Aerodynamic performances and efficiency of axial flow fan placed in cooling system

Abstract

Abstract One way to reduce the aerodynamic noise generated by the cooling system of construction machinery is to improve the fan efficiency and then drive the cooling fan at a lower speed. Computational Fluid Dynamics (CFD) is effective for clarifying the mechanisms of the fan efficiency, but there are few reports that capture the flow field around the axial fan blades installed in the cooling system of construction machinery, that is, in a high static pressure environment. Moreover, from the viewpoint of the three-dimensional flow field, the fan efficiency has not been sufficiently studied. In this study, the flow field of the entire cooling system including an axial cooling fan was visualized by numerical simulation using ANSYS-CFX17.0, and the effect of the flow field formed around the blades on the fan efficiency was investigated. In case of a single axial fan, increase or decrease in pressure caused by airflow collision or separation is higher than the entire cooling system. As a result, the loss becomes large. In addition, the increase in loss due to collision or separation occurs regardless of the blade span length, and its magnitude is proportional to the circumferential velocity at each point of the blade except for the blade tip.