The invention relates to a single-impeller axial fan in a dragging electric machine brake cooling system, replacing the two-stage impeller series operating structure with a single-impeller structure added with front guide vane, adopting a technical solution of front guide vane + impeller + rear guide vane, adding a reverse guide vane in front of the impeller, then changing axial support plate of the electric machine into streamlined guide plate designed according to air flow direction and improving vane profile design for the impeller, where the vane is wide outside and narrow inside and of a bent-swept combined shape, and the vanes are not equidistantly arranged. For improving flow field, it can further install the electric machine on the end cover of an inner cylinder body and the inner cylinder body is connected with the machine casing through the rear guide vane. As the fan runs, the air is pre-rotated through the reverse front guide vane and then flows into the impeller, thus improving work doing ability of the impeller, and the novel streamlined electric machine support plate and vane can improve fan operating conditions, raise fan efficiency, reduce air flow separation and save energy and reduce noises by a larger margin. |