A Numerical Investigation on the Influence of the Circular Ring on the Aerodynamic Noise Generated by a Cooling Fan

Abstract

The influence of the width of the circular ring of a car cooling fan on the aerodynamic noise is investigated numerically through the determination of the overall sound pressure level (OASPL). The results demonstrate that when the circular rings cover near 2/3 of the width of the blade tips of the rotor in the axis direction, the rotor has the lowest OASPL and the related total pressure efficiency and flow mass rate are better than the corresponding values obtained for a reference rotor without a circular ring. With increasing the width of the circular ring in the axis direction, the tip vortex around the trailing edge of the blade tip becomes smaller and finally disappears. Meanwhile, a separated flow field arises gradually and then grows in size around the middle of the junction of the blade tips with the ring. When the circular rings cover nearly 2/3 s of the width of the blade tips of the fan in the axis direction, the extension of the separated flow around the blade 's tip attains a minimum. KEYWORDSCooling fan; width of the circular ring; aerodynamic noise; CFD simulation Nomenclature U Flow velocity rpm Round per minute ρ Density of fluid μ Dynamic viscosity Re Reynolds number u Means velocity of the flow e u Fluctuating velocity of the flow p Pressure Q Mass rate of the flow DP total Difference between the total pressure of the downstream and upstream of the rotor This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.