﻿ Cooling Fan Model for Thermal Design of Compact Electronic EquipmentModeling of Swirl Flow at the Exit of Axial-Flow-Fan - Volume 7, No. 1, January 2018 - IJEETC
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## Cooling Fan Model for Thermal Design of Compact Electronic EquipmentModeling of Swirl Flow at the Exit of Axial-Flow-Fan

Hajime Nakamura
Department of Mechanical Engineering, National Defense Academy of Japan, Yokosuka, Japan
Abstract—In order to hasten the thermal design for forced convection electronic devices, cooling fans should be modelled to reduce a computational load. A fan-curve-model, which generates volumetric flow rate according to the PQ curve, is very simple and usually incorporated into commercial CFD codes. However, the conventional model does not specify the flow field at the exit of a fan since the PQ curve has no information on the flow swirling. Thus, in this work, the swirl force acting on the flow was modelled mathematically by introducing a non-dimensional “swirl coefficient”, which can be incorporated into the fan-curve-model. The swirl coefficient was evaluated using the detailed CFD simulation taking the rotating blades into account, and the result indicated that this coefficient can be treated as a constant regardless of radial position of the blade. Then, the flow behind the fan was simulated using the fan-curve-model incorporated with the swirl coefficient. As a result, it was confirmed that a realistic velocity distribution can be generated within the normal usable range of the fan where the rotating stall does not occur.

Index Terms—axial flow fan, modeling, PQ curve, swirl flow, thermal design, electronic equipment

Cite: Hajime Nakamura, "Cooling Fan Model for Thermal Design of Compact Electronic EquipmentModeling of Swirl Flow at the Exit of Axial-Flow-Fan," International Journal of Electrical and Electronic Engineering & Telecommunications, Vol. 7, No. 1, pp. 21-25, January 2018. Doi: 10.18178/ijeetc.7.1.21-25