Regenerative pump having rotor with blades whose inclination var

Details Regenerative pump having rotor with blades whose inclination var Regenerative pump having rotor with blades whose inclination var

1992-09-09

1994-04-05

Look, Edward K.

Rotary kinetic fluid motors or pumps

With means for re-entry of working fluid to blade set

Turbine regenerative pump

415 552, F04D 500, F04D 2918

Patent

active

052999084

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a regenerative pump of the kind comprising a housing with a pump inlet and a pump outlet, an impeller rotatably mounted within the housing and having a plurality of blades forming a series of cells spaced angularly around the axis of rotation of the impeller, and a flow channel within the housing extending between the pump inlet and pump outlet and including a guide channel in the housing located alongside the impeller so that the cells open laterally of the plane of rotation of the impeller into said guide channel and cooperate therewith to induce a spiral or helical flow of fluid through the guide channel and cells along the length of said flow channel as the impeller is rotated.
In the known regenerative pumps of this kind, the blades of the impeller may extend perpendicular to the plane of rotation of the impeller or may be inclined from this perpendicular plane forwards in the direction of rotation at their outer edge so that the cells fill more efficiently and throw the fluid forwards into the guide channel as the impeller rotates. Typically, the blades are inclined at an angle of approximately 45 degrees and the opposite surfaces of each blade are flat and parallel to one another and at their outer edges meet a flat outer surface of the blade parallel to the plane of rotation of the impeller which closely cooperates with the inner surfaces of the housing to limit the circumferential flow of fluid between adjacent cells, especially in the region known as the stripper between the pump outlet and pump inlet. In all cases, the blades are of a substantially uniform cross-section throughout their radial length; in particular those sections adjacent to the pump inlet and guide channel have the same cross-section.


DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a regenerative pump of the aforesaid kind with improved performance.
According to the present invention, a regenerative pump of the aforesaid kind has blades which are adapted so that the profile of the trailing surface of each blade varies radially, the trailing surface of the blade over a first radial portion adjacent to the pump inlet being inclined forwardly in the direction of rotation towards its outer edge as compared with the trailing surface of the blade over a second radial portion adjacent to the guide channel.
The inclination of the trailing surfaces of the blades of the impeller over said first radial portion adjacent to the pump inlet is selected so as to reduce unstable flow conditions and cavitation affects in this region and thereby reduce secondary motion in the radially outward flow in the cells. The recirculating flow in the guide channel is therefore enhanced and the head pressure generated by the pump increased. Further, flow losses in the pump are reduced and pump efficiency increased. These improvements are especially significant under low inlet pressure conditions and help to delay the onset of vapour formation in the pump that would block the through flow.
The inclination of the trailing surface of the blade over said second radial portion adjacent to the guide channel is selected to match the flow between the cells and the guide channel as the fluid recirculates between the two. This involves a difference in inclination of the trailing surfaces of said first and second radial portions, the trailing surface of the first radial portion being relatively inclined forwards in the direction of rotation towards its outer edge.
In one embodiment of the invention, the relative forward inclination of the trailing surface over said first radial portion of the blade is produced by a chamfer that extends across the rear outer portion of the blade. The leading and trailing surfaces of each blade may be substantially parallel except for this chamfer on the trailing edge over said first radial portion.
Preferably, the outer edge of each blade has a flat surface parallel to the plane of rotation of the impeller so as to cooperate with adjacent portions of the inner s

REFERENCES:
patent: 1689579 (1928-10-01), Burks
patent: 4804313 (1989-02-01), Nasvytis
patent: 5123809 (1992-06-01), Ito

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