Abstract
In the internal flow of the cross flow fan, the formation of the eccentric vortex centered on the rotor inner periphery is well known. So far, the relationship between fan shape and performance, and the formation mechanism and behavior of the eccentric vortex have been reported. However, few studies have focused on the relevance of the fan performance and the eccentric vortex. In this paper, the structure, behavior and driving power of the eccentric vortex are investigated. Next, the effect of the eccentric vortex on the performance is considered. As a result, the following becomes apparent. The entrance flow of the cross flow fan is sucked towards the eccentric vortex indicating strong suction pressure, and therefore, the velocity at the rotor inlet becomes non-uniform in the circumferential direction. Because inlet velocity becomes fast in the tongue side which is near the eccentric vortex, the driving power of the eccentric vortex becomes large. By generating swirling flow by the change of an entrance shape and decreasing tongue side velocity by the outward centrifugal force of this turning flow, the eccentric vortex power decreases and high fan efficiency is accomplished. Finally, the high-performance design guideline of the cross flow fan by controlling the eccentric vortex is proposed.
