| 摘要 |
<p>An impeller (10) having an axis (12) about which the impeller is rotatable in a working direction of rotation A. A plurality of aerofoil blades (14) are spaced from and arranged about the axis (12). The inwardly axis-facing surface (16) of each blade (14) defines a longer fluid flow path across the blade than the opposite outwardly-facing surface (18). Each blade has an angle of attack from 0° up to a positive angle of attack less than that at which the blade will induce turbulent fluid flow when the impeller is rotated in a fluid at a working speed in the working direction of rotation A. During such rotation the impeller induces an inlet fluid flow generally axially toward the impeller and an outward fluid flow away from the impeller in directions generally inclined about 30° or more or less relative to axis (12).</p> |
