Aerodynamic Noise Simulation of Propeller Fan by Large Eddy Simulation

In this paper, unsteady flow and aerodynamic noise are numerically investigated for a half-open type propeller fan used for outdoor air conditioner components. The flow field is calculated by Front Flow/Blue, which is based on Large Eddy Simulation (LES). The Standard Smagorinsky Model (SSM) and Dynamic Smagorinsky Model (DSM) were used as sub-grid scale models. Aerodynamic noise was calculated by Curle’s equation based on the pressure fluctuation on the blade surface computed by LES. The computed static pressure rise of the fan showed reasonable agreement with the measured equivalent. The time-averaged distributions of the three velocity components downstream of the blades were also compared with those measured by hotwire anemometry, which showed satisfactory agreement between the computed and measured velocity profiles. But the tip vortex passage which was detached from the blade surface predicted by LES was not stable as measured by the experiment. Finally, the predicted far-field sound spectrum agrees reasonably well with measurements in a frequency range of 100 to 1000 Hz although the sound pressure level was underpredicted in the lower frequency range.