Search

This paper studies the effects of blades' forward-swept amount in the rotation direction and forward-inclined amount in the intake direction on the flow around the fan blades of a large open-type motor. The authors have previously clarified this flow separation on the blade surface under high ventilation resistance from flow analysis and visualization experiments. To prevent flow separation, they proposed forward-swept and inclined blades, together with reduction of the air path's ventilation resistance. In this study, numerical fluid analyses were performed on the flow around forward-swept and inclined blades of axial fans for large open-type motors. Several combinations of forward-swept and inclined amounts were studied. The relationship between forward-swept and inclined amounts and flow was evaluated quantitatively, and an ideal combination was obtained. The study revealed that an axial fan with this combination showed much higher flow rate than a conventional fan without forward-swept and inclined blades. Furthermore, it significantly decreased fluid noise and axis power. [ABSTRACT FROM AUTHOR]

This paper studies the cooling performance by axial fans with forward-swept and inclined blades and a structure with low ventilation resistance for large-capacity open-type motors. The ventilation resistance of axial fans for motors is much greater than that of common fans for creating draughts. Flow separates remarkably on the blades' surfaces and fluid noise is large. We reduced the ventilation resistance inside an electric motor and adopted axial fans with forward-swept and inclined blades. We confirmed by wind tunnel experiment that the flow rate with this combination increases remarkably compared with the conventional ventilation structure and axial fans. Numerical fluid analysis was performed on the flow around the blade at this flow rate. It was confirmed that no flow separation appeared for the air flow along the blade surfaces. This was also observed in a flow visualization experiment. Furthermore, an actual motor with both the low-ventilation-resistance structure and axial fans with forward- swept and inclined blades showed that the flow rate of cooling air increased by 80% compared with that of conventional machines, and the average temperature rise of stator windings decreased by 30%. Thus, the cooling performance was greatly improved. [ABSTRACT FROM AUTHOR]