The exposure to harmful noise levels in the working areas generates accidents, reduces work efficiency, and causes noise induced hearing loss from prolong exposure. One of the most detrimental sources of noise are axial ventilation fans due to their proximity to the working areas and widespread use. High fan noise levels are a byproduct of poor aerodynamic and acoustic design characteristics. Consequently, there are opportunities to significantly reduce fan noise levels. Since fan noise scales with the 4-6th power of the fan tip speed, a popular trend to reduce fan noise has been to reduce the fan speed while increasing the fan diameter to maintain the volumetric flow rate. However, workplace constraints can significantly restrict the fan size. To that end, the present work presents a control vortex design approach to maximize the volumetric flow rate contribution of the fan blade outer sections. The resulting fan design has been fabricated and tested to experimentally demonstrate that it is possible to significantly reduce the fan diameter, speed, and noise levels while maintaining a high volumetric flow rate. Good agreement between experiments and predictions indicate that the presented control vortex design approach is a promising method for designing quiet axial fans.
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