CN113294342A

CN113294342A - Centrifugal pump

Info

Publication number: CN113294342A
Application number: CN202110743955.6A
Authority: CN
Inventors: 晁文雄; 曹庆年; 郝杰; 吴奇; 段跟定; 范文雯; 何文博
Original assignee: Xian Aeronautical University
Current assignee: Xian Aeronautical University
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2021-08-24
Anticipated expiration: 2041-06-30
Also published as: CN113294342B

Abstract

The invention discloses a centrifugal pump, which comprises a volute, a rear cover plate and an impeller, wherein the impeller is rotatably arranged between the volute and the rear cover plate, and blades are connected to the impeller; the blades are provided with axial holes, and the axial holes penetrate through the blades and the impeller; the axial holes are arranged on the blades at intervals along the extending direction of the blades, and can play at least one role of reducing liquid backflow of blade top gaps, reducing cavitation and balancing axial force, so that the efficiency of the centrifugal pump is improved.

Description

Centrifugal pump

Technical Field

The invention relates to the field of aerospace centrifugal pumps, in particular to a centrifugal pump.

Background

In order to reduce the volume and size of the centrifugal pump, the aerospace system improves the rotating speed, and the problem brought by the fact that the centrifugal pump is small in size, so that blade top gaps exist in semi-open type and full-open type centrifugal pumps under the rotating speed of tens of thousands of turns of impellers; because the pressure on the pressure surface of the blade is higher than that on the suction surface, the partial liquid flow bypasses the edge of the blade top and enters the axial gap between the shell and the blade, leakage flow is formed at the blade top gap of the blade, and finally returns to the inlet of the impeller, so that a part of liquid flow in the impeller always circulates in the gap, energy loss is caused, the flow is called gap leakage flow, and the hydraulic efficiency is reduced and the axial force problem is caused; when the impeller of the centrifugal pump rotates at a high speed to apply work to aviation liquid, cavitation is easily generated in a low-pressure area, and the pressure and flow characteristics of the centrifugal pump are reduced by the cavitation; the centrifugal pump has a plurality of methods and structures for preventing cavitation, for example, measures such as adopting a double-suction impeller and additionally arranging an inducer are adopted, but the existing centrifugal pump structure is required to be changed; for the situation that the aerospace system has limited the overall dimension, the installation interface position, the quality and the processing period of the centrifugal pump, cavitation-resisting measures such as a double-suction impeller, an additional inducer and the like cannot be adopted, and a new cavitation-resisting centrifugal pump structure needs to be designed.

Therefore, to solve the above problems, a centrifugal pump is needed, which can at least play one of the following roles, reducing the backflow of the liquid in the tip clearance, reducing the cavitation and balancing the axial force, thereby improving the efficiency of the centrifugal pump.

Disclosure of Invention

In view of the above, the present invention is directed to overcoming the drawbacks of the prior art, and providing a centrifugal pump capable of at least one of reducing the backflow of the liquid in the tip clearance, reducing the cavitation erosion, and reducing the axial force, thereby improving the efficiency of the centrifugal pump.

The centrifugal pump comprises a volute, a rear cover plate and an impeller, wherein the impeller is rotatably arranged between the volute and the rear cover plate, and blades are connected to the impeller; the blades are provided with axial holes, and the axial holes penetrate through the blades and the impeller; the axial holes are arranged on the blades at intervals along the extending direction of the blades.

Further, along the direction from the far end of the blade to the near end of the blade, the distance between adjacent holes of the axial holes is gradually increased; the near end of the blade is close to the liquid inlet of the volute in the radial direction, and the far end of the blade is far away from the liquid inlet of the volute.

Furthermore, the plurality of axial holes are communicated through radial holes, and the radial holes are arranged on the blade along the extending direction of the blade in the axial projection.

Further, normal direction hole has been seted up to the blade near-end, normal direction hole intercommunication radial hole, in axial projection the orientation of seting up of normal direction hole with radial hole's extending direction is the contained angle, and the scope of contained angle alpha formed is: alpha is more than 150 degrees and less than 90 degrees.

Furthermore, the normal holes are formed in axial holes at the near ends of the blades and communicated with the radial holes, at least two normal holes are formed in the axial holes at the near ends of the blades, and one of the normal holes and the radial hole in the radial section are located on the same plane.

Furthermore, the blade is arc-shaped in axial projection, the far end of the blade is positioned at the radial edge of the impeller, and the near end of the blade is close to the center of the impeller; the impeller is characterized in that the number of the blades is a plurality, the blades are uniformly distributed on the impeller along the radial direction, and the arc-shaped bending directions of the blades are consistent.

The impeller further comprises a plurality of auxiliary blades, the auxiliary blades are arranged between adjacent blades at intervals on the axial projection, the auxiliary blades are arc-shaped, the arc-shaped bending direction of the auxiliary blades is consistent with that of the blades, and the auxiliary blades are uniformly distributed on the impeller along the radial direction; the far end of the auxiliary blade is positioned at the radial edge of the impeller, and the near end of the auxiliary blade is positioned between the near end of the blade and the far end of the blade; the normal of the near end of the blade is intersected with the normal of the near end of the auxiliary blade.

Further, the axial height of the blade is gradually increased along the direction from the distal end of the blade to the proximal end of the blade; the axial height of the auxiliary blade is gradually increased along the direction from the far end of the auxiliary blade to the near end of the auxiliary blade; the radial circle taking the center of the impeller as the center of a circle is intersected with the blades and the auxiliary blades, and the axial height of the intersection point of the blades and the radial circle on the same radial circle is consistent with the axial height of the intersection point of the auxiliary blades and the radial circle.

Furthermore, an auxiliary axial hole is formed in the auxiliary blade and penetrates through the auxiliary blade and the impeller; the auxiliary axial holes are arranged on the auxiliary blade at intervals along the extending direction of the auxiliary blade; and the distance between adjacent holes of a plurality of auxiliary axial holes is gradually increased along the direction from the far end of the auxiliary blade to the near end of the auxiliary blade.

Further, a liquid storage cavity is formed in the rear cover plate and communicated to the inner cavity of the volute through an axial hole.

The invention has the beneficial effects that: the invention discloses a centrifugal pump, wherein an impeller is rotatably arranged on a rear cover plate through a shaft end nut and a transmission shaft matched with the shaft end nut, a volute and the rear cover plate are fixed through axial screws uniformly arranged along the radial direction, a liquid inlet of the volute is arranged at the central position of the volute along the radial direction, the impeller is connected with blades, axial holes are formed in the blades and penetrate through the blades and the impeller, the axial holes can form included angles with the blades along the axial direction to resist generated gap leakage flow so as to more fit and prevent the gap leakage flow, and the axial holes are vertically formed along the axial direction, so that the machining precision is improved, the machining difficulty is reduced, and the structural strength of the blades is ensured; the axial holes are arranged on the blades at intervals along the extending direction of the blades, so that after the impeller, the volute, the back cover plate, the transmission shaft and the shaft end nuts in the centrifugal pump are assembled, when the transmission shaft drives the impeller to rotate at a high speed, a medium applies work and is pressurized by the impeller and then flows through the volute, part of high-pressure liquid flows to a cavity between the back cover plate and the bottom end face of the impeller through a gap between the volute and the back cover plate, a flow blocking wall which is approximately closed is formed by liquid which is jetted out at a high speed in the axial holes of the blades on the impeller, the inner wall surface of the volute and the blades, leakage caused by the existence of blade top gaps such as secondary flow, vortex, backflow and the like is reduced, the volume loss and the hydraulic loss of the fuel centrifugal pump are reduced, the cavitation performance of the centrifugal pump can be reduced, the leakage of the blade top gaps can be reduced, and the appearance size, the installation interface position and the weight of the centrifugal pump can not be changed, the phenomenon of unreasonable size when the engine is installed is avoided.

Drawings

The invention is further described below with reference to the following figures and examples:

FIG. 1 is a schematic top view of the present invention;

FIG. 2 is a schematic view of the structure of FIG. 1 taken along direction A-A;

FIG. 3 is a schematic structural view of an impeller according to the present invention;

FIG. 4 is a schematic view of the structure of FIG. 3 in the direction C-C;

FIG. 5 is a schematic side view of the present invention;

FIG. 6 is a schematic view of the structure of FIG. 5 in the direction B-B;

FIG. 7 is a cross-sectional view of the present invention taken along the direction of extension of the blade.

Detailed Description

FIG. 1 is a schematic top view of the present invention; FIG. 2 is a schematic view of the structure of FIG. 1 taken along direction A-A; FIG. 3 is a schematic structural view of an impeller according to the present invention; FIG. 4 is a schematic view of the structure of FIG. 3 in the direction C-C; FIG. 5 is a schematic side view of the present invention; FIG. 6 is a schematic view of the structure of FIG. 5 in the direction B-B; FIG. 7 is a cross-sectional view of the present invention taken along the direction of extension of the blade; as shown in the figure, the axial direction in the scheme is based on the axial direction of a transmission shaft 4, and the radial direction is based on the radial direction of the transmission shaft 4, the centrifugal pump in the embodiment includes a volute 1, a back cover plate 2 and an impeller 3, the impeller 3 is rotatably disposed between the volute 1 and the back cover plate 2, as shown in the figure, the impeller 3 is rotatably mounted on the back cover plate 2 through a shaft end nut 5 and the transmission shaft 4 matched with the shaft end nut, the volute 1 and the back cover plate 2 are fixed through axial screws uniformly arranged along the radial direction, a liquid inlet of the volute 1 is disposed at the radial center position of the volute 1, the impeller 3 is connected with a blade 6, an axial hole 01 is formed in the blade 6, the axial hole 01 penetrates through the blade 6 and the impeller 3, wherein the axial hole 01 can be formed at an included angle with the blade 6 along the axial direction to resist the generated gap leakage flow so as to more appropriately and prevent the gap leakage flow, but the consideration of the comprehensive factors such as the processing difficulty, the manufacturing cost, the structural strength, the processing precision and the like is limited, the axial hole 01 is vertically arranged along the axial direction in the scheme, the processing precision is improved, the processing difficulty is reduced, and the structural strength of the blade 6 is ensured; as shown in the figure, the axial holes 01 are a plurality of, the axial holes 01 are arranged on the blades 6 at intervals along the extending direction of the blades 6, so that after the impeller 3, the volute 1, the back cover plate 2, the transmission shaft 4 and the shaft end nut 5 in the centrifugal pump are assembled, when the transmission shaft 4 drives the impeller 3 to rotate at a high speed, a medium applies work and is pressurized by the impeller 3 and then flows through the volute 1, part of high-pressure liquid flows to a cavity between the back cover plate 2 and the bottom end face of the impeller 3 through the gap between the volute 1 and the back cover plate 2, a flow blocking wall which is approximately closed is formed by the liquid which is ejected at a high speed in the axial hole 01 of the blades 6 on the impeller 3, the inner wall of the volute 1 and the blades 6, leakage caused by the existence of blade top gaps in secondary flow, vortex, backflow and the like is reduced, so that the volume loss and hydraulic loss of the centrifugal pump of fuel oil are caused, and the purpose of balancing the axial force is achieved at the same time, the cavitation performance of the centrifugal pump can be reduced, the leakage of the blade top gap can be reduced, the appearance size, the installation interface position and the weight of the centrifugal pump can be unchanged, and the phenomenon that the size is unreasonable when the centrifugal pump is installed on an engine is avoided.

In this embodiment, the distance between adjacent holes of the plurality of axial holes 01 gradually increases along the direction from the distal end of the blade 6 to the proximal end of the blade 6; because the pressure at the far end of the blade 6 is greater than the pressure at the near end of the blade 6, and the axial force generated at the corresponding position needs to be balanced, the pressure relief effect at the far end of the blade 6 needs to be improved inevitably, so that the distance between adjacent holes of the axial holes 01 is gradually increased in the scheme, the near end of the blade 6 is close to the liquid inlet of the volute 1 along the radial direction so as to balance the axial force, and the far end of the blade 6 is far away from the liquid inlet of the volute 1.

In this embodiment, the plurality of axial holes 01 are communicated with each other through a radial hole 02, and the radial hole 02 is formed in the vane 6 along the extending direction of the vane 6 in the axial projection. Certainly, the radial holes 02 may also be inserted, or crossed, etc. to communicate with the plurality of axial holes 01, so as to improve the pressure relief effect and play a corresponding role in reducing the cavitation performance of the centrifugal pump, as shown in the figure, the radial holes 02 are opened inside the vane 6, and the opened path is consistent with the extending direction of the vane 6, as described above, the distance between adjacent holes of the plurality of axial holes 01 is gradually increased, so that the pressure is gradually applied to the proximal end of the vane 6 from the axial hole 01 near the distal end of the vane 6, and in the application process, since the plurality of axial holes 01 are communicated with each other through the radial holes 02, the pressure is continuously applied inward along the opening direction of the radial hole 02 (i.e., from the distal end of the vane 6 toward the proximal end of the vane 6) when passing through one axial hole 01, so as to gradually transmit the pressure to the proximal end of the vane 6, so as to further play a role in balancing the axial force, in the scheme, the radial holes 02 are limited by the height of the blades 6 and the structural strength of the blades 6, only one radial hole 02 is formed, the number of the radial holes 02 can be increased according to actual requirements and is not more than two at most so as to ensure the structural strength of the blades 6 and the flow guide effect, and the description is omitted here, the opening diameters of the radial holes 02 and the axial holes 01 are the same, and the ratio of the opening diameters is between 0.98 and 1.02 so as to ensure good flow guide effect and balance the action of the axial force.

In this embodiment, a normal hole 03 is formed at the proximal end of the blade 6, the normal hole 03 is communicated with the radial hole 02, an included angle is formed between the forming direction of the normal hole 03 and the extending direction of the radial hole 02 in the axial projection, and the range of the included angle α is as follows: alpha is more than 150 degrees and less than 90 degrees. The normal direction hole 03 is set towards the low-pressure area of the blade 6, as shown in the figure, in the scheme, the normal direction hole 03 is set perpendicular to the radial hole 02 in the axial projection to ensure the structural strength, the processing is convenient to process and the aperture processing precision is improved, and the setting of the normal direction hole 03 communicated with the radial hole 02 has the effect of improving the pressure at the near end of the blade 6, so that the pressure transmitted from the radial hole 02 along the extension direction of the blade 6 is released and transmitted to a low-pressure area, the pressure of the low-pressure area at the inlet of the centrifugal pump impeller 3 is effectively improved by improving the local pressure, the fuel pressure is greater than the saturated vapor pressure at the local temperature, the cavitation resistance of the centrifugal pump is improved, the normal operation of the centrifugal pump is ensured, and the service life is prolonged. In this embodiment, the normal holes 03 are formed in the axial holes 01 at the proximal ends of the blades 6 and are communicated with the radial holes 02, at least two normal holes 03 are formed in the axial holes 01 at the proximal ends of the blades 6, and one of the normal holes 03 and the radial hole 02 in the radial cross section are located on the same plane. As shown in the figure, the blade 6 is provided with four normal holes 03 which are correspondingly and respectively arranged on two axial holes 01, the connecting lines of the four normal holes 03 projected along the axial direction are rectangular, the liquid inlet along the axial volute 1 is arranged at the top of the normal holes 03,

in this embodiment, a liquid storage cavity 21 is formed in the rear cover plate 2, and the liquid storage cavity 21 is communicated to an inner cavity of the volute 1 through an axial hole 01. The liquid storage cavity 21 is formed to increase the jet pressure of the axial holes 01, enable each axial hole 01 to be effectively filled with liquid, form a liquid flow blocking wall which jets towards the inner wall surface of the volute 1, and further achieve the effects of balancing the axial force and improving the anti-cavitation performance through the radial holes 02 and the normal holes 03. In this embodiment, the blades 6 are arc-shaped in axial projection, so that the radial direction of the radial hole 02 is also arc-shaped, the acceleration of the fluid is increased, the turbulence and the action of balancing axial force are improved, the far ends of the blades 6 are located at the radial edge of the impeller 3, and the near ends of the blades 6 are close to the center of the impeller 3; the blades 6 are uniformly distributed on the impeller 3 along the radial direction, and the arc-shaped bending directions of the blades 6 are consistent. As shown in the figure, the three blades 6 are uniformly arranged around the center of the impeller 3, so that the weight of the centrifugal pump is reduced, and the normal operation of the centrifugal pump can be ensured.

In the embodiment, the impeller further comprises a plurality of auxiliary blades 7, the auxiliary blades 7 are arranged between the adjacent blades 6 at intervals in the axial projection, the auxiliary blades 7 are arc-shaped, the arc-shaped bending direction of the auxiliary blades 7 is consistent with that of the blades 6, the radian of the auxiliary blades 7 is not larger than that of the blades 6, and the auxiliary blades 7 are uniformly distributed on the impeller 3 along the radial direction; the far end of the auxiliary blade 7 is positioned at the radial edge of the impeller 3, and the near end of the auxiliary blade 7 is positioned between the near end of the blade 6 and the far end of the blade 6; the normal of the proximal end of the blade 6 intersects the normal of the proximal end of the secondary blade 7. As shown, the secondary blades 7 are also three and are arranged evenly around the centre of the impeller 3, spaced between adjacent blades 6, the secondary blades 7 serving to assist the blades 6 in increasing the centrifugal effect, and the normal at the proximal end of the blades 6 being angled to the normal at the proximal end of the secondary blades 7 to increase the flow rate of the liquid.

In the present embodiment, the axial height of the vane 6 gradually increases from the distal end of the vane 6 to the proximal end of the vane 6; the axial height of the auxiliary blade 7 is gradually increased along the direction from the far end of the auxiliary blade 7 to the near end of the auxiliary blade 7; a radial circle taking the center of the impeller 3 as the center of a circle is intersected with the blades 6 and the auxiliary blades 7, and the axial height of the intersection point of the blades 6 and the radial circle on the same radial circle is consistent with the axial height of the intersection point of the auxiliary blades 7 and the radial circle. So that the flow rate of the liquid is increased, the pressure of the centrifugal pump is increased, and the axial force is balanced.

In this embodiment, the auxiliary blade 7 is provided with an auxiliary axial hole 04, and the auxiliary axial hole 04 penetrates through the auxiliary blade 7 and the impeller 3; the number of the auxiliary axial holes 04 is a plurality, and the auxiliary axial holes 04 are arranged on the auxiliary blade 7 at intervals along the extending direction of the auxiliary blade 7; the distance between adjacent holes of a plurality of auxiliary axial holes 04 is gradually increased along the direction from the far end of the auxiliary blade 7 to the near end of the auxiliary blade 7. The opening purpose of the auxiliary axial hole 04 is the same as that of the axial hole 01, and the auxiliary axial hole, the axial hole and the upper inner wall surface 200 of the volute form a choke wall 100 together, as shown in fig. 7, and as described above, the description is omitted.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A centrifugal pump characterized by: the impeller is rotatably arranged between the volute and the rear cover plate, and blades are connected to the impeller; the blades are provided with axial holes, and the axial holes penetrate through the blades and the impeller; the axial holes are arranged on the blades at intervals along the extending direction of the blades.

2. The centrifugal pump of claim 1, wherein: the distance between adjacent holes of the axial holes is gradually increased along the direction from the far end of the blade to the near end of the blade; the near end of the blade is close to the liquid inlet of the volute in the radial direction, and the far end of the blade is far away from the liquid inlet of the volute.

3. The centrifugal pump of claim 2, wherein: the axial holes are communicated through radial holes, and the radial holes are arranged on the blades along the extending direction of the blades in axial projection.

4. A centrifugal pump according to claim 3, wherein: the blade near-end has seted up normal direction hole, normal direction hole intercommunication radial hole, in axial projection the orientation of seting up of normal direction hole with the extending direction of radial hole is the contained angle, and the scope of contained angle alpha formed is: alpha is more than 150 degrees and less than 90 degrees.

5. The centrifugal pump of claim 4, wherein: the axial holes at the near ends of the blades are at least provided with two normal holes, and one of the normal holes and the radial hole on the radial section are positioned on the same plane.

6. The centrifugal pump of claim 5, wherein: the blades are arc-shaped in axial projection, the far ends of the blades are positioned at the radial edges of the impeller, and the near ends of the blades are close to the center of the impeller; the impeller is characterized in that the number of the blades is a plurality, the blades are uniformly distributed on the impeller along the radial direction, and the arc-shaped bending directions of the blades are consistent.

7. The centrifugal pump of claim 8, wherein: an auxiliary axial hole is formed in the auxiliary blade and penetrates through the auxiliary blade and the impeller; the auxiliary axial holes are arranged on the auxiliary blade at intervals along the extending direction of the auxiliary blade; and the distance between adjacent holes of a plurality of auxiliary axial holes is gradually increased along the direction from the far end of the auxiliary blade to the near end of the auxiliary blade.

8. The centrifugal pump of claim 1, wherein: the rear cover plate is provided with a liquid storage cavity, and the liquid storage cavity is communicated to the inner cavity of the volute through an axial hole.