GB910968A - Improvements in and relating to variable pitch mixed-flow pumps - Google Patents

Abstract

910,968. Centrifugal pumps. ENGLISH ELECTRIC CO. Ltd. Sept. 21, 1960 [Sept. 23, 1959], No. 32343/59. Class 110 (1). In a variable-pitch mixed-flow pump having main runner vanes 2 pivotally mounted in the runner 3 with their axes converging at a common point on the pump axis, a booster stage of runner vanes 22 is arranged upstream of the main runner vanes 2. The vanes 22 raise the local pressure at the leading edges of the main vanes 2 sufficiently to prevent cavitation without requiring deep submergence of the pump and may be fixed or, as shown, may be of adjustable pitch. As shown, the adjustment may be effected by the same rotatable control shaft 15 that effects adjustment of the pitch of the main vanes 2. Alter. natively, a separate control shaft inside the shaft 15 may be used. An arm 10 keyed to the trunnion of each main vane 2 is slotted to engage a slider block 11 carried by a pivot 12. The pivots 12 are carried by a ring 18 attached to the shaft 15, the axes of the pivots 12 converging at the same point as the axes of the main vanes 2. A similar arrangement is used for the adjustment of the vanes 22. The pump may handle liquid sodium, which may act as a lubricant for the trunnions of the adjustable vanes. Reference has been directed by the Comptroller to Specification 752,068.