Water pump runner with S swept shape, design method and optimization method thereof

Abstract

The invention belongs to the field of water pump runner blade design, and particularly relates to a water pump runner with an S swept shape, a design method and an optimization method thereof. The method comprises the steps that 1, a rotating wheel three-dimensional parameterized model is established, axial coordinates z, radial coordinates r and circumferential wrap angles theta of control points P1-P5 serve as design variables, hydraulic efficiency eta and lift H serve as optimization targets, and iterative optimization is conducted through a multi-target genetic algorithm; 2, constraint conditions in the optimization process include that the curvature radius change rate between adjacent control points is smaller than or equal to 15%; the maximum deflection of the S-shaped curve of the outlet edge is less than or equal to 0.1 D0; the rounding radius ratio RP2 / RP4 belongs to [1.5, 2.0]; and 3, fitting the relationship between the design variable and the target function through the response surface model, and finally outputting a Pareto optimal solution set. The problem that an existing water pump is single in design parameter is solved, blade surface pressure gradient distribution is improved, the vortex intensity of a wake flow area is reduced, and the performance and efficiency of the water pump are improved.

Description

Technical Field

[0001] The present invention belongs to the field of water pump impeller blade design, and in particular relates to a water pump impeller with an S-swept shape, a design method and an optimization method thereof. Background Art

[0002] Pumps are key tools for energy conversion and fluid transport in modern industry. At the same time, they also consume energy as energy-consuming components. With the implementation of sustainable development, demands for improved pump stability are shifting towards high speeds, high efficiency, and safe, stable, and long-term operation. Improving pump performance and efficiency is a key issue in the current engineering field.

[0003] The efficiency of a water pump is determined by many factors, with the impeller blades being one of the most important. Therefore, optimizing the impeller outlet edge design has become an important way to improve water pump efficiency.

[0004] The main factors affecting pump stability during operation include flow instability, system instability, and operational instability. For pumps, the key factor in improving pump efficiency is the pump's internal flow instability. Under normal operating conditions, pump performance parameters exhibit relatively stable trends, resulting in high efficiency. However, in practical engineering applications, pumps struggle to operate within their designed operating range for extended periods. During off-range operation, pump performance significantly degrades, generating significant flow instability. Due to dynamic-static interference, pressure pulsations in the flow field increase significantly, leading to intense fluid vibrations. This can cause uneven loading on the pump and shorten its service life. Therefore, expanding the design space for pumps and optimizing them under multiple operating conditions is crucial. The proper design of the runner blades significantly impacts the performance of the entire unit, with their shape and structure significantly influencing the flow characteristics and energy conversion efficiency of the fluid. Currently, the single design rule for the runner makes it difficult to maintain high pump efficiency and low instability under multiple operating conditions within this design space. Summary of the Invention

[0005] The present invention provides a water pump impeller with an S-swept shape, a design method and an optimization method thereof, which are used to solve the problem of single design parameters of current water pumps, improve the pressure gradient distribution on the blade surface, reduce the vortex intensity in the wake area, and improve the performance and efficiency of the water pump.

[0006] The present invention is achieved through the following technical solutions:

[0007] A design method for a water pump impeller having an S-swept shape, the design method comprising the following steps:

[0008] Step a: Based on the runner design parameters, the initial runner blade profile is constructed using the univariate theory;

[0009] Step b: Select five characteristic streamlines along the height direction of the flow channel and extract the spatial coordinates of each streamline at the outlet edge as control points P1-P5;

[0010] Step c: Apply positive and negative circumferential offsets to points P2 and P4 respectively to generate a discrete control point set with alternating curvature characteristics;

[0011] Step d: Use the non-uniform rational B-spline algorithm to fit and generate a continuous S-shaped outlet edge curve.

[0012] Furthermore, the circumferential offset δθ of point P2 in step c is P2 = +0.08D0 ~ +0.12D0, circumferential offset δθ of point P4 P4 =-0.10D0~-0.15D0, and satisfy |δθ P4 / δθ P2 |=1.2~1.5.

[0013] A method for optimizing a water pump runner with an S-swept shape is provided, wherein the method is based on the above-mentioned method for designing a water pump runner with an S-swept shape, and comprises the following steps:

[0014] Step 1: Establish a three-dimensional parametric model of the runner, use the axial coordinate z, radial coordinate r, and circumferential wrap angle θ of the control points P1-P5 as design variables, and use the hydraulic efficiency η and head H as optimization targets. Use a multi-objective genetic algorithm for iterative optimization.

[0015] Step 2: The constraints during the optimization process include: the curvature radius change rate between adjacent control points ≤ 15%; the maximum deflection of the S-shaped curve of the outlet edge ≤ 0.1D0; the fillet radius ratio R P2 / R P4 ∈[1.5,2.0];

[0016] Step 3: Fit the relationship between the design variables and the objective function through the response surface model, and finally output the Pareto optimal solution set.

[0017] Furthermore, the parameters of the multi-objective genetic algorithm are set as:

[0018] The population size is 50-100, the number of iterations is 100-200; the crossover probability is 0.8-0.9, and the mutation probability is 0.05-0.1; the weight distribution of the fitness function is: hydraulic efficiency η and head H each account for 50%.

[0019] Furthermore, the parameterized model in step 1 defines the outlet edge curve by the following equation:

[0020]

[0021] Where Ni,3 (u) is the cubic B-spline basis function, w i is the weight factor, and the parameter u∈[0,1] changes continuously along the curve.

[0022] Furthermore, the weight factor w i Dynamic adjustment through sensitivity analysis to meet the following requirements:

[0023]

[0024] A water pump impeller with an S-swept shape characteristic is obtained using the above-mentioned optimization method for a water pump impeller with an S-swept shape characteristic. The water pump impeller includes an upper cover plate 1, a lower cover plate 2, and a plurality of blades 3 evenly distributed between the upper cover plate and the lower cover plate; the outlet edge 4 of the impeller blades 3 is an S-shaped three-dimensional curve with a continuous spatial curvature change; the outlet edge 4 is formed by fitting a cubic spline curve by five discrete control points P1-P5, wherein the second control point P2 is convex and the fourth control point P4 is concave; the axial plane projection of the outlet edge 4 is a continuous S-shaped asymmetric curve, and presents a quadratic curve characteristic on the cylindrical surface projection.

[0025] Furthermore, the five control points include the upper endpoint P1, the lower endpoint P5 and three intermediate control points P2-P4, where P1 is the intersection of the upper cover plate 1 and the blade, and P5 is the intersection of the lower cover plate 2 and the blade; P2 and P4 are respectively located on both sides of the middle streamline of the flow channel, and P3 is located at the center of the main flow trajectory. The axial offset direction of each control point is consistent with the motion trajectory of the fluid in the flow channel inside the runner.

[0026] Furthermore, the angle distribution of the outlet edge 4 in the cylindrical projection satisfies Δθ=θ P1 -θ P5 =K·(D0 / L)^0.8, where K is the curvature correction coefficient 0.8≤K≤1.2, L is the axial length of the wheel; the angle increment Δθ at point P2 P2 = +3°~+8°, P4 point wrap angle decreases by Δθ P4 =-5°~-10°.

[0027] Furthermore, the trailing edge of the outlet edge 4 is provided with a variable radius fillet structure, and the fillet radius R satisfies R P2 / R P4 =The ratio relationship is 1.5~2.0.

[0028] The beneficial effects of the present invention are:

[0029] The present invention changes the geometric projection shape of the pump impeller outlet edge on the axial surface and the cylindrical surface, so that the impeller blades can operate stably for a long time in a wide working range, suppressing unstable characteristics, improving the regular working range of the pump, reducing the hydraulic loss of the pump, and having higher energy conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the three-dimensional structure of the runner of the present invention.

[0031] Figure 2 It is a three-dimensional schematic diagram of the S-shaped blade outlet edge of the present invention.

[0032] Figure 3 This is a distribution diagram of the control points on the outlet edge of the blade axial surface of the present invention.

[0033] Figure 4 This is a distribution diagram of S-shaped control points on the outlet side of the blade axial surface of the present invention.

[0034] Figure 5 It is the blade shaft bread angle distribution of the present invention. DETAILED DESCRIPTION

[0035] In the following description, specific details such as specific system structures and technologies are provided for illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obstructing the description of the present application with unnecessary details.

[0036] It will be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0037] It should also be understood that the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0038] The following is attached to this application specification Figure 1-5, clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of this application.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0040] Implementation Method 1

[0041] This embodiment provides a design method for a water pump runner with an S-swept feature, the design method comprising the following steps:

[0042] Step a: Based on the runner design parameters, the initial runner blade profile is constructed using the univariate theory;

[0043] Step b: Select five characteristic streamlines along the height direction of the flow channel and extract the spatial coordinates of each streamline at the outlet edge as control points P1-P5;

[0044] Step c: Apply positive and negative circumferential offsets to points P2 and P4 respectively to generate a discrete control point set with alternating curvature characteristics;

[0045] Step d: Use the non-uniform rational B-spline (NURBS) algorithm to fit and generate a continuous S-shaped outlet edge curve.

[0046] Furthermore, the circumferential offset δθ of point P2 in step c is P2 = +0.08D0 ~ +0.12D0, circumferential offset δθ of point P4 P4 =-0.10D0~-0.15D0, and satisfy |δθ P4 / δθ P2 |=1.2~1.5.

[0047] Implementation Method 2

[0048] This embodiment provides an optimization method for a water pump runner with an S-swept shape. The optimization method is based on the design method for a water pump runner with an S-swept shape described in embodiment 1. The optimization method includes the following steps:

[0049] Step 1: Establish a three-dimensional parametric model of the runner. Take the axial coordinate z, radial coordinate r, and circumferential wrap angle θ of the control points P1-P5 as design variables, and the hydraulic efficiency η and head H as optimization targets. Use the multi-objective genetic algorithm NSGA-II for iterative optimization.

[0050] Step 2: The constraints during the optimization process include: the curvature radius change rate between adjacent control points ≤ 15%; the maximum deflection of the S-shaped curve of the outlet edge ≤ 0.1D0; the fillet radius ratio R P2 / R P4 ∈[1.5,2.0];

[0051] Step 3: Fit the relationship between the design variables and the objective function through the response surface model RSM, and finally output the Pareto optimal solution set.

[0052] Furthermore, the parameters of the multi-objective genetic algorithm are set as:

[0053] The population size is 50-100, the number of iterations is 100-200; the crossover probability is 0.8-0.9, and the mutation probability is 0.05-0.1; the weight distribution of the fitness function is: hydraulic efficiency η and head H each account for 50%.

[0054] Furthermore, the parameterized model in step 1 defines the outlet edge curve by the following equation:

[0055]

[0056] Where N i,3 (u) is the cubic B-spline basis function, w i The weight factors P2 and P4 are set to 1.2 to 1.5, and the weights of the other points are 1.0. The parameter u∈[0,1] changes continuously along the curve.

[0057] Furthermore, the weight factor w i Dynamic adjustment through sensitivity analysis to meet the following requirements:

[0058]

[0059] Implementation Method 3

[0060] The present embodiment provides a water pump impeller with an S-swept shape feature, which is obtained by using an optimization method for a water pump impeller with an S-swept shape feature described in Embodiment 2. The water pump impeller includes an upper cover plate 1, a lower cover plate 2, and a plurality of blades 3 evenly distributed between the upper cover plate and the lower cover plate; the blades 3 are in a spatially distorted state along the z-axis direction; it is characterized in that: the outlet edge 4 of the impeller blade 3 is an S-shaped three-dimensional curve with a continuous spatial curvature change; the outlet edge 4 is formed by fitting a cubic spline curve by five discrete control points P1-P5, wherein the second control point P2 is convex and the fourth control point P4 is concave; the axial plane projection of the outlet edge 4 is a continuous S-shaped asymmetric curve, and presents a quadratic curve characteristic on the cylindrical surface projection.

[0061] Furthermore, the five control points include an upper endpoint P1, a lower endpoint P5 and three intermediate control points P2-P4, wherein the discrete control point P1 is the intersection of the upper cover plate 1 and the blade, and the discrete control point P5 is the intersection of the lower cover plate 2 and the blade; the discrete control point P2 and the discrete control point P4 are respectively located on both sides of the middle streamline of the flow channel, and the discrete control point P3 is located at the center of the mainstream trajectory. The axial offset direction of each control point is consistent with the motion trajectory of the fluid in the flow channel inside the runner.

[0062] Furthermore, the control point diameter satisfies D P1 =0.95D±2%, D P2 =1.05D±2%, D P3 =D, D P4 =0.93D±2%, D P5 =0.98D±2%, where D0 is the nominal outer diameter of the runner; the rate of change of the curvature radius between adjacent control points does not exceed 15%.

[0063] Furthermore, the angle distribution of the outlet edge 4 in the cylindrical projection satisfies Δθ=θ P1 -θ P5 =K·(D0 / L)^0.8, where K is the curvature correction coefficient 0.8≤K≤1.2, L is the axial length of the wheel; the angle increment Δθ at point P2 P2 = +3°~+8°, P4 point wrap angle decreases by Δθ P4 =-5°~-10°;

[0064] The trailing edge of the outlet edge 4 is provided with a variable radius fillet structure, and the fillet radius R satisfies R P2 / R P4 =The ratio relationship is 1.5~2.0.

Claims

1. A design method for a water pump impeller with an S-swept shape, characterized in that: The design method comprises the following steps: Step a: Based on the runner design parameters, the initial runner blade profile is constructed using the univariate theory; Step b: Select five characteristic streamlines along the height direction of the flow channel and extract the spatial coordinates of each streamline at the outlet edge as control points P1-P5; Step c: Apply positive and negative circumferential offsets to points P2 and P4 respectively to generate a discrete control point set with alternating curvature characteristics; Step d: Use the non-uniform rational B-spline algorithm to fit and generate a continuous S-shaped outlet edge curve.

2. The design method according to claim 1, characterized in that: The circumferential offset δθ of point P2 in step c P2 = +0.08D0 ~ +0.12D0, circumferential offset δθ of point P4 P4 =-0.10D0~-0.15D0, and satisfy |δθ P4 / δθ P2 |=1.2~1.

5.

3. A method for optimizing a water pump impeller having an S-swept characteristic, characterized in that: The optimization method is a design method for a water pump impeller with an S-swept shape according to any one of claims 1-2, and the optimization method comprises the following steps: Step 1: Establish a three-dimensional parametric model of the runner, use the axial coordinate z, radial coordinate r, and circumferential wrap angle θ of the control points P1-P5 as design variables, and use the hydraulic efficiency η and head H as optimization targets. Use a multi-objective genetic algorithm for iterative optimization. Step 2: The constraints during the optimization process include: the curvature radius change rate between adjacent control points ≤ 15%; the maximum deflection of the S-shaped curve of the outlet edge ≤ 0.1D0; the fillet radius ratio R P2 / R P4 ∈[1.5,2.0]; Step 3: Fit the relationship between the design variables and the objective function through the response surface model, and finally output the Pareto optimal solution set.

4. The optimization method according to claim 3, characterized in that The parameters of the multi-objective genetic algorithm are set as: The population size is 50-100, the number of iterations is 100-200; the crossover probability is 0.8-0.9, and the mutation probability is 0.05-0.1; the weight distribution of the fitness function is: hydraulic efficiency η and head H each account for 50%.

5. The optimization method according to claim 3, characterized in that: The parameterized model in step 1 defines the outlet edge curve by the following equation: Where N i,3 (u) is the cubic B-spline basis function, w i is the weight factor, and the parameter u∈[0,1] changes continuously along the curve.

6. The optimization method according to claim 4, characterized in that: The weight factor w i Dynamic adjustment through sensitivity analysis to meet the following requirements:

7. A water pump impeller with an S-swept shape, characterized in that: The water pump impeller is obtained by using the optimization method of a water pump impeller with an S-swept characteristic according to any one of claims 3 to 6, and the water pump impeller comprises an upper cover plate (1), a lower cover plate (2), and a plurality of blades (3) evenly distributed between the upper cover plate and the lower cover plate; The outlet edge (4) of the runner blade (3) is an S-shaped three-dimensional curve with a continuous spatial curvature change; the outlet edge (4) is formed by five discrete control points P1-P5, the second control point P2 of which is in a convex shape, and the fourth control point P4 is in a concave shape; the axial plane projection of the outlet edge (4) is a continuous S-shaped asymmetric curve, and presents a quadratic curve characteristic on a cylindrical surface projection.

8. The pump impeller according to claim 7, characterized in that The discrete control point P1 is the intersection of the upper cover plate (1) and the blade, and the discrete control point P5 is the intersection of the lower cover plate (2) and the blade; The discrete control points P2 and P4 are located on both sides of the middle streamline of the flow channel, respectively. The discrete control point P3 is located at the center of the mainstream trace. The axial offset direction of each control point is consistent with the fluid motion trajectory of the flow channel inside the runner.

9. The water pump impeller according to claim 7, characterized in that: The wrap angle distribution of the outlet edge (4) in the cylindrical projection satisfies Δθ=θ P1 -θ P5 =K·(D0 / L)^0.8, where K is the curvature correction coefficient (0.8≤K≤1.2), L is the axial length of the wheel; the angle increment Δθ at point P2 P2 = +3°~+8°, P4 point wrap angle decreases by Δθ P4 =-5°~-10°.

10. The water pump impeller according to claim 7, characterized in that: The trailing edge of the outlet edge (4) is provided with a variable radius fillet structure, and the fillet radius R satisfies R P2 / R P4 =The ratio relationship is 1.5~2.0.

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