cross section and the change of the airfoil install angles can visibly reduce vortex–body interaction noise compared to the baseline rod–airfoil containing the circular rod and the airfoil at zero angles. A near-field microphone array was applied to locate the noise sources on the rod–airfoil model, and a far-field microphone array determined the noise level and radiation directivity.
This paper aims to assess the effects of these parameters on the characteristics of vortex–body interaction noise. The model configuration varies by changing either the rod cross section (circular, square, rhombic, and elliptical) or the install angle of the airfoil at three directions (attack angle α, sweep angle β, and lean angle γ) independently. Vortex–body interaction noise from a rod–airfoil model has been investigated experimentally in an aeroacoustic wind tunnel.
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