Abstract
Flow fields in half ducted propeller fans have been investigated by FrontFlow/blue, which was computational fluid dynamics software based on Large Eddy Simulation (LES). Aerodynamic noise was calculated by Curie's equation based on pressure fluctuation calculated by LES. 2-blade and 4-blade propeller fans were intended. Noise level of the 2-blade was smaller than the 4-blade by 5.2dB experimentally. LES was conducted to capture the tip vortex, which was characteristic flow field in half ducted propeller fans. Calculated noise level and pressure fluctuation at a suction surface of the 2-blade were smaller than the 4-blade. Difference of overall noise level was 4.8dB. The difference of calculated noise level 4.8dB showed reasonable agreement with measured noise level 5.2dB. The pressure fluctuation near a tip of a trailing edge in the 4-blade was strong. The pressure fluctuation at the tip was therefore found to have a great influence on the noise level.
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