<p>Hub-less rim-driven fans have newly emerged as the most compact type of axial flow fans,&nbsp;which permits&nbsp;flexible configuration arrangements, large relative flow area and low-noise level operation.&nbsp;However, previous publications on hub-less axial flow fans are rarely found in the open literature, and the flow mechanism and design principle of such promising fans haven’t yet been well-understood and established. This paper has been focused on a preliminary study of the hub-less axial flow fan design and flow mechanism. A design method of the hub-less fans is proposed on the basis of the isolated airfoil scheme and the exponential non-constant circulation rule. It is further incorporated into a FORTRAN code and suited for designing the hub-less rim-driven&nbsp;fans of low-pressure levels.</p><p>For validation purpose, a conventional hub-type fan is redesigned with the developed method and its flow behavior and overall performance are investigated numerically. A&nbsp;parametric study on the designed fan is further conducted respectively for the aerodynamic loading factor, non-constant&nbsp;exponential&nbsp;and sweep angle and their influence on the fan flow characteristics and overall performance are explored and highlighted. On such a basis, the developed design method for the hub-less axial flow fan is further improved. In comparison with the conventionally designed fan at identical rotating speed, significant comprehensive gains are arising from the redesigned fan of hub-less configuration: the overall pressure rise and static pressure efficiency is enhanced respectively by 6.2% and 11.5%, whereas the diameter of the fan is reduced by 12.5% simultaneously. It is demonstrated that the rim-driven hub-less configuration is promising for the enhancing the fan overall performance with even reduced dimensions.</p>

Design and Flow Analysis  of the Rim-Driven Hub-Less Axial Flow Fan

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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