RU2731552C1 - Vane pump - Google Patents

Abstract

FIELD: pumps.

SUBSTANCE: invention relates to pump engineering and can be used in pumps of aircraft and liquid-propellant rocket engines. Blade pump comprises housing (1), feed (2), impeller (4) with cover disc (7), non-contact seal (8) located on cover disk (7), annular cavity (9) at outlet of seal (8). Annular cavity (9) is connected to pump inlet (2) by bypass channels (10) made in supply (2), and is made on the side of supply (2) directly in its body.

EFFECT: invention is aimed at improving reliability and simplifying the design of the vane pump.

5 cl, 3 dwg

Description

The invention relates to the field of pumping and can be used in general-purpose pumps and pumps of aircraft and liquid-propellant rocket engines.

In various industries, vane (vane) centrifugal and screw centrifugal pumps are used, in which contactless impeller seals are used. One of the features of the application of such pumps is the leakage of working fluid through the front contactless seal of the pump impeller, which affects the efficiency and cavitation characteristics of the pump. This issue is especially relevant for pumps pumping cryogenic liquids.

The known design of a screw centrifugal pump, consisting of a housing, an impeller, a screw, a seal (Construction and design of liquid-propellant rocket engines: A textbook for university students specializing in "Aircraft engines and power plants" GG Gakhun, VI Baulin, V. A. Volodin and others; Under the general editorship of G.G. Gakhun. - M .: Mashinostroenie, 1989. P. 211, Fig. 10.12. Ovsyannikov B.V., Chebaevsky V.F. and others. High-speed scapular pumps. - M. Mashinostroenie, 1975. S. 203, Fig. 3.43)

The disadvantage of this design is that drainage of leaks to the inlet of the centrifugal impeller distorts the velocity field at the inlet to the peripheral part of the input edges of the impeller, which are most prone to the development of cavitation phenomena. In the case of using a screw centrifugal impeller in the pump, leakage into the outlet of the screw disrupts the flow of liquid not only at the inlet to the centrifugal wheel, but also in the screw, which worsens the cavitation characteristics of both the centrifugal wheel and the screw.

A known variant of the design of a vane pump, containing a housing, a pump inlet, a pump impeller with a cover disk, a contactless seal located on the cover disk, aimed at minimizing the effect of these leaks on the pressure head and cavitation characteristics. (RF patent 2380575. Screw centrifugal pump, published on January 27, 2010 Bull. No. 3).

The disadvantages of this design are:

- an increase in the diameter of the seal due to the location of the two seals of the covering disk one above the other leads to an increase in leakage through the seal and, as a consequence, a decrease in its efficiency and deterioration of cavitation characteristics;

- the presence of two seals located on the cover disk increases the length and mass of the sealing band, which for a high-speed rotor can lead to a deterioration in its dynamic characteristics;

- a combination of gaps in two closely spaced seals can lead to dynamic instability of the rotor due to a combination of gaps and hydraulic resistance in the seals (Lomakin effect).

A known variant of the design of a vane pump, containing a housing, a pump inlet, a pump impeller with a cover disk, a contactless seal located on the cover disk, aimed at minimizing the influence of these leaks on the pressure head and cavitation characteristics, taken as a prototype. (RF Patent 2534334. Auger centrifugal pump , published on November 27, 2014 Bul. No. 33 - prototype).

The disadvantages of this design are:

- an increase in the length of the sealing band leads to a displacement of the leakage injection zone after the seal, located on the cover disk to the inlet to the impeller (auger), which worsens the cavitation characteristics of the impeller and the entire pump;

- local injection of a leak at the pump inlet creates an asymmetric field of temperature and flow rate at the inlet to the impeller, which leads to a deterioration in the pump's cavitation qualities.

- when the pump operates on cryogenic components, especially on hydrogen, reliable thermal protection of the leakage pipeline to the pump inlet is required to prevent liquid vapors from entering the pump, which worsen the anti-cavitation qualities of the pump;

- the presence of a pipeline for diverting leaks to the pump inlet complicates the design and increases the mass of the pump, reduces its reliability when operating as part of an engine due to the possibility of pipeline destruction due to vibration loads,

- the presence of two seals located on the cover disk increases the length and mass of the sealing band, which for a high-speed rotor can lead to a deterioration in its dynamic characteristics;

- the combination of clearances in two closely spaced seals can lead to dynamic instability of the rotor due to the combination of clearances and hydraulic resistance in the seals (Lomakin effect).

The objective of the present invention is to eliminate the indicated disadvantages of the vane pump, increase its reliability and simplify the design.

The technical result is achieved by the fact that in a vane pump containing a housing, a pump inlet, a pump impeller with a cover disk, a contactless seal located on the cover disk, an annular cavity at the outlet of the seal, while the annular cavity is connected to the supply by bypass channels made in inlet, according to the invention, an annular cavity is made from the inlet side, directly in its body. The bypass channels can be made widening towards the pump inlet. The area of the annular cavity can be made larger than the flow area of the contactless seal. The area of the bypass openings of the channels can be made larger than the flow area of the contactless seal. The area of the annular cavity and the area of the bypass channels can be made larger than the flow area of the contactless seal.

The vane pump is represented by drawings:

figure 1 shows a vane pump with a radial supply;

in fig. 2 - node A in figure 1;

in fig. 3 - vane pump with axial supply, where:

1 - case;

2 - pump inlet;

3 - pump outlet;

4 - pump impeller;

5 - impeller;

6 - auger;

7 - cover disc;

8 - non-contact seal;

9 - annular cavity;

10 - bypass channels.

The vane pump consists of a housing 1 with a radial inlet 2 (Figs. 1-2) or an axial inlet 2 (Fig. 3) and an outlet 3, an impeller 4 of the pump. In the version of the centrifugal pump, the impeller 4 consists of an impeller 5 and a screw 6. In the version of a centrifugal pump, the impeller 4 consists only of the impeller 5. The impeller 4 of the pump is made with a cover disk 7. On the cover disk 7 of the impeller 4 there is a non-contact seal 8, at the outlet of which, on the side of the pump inlet 2, an annular cavity 9 is made, and the cavity 9 is made directly in the body of the inlet 2. Bypass channels 10 connect the annular cavity 9 with the pump inlet 2. The annular cavity 9 is made with a cross-sectional area exceeding the flow area of the contactless seal 8. The bypass holes 10 are made with an area exceeding the flow area of the contactless seal 8. The bypass channels 10 are made expanding towards the pump inlet 2.

When the vane pump is operating (Fig. 1-3), the working fluid (liquid) comes from inlet 2 to the inlet to the impeller 4. In the variant of the centrifugal screw pump, the liquid enters first into the screw 6, and then into the impeller 5. In the variant of the centrifugal pump, the liquid enters directly into the impeller 5. From the impeller 4 of the pump, the liquid enters the outlet 3, made in the housing 1, and part of the liquid through the contactless seal 8 located on the cover disk 7, under the influence of the pressure difference enters the annular cavity 9 made from the inlet side 2 , directly in its body, and through the bypass channels 10 is diverted into the pump inlet 2, while the liquid is removed either at a distance from the impeller 4, and in the presence of the screw 5 either at a distance from it, or in the part of the pump inlet 2 adjacent to the peripheral part of the screw 5. Removal of liquid from the annular cavity 9 through the bypass channels 10 into the pump inlet 2 at a distance from the impeller 4 minimizes or eliminates the effects e liquid leaks through the contactless seal 8 to the flow in the flow path of the impeller 4 of the pump, which increases the anti-cavitation qualities of the pump.

The excess of the area of the annular cavity 9 in cross-section over the flow area of the contactless seal 8 prevents the occurrence of dynamic flow instability (Lomakin effect), which favorably affects the dynamic characteristics of the pump rotor.

The excess of the cross-sectional area of the bypass channels 10 over the flow area of the non-contact seal 8 with a certain combination of the cross-sectional areas of the non-contact seal 8, the cross-section of the annular cavity 9 and the by-pass channels 10, ensures complete elimination of leaks from the non-contact seal 8 at the entrance to the pump impeller 4. This provides high anti-cavitation properties of the pump by eliminating the influence of leaks through the contactless seal 8 on the fluid flow in the flow path of the pump impeller 4 and in the pump inlet 2. Since the leakage to the pump inlet is discharged through channels 10 made directly in the casing, its input into the flow is uniform and has a minimal effect on the pump's cavitation characteristics, the execution of channels 10 directly in the pump casing does not require their additional thermal insulation when using a cryogenic working fluid.

The bypass channels 10 expanding towards the pump inlet 2 provide a low fluid velocity at the inlet to the flow path of the inlet 2 and minimal pressure losses in the inlet due to the effect of the liquid flowing out from the bypass channels 10.

Experimental studies have shown that thanks to the proposed invention, the anti-cavitation qualities of vane pumps, especially small-sized ones, are significantly improved.

Claims (5)

1. A vane pump containing a housing, a pump inlet, a pump impeller with a cover disk, a non-contact seal located on the cover disk, an annular cavity at the outlet of the seal, while the annular cavity is connected to the inlet by bypass channels made in the inlet, characterized in that, that the annular cavity is made from the inlet side, directly in its body 2. A vane pump according to claim 1, characterized in that the bypass channels are made expanding towards the pump inlet. 3. A paddle pump according to claim 1, characterized in that the area of the annular cavity in its cross section is larger than the flow area of the contactless seal. 4. A paddle pump according to claim 1, characterized in that the area of the bypass openings of the channels is made larger than the flow area of the contactless seal. 5. A vane pump according to claim 1, characterized in that the area of the annular cavity and the area of the bypass channels are made larger than the flow area of the contactless seal.

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