| 摘要 |
<p>Axial flow impeller having at least two rows, preferably three rows, of a plurality of blades secured substantially radially to a rotor for rotation in a plane about the axis of the rotor. The blades have the same pitch throughout their lengths with the blades of the first row having a pitch angle less than the stall angle of the blades, preferably about 22.degree., the blades of the second row having a pitch angle greater than the pitch angle of the blades of the first row and less than the stall angle of the blades, preferably about 13.degree. greater than the pitch angle of the first row of blades, and the blades of a third row of blades having a pitch angle greater than the pitch angle of the blades of the second row and less than the stall angle of the blades, preferably about 13.degree. greater than the pitch angle of the second row of blades. The blades of a row of blades are circumferentially spaced apart relative to the chord length of the blades at a ratio of spacing to chord length within the range of about 0.75:1 to 1.5:1, preferably about unity. Each blade in the second row of blades, and in a third row of blades, is axially displaced from a blade in the preceding row of blades up to about one-half of the chord length of the preceding blade, preferably about one-third chord length, and each successive blade of a set of blades is laterally displaced not less than the chord thickness below the preceding blade such that the combined airflow from the preceding blade is directed over top of the said blade.</p> |
