A single-stage centrifugal pump having an impeller and a design method of the impeller in the single-stage centrifugal pump

Abstract

This invention relates to a single-stage centrifugal pump with an impeller and a design method for the impeller in the single-stage centrifugal pump. The single-stage centrifugal pump includes: a front cover plate, a rear cover plate, circumferentially distributed main blades, and offset secondary blades located within the flow channel. The offset secondary blades are circumferentially offset towards the suction surface side of the main blade in front of them within the flow channel. The circumferential width of the flow channel is defined as L, the distance from the skeletal line of the secondary blade to the skeletal line of the main blade in front is defined as A, and the offset coefficient k = A / L, where the value of k ranges from 0.2 to 0.45. The impeller of this invention can more effectively eliminate the low-speed separation zone, making the outlet flow field more uniform, thereby achieving higher hydraulic efficiency and a flatter head curve, significantly widening the high-efficiency operating range. The product solution of this invention only changes the blade position, without adding complex components, and is easy to manufacture; this invention significantly improves design efficiency and result reliability.

Description

Technical Field

[0001] This invention relates to a single-stage centrifugal pump and a design method for the impeller in a single-stage centrifugal pump, specifically to a single-stage centrifugal pump with an impeller and a design method for the impeller in a single-stage centrifugal pump. Background Technology

[0002] Centrifugal pumps are key fluid transport equipment widely used in energy, chemical, and water conservancy industries, with the impeller being its core working component. To balance high efficiency and stable operation, especially by widening the high-efficiency range and improving low-flow performance, the industry commonly employs a composite impeller design that adds secondary blades, also known as flow dividers or small blades, between adjacent main blades. This design enhances performance by dividing the flow channel, suppressing secondary flow, and improving the uniformity of the outlet flow field.

[0003] The closest implementation to this invention is a centrifugal impeller with uniformly spaced main and auxiliary blades. In this design, the auxiliary blades are circumferentially symmetrically positioned at the center of the flow channel formed by the two main blades. This is a conventional design approach based on geometric symmetry and ease of manufacturing, implicitly assuming that the flow distribution within the flow channel is uniform or symmetrical. This approach improves performance to some extent and has become a standard design method.

[0004] Figure 1 This is a schematic diagram of a commonly used structure. Figure 2 A schematic diagram of a traditional impeller with centrally arranged secondary blades. The centrifugal pump impeller includes a front cover plate 1, a rear cover plate 2, main blades 3, and secondary blades 4. The main blades 3 are circumferentially and evenly fixed between the front cover plate 1 and the rear cover plate 2. The secondary blades 4 are also fixed between the front cover plate 1 and the rear cover plate 2.

[0005] The main drawback of existing technology stems from the fundamental contradiction between its "symmetrical centering" design premise and the actual "highly asymmetrical" flow inside the impeller:

[0006] (1) In a high-speed rotating centrifugal impeller, due to the combined effect of the flow channel curvature and boundary layer development, the mainstream region in the flow channel is severely biased toward the working surface of the main blade, while the region near the suction surface of the main blade is prone to generating a low-speed, separated wake region. Mechanically placing the secondary blades in the center of the flow channel fails to accurately and effectively control the low-energy, unstable region that most needs intervention.

[0007] (2) The central secondary blade has limited effect on improving the flow separation on the suction surface and reducing the jet-wake structure, which limits its performance improvement and fails to fully realize the potential of the main and secondary blade structure.

[0008] (3) Existing designs rely heavily on experience, analogy or simple numerical trial and error, lacking a systematic method to scientifically determine the optimal position of the secondary blades based on the flow mechanism. Summary of the Invention

[0009] To address the above problems, the objective of this invention is:

[0010] (1) Provide a centrifugal pump impeller with better performance. By breaking the design pattern that the secondary blades must be centered, the layout of the impeller is more in line with the actual flow law, thereby more effectively controlling the flow field, improving efficiency and operational stability.

[0011] (2) Provide a systematic and verifiable design method. This method is based on the principle of bionics, can be quantitatively analyzed, and can scientifically and reliably determine the optimal asymmetric position of the secondary blades and other key geometric parameters, ensuring the necessity and repeatability of performance improvement.

[0012] The present invention solves the above-mentioned technical problems through the following technical solution: a single-stage centrifugal pump with an impeller, the single-stage centrifugal pump with an impeller comprising: a front cover plate, a rear cover plate, circumferentially distributed main blades, and offset secondary blades located in the flow channel, the offset secondary blades being circumferentially offset towards the suction surface side of the main blade in front of them in the flow channel; the circumferential width of the flow channel is defined as L, the distance from the rib line of the secondary blade to the rib line of the main blade in front is defined as A, and the offset coefficient k = A / L, wherein the value of k ranges from 0.2 to 0.45.

[0013] In a specific embodiment of the present invention, the value of k ranges from 0.25 to 0.35.

[0014] A design method for the impeller in a single-stage centrifugal pump, comprising the following steps:

[0015] Step (1), benchmark modeling and analysis: Perform flow field analysis on the original model without secondary blades. At the flow separation point, which is the leading edge position of the secondary blade, create an initial impeller model with the secondary blade in the center. The blade is centered at k=0.5. Perform CFD simulation to obtain the benchmark flow field.

[0016] Step (2), Flow field diagnosis and target location: Analyze the baseline flow field, identify and quantify the low-velocity area near the suction surface of the main blade in each flow channel. This area is the target area that needs the intervention of "bionic microfin".

[0017] Step (3), parameterization and space construction: Define the circumferential position of the secondary blade as the core design variable - the offset coefficient k; set the optimization search range of k, the value range of k is 0.2 to 0.45;

[0018] Step (4): Optimize the automated agent model;

[0019] Step (5), Scheme Determination and Verification: Select the optimal scheme from the Pareto solution set, perform high-precision CFD verification, including unsteady calculations, and finally output the optimized three-dimensional geometry of the impeller.

[0020] In a specific implementation of the present invention, the specific sub-steps of step (4) are as follows:

[0021] Step (401): Perform layered sampling within the design space, automatically generate multiple candidate impeller models, and perform CFD calculations;

[0022] Step (402): Extract the key performance indicators of each scheme, including hydraulic efficiency η and low-velocity zone volume S. V Volume E of the high turbulent kinetic energy region V ;

[0023] Step (403): Construct a Kriging proxy model based on sample data, and establish the relationship between design variable k and performance target η,S. V E V Approximate mathematical relationships;

[0024] Step (404): Use a multi-objective optimization algorithm to perform efficient global optimization on the surrogate model and find the Pareto optimal solution set.

[0025] The positive and progressive effects of this invention are as follows: The single-stage centrifugal pump with impeller provided by this invention has the following advantages:

[0026] 1. The performance of this invention is significantly improved: Since the secondary blades act precisely on the flow separation zone, the impeller of this invention can more effectively eliminate the low-speed separation zone, making the outlet flow field more uniform, thereby achieving higher hydraulic efficiency and a flatter head curve, and significantly expanding the high-efficiency operating range.

[0027] 2. This invention provides a methodology that is repeatable and efficient: This invention not only provides a better product, but also a replicable and scalable design methodology. This method solidifies the designer's experience into the process, so that "optimal bias design" no longer depends on personal inspiration or a lot of trial and error, but can be stably produced through a standardized digital process, which greatly improves design efficiency and result reliability.

[0028] 3. This invention has strong engineering practicality: the product solution only changes the blade position, does not add complex components, and is easy to manufacture. The method is based on a mature CAE / optimization software platform, which is easy to implement in the R&D system and has high engineering practical value. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a commonly used structure.

[0030] Figure 2 A schematic diagram of the structure of a traditional impeller with centrally arranged secondary blades.

[0031] Figure 3 This is a schematic diagram of the structure of the offset secondary blade arrangement of the impeller in this invention.

[0032] Figure 4 This is a schematic diagram of the three-dimensional overall structure of the impeller with non-centrally arranged auxiliary blades according to the present invention.

[0033] Figure 5 A single-stage centrifugal pump with a biomimetic impeller.

[0034] Figure 6-1 The streamline development diagram is for the cascade with k=0.5.

[0035] Figure 6-2 The streamline development diagram is for the cascade with k=0.28.

[0036] Figure 7-1 The diagram shows the turbulent kinetic energy distribution at the axial section with k=0.5.

[0037] Figure 7-2 The diagram shows the turbulent kinetic energy distribution at the axial section with k=0.28.

[0038] The following are the names corresponding to the reference numerals in this invention:

[0039] Figures 1-5 In the middle: front cover plate 1, rear cover plate 2, main blade 3, offset secondary blade 4, main blade working surface 5, main blade suction surface 6, secondary blade working surface 7, secondary blade suction surface 8, main blade skeletal line 9, secondary blade skeletal line 10, pump cover 11, pump body 12, traditional impeller 13, bionic impeller 14. Detailed Implementation

[0040] The preferred embodiments of the present invention are given below with reference to the accompanying drawings to illustrate the technical solution of the present invention in detail.

[0041] Figure 3 This is a schematic diagram of the structure of the offset secondary blade arrangement of the impeller in this invention. Figure 4 This is a schematic diagram of the three-dimensional overall structure of the impeller with non-centrally arranged auxiliary blades according to the present invention. Figure 5 Single-stage centrifugal pumps with biomimetic impellers, such as Figures 3-5 As shown: This invention proposes a single-stage centrifugal pump with an impeller, comprising: a front cover plate 1, a rear cover plate 2, circumferentially distributed main blades 3, and offset secondary blades 4 located within their flow channels. The offset secondary blades 4 are circumferentially offset towards the suction surface side of the main blades 3 in front of them within the flow channels. The circumferential width of the flow channel is defined as L, the distance from the rib line of the secondary blade to the rib line of the main blade in front is defined as A, and the offset coefficient k = A / L, where the value of k ranges from 0.2 to 0.45.

[0042] In specific implementation, the value range of k in this invention is preferably 0.25 to 0.35.

[0043] The present invention also provides a design method for an impeller in a single-stage centrifugal pump, the steps of which are as follows:

[0044] Step (1), benchmark modeling and analysis: Perform flow field analysis on the original model without secondary blades. At the flow separation point, which is the leading edge position of the secondary blade, create an initial impeller model with the secondary blade in the center. The blade is centered at k=0.5. Perform CFD simulation to obtain the benchmark flow field.

[0045] Step (2), Flow field diagnosis and target location: Analyze the baseline flow field, identify and quantify the low-velocity area near the suction surface of the main blade in each flow channel. This area is the target area that needs the intervention of "bionic microfin".

[0046] Step (3), parameterization and space construction: Define the circumferential position of the secondary blade as the core design variable - the offset coefficient k; set the optimization search range of k, the value range of k is 0.2 to 0.45;

[0047] Step (4), Optimization of the automated agent model:

[0048] Step (5), Scheme Determination and Verification: Select the optimal scheme from the Pareto solution set, perform high-precision CFD verification, including unsteady calculations, and finally output the optimized three-dimensional geometry of the impeller.

[0049] The specific sub-steps of step (4) include:

[0050] Step (401): Perform layered sampling within the design space, automatically generate multiple candidate impeller models, and perform CFD calculations;

[0051] Step (402): Extract the key performance indicators of each scheme, including hydraulic efficiency η and low-velocity zone volume S. V Volume E of the high turbulent kinetic energy region V ;

[0052] Step (403): Construct a Kriging proxy model based on sample data, and establish the relationship between design variable k and performance target η,S. V E V Approximate mathematical relationships;

[0053] Step (404): Use a multi-objective optimization algorithm to perform efficient global optimization on the surrogate model and find the Pareto optimal solution set.

[0054] Below is an example with specific data or formulas:

[0055] Taking a single-stage centrifugal pump with a specific speed of 60 as an example, the pump's design parameters are as follows: flow rate 160 m³ / h 3 / h, head 125m, speed 2960rpm.

[0056] (1) A conventional bladeless design scheme was performed and CFD calculations were conducted. The calculation results are shown in Table 1:

[0057] Table 1

[0058]

[0059] (2) Flow field analysis was performed on the original model without auxiliary blades. The flow separation point was taken as the leading edge position of the auxiliary blade. A scheme with the auxiliary blade centered at k=0.5 was designed first, and CFD calculations were performed. The calculation results are shown in Table 2:

[0060] Table 2

[0061]

[0062] The low-speed zone is defined as: an absolute velocity below 5 m / s; the high turbulent kinetic energy zone is defined as: a turbulent kinetic energy above 8 m / s. 2 / s 2 .

[0063] (3) Layered sampling: CFD calculations were performed on six schemes with k=0.2, 0.25, 0.3, 0.35, 0.4, and 0.45 respectively, calculating only the parameters at the design points. The calculated η and S were then used as a proxy model. V E V An approximate mathematical relationship can be established with the value of k as follows:

[0064] Table 3

[0065]

[0066]

[0067]

[0068]

[0069] (4) Use a multi-objective optimization algorithm to find the global optimization on the surrogate model:

[0070]

[0071] Among them, the benchmark value =76000, =14400.

[0072] Balanced weights (w1=1, w2=1, w3=1)

[0073]

[0074] Emphasis is placed on flow quality (w1=1, w2=2, w3=2).

[0075]

[0076] Prioritize efficiency (w1=2, w2=1, w3=1)

[0077]

[0078] The calculation results are shown in Table 4:

[0079] Table 4

[0080]

[0081] Optimal k value:

[0082] f1(k): k = 0.28 - 0.30

[0083] f2(k): k = 0.26 - 0.28

[0084] f3(k): k = 0.28 - 0.30

[0085] Finally, k=0.28 was selected for CFD calculation verification, and compared with the k=0.5 scheme, see Table 5.

[0086] Table 5

[0087]

[0088] The flow field comparison analysis shows that the internal streamlines of the k=0.28 scheme are smoother and there are no obvious vortices. The flow field is greatly improved and the turbulent kinetic energy is also significantly reduced, indicating that the optimization results of this scheme are very effective.

[0089] Figure 6-1 The streamline development diagram is for the blade cascade with k=0.5. Figure 6-2 This is the streamline development diagram for the cascade with k=0.28. From... Figure 6-1 and Figure 6-2 The comparison shows that when k=0.5, there are obvious signs of flow separation and backflow on the back of the main blade, especially at the blade inlet where there is significant impact. However, when k=0.28, the flow field is smoother, with the fluid smoothly transitioning along the blade wall. This demonstrates that the impeller with k=0.28 has a stronger ability to confine the fluid, better optimizes the flow field, and improves impeller efficiency.

[0090] Figure 7-1 The diagram shows the turbulent kinetic energy distribution at the axial section with k=0.5. Figure 7-2 This is a diagram showing the turbulent kinetic energy distribution at the axial section with k=0.28. From... Figure 7-1 and Figure 7-2The comparison shows that when k=0.5, a strong turbulent kinetic energy zone appears near the impeller outlet and the volute tongue due to dynamic and static interference. The stronger the turbulent kinetic energy, the more turbulent the fluid flow is at this location. Therefore, when k=0.28, the impeller turbulent kinetic energy zone is significantly reduced, and the internal flow state of the impeller is greatly improved. Furthermore, the blades arranged at this ratio are better able to adapt to the dynamic and static interference with the volute.

[0091] In this invention, the secondary blades are asymmetrically and directionally biased toward a specific position on the suction surface side of the main blade (k∈[0.2,0.45]).

[0092] This invention translates the biomimetic bias concept into a design process that integrates flow field diagnosis and localization, parametric modeling, and global optimization using a surrogate model and a multi-objective genetic algorithm. Specifically, it uses a baseline flow field diagnosis to identify the target region to guide the design direction, and combines a surrogate model with the optimization algorithm to efficiently determine the optimal bias parameters. This protects centrifugal pump impellers with the aforementioned specific bias coefficient range (k∈[0.2,0.45]).

[0093] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. A single-stage centrifugal pump with an impeller, characterized in that: The single-stage centrifugal pump with an impeller includes: a front cover plate, a rear cover plate, circumferentially distributed main blades, and offset secondary blades located in its flow channel. The offset secondary blades are circumferentially offset towards the suction side in the direction of impeller rotation within the flow channel. The circumferential width of the flow channel is defined as L, the distance from the secondary blade skeletal line to the front main blade skeletal line is defined as A, and the offset coefficient k = A / L, where the value of k ranges from 0.2 to 0.

45.

2. The single-stage centrifugal pump with an impeller according to claim 1, characterized in that: The value of k ranges from 0.25 to 0.

35.

3. A method for designing an impeller in a single-stage centrifugal pump, characterized in that: The steps of the design method are as follows: Step (1), Benchmark Modeling and Analysis: Perform flow field analysis on the original model without secondary blades. At the flow separation point, which is the leading edge position of the secondary blade, create an initial impeller model with the secondary blade in the center. The blade is centered at k=0.

5. Perform CFD simulation to obtain the benchmark flow field. Step (2), Flow field diagnosis and target localization: Analyze the baseline flow field, identify and quantify the low-velocity zone near the suction surface of the main blade in each flow channel; Step (3), parameterization and space construction: Define the circumferential position of the secondary blade as the core design variable - the offset coefficient k; set the optimization search range of k, the value range of k is 0.2 to 0.45; Step (4): Optimize the automated agent model; Step (5), Scheme Determination and Verification: Select the optimal scheme from step (4), perform high-precision CFD verification, including unsteady calculation, and finally output the optimized three-dimensional geometry of the impeller.

4. The impeller design method in a single-stage centrifugal pump with an impeller according to claim 3, characterized in that: The specific sub-steps of step (4): Step (401): Perform layered sampling within the design space, automatically generate multiple candidate impeller models, and perform CFD calculations; Step (402): Extract the key performance indicators of each scheme, including hydraulic efficiency η and low-velocity zone volume S. V Volume E of the high turbulent kinetic energy region V ; Step (403): Construct a Kriging proxy model based on sample data, and establish the relationship between design variable k and performance target η,S. V E V Approximate mathematical relationship; Step (404): Use a multi-objective optimization algorithm to perform efficient global optimization on the surrogate model and find the optimal solution set.

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