Numerical Investigation of Performance Curve and Aeroacoustic Characteristics of an Axial Fan System

Totally-Enclosed-Fan-Cooled (TEFC) motor is extensively utilized in modern industry. To reach the purposes of improving the motor cooling effect and according with the factory noise control standard, the research of aerodynamic and acoustic characteristics of the fan cooling system become important issues. In this study, we mainly use the computational fluid dynamics software, ANSYS Fluent and its build-in rotating model, Multiple Reference Frame (MRF) and sliding mesh (SM) models to simulate the swirling flow. We first construct a numerical wind tunnel which is conducted by two boundary conditions, the conventional method and the Downstream Flow Resistance (DFR) method, calculate the flow field of the Multi-Wing axial fan and verify the fan performance measurement. In comparison to the experimental data, the maximum error of the conventional method result is up to 65.8% and the DFR method result becomes more accurate and its maximum error is reduced to 8.72%. We then compute the transient result which begins from the quasi-steady initial solution by the sliding mesh model, and the errors are all less than 5%. These results verify that the numerical wind tunnel is feasible. In the last half of this research, we apply the previous numerical wind tunnel to compute the system performance curve and the acoustic field of the fan cooling system including the safety mesh, fan, shroud, and plate. The safety mesh is simplified by the porous zone. We try four strategies to modify the geometry of the system on the purposes of improving the volume flow rate and reducing the noise of the original system. The results show that the modified system has the ability to improve the system volume flow rate obviously, but the system noise also increases a little due to the interaction between the deflected pathway and the fluid in comparison to the original system. Keywords: Totally-Enclosed-Fan-Cooled motor, Multiple Reference Frame, Sliding mesh, Fan performance curve, Downstream flow resistance method