| 摘要 |
An axial flow, reversible fan for use as a plug unit in a heat treating furnace comprises a shaft, an impeller having opposing faces mounted on an end of the shaft and comprising a tankhead and a plurality of flat blades disposed about and extending radially therefrom, a first set of fixed concavo-convex vanes disposed about and extending radially from the shaft adjacent a face of the impeller, a second set of fixed concavo-convex vanes disposed about and extending radially from the shaft adjacent the opposite face of the impeller, and a driving means for rotating the impeller which is attached to the shaft. The vanes of the first and second sets of vanes each has a cross sectional radius of curvature which varies along the length of the vane such that, for a predetermined impeller diameter and fluid flow rate, a fluid drawn across the first and second set of vanes and into the spinning impeller is deflected by the vanes so that the relative velocity of the fluid to the blade as it enters the impeller is tangent to the blade and as the fluid exits the impeller, the other set of vanes is curved so that the velocity of the fluid exiting the impeller relative to the vane is tangent to the vane and the exiting fluid is deflected so that the helical swirl of the exiting fluid is eliminated. |
