Centrifugal impeller axial force self-adaptive balancing method and system based on L-shaped gap and labyrinth groove composite structure

Abstract

The invention relates to the technical field of fluid machinery, and discloses a centrifugal impeller axial force self-adaptive balancing method and system based on an L-shaped gap and labyrinth groove composite structure. A composite pressure drop structure is arranged between the back face of an impeller rear cover plate and the inner side wall of a pump cover in a non-contact mode and sequentially comprises an outer side L-shaped composite gap structure and an inner side labyrinth composite gap structure from outside to inside in the radial direction. An outer side annular cutting area and an inner side labyrinth type annular groove set are arranged on the back face of an impeller rear cover plate and matched with a corresponding protruding structure on the inner side of a pump cover, and a composite gap flow channel structure is defined and formed. The method comprises the steps of obtaining impeller design parameters, machining an outer side annular cutting area, determining and machining a labyrinth type annular groove set, assembling an impeller and a pump cover and the like. The axial force self-adaptive balance design method is simple in structure, high in adaptability and suitable for axial force self-adaptive balance design of different types of centrifugal pumps.

Description

An adaptive axial force balancing method and system for centrifugal impellers based on a composite structure of L-shaped gap and labyrinth groove Technical Field

[0001] This invention relates to the field of fluid machinery technology, and more specifically, to a method and system for adaptive axial force balancing of a centrifugal impeller based on a composite structure of L-shaped gap and labyrinth groove. Background Technology

[0002] During operation, centrifugal pumps typically generate significant axial forces due to uneven fluid pressure distribution on both sides of the impeller's front and rear cover plates. If these axial forces are not effectively controlled, they can lead to increased bearing load, accelerated wear, and even rotor system instability, ultimately affecting the pump's operational reliability and service life. Therefore, axial force balance remains a crucial technology in the hydraulic and structural design of centrifugal pumps.

[0003] Existing axial force balancing technologies for centrifugal pumps mainly include structural forms such as back vanes, balancing holes, balancing discs, or balancing drums. While back vanes and balancing holes can reduce axial force to some extent, they often disrupt the flow field structure on the back of the impeller, leading to volumetric losses and reduced efficiency. Balancing discs and drums, although possessing strong balancing capabilities, are structurally complex, require high precision in manufacturing and assembly, significantly increase costs, and still negatively impact system stability and reliability under certain operating conditions. Especially in modern centrifugal pump designs that prioritize high efficiency, compactness, and reliability, the above solutions struggle to achieve a balance between axial force control and hydraulic performance maintenance.

[0004] Therefore, there is an urgent need for a centrifugal impeller axial force balancing method and system that requires no additional complex components, has minimal impact on the original hydraulic performance of the pump, and can achieve fine control of axial force through the structure itself, so as to meet the actual needs of different working conditions and pump types for axial force control. Summary of the Invention

[0005] The purpose of this invention is to address the problems of significant efficiency loss, complex structure, and high cost that are common in existing centrifugal pump axial force balancing technologies. This invention proposes an adaptive axial force balancing method and system for centrifugal impellers based on a composite structure of L-shaped gaps and labyrinth grooves. By rationally configuring the gap and flow structure characteristics on the back of the impeller's rear cover plate, the fluid pressure on the back of the impeller forms an adaptive attenuation distribution, thereby ensuring that the direction and magnitude of the axial force are in a stable equilibrium state while maximizing the preservation of the original hydraulic performance of the centrifugal pump.

[0006] The embodiments of this application can be implemented through the following technical solutions:

[0007] An adaptive axial force balancing system for a centrifugal impeller based on a composite structure of L-shaped gap and labyrinth groove includes:

[0008] The impeller includes a front cover plate and a rear cover plate;

[0009] A pump cover is disposed on one side of the impeller and is disposed opposite to the rear cover plate of the impeller;

[0010] And a composite pressure drop structure that is non-contactly disposed between the back of the impeller rear cover plate and the inner wall of the pump cover;

[0011] The composite pressure drop structure includes an outer L-shaped composite gap structure and an inner labyrinth composite gap structure.

[0012] The outer L-shaped composite gap structure and the inner labyrinth composite gap structure are arranged sequentially from the outside to the inside in the radial direction.

[0013] Furthermore, an outer annular cutting area is provided on the outer side of the back of the impeller rear cover plate. The outer annular cutting area includes an outer L-shaped annular cutting step, an outer annular cutting bottom surface, and an outer annular cutting sidewall.

[0014] The outer annular cutting area is positioned opposite to the pump cover protrusion structure on the inner wall of the pump cover, and an outer L-shaped composite gap structure with an L-shaped cross-section is defined between the two.

[0015] Furthermore, the outer L-shaped composite gap structure includes radial micro-gap and axial micro-gap;

[0016] The radial micro-gap has a gap size of 1.0 mm to 1.2 mm, and the axial micro-gap has a gap size of 0.8 mm to 1.0 mm.

[0017] Furthermore, an inner labyrinthine annular groove group is provided on the inner side of the back of the impeller rear cover plate. The inner labyrinthine annular groove group is composed of one to three annular labyrinthine grooves. The one to three annular labyrinthine grooves are spaced apart in the radial direction and define an inner labyrinthine composite gap structure with the pump cover protrusion structure.

[0018] Furthermore, the inner labyrinthine annular groove group includes at least a first annular labyrinth groove and a second annular labyrinth groove, and each annular labyrinth groove is formed by the bottom of the annular groove and the wall of the annular groove.

[0019] Furthermore, the inner labyrinth composite gap structure includes a radial labyrinth gap and an axial labyrinth gap;

[0020] The radial labyrinth gap has a gap size of 1.0 mm to 1.2 mm, and the axial labyrinth gap has a gap size of 0.8 mm to 1.0 mm.

[0021] Furthermore, the impeller rear cover plate has a thickness δ, and the impeller has an outlet diameter D2; the cutting depth h of the outer annular cutting area is 0.25 to 0.3 times the thickness δ, and the outer annular cutting area has a circumferential cutting width b, which is 0.05 to 0.1 times the impeller outlet diameter D2.

[0022] Furthermore, in the inner labyrinthine annular groove assembly, the ratio of the labyrinth groove depth h1 to the impeller rear cover plate thickness δ is 0.2 to 0.25; the labyrinth groove width b1 is 0.6 to 0.8 times the circumferential cutting width b of the outer annular cutting area; and the groove spacing d between adjacent labyrinth grooves is 0.15 to 0.2 times the impeller outlet diameter D2.

[0023] An adaptive axial force balancing method for a centrifugal impeller based on a composite structure of L-shaped gap and labyrinth groove includes the following steps:

[0024] Select the target centrifugal pump model and obtain the impeller design parameters;

[0025] An outer annular cutting area is machined on the outer side of the back cover of the impeller, so that after it is assembled with the corresponding protruding structure on the inner side of the pump cover, it is limited to form an outer L-shaped composite gap structure.

[0026] The arrangement area of ​​the labyrinthine annular groove group is determined in the inner area on the back of the impeller rear cover plate;

[0027] Based on the structural dimensional relationship defined by the outer L-shaped composite gap structure, the structural parameters of the labyrinth-type annular groove group are determined.

[0028] The labyrinthine annular groove assembly is machined according to the determined structural parameters, and the machined impeller is assembled with the pump cover having a corresponding protruding structure.

[0029] Furthermore, obtaining the impeller design parameters includes: obtaining the impeller back cover plate thickness δ and the impeller outlet diameter D2; processing the outer annular cutting area includes: processing to form an outer annular cutting area with a cutting depth of h and a circumferential cutting width of b, wherein the cutting depth h is 0.25 to 0.3 times the impeller back cover plate thickness δ, and the circumferential cutting width b is 0.05 to 0.1 times the outlet diameter D2; determining the structural parameters of the labyrinth-type annular groove group includes: determining the labyrinth groove depth h1, the labyrinth groove width b1, and the groove spacing d between adjacent labyrinth grooves, and controlling the ratio of the labyrinth groove depth h1 to the impeller back cover plate thickness δ to be 0.2 to 0.25, controlling the labyrinth groove width b1 to be 0.6 to 0.8 times the circumferential cutting width b, and controlling the groove spacing d to be 0.15 to 0.2 times the outlet diameter D2.

[0030] Beneficial effects

[0031] 1. This invention uses a non-contact L-shaped composite gap structure and a labyrinth composite gap structure between the back of the impeller rear cover plate and the pump cover to adjust the fluid pressure on the back of the impeller by using a multi-stage pressure drop formed by the tiny gap. This avoids the use of high-energy-consuming structures such as back blades and has less impact on the pump's core hydraulic performance such as head and efficiency. It is beneficial to maintain the high-efficiency operation of the centrifugal pump while achieving axial force balance.

[0032] 2. This invention adopts a composite structure combining an outer L-shaped gap and an inner labyrinth groove. The L-shaped composite gap is used to form the main pressure drop, and the labyrinth-type annular groove group is used to adjust the residual pressure in stages. By changing the number of labyrinth grooves and their structural parameters, flexible and adjustable axial force balance can be achieved according to different pump types and operating conditions. It has strong adaptability and high control precision.

[0033] 3. The overall structure of the present invention is simple and reliable. It only requires machining the corresponding groove or protrusion structure on the back of the impeller rear cover plate and the inner wall of the pump cover. There is no need to set up independent components such as balance drum and balance disc, which reduces the complexity of manufacturing and assembly, reduces the number of parts, and helps to reduce manufacturing costs and improve the operational stability and long-term reliability of the rotor system. Attached Figure Description

[0034] Figure 1 is a schematic flowchart of the design method of the present invention;

[0035] Figure 2 is a schematic diagram of the impeller structure of the present invention;

[0036] Figure 3 is a schematic diagram of the pump cover structure of the present invention;

[0037] Figure 4 is a cross-sectional view of the impeller structure of the present invention;

[0038] Figure 5 is a cross-sectional view of the impeller and pump cover of the present invention.

[0039] In the figure, the correspondence between the component names and the attached drawing numbers is as follows: Impeller 1, Impeller front cover plate 11, Impeller rear cover plate 12, Pump cover 2, Pump cover inner wall 21, Pump cover protruding structure 22, Outer annular cutting area 3, Outer L-shaped annular cutting step 31, Outer annular cutting bottom surface 32, Outer annular cutting side wall 33, Inner labyrinth annular groove group 4, First annular labyrinth groove 41, Second annular labyrinth groove 42, Annular groove bottom 43, Annular groove wall 44, L-shaped composite gap structure 5, Radial micro-gap 51, Axial micro-gap 52, Labyrinth composite gap structure 6, Radial labyrinth gap 61, Axial labyrinth gap 62. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0041] As shown in Figures 2 to 5, this embodiment provides a centrifugal impeller axial force adaptive balancing system based on a composite structure of L-shaped gap and labyrinth groove. Its core components include an impeller 1 and a pump cover 2. The impeller 1 is mainly composed of a front impeller cover plate 11 and a rear impeller cover plate 12. The pump cover 2 is located on one side of the impeller 1 and is positioned opposite to the rear impeller cover plate 12. To achieve non-contact axial force adjustment, a composite pressure drop structure is provided between the back of the rear impeller cover plate 12 and the inner wall 21 of the pump cover. This composite pressure drop structure is arranged sequentially from the outside to the inside in the radial direction, mainly including an outer L-shaped composite gap structure 5 and an inner labyrinth composite gap structure 6, allowing the fluid to pass through different shaped flow channel sections sequentially in the radial direction.

[0042] As shown in Figure 4, regarding the specific construction of the aforementioned outer L-shaped composite gap structure 5, an outer annular cutting area 3 is formed on the outer side of the back of the impeller rear cover plate 12 through machining. This outer annular cutting area 3 specifically includes an outer L-shaped annular cutting step 31, an outer annular cutting bottom surface 32, and an outer annular cutting sidewall 33. Correspondingly, a pump cover protrusion structure 22 is machined on the inner sidewall 21 of the pump cover. The outer annular cutting area 3 and the pump cover protrusion structure 22 are positioned opposite each other, thereby defining an outer L-shaped composite gap structure 5 with an L-shaped cross-section on their non-contact assembly surfaces. This gap structure is further subdivided into radial micro-gap 51 and axial micro-gap 52. To balance the assembly tolerances of the rotor system with the fluid resistance effect, the gap size of the radial micro-gap 51 is strictly controlled between 1.0 mm and 1.2 mm, and the gap size of the axial micro-gap 52 is controlled between 0.8 mm and 1.0 mm.

[0043] On the radially inner side of the outer annular cutting area 3, i.e., the inner region of the back side of the impeller rear cover plate 12, an inner labyrinthine annular groove group 4 is further provided. In this embodiment, the inner labyrinthine annular groove group 4 is preferably composed of two annular labyrinthine grooves, namely a first annular labyrinthine groove 41 and a second annular labyrinthine groove 42. Each of the annular labyrinthine grooves is formed by the groove bottom 43 and the groove wall 44, and maintains a reasonable interval in the radial direction. The inner labyrinthine annular groove group 4 and the inwardly extending pump cover protrusion structure 22 together define an inner labyrinthine composite gap structure 6. Corresponding to the outer structure, the inner labyrinthine composite gap structure 6 includes a radial labyrinthine gap 61 and an axial labyrinthine gap 62; the gap size of the radial labyrinthine gap 61 is set to 1.0mm to 1.2mm, and the gap size of the axial labyrinthine gap 62 is set to 0.8mm to 1.0mm.

[0044] To achieve precise stepped pressure drop while ensuring the impeller's structural strength, this embodiment strictly limits the proportional linkage of various dimensional parameters of the aforementioned inner and outer composite structures. The base thickness of the impeller rear cover plate 12 is known to be δ, and the overall outlet diameter of the impeller 1 is D2. For the outer region, the cutting depth h of the outer annular cutting area 3 is controlled to be 0.25 to 0.3 times the thickness δ, while its circumferential cutting width b is controlled to be 0.05 to 0.1 times the outlet diameter D2. Based on the dimensional reference of the outer structure, the characteristic dimensions of the inner labyrinthine annular groove group 4 are further calculated and limited: the ratio of the labyrinth groove depth h1 to the thickness δ is controlled to be 0.2 to 0.25, the labyrinth groove width b1 is controlled to be 0.6 to 0.8 times the aforementioned outer circumferential cutting width b, and the groove spacing d between adjacent labyrinth grooves is controlled to be 0.15 to 0.2 times the outlet diameter D2. This parameter setting ensures a smooth transition in volume and drag coefficient between the inner and outer flow channels.

[0045] As shown in Figure 1, based on the above system structure, the centrifugal impeller axial force adaptive balancing method of this embodiment is carried out in an orderly manner in actual production and manufacturing as follows: First, the basic parameters of the impeller design are obtained according to the target centrifugal pump model, and the thickness δ of the impeller back cover plate and the impeller outlet diameter D2 are extracted. Second, cutting is performed on the outer area of ​​the back of the impeller back cover plate 12. According to the preset proportional relationship, that is, the cutting depth h is 0.25 to 0.3 times the thickness δ, and the circumferential cutting width b is 0.05 to 0.1 times the outlet diameter D2, the outer annular cutting area 3 is processed. Subsequently, based on the determined outer cutting width b and the basic parameters δ and D2, the precise layout parameters of the inner labyrinth-type annular groove group 4 are calculated, that is, the labyrinth groove depth h1 is set to be 0.2 to 0.25 times δ, the labyrinth groove width b1 is set to be 0.6 to 0.8 times b, and the groove spacing d between adjacent labyrinth grooves is set to be 0.15 to 0.2 times D2. Next, the first annular labyrinth groove 41 and the second annular labyrinth groove 42 are machined in the inner region of the impeller rear cover plate 12 according to the determined parameters. Finally, the machined impeller 1 is precisely assembled with the pump cover 2, which has a corresponding pump cover protrusion structure 22, to ensure that the clearance dimensions of the outer L-shaped composite gap structure 5 and the inner labyrinth composite gap structure 6 in each direction meet the design tolerances, thereby finally completing the construction of the adaptive balancing system.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art may make changes or modifications to the above technical content to create equivalent embodiments. Here, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An adaptive axial force balancing system for a centrifugal impeller based on a composite structure of L-shaped gap and labyrinth groove, characterized in that, include: Impeller (1), the impeller (1) includes an impeller front cover plate (11) and an impeller rear cover plate (12); pump cover (2), disposed on one side of the impeller (1) and opposite to the impeller rear cover plate (12); and a composite pressure drop structure disposed non-contactly between the back of the impeller rear cover plate (12) and the inner wall (21) of the pump cover; wherein the composite pressure drop structure includes an outer L-shaped composite gap structure (5) and an inner labyrinth composite gap structure (6); the outer L-shaped composite gap structure (5) and the inner labyrinth composite gap structure (6) are arranged sequentially from the outside to the inside in the radial direction.

2. The system according to claim 1, characterized in that: An outer annular cutting area (3) is provided on the outer side of the back of the impeller rear cover plate (12). The outer annular cutting area (3) includes an outer L-shaped annular cutting step (31), an outer annular cutting bottom surface (32), and an outer annular cutting sidewall (33). The outer annular cutting area (3) is arranged opposite to the pump cover protrusion structure (22) provided on the inner sidewall (21) of the pump cover, and an outer L-shaped composite gap structure (5) with an L-shaped cross section is defined between the two.

3. The system according to claim 2, characterized in that: The outer L-shaped composite gap structure (5) includes a radial micro-gap (51) and an axial micro-gap (52); wherein the gap size of the radial micro-gap (51) is 1.0mm to 1.2mm, and the gap size of the axial micro-gap (52) is 0.8mm to 1.0mm.

4. The system according to claim 2, characterized in that: An inner labyrinthine annular groove group (4) is provided on the inner side of the back of the impeller rear cover plate (12). The inner labyrinthine annular groove group (4) is composed of one to three annular labyrinthine grooves. The one to three annular labyrinthine grooves are spaced apart in the radial direction and are defined with the pump cover protrusion structure (22) to form an inner labyrinthine composite gap structure (6).

5. The system according to claim 4, characterized in that: The inner labyrinthine annular groove group (4) includes at least a first annular labyrinth groove (41) and a second annular labyrinth groove (42), and each annular labyrinth groove is formed by the bottom (43) and the wall (44) of the annular groove.

6. The system according to claim 4, characterized in that: The inner labyrinth composite gap structure (6) includes a radial labyrinth gap (61) and an axial labyrinth gap (62); wherein the gap size of the radial labyrinth gap (61) is 1.0mm to 1.2mm, and the gap size of the axial labyrinth gap (62) is 0.8mm to 1.0mm.

7. The system according to claim 4, characterized in that: The impeller rear cover plate (12) has a thickness δ, and the impeller (1) has an outlet diameter D2; the outer annular cutting area (3) has a cutting depth h that is 0.25 to 0.3 times the thickness δ, and the outer annular cutting area (3) has a circumferential cutting width b that is 0.05 to 0.1 times the outlet diameter D2 of the impeller (1).

8. The system according to claim 7, characterized in that: In the inner labyrinth-type annular groove group (4), the ratio of the labyrinth groove depth h1 to the impeller rear cover plate (12) thickness δ is 0.2 to 0.25; the labyrinth groove width b1 is 0.6 to 0.8 times the circumferential cutting width b of the outer annular cutting area (3); the groove spacing d between adjacent labyrinth grooves is 0.15 to 0.2 times the impeller (1) outlet diameter D2.

9. A method for adaptive axial force balancing of a centrifugal impeller based on a composite structure of L-shaped gap and labyrinth groove, characterized in that, The process includes the following steps: selecting the target centrifugal pump model and obtaining the impeller design parameters; machining an outer annular cutting area on the outer side of the back cover of the impeller, so that it forms an outer L-shaped composite gap structure after being assembled with the corresponding protruding structure on the inner side of the pump cover; determining the arrangement area of ​​the labyrinth-type annular groove group on the inner side of the back cover of the impeller; determining the structural parameters of the labyrinth-type annular groove group according to the structural dimensional relationship after the outer L-shaped composite gap structure is formed; machining the labyrinth-type annular groove group according to the determined structural parameters, and assembling the machined impeller with the pump cover having the corresponding protruding structure.

10. The method according to claim 9, characterized in that: The process of obtaining the impeller design parameters includes: obtaining the impeller back cover plate thickness δ and the impeller outlet diameter D2; the process of machining the outer annular cutting area includes: machining an outer annular cutting area with a cutting depth of h and a circumferential cutting width of b, wherein the cutting depth h is 0.25 to 0.3 times the impeller back cover plate thickness δ, and the circumferential cutting width b is 0.05 to 0.1 times the outlet diameter D2; the process of determining the structural parameters of the labyrinth-type annular groove group includes: determining the labyrinth groove depth h1, the labyrinth groove width b1, and the groove spacing d between adjacent labyrinth grooves, and controlling the ratio of the labyrinth groove depth h1 to the impeller back cover plate thickness δ to be 0.2 to 0.25, controlling the labyrinth groove width b1 to be 0.6 to 0.8 times the circumferential cutting width b, and controlling the groove spacing d to be 0.15 to 0.2 times the outlet diameter D2.

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