Experimental and numerical study on the inlet nozzle of a small squirrel-cage fan

The squirrel-cage fan performance is sensitive to the inlet nozzle configuration. In this paper, an experimental study combined with numerical simulation has been conducted to investigate the effects of the geometry and the installation of the inlet nozzle on the aerodynamic and acoustic performance of a small squirrel-cage fan. Both the eccentric inlet nozzle and the elliptical inlet nozzle with different levels of the eccentricity ratio and the attitude angle have been tested to search an optimal assembly to improve the aerodynamic and acoustic performance of the studied squirrel-cage fan. Based on the experimental result, three-dimensional steady viscous flow fields in the squirrel-cage fan have been simulated to reveal the flow mechanism of the performance improvement. The result indicates that an optimal elliptical inlet nozzle can reduce flow loss before fluid entering into the impeller passages and induce a tip flow pattern, contributing to promote the volume flow rate and suppress the leaking flow loss.