Design method and application of multi-stage centrifugal pump transition runner splitter plate

Abstract

The invention discloses a design method and application of a multi-stage centrifugal pump transition runner splitter plate. Relates to the design improvement of the transition runner splitter plate structure of the multi-stage middle-open centrifugal pump. By improving the structure of the transition flow channel, the hydraulic loss in the transition flow channel is reduced, the working efficiency is improved, and the purpose of saving energy is achieved. The method comprises the following steps that S1, a mathematical model of the deviation angle of the transition flow channel splitter plate is established, S2, numerical simulation verification of the multi-stage centrifugal pump is conducted according to the mathematical model, and S3, a target model is found according to the numerical simulation verification result. According to the design method, the hydraulic characteristics of the multi-stage centrifugal pump in actual operation are analyzed, the arrangement rule of the longitudinal splitter plates is creatively revealed, and a better solution of a target model is obtained on the basis of a nonlinear rule. According to the method, r / R and alpha serve as interactive variables, and the comprehensive influence of r / R and alpha on lift and efficiency is researched through numerical simulation. The limitation of a single parameter in a traditional design is broken through, and a new thought and technical means are provided for improving the performance of the multi-stage pump.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal pumps, and particularly to the design improvement of the diverter plate structure of the transition flow passage of a multi-stage split-case centrifugal pump. Background Art

[0002] Due to its advantages such as simple structure, reliable operation, and convenient maintenance, centrifugal pumps are widely used in multiple industries such as water supply and drainage, petrochemical industry, and electric power. A multi-stage split-case centrifugal pump realizes low-flow high-pressure transportation through the series connection of multiple impellers. Among them, the transition flow passage, as a key component for fluid transfer between the front and rear two-stage impellers, its structure plays a crucial guiding role in the flow state of the medium.

[0003] The design of the transition flow passage of existing multi-stage centrifugal pumps usually does not adopt a diverter plate or adopts a simple longitudinal diverter plate structure, as well as a cross-diverter plate flow passage with transverse and longitudinal diverter plates added. Each of the above designs has its own characteristics, but there are many problems in actual operation. Specifically:

[0004] (1) Without a diverter plate structure: As Figure 13 shown, the transition flow passage 4 includes a volute chamber 10, a diffuser section 11, and a suction chamber 12. When rotating clockwise according to the arrow in Figure 13 , the flow passage is a simple curved channel, relying on the geometric shape of the volute itself for flow guidance. However, its pressure recovery ability is weak, and the efficiency of converting kinetic energy into static pressure is low. It is only applicable to low-lift, small-power multi-stage pumps, or applications that are cost-sensitive and have stable working conditions.

[0005] (2) Longitudinal diverter plate type transition flow passage: As Figure 14 shown, a pair of longitudinal diverter plates 13 are provided on the suction chamber 12 in the transition flow passage 4. For the transition flow passage adopting the longitudinal diverter plate structure, its main design idea is to evenly divide the suction chamber 12 according to the area and adopt an arc-shaped cross-section structure. However, it is found in actual operation that the fluid flowing from the volute chamber 10 and the diffuser section 11 into the suction chamber 12 mostly flows to the outer wall side, while the inner wall side shows a mixed flow state. Although this design has a certain flow guiding effect and can also improve a certain hydraulic efficiency, there is still a large impact loss at the leading edge of the diverter plate 13, as well as vortices generated by flow separation at the trailing edge. This greatly increases the generation of pump body vibration and noise phenomena, and reduces the running stability of the pump.

[0006] (3) Cross-diverter plate type transition flow passage: As Figure 15As shown, a pair of longitudinal diverter plates 13 and a pair of transverse diverter plates 14 are provided on the transition channel 4. The cross-diverter plate type channel significantly optimizes the flow field distribution, suppresses turbulence and secondary flow, balances the inter-stage pressure gradient, and can adapt to complex working conditions containing particles or high-viscosity media through the combined layout of the longitudinal diverter plates 13 and the transverse diverter plates 14. However, its structural complexity leads to increased flow resistance and increased manufacturing costs, and the horizontal transverse diverter plates are prone to cause flow stratification and vibration fatigue, and have poor adaptability to variable working conditions. It needs to rely on high-precision manufacturing and wear-resistant materials, and is more suitable for high-efficiency pumps in fixed working conditions and high-cleanliness environments, but is limited in scenarios with high solid content or strong corrosiveness.

[0007] In summary, the shortcomings of the existing technology are mainly reflected in the following aspects:

[0008] First, the fluid flow loss is large, resulting in low pump efficiency;

[0009] Second, the pressure distribution is unreasonable, which affects the pump head and flow stability;

[0010] Third, it is difficult to meet the industrial production needs for high efficiency, energy saving and stable operation.

[0011] The transition channel design of existing multi-stage split-case centrifugal pumps presents numerous challenges, such as significant fluid flow losses, vibration, and noise. These issues result in low pump efficiency and poor operational stability, making it difficult to meet the industrial demand for high efficiency, energy conservation, and stable operation. The urgent technical challenge in this field is to optimize the positioning parameters of the longitudinal manifolds within the cross-type manifold transition channel structure to effectively improve fluid flow characteristics, reduce flow losses, and enhance pump efficiency and operational stability. Summary of the Invention

[0012] In response to the above technical problems, the present invention provides a design method and application of a transition channel manifold plate for a multi-stage centrifugal pump, which reduces hydraulic losses in the transition channel, improves working efficiency, and achieves energy saving by improving the structure of the transition channel.

[0013] The present invention provides a method for designing a diverter plate for a transition channel of a multi-stage centrifugal pump. The transition channel structure includes: a water pressure chamber, a diffusion section, and a suction chamber; a longitudinal diverter plate and a transverse diverter plate are provided in the suction chamber, and the method includes the following steps:

[0014] S1. Establish a mathematical model for the angle of the diverter plate in the transition channel.

[0015] The ratio of the arc radius r of the longitudinal splitter plate to the maximum curvature radius R of the transition channel wall is selected to be 0.4-0.5.

[0016] Select the deflection angle α of the transition channel manifold to be between 0-10°.

[0017] Conduct at least nine groups of parameter combinations to establish a mathematical model for the deflection angle of the transition flow channel diverter plate;

[0018] S2. According to the mathematical model, conduct numerical simulation verification for the multistage centrifugal pump,

[0019] Through CFD numerical simulation, conduct numerical simulation verification for at least 9 groups of parameter combinations established for the curvature radius ratio r / R and the longitudinal diverter plate deflection angle α of the multistage centrifugal pump;

[0020] S3. According to the results of the numerical simulation verification, find the target model,

[0021] Taking efficiency and head as output indicators, generate a response surface by interpolation using the random thin plate spline method in Origin software, and then obtain the target model.

[0022] Furthermore, the geometric parameters in the transition flow channel structure also include:

[0023] Datum positioning dimension: The shaft diameter D is the diameter of the shaft at the transition flow channel of the multistage pump. The longitudinal diverter plate positioning height S and the longitudinal diverter plate working height s remain unchanged when α = 0°, and change with the deflection angle in the deflection angle range of 0° < α ≤ 10°;

[0024] Furthermore, the leading edge of the longitudinal diverter plate and the outlet of the diffuser section are connected by a progressive transition, and the trailing edge of the longitudinal diverter plate extends to the throat of the suction chamber to form a fluid guiding surface.

[0025] Furthermore, the specific process of conducting numerical simulation verification for the multistage centrifugal pump in S2 is as follows:

[0026] Through CFD numerical simulation, conduct simulation for at least 9 groups of parameter combinations established for the curvature radius ratio r / R and the longitudinal diverter plate deflection angle α, and take the head H and efficiency η as output indicators,

[0027]

[0028] Where: P in and P out are the pressures at the inlet and outlet of the pump, with the unit of Pa; ρ is the medium density, with the unit: kg / m 3 , g is the acceleration due to gravity, with the unit kg / s 2 ;

[0029]

[0030] Where: Q is the pump inlet flow rate, with the unit of m 3 / h, and N is the shaft power, with the unit of W.

[0031] Further, in step S3, based on 9 groups of CFD numerical simulation data by using Origin software, a continuous and smooth surface of head and efficiency is interpolated and generated through the method of stochastic thin plate spline,

[0032] Specifically, the data points are fitted by minimizing the bending energy of the surface, and its objective function is:

[0033]

[0034] In the formula:

[0035] The first term: Represents the data fitting error;

[0036] The second term: Represents the bending energy of the surface, which is controlled by the smoothing parameter λ;

[0037]

[0038] Where f(x,y) is the head or efficiency, x is r / R, y is the deflection angle α, φ(r)=r 2 lnr is the radial basis function, a0, a1, a2 and w i Are undetermined coefficients,

[0039] Specific analysis shows that: when the longitudinal splitter plate deflection angle 0°<α≤10° and the curvature radius ratio 0.4≤r / R≤0.5, the head H and efficiency η meet the target model level.

[0040] Further, when r / R = 0.45 and α = 5°, the efficiency η reaches the peak value of 78.55%, and the target model is obtained.

[0041] The application of the design method of the present invention on the splitter plate of the transition flow passage of a multistage centrifugal pump, where the longitudinal splitter plate deflection angle of the splitter plate of the transition flow passage of the multistage centrifugal pump is 0°<α≤10°, and the curvature radius ratio is 0.4≤r / R≤0.5.

[0042] Further, r / R = 0.45 and α = 5°.

[0043] Further, the longitudinal splitter plate is made of the same material as the pump body, and the surface roughness Ra of the longitudinal splitter plate is ≤6.3μm.

[0044] The design method proposed by the present invention utilizes the change of the position parameters of the longitudinal flow splitter plate to analyze the hydraulic characteristics of a multistage centrifugal pump (horizontal split-case multistage pump) during actual operation, and then innovatively reveals the layout law of the longitudinal flow splitter plate. Based on the non-linear law, a better solution for the target model is obtained, which can provide better reference for the design of multistage centrifugal pumps of different specifications, maximize the improvement of fluid flow characteristics, reduce flow losses, and improve the efficiency and operation stability of the pump.

[0045] The present invention takes the radius ratio r / R and the deflection angle α of the flow splitter plate as interactive variables, and studies their comprehensive influence on the head and efficiency through numerical simulation. This multi-variable optimization method breaks through the limitation of single-parameter adjustment in traditional design, providing new ideas and technical means for improving the performance of multistage pumps. At the same time, this method can flexibly adjust parameters according to different industrial requirements to achieve the best combination of head and efficiency, with strong practicability and popularization value. Brief Description of the Drawings

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0047] Figure 1 is the flow chart of the present invention,

[0048] Figure 2 is the structural schematic diagram of the impeller of the present invention,

[0049] Figure 3 is Figure 2 the right view of

[0050] Figure 4 is the three-dimensional hydraulic model schematic diagram of the present invention,

[0051] Figure 5 is Figure 4 the rear view of

[0052] Figure 6 is the structural schematic diagram of the multistage split-case centrifugal pump in the present invention,

[0053] Figure 7 is the response relationship surface diagram of r / R, α and head in the present invention,

[0054] Figure 8 is the response relationship surface diagram of r / R, α and efficiency in the present invention,

[0055] Figure 9It is the velocity streamline diagram of the middle section of the suction chamber when α = 0°,

[0056] Figure 10 It is the velocity streamline diagram of the middle section of the suction chamber when α = 5°,

[0057] Figure 11 It is the pressure nephogram of the middle section of the suction chamber when α = 0°,

[0058] Figure 12 It is the pressure nephogram of the middle section of the suction chamber when α = 5°,

[0059] Figure 13 It is the structural schematic diagram of the prior art without a diverter plate,

[0060] Figure 14 It is the structural schematic diagram of the prior art with a longitudinal diverter plate type transition flow channel,

[0061] Figure 15 It is the structural schematic diagram of the prior art with a cross diverter plate type transition flow channel;

[0062] In the figure, 1 is the shaft, 2 is the suction chamber, 3 is the low-pressure impeller, 4 is the low-pressure transition flow channel, 5 is the discharge chamber, 6 is the high-pressure transition flow channel, 7 is the high-pressure impeller, 8 is the long transition flow channel, 9 is the bearing and seal assembly, 10 is the water pressure chamber, 11 is the diffuser section, 12 is the suction chamber, 13 is the longitudinal diverter plate, 14 is the transverse diverter plate;

[0063] α is the deflection angle of the longitudinal diverter plate, S is the positioning height of the lower edge of the longitudinal diverter plate, s is the working height of the longitudinal diverter plate, R is the large curvature radius of the transition flow channel wall, r is the arc radius of the longitudinal diverter plate, D is the shaft diameter;

[0064] H is the head, η is the efficiency. Detailed implementation manners

[0065] The following combines the attached Figures 1 - 12 drawings and further illustrates the technical solutions of the present invention through specific implementation manners.

[0066] Among them, the attached drawings are only for illustrative purposes, showing only schematic diagrams, rather than physical diagrams, and cannot be understood as a limitation to this patent; in order to better illustrate the embodiments of the present invention, some components in the attached drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted.

[0067] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if terms such as "upper", "lower", "left", "right", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be construed as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0068] In the description of the present invention, unless otherwise clearly specified and limited, if terms such as "connection" are used to indicate the connection relationship between components, this term should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] A design method for the shunt plate of the transition flow channel of a multistage centrifugal pump of the present invention, the transition flow channel structure includes: a volute chamber 10, a diffuser section 11, and a suction chamber 12; a longitudinal shunt plate 13 and a transverse shunt plate 14 are provided in the suction chamber 12, and the method includes the following steps:

[0070] S1. Establish a mathematical model for the deflection angle of the shunt plate of the transition flow channel.

[0071] Select the ratio r / R of the arc radius r of the longitudinal shunt plate 13 to the large curvature radius R of the transition flow channel wall surface to be between 0.4 and 0.5.

[0072] Select the deflection angle α value of the longitudinal transition flow channel shunt plate 13 to be between 0° and 10°.

[0073] Perform at least 9 groups of parameter combinations to establish a mathematical model for the deflection angle of the longitudinal transition flow channel shunt plate 13.

[0074] The 9 groups of parameter combinations are shown in Table 1:

[0075] Table 1

[0076] Serial number r / R α 1 0.4 0° 2 0.4 5° 3 0.45 5° 4 0.45 10° 5 0.5 10° 6 0.5 0° 7 0.4 10° 8 0.45 0° 9 0.5 5°

[0077] S2. According to the mathematical model, conduct numerical simulation verification of the multistage centrifugal pump.

[0078] At least 9 groups of parameter combinations established for the curvature radius ratio r / R and the longitudinal splitter plate deflection angle α are verified through CFD numerical simulation for a multistage centrifugal pump.

[0079] S3. According to the numerical simulation verification results, a target model is obtained.

[0080] Taking the efficiency η and the head H as output indicators, a response surface is interpolated and generated by the random thin plate spline method in Origin software, and then the target model is obtained.

[0081] Figure 6 It is a structural schematic diagram of a multistage centrifugal pump of the present invention. Figure 6 The main components in it: shaft 1, suction chamber 2, low-pressure impeller 3, low-pressure transition flow passage 4, volute chamber 5, high-pressure transition flow passage 6, high-pressure impeller 7, long transition flow passage 8, bearing and seal assembly 9. When the multistage pump operates, the fluid evenly enters the low-pressure boosting section from the suction chamber 2 and flows through the first four stages of low-pressure impellers 3 and low-pressure transition flow passages 4 in sequence for step-by-step boosting: each low-pressure impeller converts the kinetic energy of the fluid into pressure energy through centrifugal force, and the low-pressure transition flow passage guides the fluid to turn gently and expand, converting part of the kinetic energy into static pressure further. Subsequently, the fluid enters the fifth-stage low-pressure impeller to complete the final boosting in the low-pressure section, and then is transported to the first-stage high-pressure impeller in the high-pressure boosting section through the long transition flow passage 8 to complete the transition of the fluid from low pressure to high pressure. After that, the fluid enters the high-pressure boosting section and flows through four groups of high-pressure impellers 7 and high-pressure transition flow passages 6 in sequence: both the high-pressure impeller 7 and the high-pressure transition flow passage 6 adopt a design symmetrical to the low-pressure impeller 3 and the low-pressure transition flow passage 4 to ensure efficient energy transfer. Finally, the fluid is boosted by the tenth-stage high-pressure impeller 7 to the volute chamber 5, where the final conversion of kinetic energy into static pressure energy is completed, and is output through the outlet pipe. The bearing and seal assembly 9 supports the stable rotation of the shaft 1 throughout the process and prevents leakage, ensuring the reliable operation of the multistage pump under high pressure difference.

[0082] During the implementation of the present invention, further, the geometric parameters in the transition flow passage structure also include:

[0083] Reference positioning dimensions: the shaft diameter D is the diameter of the shaft 1 at the transition flow passage of the multistage pump, the positioning height S and the working height s of the longitudinal splitter plate 13 remain unchanged when α = 0°, and change with the deflection angle in the deflection angle range of 0° < α ≤ 10°.

[0084] Further, the transition flow passage is an axisymmetric structure, the leading edge of the longitudinal splitter plate 13 and the outlet of the diffuser section 11 are connected by a progressive transition, and the trailing edge of the longitudinal splitter plate 13 extends to the throat of the suction chamber 12 to form a fluid guiding surface to ensure that the fluid evenly flows into the lower-stage impeller.

[0085] Further, the specific implementation of the multistage centrifugal pump numerical simulation verification in S2 is as follows:

[0086] Through CFD numerical simulation (ANSYS CFX, SST k-ω turbulence model, with 12.77 million grids, the medium is water, the inlet pressure is 1 atm, and the mass flow rate is 160 m 3 / h at the outlet), at least 9 groups of parameter combinations established for the curvature radius ratio r / R and the longitudinal splitter plate deflection angle α are simulated, and the head H and efficiency η are used as output indicators. The calculations of the head and efficiency are represented by formulas (1) and (2):

[0087]

[0088] In the formula: P in and P out are the pressures at the inlet and outlet of the pump, in Pa; ρ is the medium density, in kg / m 3 , g is the acceleration due to gravity, in kg / s 2 ;

[0089]

[0090] In the formula: Q is the inlet flow rate of the pump, in m 3 / h, and N is the shaft power, in W.

[0091] The final numerical simulation results are shown in Table 2:

[0092] Table 2

[0093] Serial number r / R α Efficiency Head (m) 1 0.4 0° 78.01％ 1424.5 2 0.4 5° 78.26％ 1421.7 3 0.45 5° 78.55％ 1417.4 4 0.45 10° 77.87％ 1426.3 5 0.5 10° 78.51％ 1417.5 6 0.5 0° 78.09％ 1421.6 7 0.4 10° 78.41％ 1409.6 8 0.45 0° 78.27％ 1415.4 9 0.5 5° 78.16％ 1409.3

[0094] Among the 9 parameter results of the numerical simulation, compared with the original model (α = 0°, r / R = 0.45), the target model (α = 5°, r / R = 0.45) has an efficiency improvement of 0.28% and a synchronous head improvement of 0.14%.

[0095] Furthermore, in S3, using Origin software, based on 9 groups of CFD numerical simulation data, a continuous and smooth surface (both the row and column grid numbers are set to 100) regarding the head and efficiency is interpolated through the Randomized Thin Plate Spline method, that is, the response surface.

[0096] The core idea of thin plate spline interpolation is to fit the data points by minimizing the "bending energy" of the surface, and its objective function is:[[]]

[0097]

[0098] In the formula:

[0099] The first term: represents the data fitting error;

[0100] Second item: Represents the bending energy of the curved surface, controlled by the smoothing parameter λ;

[0101] Form of the solution:

[0102]

[0103] where f(x, y) is the head or efficiency, x is r / R, y is the deflection angle α, φ(r) = r 2 lnr is the radial basis function, a0, a1, a2 and w i are undetermined coefficients. Given the above undetermined coefficients, those skilled in the art can clearly obtain them according to the foregoing technical measures of the present invention, and will not be elaborated herein.

[0104] Specific analysis shows that: when the longitudinal splitter plate deflection angle 0° < α ≤ 10° and the curvature radius ratio 0.4 ≤ r / R ≤ 0.5, the head H and efficiency η meet the target model level. In this range, both the head and efficiency can be maintained at a relatively high level (efficiency deviation within 0.4%, head deviation within 0.8%). This parameter range has been verified through a large number of simulations and can ensure excellent performance of the multi-stage pump in the transition flow channel design.

[0105] Furthermore, when r / R = 0.45 and α = 5°, the efficiency η reaches a peak value of 78.55%, obtaining the target model.

[0106] Figure 7 , 8 are the response surface diagrams of r / R, α and head, efficiency in the present invention. The response surface diagrams are drawn using Origin software. With the radius ratio r / R and the splitter plate deflection angle α as independent variables, and the head (unit: m) and efficiency as dependent variables respectively, based on 9 groups of CFD numerical simulation data, a continuous smooth surface is generated by interpolation using the Randomized Thin Plate Spline method (the row and column grid numbers are both set to 100), and the color gradient maps the performance changes (head / efficiency: dark red to high, blue-violet to low). Specific analysis shows that the head response ( Figure 7 ): when r / R < 0.45, the head increases significantly with the increase of the radius ratio, and the peak value reaches 1426 meters (r / R = 0.45, α = 5°); when r / R > 0.45 or α > 5°, the head decreases due to flow separation or trailing edge vortex loss, and drops to 1409 meters when r / R = 0.5 and α = 10°. The efficiency response ( Figure 8 ): the efficiency reaches a peak value of 78.55% when r / R = 0.45 and α = 5°, which is 0.28% higher than the original model (r / R = 0.45, α = 0°).

[0107] Figure 9 and Figure 10Streamline diagrams of the middle cross-section velocity in the suction chamber at α = 0° (original) and α = 5° (the present invention) respectively. The streamline arrows in the figure indicate the flow direction. It can be found from the comparison of the streamlines that under the flow splitting action of the flow splitting plate for the fluid entering the suction chamber, there are several relatively large vortices on the inner wall side of the structure in the original design ( Figure 9 marked by the upper right elliptical curve frame in the middle), almost occupying 2 / 3 of the flow channel area inside the flow splitting plate. In contrast, for the design structure of the present invention, when the deviation angle α = 5°, only local small-scale vortices exist on the inner wall side ( Figure 10 marked by the upper right elliptical curve frame in the middle), greatly improving the flow state in the suction chamber and reducing the eddy current loss.

[0108] Figure 11 and Figure 12 Pressure nephograms of the middle cross-section in the suction chamber at α = 0° (original) and α = 5° (the present invention) respectively. The pressure increases with the color depth. In the case of α = 0°, there is a phenomenon of uneven pressure distribution inside the flow splitting plate, especially in the lower region of the flow channel, where the pressure gradient changes greatly, which may lead to unstable fluid flow and increase energy loss. In the case of α = 5°, the pressure distribution is relatively more uniform, especially in the lower region of the flow channel, where the pressure gradient changes less, which helps to improve the stability of fluid flow and reduce energy loss.

[0109] Application of the design method of the present invention on the flow splitting plate of the transition channel of a multistage centrifugal pump, where the longitudinal flow splitting plate deviation angle of the flow splitting plate of the multistage centrifugal pump transition channel is 0° < α ≤ 10°, and the curvature radius ratio is 0.4 ≤ r / R ≤ 0.5.

[0110] Furthermore, r / R = 0.45 and α = 5°.

[0111] Furthermore, the longitudinal flow splitting plate is made of the same material as the pump body, and the surface roughness Ra of the longitudinal flow splitting plate ≤ 6.3 μm.

[0112] Figures 13 - 15They are respectively the structural diagrams of a transition flow channel without a diverter plate, a longitudinal diverter plate type transition flow channel, and a cross diverter plate type transition flow channel. The transition flow channels of these three structures all include a pressure water chamber 10, a diffuser section 11, and a suction chamber 12. The transition flow channel without a diverter plate has no longitudinal and transverse diverter plates; the longitudinal diverter plate type transition flow channel only has a longitudinally axially symmetric diverter plate structure; the cross diverter plate type transition flow channel has diverter plate structures both longitudinally and transversely, and is also axially symmetrically distributed. The transition flow channel without a diverter plate is a simple curved channel, relying on the geometric diversion of the volute, with low pressure recovery efficiency, and is suitable for scenarios with low head, small power, or cost sensitivity and stable working conditions; the longitudinal diverter plate type transition flow channel realizes diversion through evenly dividing the suction chamber and the arc-shaped cross-section design, which can improve a certain hydraulic efficiency, but the impact loss at the leading edge of the diverter plate and the problem of flow separation vortices at the trailing edge are prominent, resulting in large vibration and noise of the pump body and insufficient operating stability; the cross diverter plate type transition flow channel adopts a combination of longitudinal and transverse diverter plates to optimize the flow field distribution, suppress turbulence and secondary flow, and adapt to complex working conditions such as containing particles or high viscosity, but due to its complex structure, it has a large flow resistance, high manufacturing cost, and problems such as flow stratification and vibration fatigue, and has poor adaptability to variable working conditions. It is more suitable for high-efficiency pumps in fixed working conditions and high-clean environments, and is limited in application in scenarios with high solid content or strong corrosion.

[0113] However, after the present invention changes the layout position relationship of the longitudinal diverter plate, the flow state of the suction chamber is greatly improved, and the eddy current loss is reduced. The stability of fluid flow is improved, and the energy loss is reduced. Both the head and efficiency are greatly improved.

[0114] It should be stated that the above specific implementation manners are only the preferred embodiments of the present invention and the applied technical principles. Those skilled in the art should understand that based on the technical content disclosed in this application document, various modifications, equivalent replacements, changes, etc. can be made to the present invention. However, as long as these transformations do not deviate from the spirit of the present invention, they should be within the protection scope of the present invention. In addition, some terms used in the specification and claims of this application are not restrictive, but are only for the convenience of description.

Claims

1. A design method for the flow dividing plate of the transition flow passage of a multi-stage centrifugal pump, the transition flow passage structure comprising: A pressurized water chamber, a diffuser section, and a suction chamber; a longitudinal shunt plate and a transverse shunt plate are provided in the suction chamber, and it is characterized by including the following steps: S1. Establish a mathematical model for the deflection angle of the transition flow channel shunt plate. Select the ratio r / R of the arc radius r of the longitudinal shunt plate to the large curvature radius R of the transition flow channel wall surface to be in the range of 0.4 - 0.

5. Select the deflection angle α value of the transition flow channel shunt plate to be in the range of 0 - 10°. Conduct at least nine groups of parameter combinations to establish a mathematical model for the deflection angle of the transition flow channel shunt plate. S2. According to the mathematical model, conduct numerical simulation verification of a multistage centrifugal pump. Through CFD numerical simulation, conduct numerical simulation verification of at least 9 groups of parameter combinations established for the curvature radius ratio r / R and the longitudinal shunt plate deflection angle α of a multistage centrifugal pump. S3. According to the numerical simulation verification results, obtain the target model. Taking efficiency and head as output indicators, generate a response surface by interpolation using the random thin plate spline method in Origin software, and then obtain the target model.

2. The design method of the flow dividing plate for the transition flow path of a multistage centrifugal pump according to claim 1, wherein The geometric parameters in the transition flow channel structure also include: Reference positioning dimensions: The shaft diameter D is the diameter of the shaft at the transition flow channel of the multistage pump. The positioning height S and the working height s of the longitudinal shunt plate remain unchanged when α = 0°, and change with the deflection angle in the deflection angle range of 0° < α ≤ 10°.

3. A design method for the flow dividing plate of the transition flow path of a multi-stage centrifugal pump according to claim 1, characterized in that The leading edge of the longitudinal shunt plate is connected to the outlet of the diffuser section by a progressive transition, and the trailing edge of the longitudinal shunt plate extends to the throat of the suction chamber to form a fluid guiding surface.

4. A design method for the flow dividing plate of the transition flow path of a multi-stage centrifugal pump according to claim 1, characterized in that, The specific process of conducting numerical simulation verification of the multistage centrifugal pump in S2 is as follows: Through CFD numerical simulation, simulate at least 9 groups of parameter combinations established for the curvature radius ratio r / R and the longitudinal shunt plate deflection angle α, and take the head H and efficiency η as output indicators. Where: P in and P out are the inlet and outlet pressures of the pump, with the unit of Pa; ρ is the medium density, unit: kg / m 3 , g is the acceleration due to gravity, unit kg / s 2 ; Where: Q is the pump inlet flow rate, with the unit of m 3 / h, and N is the shaft power, with the unit of W.

5. A design method for the flow dividing plate of the transition flow passage of a multi-stage centrifugal pump according to claim 1, characterized in that In S3, based on 9 groups of CFD numerical simulation data using Origin software, generate a continuous and smooth surface regarding the head and efficiency by interpolation using the random thin plate spline method. Specifically, it is to fit the data points by minimizing the bending energy of the surface, and its objective function is: In the formula: Item 1: Indicates the data fitting error; Item 2: Represents the bending energy of the surface, controlled by the smoothing parameter λ; where f(x, y) is the head or efficiency, x is r / R, y is the deflection angle α, and φ(r) = r 2 lnr is the radial basis function, and a0, a1, a2, and w i are undetermined coefficients Specific analysis shows that when the longitudinal shunt plate deflection angle 0° < α ≤ 10° and the curvature radius ratio 0.4 ≤ r / R ≤ 0.5, the head H and efficiency η meet the target model level.

6. A design method for the diversion plate of the transition flow passage of a multistage centrifugal pump according to claim 5, characterized in that When r / R = 0.45 and α = 5°, the efficiency η reaches a peak value of 78.55%, and the target model is obtained.

7. Application of the design method according to claim 1 to the flow dividing plate of the transition flow path of a multistage centrifugal pump, characterized in that, For the longitudinal shunt plate of the multistage centrifugal pump transition flow channel shunt plate, the deflection angle 0° < α ≤ 10° and the curvature radius ratio 0.4 ≤ r / R ≤ 0.

5.

8. Application of the design method according to claim 7 to the flow dividing plate of the transition flow passage of a multistage centrifugal pump, characterized in that, r / R = 0.45 and α = 5°.

9. Application of the design method according to claim 7 to the flow dividing plate of the transition flow passage of a multistage centrifugal pump, characterized in that, The longitudinal shunt plate is made of the same material as the pump body, and the surface roughness Ra of the longitudinal shunt plate ≤ 6.3 μm.

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