Axial flow fan strength optimization design method

Abstract

The invention relates to the technical field of axial flow fan design, in particular to an axial flow fan strength optimization design method which comprises the steps that an axial flow fan 3D model is established; performing digital calculation analysis on the strength of the axial fan, and calculating the structural strength of the axial fan; identifying a weak position, adding a material to the weak position and defining an optimization area; defining an optimization design boundary condition, performing automatic structure optimization by adopting a topological optimization algorithm, and outputting an optimized 3D model; reconstructing a 3D model of the axial fan by referring to the optimized 3D model; and carrying out digital calculation analysis according to the reconstructed axial fan 3D model, and evaluating whether a weak position exists or not. The method comprises the following steps: establishing a 3D model, carrying out digital calculation analysis on the axial fan, identifying and strengthening a weak position, automatically optimizing the structure by adopting a topological optimization algorithm, and finally outputting the optimized 3D model. The problem of evaluating the design strength and cost of the axial fan of the air conditioner is solved, the strength evaluation and optimization design of the axial fan are efficiently completed, and the lean design of the axial fan product is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of axial flow fan design, and specifically provides a method for optimizing the strength design of an axial flow fan. Background Art

[0002] In an air conditioner outdoor unit system, an axial flow fan is a key core moving component that accelerates the heat exchange process of the outdoor heat exchanger. Its operating reliability directly affects the overall performance of the unit and whether the air conditioner works properly. The outdoor unit of the air conditioner often operates in a high-temperature and airtight environment, and the operating reliability of the axial flow fan is a key aspect to be considered. If, during the development stage of the axial flow fan, due to insufficient strength design, cracking, fracture and other damage problems may occur to the axial flow fan during the life cycle of the air conditioner. At the same time, if the design of the axial flow fan is too conservative due to strength problems, it will lead to an increase in material costs and a decline in product competitiveness. The material of the fan prototype is different from that of the molded part, resulting in the inability to accurately evaluate the strength of the fan by the prototype part, increasing the risk of mold opening. Currently, there is a lack of an accurate evaluation method for the strength of axial flow fans. The probability of unqualified strength verification after the axial flow fan is molded is high, resulting in repeated mold repairs, prolonging the fan development cycle and increasing development costs. Therefore, there is an urgent need for a design method that can efficiently evaluate and optimize the strength of axial flow fans. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for optimizing the strength design of an axial flow fan to solve the technical problem that during the development stage of the axial flow fan, due to insufficient strength design, cracking and fracture of the axial flow fan occur during the life cycle of the air conditioner.

[0004] The basic solution provided by the present invention: A method for optimizing the strength design of an axial flow fan includes the steps of:

[0005] S1: Establish a 3D model of the axial flow fan;

[0006] S2: Numerically calculate and analyze the strength of the axial flow fan to calculate the structural strength of the axial flow fan;

[0007] S3: Identify the weak positions, add materials to the weak positions and define the optimization areas;

[0008] S4: Define the boundary conditions for the optimization design, and use the topology optimization algorithm to automatically optimize the structure of the 3D model of the axial flow fan to output an optimized 3D model;

[0009] The boundary conditions for the optimization design include:

[0010] ①: Add a contact setting between the added material and the original model;

[0011] ②: Set the optimization area as the area of the added material, and the rest is not used as the optimization area;

[0012] ③: Set the optimization condition as the maximum stress being less than the first stress threshold;

[0013] S5: Reconstruct the axial flow fan 3D model with reference to the optimized 3D model.

[0014] Furthermore, the S2 includes the steps of:

[0015] S201: Perform mesh division on the 3D structure of the axial flow fan;

[0016] S202: Add the material properties of the axial flow fan;

[0017] S203: Calculate the structural stress during the operation of the axial flow fan.

[0018] Furthermore, the S3 includes the steps of:

[0019] S301: Adjust the rotational speed of the axial flow fan to the test rotational speed, identify the position where the stress reaches the material tensile strength during the operation of the axial flow fan at the test rotational speed and define it as the weak position;

[0020] S302: Add material to the weak position and define the optimization area.

[0021] Furthermore, the material of the axial flow fan in S202 is AS + GF20%, the tensile strength of this material is 100 MPa, the elastic modulus is 8848 MPa, the Poisson's ratio is 0.38, and the density is 1.2 g / cm³.

[0022] Furthermore, the S203 includes the steps of:

[0023] S2031: Input the material data of the axial flow fan into the digital calculation theoretical model;

[0024] S2032: Apply fixed constraints to the mounting holes of the hub motor of the axial flow fan, and apply the rotational speed during operation to the entire blade;

[0025] S2033: Calculate the structural stress during the operation of the axial flow fan and obtain the position where the maximum stress occurs.

[0026] Furthermore, the material data of the axial flow fan is obtained through the material tensile test method.

[0027] Furthermore, when calculating the structural strength of the axial flow fan in S2, only the structural stress is considered, and the flow field stress is ignored.

[0028] Furthermore, it also includes S6: Perform digital calculation analysis based on the reconstructed 3D model of the axial flow fan to evaluate whether there are weak positions.

[0029] The principle and advantages of the present invention are as follows: The present invention provides a method for optimizing the strength design of an axial flow fan, aiming to solve the problems of cracking and fracture caused by insufficient strength design during the development stage of the axial flow fan. This method analyzes the axial flow fan through digital calculation by establishing a 3D model, identifies and strengthens weak positions, automatically optimizes the structure using a topology optimization algorithm, and finally outputs the optimized 3D model. This method not only improves the structural strength and operating reliability of the axial flow fan, but also reduces the material cost and enhances the product competitiveness. Through accurate digital calculation analysis and input of material data, the accuracy and effectiveness of the design are ensured, the mold opening risk and the number of mold repair times are reduced, the development cycle is shortened, and the development cost is reduced. Therefore, the present invention provides an efficient, accurate and economical solution for the design and development of axial flow fans. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a flowchart of the steps of an embodiment of a method for optimizing the strength design of an axial flow fan according to the present invention.

[0031] Figure 2 FIG. is a schematic structural diagram of an axial flow fan in an embodiment of a method for optimizing the strength design of an axial flow fan according to the present invention.

[0032] Figure 3 FIG. is a schematic strength diagram of an axial flow fan in an embodiment of a method for optimizing the strength design of an axial flow fan according to the present invention.

[0033] Figure 4 FIG. is a schematic diagram of the weak area of an axial flow fan in an embodiment of a method for optimizing the strength design of an axial flow fan according to the present invention.

[0034] Figure 5 FIG. is a schematic diagram of the optimization model of an axial flow fan in an embodiment of a method for optimizing the strength design of an axial flow fan according to the present invention.

[0035] Figure 6 FIG. is a schematic diagram of an axial flow fan model in an embodiment of a method for optimizing the strength design of an axial flow fan according to the present invention.

[0036] Figure 7 FIG. is a schematic strength diagram of the improved axial flow fan in an embodiment of a method for optimizing the strength design of an axial flow fan according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following is a further detailed description through specific embodiments:

[0038] The specific implementation process is as follows:

[0039] Embodiment 1

[0040] Embodiment 1 is basically as shown in the appendix Figure 1 A method for optimizing the strength design of an axial flow fan includes the steps:

[0041] S1: Establish a 3D model of the axial flow fan.

[0042] S2: Conduct digital calculation and analysis on the strength of the axial flow fan to calculate the structural strength of the axial flow fan.

[0043] S3: Identify the weak positions, add materials to the weak positions and define the optimization areas.

[0044] S4: Define the boundary conditions for the optimization design, use the topology optimization algorithm to automatically optimize the structure of the 3D model of the axial flow fan, and output the optimized 3D model.

[0045] S5: Reconstruct the 3D model of the axial flow fan with reference to the optimized 3D model.

[0046] S6: Conduct digital calculation and analysis based on the reconstructed 3D model of the axial flow fan to evaluate whether there are weak positions.

[0047] Specifically, in S1, this solution first established a 3D model of the axial flow fan. As shown in the appendix Figure 2 The axial flow fan can be in the structural forms of two-blade, three-blade, four-blade axial flow fans, etc.

[0048] In S2, this solution carried out mesh division on the 3D structure of the axial flow fan, added the material properties of the axial flow fan. The material of the axial flow fan is AS+GF20%. The experimental data of this material was obtained based on the material tensile test method. The tensile strength of this material is 100 MPa, the elastic modulus is 8848 MPa, the Poisson's ratio is 0.38, and the density is 1.2 g / cm³. Apply fixed constraints to the mounting holes of the hub motor of the axial flow fan, and apply the rotational speed during operation to the entire blade. Calculate the structural stress during the operation of the axial flow fan, that is, the position where the maximum stress occurs. As shown in the appendix Figure 3 Through digital calculation and analysis using existing simulation software, it is locked that the stress concentration part (the weakest position in strength) of the axial flow fan is the root of the connection between the blade and the hub, and the maximum stress is 14.5 Mpa.

[0049] Generally, the stress concentration part of the axial flow fan is located near the back of the front edge root of the fan, which belongs to tensile stress; the stress value of the flow field is very small (only 10.5% of the structural stress), and the stress here is compressive stress, and the maximum stress decreases after superposition. Therefore, in S3, this solution takes into account that the flow field stress is relatively small compared to the structural stress, and the maximum stress is even smaller after superposition. The structural strength of the fan is evaluated by the test speed, that is, three times the speed (the strength experiment of the axial flow fan is evaluated by the three-fold speed experiment). At this time, only the structural stress is considered, and the flow field stress is ignored. The structural stress at three times the speed is 9 times that of the original speed, that is, the stress is proportional to the square of the speed. Based on the tensile strength of 100 MPa of the axial flow fan material AS+GF20%, the stress at three times the speed should be less than 100 MPa, and the stress at single speed should be less than 12 Mpa for the axial flow fan not to crack. As shown in the appendixFigure 3 It can be seen that the strength at the root of the axial flow fan is insufficient. Therefore, at the root of the axial flow fan blades, materials are added around the hub, such as the green part shown in the appendix Figure 4 as shown.

[0050] In S4, the optimization design boundary conditions are defined in this solution, and the topology optimization algorithm is used to automatically optimize the structure, and the optimized 3D model is output as shown in the appendix Figure 5 as shown. Among them, the optimization design boundary conditions include:

[0051] ①: A contact setting is added between the added material and the original model.

[0052] ②: The optimization area is set as the area of the added material, and the rest is not used as the optimization area.

[0053] ③: The optimization condition is set as the maximum stress being less than the first stress threshold.

[0054] Among them, the first stress threshold is the stress value at single - speed rotation, which is 12 Mpa in this embodiment.

[0055] In S5, the 3D model of the axial flow fan is reconstructed in this solution with reference to the optimized 3D model as shown in the appendix Figure 6 as shown.

[0056] In S6, as shown in the appendix Figure 7 as shown, in this solution, digital calculation and analysis are carried out based on the reconstructed 3D model of the axial flow fan to evaluate whether there are weak positions. In this embodiment, the reconstructed 3D model is verified by digital calculation again, and the stress is 11.6 Mpa, and the evaluation is qualified.

[0057] To sum up, in this solution, by establishing a 3D model, digital calculation and analysis are carried out on the axial flow fan, weak positions are identified and strengthened, the topology optimization algorithm is used to automatically optimize the structure, and finally the optimized 3D model is output. This method not only improves the structural strength and operation reliability of the axial flow fan, but also reduces the material cost and enhances the product competitiveness. Through accurate digital calculation and analysis and material data input, the accuracy and effectiveness of the design are ensured, the mold - opening risk and the number of mold - repair times are reduced, the development cycle is shortened, and the development cost is reduced.

[0058] The above are only embodiments of the present invention. Common knowledge such as specific structures and characteristics known in the art is not described in detail herein. Those of ordinary skill in the art know all the general technical knowledge in the technical field to which the invention pertains before the filing date or the priority date, are able to obtain all the prior art in this field, and have the ability to apply conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, complete and implement this solution in combination with their own abilities. Some typical well-known structures or well-known methods should not become obstacles for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. An axial flow fan strength optimization design method, characterized in that: Including the steps: S1: Establish a 3D model of the axial flow fan; S2: Conduct digital calculation and analysis on the strength of the axial flow fan to calculate the structural strength of the axial flow fan; S3: Identify the weak positions, add materials to the weak positions and define the optimization areas; S4: Define the boundary conditions for the optimization design, use the topology optimization algorithm to automatically optimize the structure of the 3D model of the axial flow fan, and output the optimized 3D model; The boundary conditions for the optimization design include: ①: Add contact settings between the added material and the original model; ②: Set the optimization area as the area of the added material, and the rest is not used as the optimization area; ③: Set the optimization condition as the maximum stress being less than the first stress threshold; S5: Reconstruct the 3D model of the axial flow fan with reference to the optimized 3D model.

2. The axial flow fan strength optimization design method according to claim 1, characterized in that: The steps included in S2 are: S201: Mesh the 3D structure of the axial flow fan; S202: Add the material properties of the axial flow fan; S203: Calculate the structural stress during the operation of the axial flow fan.

3. The method for optimizing the strength design of an axial flow fan according to claim 2, characterized in that: The steps included in S3 are: S301: Adjust the rotational speed of the axial flow fan to the test rotational speed, identify the positions where the stress reaches the material tensile strength during the operation of the axial flow fan at the test rotational speed and define them as weak positions; S302: Add materials to the weak positions and define the optimization areas.

4. A method for optimizing the strength design of an axial flow fan according to claim 3, characterized in that: In S202, the material of the axial flow fan is AS + GF20%, the tensile strength of this material is 100 MPa, the elastic modulus is 8848 MPa, the Poisson's ratio is 0.38, and the density is 1.2 g / cm³.

5. A method for optimizing the strength design of an axial flow fan according to claim 4, characterized in that: The steps included in S203 are: S2031: Input the material data of the axial flow fan into the digital calculation theoretical model; S2032: Apply fixed constraints to the hub motor mounting holes of the axial flow fan and apply the rotational speed during operation to the entire blade; S2033: Calculate the structural stress during the operation of the axial flow fan and obtain the position where the maximum stress occurs.

6. The method for optimizing the strength design of an axial flow fan according to claim 5, characterized in that: The material data of the axial flow fan is obtained through the material tensile test method.

7. A method for optimizing the strength design of an axial flow fan according to claim 6, characterized in that: When calculating the structural strength of the axial flow fan in S2, only the structural stress is considered, and the flow field stress is ignored.

8. A method for optimizing the strength design of an axial flow fan according to claim 1, characterized in that, It also includes S6: Conduct digital calculation and analysis based on the reconstructed 3D model of the axial flow fan to evaluate whether there are weak positions.

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