Reduction of flow-induced noise in a household air purifier

Abstract

In this study, we propose a design for a household air purifier that reduces the flow-induced noise caused by the impeller of the fan system. The noise of the air purifier was identified in experiments as induced by the air flow generated by the impeller of the purifier. This noise can be classified into tonal noise and wide-band frequency noise: The former is the noise from the impeller blade turning, and the latter is from air flow turbulence. Using a commercial computational fluid dynamics (CFD) analysis code, it was shown that flow separation occurs at the outlet of the scroll by the adverse pressure gradient, which significantly reduces the flow rate of the purifier. To avoid flow separation and maximize flow rate within the adjustable ranges of the design parameters, an improved air purifier was redesigned using an orthogonal array table. By CFD analysis, the improved design showed an increased flow rate without flow separation. Finally, after fabricating a prototype with the improved design, it was experimentally proven that noise was reduced by 4.2 dBA without sacrificing flow rate.