| 摘要 |
<p>The gap between the, e.g., screw-shaped impeller blade (3) and the casing (17) should be as small as possible to achieve high efficiency. In order to counteract the accumulation of solid particles in the gap and the friction resistance produced as a result, the gap has a portion (g), whose cross-section is trapezoidal, which expands towards the suction side with an angle (e) between 15 and 40 DEG , and is bounded by a bevel at the outer blade rim. The remaining gap part, bounded by the peripheral surface (f), is preferably narrower than half the blade thickness (d). Alternatively, the cross-section of the entire gap may be trapezoidal. In that case, the blade (3) has an edge instead of the face (f). <IMAGE></p> |
