Abstract
In order to clarify the generation mechanism of aerodynamic noise from axial flow fans, unsteady pressure fluctuation on the surface of blades were measured by time resolved Pressure Sensitive Paint based on micro-material slurry (MS-PSP). The frequency resolution of the developed PSP is up to 300Hz and the sensitivity is almost the same as the conventional PSP. We also developed image-rotator apparatus composed of an image-rotation prism and MS-PSP system. By using this rotating prism synchronized with the rotation of the fan, we can capture an image that is stationary relative to the moving objects. The results showed that the strong pressure fluctuations were observed around the tip of blade at the suction side. Since the dominant noise sources of axial fans are located around tip of the blades, the present result is reasonable and it reveals the measurements of PSP were identified aerodynamic noise source on the surface of the axial fan. It indicates that the pressure fluctuation measurement with MS-PSP and the image-rotation prism will help to identify the sound source of aerodynamic noise.-
