Profile Scaling Of Miniature Centrifugal Fans

摘要

This paper addresses issues that relate to downscaling the height of centrifugal fans for application in low profile technologies, such as the cooling of portable power electronics. The parameters studied include flow rate, pressure rise, and power consumption characteristics. The former two of these are measured using a fan characterization rig and the latter by directly measuring the power supplied to the fan. These are studied for fan diameters ranging from 15 to 30 mm with numerous profile heights between 0.3 mm and 15 mm. It is found that all of the phenomena encountered are best described in terms of fan aspect ratio. The results show that the conventional scaling laws cannot be accurately applied when blade profile alone is scaled. Indeed, the only parameter reasonably well predicted was the pressure rise attainable, but that was only accurate for fan aspect ratios greater than 0.17. Below this, the pressure rise generated reduces logarithmically toward zero. The study also reveals that no advantage is gained by using fans of aspect ratio greater than 0.3, as the maximum flow rate attainable decreases slightly above this. Overall, the scaling phenomena reported herein provide invaluable information for the future design of efficient low-profile cooling solutions that are to incorporate such fans.