Influence of the Spatial Position of the Semi-open Impeller on the Internal Flow Field in Centrifugal Fans

Abstract

This paper takes as its background the study of centrifugal fans in powered air-purifying respirators. To improve the efficiency of the centrifugal fan and the uniformity of the internal flow field, a steady-state simulation based on the realizable k-ε turbulence model, using the “frozen rotor method”, was carried out to analyze the effect of the spatial position of the impeller in the centrifugal fan on the internal flow field by matching the impeller to the worm gear. The results show that varying the eccentric angle, eccentric distance, and longitudinal depth of the semi-open impeller in the volute affects the internal flow field of the centrifugal fan to varying degrees. The concentric arrangement was not found to be optimal, and when the impeller rotates slightly further away from the worm tongue, the flow field inside the centrifugal fan is more uniform and the phenomena such as “wake-jet” and boundary layer separation are significantly reduced. In addition, it was found that the pressure distribution at the inlet is approximately the same as the pressure distribution in the flow field.