CZ300288B6 - Impeller, particularly centrifugal pump impeller - Google Patents

Abstract

In the present invention, there is disclosed an impeller, particularly a centrifugal pump impeller being formed by a supporting disk (1) provided with main blades (2) creating through-flow passages (3) with short blades disposed therein, whereby said short blades (4) are performed and located so that for the total inlet flow surface (Si1) of the passage (3) at the level of the short blade (4) admission edge (41) and the total outlet flow surface (Si2) of the passage (3) at the level of the short blade (4) trailing edge holds that the relationship Si1 is greater than or equal to 1/3 Si2 and wherein for the total outlet flow surface (Si2) and an upper inlet flow surface (SiA) and the lower inlet flow surface (SiB) obtained by division of the passage (3) at the level of the short blade (4) admission edge (41) holds that a relationship (SiB - SiA) is less than or equal to 0,1 Si2, wherein SiB + SiA = Si1.

Description

Technical field

The invention relates to a new impeller design, in particular a low speed centrifugal pump.

io Hitherto celebrated technology

For low speed centrifugal pumps characterized by the specific speed given by i? n _s <40 rpm, which are designed for low flow rates and high head, impellers are generally used. which are characterized by a small width and a large diameter, resulting in a large length of the blades at their small thickness. These design requirements result in the inlet channel width of the impeller being much smaller than the outlet channel width, and this disproportion leads to the formation of vortices in the channel space during operation of the pump. which causes large hydraulic losses. Hydraulic losses then increase significantly as the impeller width decreases and its impeller thickness increases.

One possibility of reducing hydraulic losses in this type of impeller is by inserting intermediate blades in the channels as described, for example, in US 3 953 150, JP 59165895. JP 9042194. WO2005 / 108796 or EP 684386. A common feature of the present solutions is. The intermediate blades have substantially the same hydraulic shape as the main blades, but have a shortened length and are located in the center of the channel. Although these solutions lead to an increase in head, they result in deterioration in hydraulic efficiency, due to the fact that the nozzle of relative velocities does not connect continuously to the inlet portion of the intermediate shoe, so that the boundary layer tears off and the hydraulic loss increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solution which overcomes the above-mentioned drawbacks, utilizing the latest knowledge and results of experiments in monitoring and researching relative velocity streams.

SUMMARY OF THE INVENTION

This is achieved by the invention, which is an impeller, in particular a centrifugal pump, comprising a support disk provided with main blades forming flow channels in which intermediate blades are inserted, the principle being that the intermediate blades are designed and positioned so that for the total inlet flow area S] of the channel at the level of the inlet edge of the intermediate stop and the total outlet flow area of S _{2 of the} channel at the level of the outlet edge of the stop

S,> 1/3 S ₂ .

5 (i, where the relation (S _K - S _A ) <0.1 S _? Applies between the total outlet flow area S ₂ and the upper inlet flow area S _A and the lower inlet flow area S _R.

where

S | _S + S.

It is a further object of the invention that the relation βν = (0.8 to 1.2) βμ applies between the intermediate exit angle β _{ν of} the intermediate stop edge and the main exit angle βμ of the main blade outlet edge.

io The new impeller design achieves a higher effect by increasing the pump head and the hydraulic efficiency of the pump, resulting in energy savings. Increasing efficiency allows the impeller diameter to be reduced, and this results in reduced pump weight. Another process is that by removing the impact component of the velocity at the inlet to the intermediate bladder, the acoustic noise and the vibration of the pump are reduced, thereby transferring smaller forces to the i? basis. An important factor is also the reduction of pressure pulsations transmitted by the pump discharge to the hydraulic system.

Overview of the drawings

A particular embodiment of the invention is shown schematically in the accompanying drawings, in which Fig. T is a cross-section of the impeller in a plan view, Fig. 2 is a cross-section. the impeller of FIG. 1 with an axonometric representation of the flow surfaces of the channel.

DETAILED DESCRIPTION OF THE INVENTION

The impeller of the centrifugal pump according to the invention is formed by a support disk K on the upper surface of which the main blades 2 are regularly arranged, forming the flow channels 3. Intermediate shoes 4 are inserted in the flow channels 3 and designed so that at the level of the inlet edge 41 of the intermediate stop 4 and the total outlet passage area S _{2 of the} channel 3 at the level of the outlet edge 42 of the intermediate stop 4, and hence of the main blade 2.

S,> 1/3 S ₂ .

jo same time, then the total exit flow area _S2 and the upper inlet flow area S \ and a lower inlet flow area _LI, resulting from the splitting channel 3, at the inlet edge 44 of the short blade 4, the relationship _{(S! t} - _S) <0 1 S ₂ , where

Sb ⁺ S _A = S |

5o The intermediate blades 4 are further designed such that the relationship between the secondary exit angle k k of the exit edge 42 of the intermediate blades 4 and the main exit angle βμ of the exit edge 22 of the main blade 2 applies

3v = (0.8 to 1.2) βμ

CZ 300288 Bo

A prerequisite for achieving the desired efficiency and performance of the pump is that the inlet angle 44 of the intermediate blade 4 (not shown) is connected to the shape of the central nozzle of the relative velocities of the pumped medium.

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The described embodiment of the invention is not the only possible constructional solution, when it can be used for both full and shortened impellers K and o

The impeller construction according to the invention can be used in particular for centrifugal pumps intended for low flow rates and high head heights.

Claims (1)

I. Impeller. in particular a centrifugal pump, comprising a support disk (1) provided with main vanes (2) forming flow channels (3) in which intermediate blades (4) are inserted. characterized in that the intermediate flaps (4) are formed and positioned such that for the total inlet flow area (S1) of the channel (3) at the level of the inlet edge (41) of the intermediate flaps (4) and the total outlet flow area (S ₂ ) channel (3) at the level of the output edge (42) of the intermediate stop (4) applies S,> 1/3 S ₂ . su wherein between the total outlet flow area (S ₂ ) and the upper inlet flow area (S _A ) and the lower inlet flow area (Su). by dividing the channel (3) at the level of the inlet edge (41) of the intermediate shoe (4). (S _B --S., \) <0.1 S ₂ . where S | t + S _A - S | An impeller according to claim 1. characterized in that the relation βν = (0,8 to 1) applies between the minor exit angle (β _ν ) of the exit edge (42) of the intermediate blade (4) and the main exit angle (β _Μ ) of the exit edge (22) of the main blade (2). 2) β '. ! drawing