G0510206 Effect on the Pressure Fluctuation on Blade in Small Axial Flow Fan when Changing the Inflow Turbulence

Abstract

Numerical simulations were conducted by using LES (Large Eddy Simulation) with DSM (Dynamic Smagorinsky Model) about the axial flow small fan for cooling electronic devices. In this study, the tested fan has grid for turbulence located in the suction side. Using two type of grid for turbulence were used for study. One has diameter of 3mm and pitch of 15mm, the other has diameter of 4mm and pitch of 20mm. The flow pattern around the fan blade and RMS of pressure fluctuation on the fan blade surfaces were compared under the two turbulence conditions and no turbulence condition. As a result, it is shown that noise is increased by the grid for turbulence. These cause are considered large pressure fluctuations which were revealed by numerical analysis. In addition, we found that increase in RMS of pressure fluctuation is related to incidence angle fluctuation. This phenomenon is likely to occur at leading edge. And this area is influenced by inflow turbulence.