| 摘要 |
PURPOSE:To prevent a back-flow phenomenon being produced at the impeller inlet even in the range of a discharge below the design capacity, by installing a circular restriction body (orifice) with an auxiliary vane within the circumference in the impeller inlet end. CONSTITUTION:In order to raise pump performance, even when a pump that is made to enlarge a suction eye diameter De is operated below the design cacity, in case of this pump, the inlet diameter of an impeller 14 is so designed to be narrower than said De, i.e. De', by an orifice 19 so that a counter-flow phenomenon in the vicinity of an internal surface 6a of a side plate 16 is well prevented. In addition, thanks to an auxiliary vane 23 at an internal circumferential surface 19a of the orifice 19, fluid going toward a vane 18 is pre-turned as in the regular preturn direction of the vane 18 and at the same time its pressure goes up somewhat so that the prevention of a back flow is achieved positively. Therefore, suction performance becomes improved over the operational range of discharge pumps. |
