Design method of axial flow fan and axial flow fan
By establishing an airfoil parameter optimization matrix and using an iterative method to optimize axial fan design, the complexity of airfoil parameter coupling was solved, achieving coordinated optimization of airflow, efficiency, and noise, thus improving design efficiency and reducing costs.
Patent Information
- Application Number
- CN202511403825.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-28
- Publication Date
- 2026-01-13
AI Technical Summary
In axial fan design, the complex nonlinear coupling relationship between blade parameters makes it difficult to achieve coordinated optimization of multiple performance objectives such as airflow, efficiency and noise. Traditional design methods have long design cycles, high costs and difficulty in achieving coordinated optimization of multiple blade parameters and multiple objectives.
By establishing an initial blade profile parameter optimization matrix, an iterative method is used to find the optimal solution of the objective function, scientifically coordinate the coupling relationship between blade profile parameters, and combine sensitivity analysis and a differentiated iteration step size strategy to optimize the blade design.
It achieves multi-objective collaborative optimization of axial fan airflow, efficiency, and noise, shortens the design cycle, reduces manpower and experimental costs, and improves the automation level and efficiency of the design process.
Smart Images
Figure CN121328013A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of axial flow fan design, and particularly relates to a design method of an axial flow fan and the axial flow fan. BACKGROUND
[0002] The design of an axial flow fan needs to coordinate multiple mutually related aerodynamic blade profile parameters to achieve a balance of multiple performance targets such as air volume, efficiency and noise. These blade profile parameters include meridian plane shape, blade sweep angle, wrap angle, installation angle, inlet and outlet angle, camber line curvature and blade deflection, and there is a complex nonlinear coupling relationship between these blade profile parameters. The adjustment of any one blade profile parameter will cause changes in other blade profile parameters, and then affect the overall performance of the fan. Therefore, the design of an axial flow fan is essentially to coordinate and optimize the coupling relationship of multiple blade profile parameters.
[0003] The design method of an axial flow fan usually adopts a method combining blade profile parameter trial and error with experimental verification. Design personnel need to propose a large number of candidate blade profile parameter schemes based on experience, verify the performance of each scheme one by one through physical experiments or simulation, and then correct the blade profile parameters according to the verification results. The entire process needs to be iterated repeatedly, which not only has a long design cycle and high cost, but also is difficult to realize the collaborative optimization of multiple blade profile parameters and multiple targets.
[0004] In view of this, the present application is proposed. SUMMARY
[0005] In view of the deficiencies in the related art, the present application provides a design method of an axial flow fan and the axial flow fan. The optimization matrix is established by using the blade profile parameters of an initial blade, the target function representing the overall performance of the blade is iteratively optimized from the optimization matrix to obtain the specific values of the blade profile parameters when the overall performance of the initial blade is optimal, and finally the initial blade is optimized based on the specific values of the blade profile parameters to obtain an optimized blade.
[0006] In a first aspect, the present application provides a design method of an axial flow fan, comprising the following steps: An initial blade to be optimized is taken, and the geometric characteristics of the initial blade are geometrically parameterized to obtain blade profile parameters corresponding to the geometric characteristics, and an optimization matrix is established by using the blade profile parameters; An evaluation index of the axial flow fan is selected, a relationship between the blade profile parameters and the evaluation index is established, and a sensitivity analysis is performed on the blade profile parameters affecting the evaluation index to determine the optimization step length of each blade profile parameter; A target function is established by using the evaluation index, and an iterative method is used to find the optimal solution of the target function in the optimization matrix; and the specific values of the blade profile parameters when the target function is optimal are obtained; The initial blade is optimized according to specific values of the blade profile parameters to obtain a final blade.
[0007] In the technical scheme, the blade profile parameters of the initial blade are acquired, and an optimization matrix is established based on the blade profile parameters of the initial blade to integrate the discrete and isolated blade profile parameters into a unified mathematical model, so that a dynamic connection is established between the blade profile parameters; an evaluation index is selected to establish an objective function, and an optimal solution of the objective function is selected from the optimization matrix to scientifically coordinate the coupling relationship between the blade profile parameters, reduce blindness and uncertainty in the design process, and thus more efficiently realize collaborative optimization of multiple targets such as air volume, efficiency and noise of the axial flow fan; an iterative method is used to automatically find the optimal solution, which replaces manual repeated adjustment and verification, improves the automation level and efficiency of the design process, shortens the design cycle, reduces labor and experimental costs, and realizes collaborative optimization of multiple performance targets that is difficult to achieve by traditional methods.
[0008] In some embodiments of the present application, the blade is connected to the hub, and the blade comprises: a leading edge connected to the hub; the leading edge is located at the front end of the blade in the rotation direction; a trailing edge connected to the hub; the trailing edge is located at the tail end of the blade in the rotation direction; a first straight line is defined, the first straight line passes through the connecting point of the trailing edge and the hub and is perpendicular to the central axis of the hub; a second straight line is defined, the second straight line is perpendicular to the first straight line and the central axis of the hub; a rectangular coordinate system is established with the first straight line as the x-axis, the second straight line as the y-axis, the central axis of the hub as the z-axis, and the intersection O of the first straight line, the second straight line and the central axis of the hub as the origin, to obtain the blade profile parameters of the initial blade in the axial direction and the radial direction of the axial flow fan.
[0009] In the technical scheme, a rectangular coordinate system is established on the initial blade to geometrically parameterize the blade profile characteristics of the initial blade, so as to obtain the related blade profile parameters of the initial blade.
[0010] In some embodiments of the present application, the CST method is used to obtain the blade profile curve of the initial blade to obtain the blade profile parameters of the initial blade on the blade profile surface.
[0011] In the technical scheme, the CST method is used to obtain the blade profile curve of the initial blade to geometrically parameterize the blade profile characteristics of the initial blade on the blade profile surface, so as to obtain the related blade profile parameters of the initial blade.
[0012] In the technical scheme, the blade profile parameters include a front bending angle of the blade, a wrap angle of the blade, and a projection pattern of the blade in a meridian plane, the front bending angle of the blade, the wrap angle of the blade, and the projection pattern of the blade in the meridian plane are optimized, the air flow acceleration process is optimized, the vortex and flow separation loss is reduced, and the blade shape is adjusted, so that the aerodynamic efficiency is effectively improved, the noise generation is inhibited, and better wind volume, efficiency and noise balance are achieved.
[0013] In some embodiments of the present application, Latin hypercube sampling is used to obtain parameter samples of the CST. The value range of each blade profile parameter is divided into m intervals, and a value is randomly selected in each interval, so that each blade profile parameter includes m specific values, the blade profile parameters include n categories, and the optimization matrix is a matrix including m*n data.
[0014] In some embodiments of the present application, the geometric characteristics of the initial blade include at least a front bending angle of the initial blade, a wrap angle of the initial blade, and a projection pattern of the initial blade in a meridian plane.
[0015] In the technical scheme, the value range of each blade profile parameter is divided into multiple intervals and sample points are randomly selected, so that the sample points uniformly cover the entire possible variation range of the blade profile parameters, instead of being concentrated in a local area. This Latin hypercube sampling method improves the possibility of finding the optimal solution, makes the optimization result more reliable and accurate, and better adapts to the actual situation that the blade profile parameter values are different at different positions on the initial blade.
[0016] In some embodiments of the present application, the evaluation indexes include at least flow rate, static pressure efficiency and noise.
[0017] In the technical scheme, the evaluation indexes such as fan flow rate, static pressure efficiency and noise are selected, so that the objective function can better represent the overall performance of the axial flow fan, and the accuracy of the blade design is ensured.
[0018] In some embodiments of the present application, when performing sensitivity analysis, the sensitivities of the blade profile parameters commonly involved in different evaluation indexes in different evaluation indexes are independent of each other.
[0019] In the technical scheme, the sensitivities of the same blade profile parameter in different indexes are different, so that the influence of each blade profile parameter on different performance dimensions is given a proper weight, and the accuracy of different evaluation indexes is ensured according to the real degree of influence of the blade profile parameters on the change law of each evaluation index of wind volume, efficiency and noise. In some embodiments of the present application, orthogonal test is used to perform sensitivity analysis on the blade profile parameters affecting the evaluation indexes.
[0020] In the technical solution, the orthogonal test is used to respectively analyze the sensitivity of the blade profile parameters affecting the fan flow, static pressure efficiency and noise, so that the influence of each blade profile parameter on different evaluation indexes can be efficiently determined. The orthogonal test method can obtain comprehensive blade profile parameter information through fewer test times, reduces the test workload and cost, and improves the efficiency of the sensitivity analysis.
[0021] In some embodiments of the present application, when iteratively searching for the optimal solution of the target function, the iteration step size of the blade profile parameter with high sensitivity is small, and the iteration step size of the blade profile parameter with low sensitivity is large.
[0022] In the technical solution, the iteration step size is determined according to the sensitivity of the blade profile parameter. For the blade profile parameter with high sensitivity, a small step iteration is adopted to finely adjust the blade profile parameter and avoid missing the optimal solution due to a large step size. For the blade profile parameter with low sensitivity, a large step iteration is adopted to improve the optimization efficiency and reduce unnecessary calculation amount. This differentiated step strategy can minimize the required iteration times, speed up the optimization process, and improve the calculation efficiency while ensuring the accuracy of the results.
[0023] In a second aspect, the present application also provides a design method of an axial flow fan.
[0024] In the technical solution, the axial flow fan is designed by using the above design method, which not only reduces the design period and design cost of the axial flow fan, but also balances the performance of the axial flow fan in terms of air volume, static pressure efficiency, noise and the like, and has good overall performance.
[0025] In the above embodiments, the design method of the axial flow fan establishes an optimization matrix based on the blade profile parameters of the initial blade, iteratively optimizes the target function representing the overall performance of the blade from the optimization matrix to obtain the specific values of the blade profile parameters when the overall performance of the initial blade is optimal, and optimizes the initial blade based on the specific values of the blade profile parameters. This not only scientifically coordinates the coupling relationship between multiple blade profile parameters, reduces the blindness and uncertainty in the design process, and thus more efficiently realizes the collaborative optimization of multiple targets such as air volume, efficiency and noise of the axial flow fan, but also shortens the design period and reduces the labor and experimental cost, and realizes the collaborative optimization of multiple performance targets that is difficult to achieve by traditional methods. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 is a flow chart of an embodiment of the design method of the axial flow fan in the present application; Figure 2 is a structural schematic diagram of an initial blade in an embodiment of the design method of the axial flow fan in the present application; Figure 3 is a structural schematic diagram of a final blade in an embodiment of the design method of the axial flow fan in the present application; Figure 4 is a structural diagram of another angle of the final blade in one embodiment of the design method of the axial flow fan in the present application; Figure 5 is a diagram of the blade in a rectangular coordinate system in one embodiment of the design method of the axial flow fan in the present application; Figure 6 is a diagram of the projection of the blade on the plane xOy in one embodiment of the design method of the axial flow fan in the present application; Figure 7 is a diagram of the projection curve of the blade tip and the blade root on the plane xOy in one embodiment of the design method of the axial flow fan in the present application; Figure 8 is a diagram of the projection of the blade on the plane yOz in one embodiment of the design method of the axial flow fan in the present application; Figure 9 is a diagram of the cross section of the blade on the first plane in one embodiment of the design method of the axial flow fan in the present application; Figure 10 is a diagram of the fourth angle and the fifth angle in one embodiment of the design method of the axial flow fan in the present application; Figure 11 is a diagram of the meridian plane control point in one embodiment of the design method of the axial flow fan in the present application; Figure 12 is a diagram of the response surface in one embodiment of the design method of the axial flow fan in the present application; Figure 13 is a diagram of the five middle arcs in one embodiment of the axial flow fan in the present application; Figure 14 is a blade tip vortex cloud chart of the axial flow fan in the related art; Figure 15 is a blade tip vortex cloud chart in one embodiment of the axial flow fan in the present application; Figure 16 is a comparison chart of the static pressure efficiency of one embodiment of the axial flow fan in the present application and the axial flow fan in the related art; Figure 17 is a comparison chart of the specific noise of one embodiment of the axial flow fan in the present application and the axial flow fan in the related art.
[0027] In the figure, 100, blade; 200, hub; 110, leading edge; 120, trailing edge; 130, blade tip; 140, blade root; 101, first curve; 102, second curve; 103, third curve; 104, fourth curve; 105, camber line; 106, first camber line; 107, second camber line; 108, third camber line; 109, fourth camber line; 1010, fifth camber line; 1011, second projected camber line; 1012, third projected camber line; 1013, fourth projected camber line. DETAILED DESCRIPTION
[0028] For the purpose of making the objectives and implementations of the present application clearer, the following will clearly and completely describe the exemplary implementations of the present application with reference to the accompanying drawings in the exemplary implementations of the present application. Obviously, the described exemplary implementations are only a part of the implementations of the present application but not all implementations of the present application.
[0029] It should be noted that the brief description of the terms in the present application is only for the convenience of understanding the implementations described next and is not intended to limit the implementations of the present application. Unless otherwise specified, these terms should be understood according to their ordinary and general meanings.
[0030] The terms "first", "second", "third", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar or identical objects or entities and do not necessarily mean to limit a specific order or sequence, unless otherwise noted. It should be understood that the terms used in this way can be interchanged under appropriate circumstances.
[0031] The terms "include" and "have" and any variations thereof are intended to cover but not exclusively include, for example, a product or device that includes a series of components does not have to be limited to all the components listed clearly but can include other components that are not listed clearly or inherent to the product or device.
[0032] In an axial flow fan, the meridian plane shape directly affects the flow path and velocity distribution of the airflow in the fan flow passage, the blade sweep angle, the wrap angle and the installation angle jointly determine the action range and impact angle of the blade and the airflow, and the inlet and outlet angles and the camber line curvature play a key role in regulating the pressure gradient on the blade surface and the airflow attachment state, and the blade deflection is related to the structural stability and aerodynamic performance consistency during the fan operation. The above-mentioned blade profile parameters are not independent of each other, but there is a complex nonlinear coupling relationship, and the adjustment of any blade profile parameter will break the balance of the original design system and trigger the chain effect of other related blade profile parameters on the overall performance of the fan, so the design process of the axial flow fan is essentially a process of coordinating and optimizing the coupling relationship of multiple blade profile parameters.
[0033] The nonlinear coupling characteristics of multi-blade parameters pose a significant challenge to balancing the blade parameters of axial fans. In practical designs, optimizing blade lift characteristics to improve fan efficiency often requires adjusting key blade parameters such as the mid-curvature. However, such adjustments can easily disrupt the airflow on the blade surface, leading to problems such as airflow separation, vortex generation, or boundary layer shedding, which in turn causes high-frequency noise, creating a conflict between the design objectives of "efficiency improvement" and "noise control." Furthermore, due to the complexity of the coupling relationships between blade parameters, designers find it difficult to accurately predict the final effect of blade parameter adjustments, easily falling into the trap of local optima and failing to achieve a design blade that balances both efficiency and noise levels.
[0034] To address this issue, many related technologies employ an experience-based trial-and-error approach to airfoil parameters. This involves repeatedly adjusting one or a few airfoil parameters and combining this with experimental verification to evaluate the design effectiveness. The aim is to find feasible solutions under the constraints of multi-objective conflicts and airfoil parameter coupling. However, this approach lacks a systematic analysis of the coupling relationship between airfoil parameters and is therefore unable to fundamentally solve the problem of multi-objective balance and local optima.
[0035] Based on this, this application provides a design method for an axial flow fan. By establishing an optimization matrix with the blade profile parameters of the initial blade, the objective function characterizing the overall performance of the blade is iteratively optimized from the optimization matrix to obtain the specific values of each blade profile parameter when the overall performance of the initial blade is optimal. Then, the initial blade is optimized based on the specific values of the blade profile parameters to obtain the optimized blade.
[0036] like Figure 1 As shown, the design method of an axial fan provided in this application includes the following steps: S1. Take the initial blade to be optimized, and perform geometric parameterization on the geometric features of the initial blade to obtain the blade shape parameters corresponding to the geometric features, and establish the optimization matrix based on the blade shape parameters; S2. Select evaluation indicators for axial flow fans, establish the relationship between blade profile parameters and evaluation indicators, conduct sensitivity analysis on blade profile parameters that affect evaluation indicators, and determine the optimization step size for each blade profile parameter. S3. Establish an objective function based on evaluation indicators, and use an iterative method to find the optimal solution of the objective function in the optimization matrix; and obtain the specific values of the airfoil parameters when the objective function is optimal; S4. Optimize the initial blades based on the specific values of the blade shape parameters to obtain the final blades.
[0037] By establishing an optimization matrix based on airfoil parameters, discrete and isolated airfoil parameters are integrated into a unified mathematical model, enabling dynamic connections between various airfoil parameters. The optimal solution of the objective function is selected from the optimization matrix to scientifically coordinate the coupling relationship between multiple airfoil parameters, thereby achieving more efficient synergistic optimization of multiple objectives such as airflow, efficiency, and noise of axial flow fans.
[0038] The iterative method is used to automatically find the optimal solution, replacing manual repeated adjustments and verifications. This improves the automation level and efficiency of the design process, shortens the design cycle, reduces manpower and experimental costs, and achieves collaborative optimization of multiple performance objectives that are difficult to achieve with traditional methods.
[0039] By performing sensitivity analysis on the airfoil parameters and setting corresponding iteration step sizes for each airfoil parameter, this differentiated step size strategy can minimize the number of iterations required while ensuring the accuracy of the results, thereby accelerating the optimization process and improving computational efficiency.
[0040] It should be noted that selecting the optimal solution of the objective function from the optimization matrix can also be considered as optimizing the specific values of the airfoil parameters. In other words, the airfoil parameters that make up the optimization matrix are the parameters that need to be optimized.
[0041] like Figures 2-4 As shown, the blade 100 includes a blade tip 130, which is disposed away from the hub 200 relative to the blade root 140. The blade tip 130 and the blade root 140 are disposed opposite each other in the radial direction of the axial flow fan. The blade tip 130 and the blade root 140 are respectively located at opposite ends of the blade 100 in the radial direction of the axial flow fan.
[0042] like Figures 2-4 As shown, the blade 100 includes a blade root 140, which is connected to the hub 200.
[0043] The blade 100 includes a leading edge 110, which is located at the front end of the blade 100 in the direction of rotation and connects the blade tip 130 and the blade root 140.
[0044] The leading edge 110 does not extend straight along the radial direction of the axial fan. Instead, the leading edge 110 is typically curved backward along the direction of rotation of the blade 100 so that the leading edge 110 can smoothly cut the oncoming fluid and show the flow of the cut fluid along the top and bottom of the blade 100, thereby minimizing drag, avoiding flow separation, and accommodating a wider angle of attack of the incoming flow.
[0045] In some embodiments, the leading edge 110 has a sharp corner at one end near the blade tip 130. The sharp corner design can reduce the contact area between the leading edge 110 and the air, thereby reducing air resistance. The middle portion of the leading edge 110 is bent backward along the rotation direction of the blade 100 to optimize the matching relationship between the oncoming airflow and the leading edge 110 and suppress airflow separation.
[0046] like Figures 2-4 As shown, the blade 100 includes a trailing edge 120, which is located at the rear end of the blade 100 in the direction of rotation and connects the blade tip 130 and the blade root 140. The trailing edge 120 is the part where the airflow leaves the blade 100, and it is prone to generating unstable vortices, which is one of the main sources of aerodynamic noise.
[0047] The trailing edge 120 does not extend straight along the radial direction of the axial fan, so that the two fluids flowing from the upper and lower surfaces of the blade 100 can merge, avoiding the generation of eddies and pressure drag, ensuring that energy is efficiently transferred to the fluid, optimizing the fluid flow state, and significantly improving the lift-to-drag ratio and operating efficiency of the blade 100.
[0048] In some embodiments, the end of the trailing edge 120 near the blade tip 130 bends forward along the rotation direction of the blade 100, while the other portion of the trailing edge 120 bends backward along the rotation direction of the blade 100.
[0049] The geometric characteristics of the blades include the blade leading angle, which determines the intake state of the leading edge 110° and has a significant impact on the air delivery performance of axial fans. By optimizing the initial blade leading angle, the airflow acceleration process can be optimized, vortex and flow separation losses can be reduced, thereby effectively improving aerodynamic efficiency and suppressing noise generation.
[0050] The geometric characteristics of the blades include the blade wrap angle, which determines the contact area between the blade and the air, and also affects the size of the blade's forward bend angle, thus influencing the airflow and airflow resistance of the axial fan. By optimizing the blade wrap angle of the initial blades, the airflow acceleration process can be optimized, eddy current and flow separation losses can be reduced, thereby effectively improving aerodynamic efficiency and suppressing noise generation.
[0051] The geometric characteristics of the blades include their projection onto the meridional plane. This projection reflects the axial and radial shape changes of the blades, controlling the expansion or contraction of airflow from the inlet to the outlet, and directly affecting the fan's flow rate, pressure ratio, and stable operating range. By optimizing the initial projection of the blades onto the meridional plane, the blade shape can be adjusted to achieve a better balance between airflow, efficiency, and noise.
[0052] The geometric characteristics of the blade include the blade inlet angle, which affects the acceleration or deceleration of the airflow when it passes through the blade. By optimizing the initial blade inlet angle, the airflow impact noise can be reduced, while the airflow can be driven more efficiently, thereby increasing the exchange rate.
[0053] The geometric characteristics of the blade include the blade exit angle, which affects the acceleration or deceleration of the airflow when it passes through the blade. By optimizing the blade exit angle of the initial blade, the airflow impact noise can be reduced, and the airflow can be driven more efficiently to improve the exchange rate.
[0054] The geometric features of the blade include the shape of its mid-curve. The blade 100 is defined by a mid-curve along its direction of rotation, with one end located at the leading edge 110 and the other at the trailing edge 120. The mid-curve determines the direction of airflow deflection and energy loading within the blade passage. The shape and curvature of the mid-curve affect the size and direction of the blade inlet and outlet angles, the aerodynamic load distribution, and the surface static pressure gradient. By optimizing the shape of the initial blade's mid-curve, a better balance between airflow, efficiency, and noise can be achieved.
[0055] It should be noted that the geometric features of the blade also include the blade installation angle, etc. The geometric features of the blade are common knowledge in this field, and will not be elaborated here.
[0056] In this application, the geometric features of the blade, including the blade leading angle, blade wrap angle, the projection pattern of the blade on the meridional plane, the blade inlet angle, the blade outlet angle, and the mid-curve shape, are used as examples for description.
[0057] Among them, the blade leading angle and the blade wrap angle are the geometric features of the blade in the radial direction of the axial flow fan, the projection pattern of the blade on the meridional plane is the geometric feature in the axial direction of the axial flow fan, and the mid-curve, the blade inlet angle, and the blade outlet angle are the geometric features on the airfoil surface.
[0058] In this application, the geometric features of the blades are parameterized to establish a relationship between the geometric features of the blades.
[0059] In this application, a Cartesian coordinate system is established on the initial blade to obtain the specific values of the blade profile parameters of the initial blade in the axial and radial directions of the axial flow fan.
[0060] Specifically, a first straight line is defined, which passes through the connection point between the trailing edge 120 and the hub 200 and is perpendicular to the central axis of the hub 200. Define a second straight line, which is perpendicular to the first straight line and the centerline of hub 200.
[0061] like Figure 5As shown, a rectangular coordinate system is established with the first straight line as the x-axis, the second straight line as the y-axis, the central axis of the hub 200 as the z-axis, and the intersection point O of the first straight line, the second straight line and the central axis of the hub 200 as the origin.
[0062] In a rectangular coordinate system, three mutually perpendicular planes are defined: plane xOy, plane yOz, and plane xOz.
[0063] like Figure 6 As shown, the projection of the leading edge 110 onto the plane xOy forms the first curve 101. Point A on the first curve 101 and point O form a line OA. The line OA and the y-axis form a first angle α1. The first angle α1 is also the blade's forward bending angle.
[0064] In some embodiments, the first included angle α1 satisfies: α1≥4°, α1≤45°, so as to ensure that the blade 100 has the ability to guide the airflow to maintain a high heat exchange efficiency, and to avoid airflow turbulence caused by excessively large or small angles, so that the performance of the axial fan can more stably meet the needs of the outdoor unit of the air conditioner.
[0065] If α1 < 4°, the leading edge 110 is too straight, and its curvature cannot smoothly guide the airflow. This can easily lead to flow separation when the airflow impacts the leading edge 110, generating eddies and turbulence, thereby increasing air resistance and aerodynamic noise. At the same time, the narrow intake angle of attack will reduce adaptability, making the air delivery performance of the axial fan unstable and reducing the heat exchanger's heat exchange efficiency.
[0066] If α1 > 45°, the leading edge 110 will bend excessively backward. Although this can increase the guiding effect on the airflow, it can easily lead to a reduction in the effective working area of the blade 100. Excessive bending will make the airflow path along the surface of the blade 100 too long, increasing friction loss. At the same time, it may form a new flow separation zone at the blade tip 130, reducing the working efficiency of the axial fan and leading to increased energy consumption.
[0067] It should be noted that the value of the first included angle α1 is different when point A is in different positions. Specifically, the value of the first included angle α1 is the largest when point A is located at the connection point H between the leading edge 110 and the leaf root 140; and the value of the first included angle α1 is the smallest when point A is located at the connection point K between the leading edge 110 and the leaf tip 130.
[0068] like Figure 6As shown, the projection of the trailing edge 120 onto the plane xOy forms a second curve 102. Point B of the second curve 102 and point O form a line OB. The line OB and the y-axis form a second included angle α2. The second included angle α2 is the blade wrap angle. The second included angle α2 determines the projected area of the blade 100 on the plane xOy, and also affects the size of the first included angle α1, thereby affecting the air volume and air resistance of the axial flow fan.
[0069] It should be noted that the value of the second included angle α2 is different when point B is in different positions. Specifically, the value of the second included angle α2 is the largest when point B is located at the connection point G between the trailing edge 120 and the leaf root 140; and the value of the second included angle α2 is the smallest when point B is located at the connection point K' between the trailing edge 120 and the leaf tip 130.
[0070] In some embodiments, the second included angle α2 satisfies: α2≥47°, α2≤55°, so as to ensure that the blade 100 has the ability to guide the airflow to maintain a high heat exchange efficiency, and to avoid airflow turbulence caused by excessively large or small angles, so that the performance of the axial fan can more stably meet the needs of equipment such as air conditioning outdoor units.
[0071] If α2 < 47°, the wrap angle of the trailing edge 120 is too small, which will reduce the effective projected area of the blade 100 on the plane xOy. The shape of the blade 100 is too "upright", resulting in insufficient contact range between the blade 100 and the airflow, and a reduction in the air volume. The airflow does not converge smoothly at the trailing edge 120, which can easily form eddies and pressure drag, increase energy consumption and noise, and also disrupt the overall aerodynamic balance of the blade 100, affecting the operating efficiency and stability of the axial fan.
[0072] If α2 > 55°, the wrap angle of the trailing edge 120 is too large, and the blades 100 are too "flat" in the plane of rotation. Although the projected area increases, it will cause the flow channel between the blades 100 to become narrow and tortuous, increasing the frictional resistance and pressure resistance of the airflow. This will require the axial fan to consume more power to overcome the resistance. It will also easily cause vortex shedding and airflow separation at the trailing edge 120, generating huge aerodynamic noise. It may also cause vibration and shaking during the operation of the axial fan, reducing the air delivery efficiency and the stability of the axial fan operation.
[0073] like Figure 8 As shown, plane yOz is also the meridional plane of the axial fan, and the projection of the initial blade on plane yOz is the projection of the initial blade on the meridional plane.
[0074] In some embodiments of this application, the CST method is used to obtain the blade profile curve of the initial blade, so as to calculate the blade profile parameters on the blade profile surface and thus determine the specific values of the relevant blade profile parameters.
[0075] The CST method has advantages such as clear geometric meaning, fewer control parameters, strong adaptability, and high accuracy. Based on the parametric modeling of a blade cross-section, it describes the profile using curve functions (a combination of class functions and shape functions), effectively describing complex blade profiles with a finite set of blade parameters, facilitating subsequent optimization and sensitivity analysis. The CST blade profile parametric process is as follows:
[0076]
[0077]
[0078]
[0079] Where x, y—horizontal and vertical coordinates; y TE — The ordinates of the trailing edges of the upper and lower surfaces; C(x) — A class function that determines the overall shape characteristics of the profile; S(x) — A profile function that adjusts the specific profile shape through the airfoil parameters; N1=0.5; N2=1.0; Ai — CST airfoil parameters; Si(x) — A Bernstein polynomial. The higher the order, the stronger the profile fitting ability, but the number of airfoil parameters also increases.
[0080] Using the CST method to obtain the blade profile is a conventional technique in this field. In this application, ANSYS software is used to obtain the geometric parameter characteristics of the axial fan, and CFturbo-CFX software is used for blade profile optimization, which will not be elaborated here.
[0081] In other embodiments of this application, a first plane is defined, which is parallel to the plane xOz; such as Figure 9 As shown, the cross-sectional shape of the blade 100 on the first plane is the blade profile curve.
[0082] like Figure 9 As shown, the leaf-shaped curve has a middle arc 105, one end of which is located at the leading edge and the other end at the trailing edge; the ratio w of the y-coordinate to the z-coordinate of any point C on the middle arc 105 in the rectangular coordinate system is the first parameter.
[0083] like Figure 10 As shown, the endpoint D of the middle arc 105 is located on the leading edge, and the endpoint E of the middle arc 105 is located on the trailing edge; the tangent of the middle arc 105 at point D forms a fourth included angle β1 with the z-axis, and the fourth included angle β1 is the inlet angle of the blade.
[0084] In some embodiments, the fourth included angle β1 satisfies: β1≥19°, β1≤38.5°, so that the angle of the leading edge 110 is within a suitable working range while ensuring the reasonable structure of the blade 100. This reduces airflow impact noise and efficiently drives the airflow, increasing the exchange speed, thereby reducing fan power while enhancing the heat exchange effect of the outdoor heat exchanger.
[0085] If the fourth included angle β1 < 19°, the leading edge 110 is too "flat" in the axial direction of the axial fan, which can easily weaken the ability of the leading edge 110 of the blade 100 to capture the oncoming airflow and reduce the effective working area. Too small an angle will make the angle of airflow impact on the pressure surface of the blade 100 too steep, which can easily cause airflow separation and flow loss, and at the same time, it cannot effectively guide the airflow, thereby reducing the fan's working efficiency, wind pressure and air volume, and may increase intake noise.
[0086] If the fourth included angle β1 > 38.5°, the leading edge 110 will be too "upright" in the axial direction of the axial fan. Although this can increase the guiding effect of the leading edge 110 on the airflow, it will result in an excessively large axial projected area of the blade 100, significantly increasing the wind resistance in the forward direction and the bending stress of the blade 100 itself. An excessively large tilt angle will also make the blade root 140 too thick, affecting the smooth transition of airflow from the blade root 140 to the blade tip 130, and easily generating strong leakage vortices in the blade tip 130 region, increasing vortex noise and aerodynamic losses.
[0087] like Figure 10 As shown, the tangent of the middle arc line 105 at point E forms a fifth included angle β2 with the z-axis; the fifth included angle β2 is the exit angle of the blade.
[0088] The fifth included angle β2 satisfies: β2≥25°, β2≤64.7°, so that while ensuring the reasonable structure of the blade 100, the angle of the trailing edge 120 is within a suitable working range. This reduces airflow impact noise and efficiently drives the airflow, increasing the exchange speed. Thus, while reducing fan power, it enhances the heat exchange effect of the outdoor heat exchanger.
[0089] If the fifth included angle β2 < 25°, the trailing edge 120 is too "flat" in the axial direction, which can easily lead to insufficient axial velocity component and excessive circumferential velocity component when the airflow leaves the blade 100. That is, the airflow has a large rotation or vortex, and fails to effectively convert the rotational kinetic energy into the required axial kinetic energy. This rotating outlet airflow not only has large energy loss and low efficiency, but also easily impacts components such as heat exchangers, generating aerodynamic noise and reducing the overall heat exchange efficiency of the system.
[0090] If the fifth included angle β2 > 64.7°, the trailing edge 120 will be too "upright" in the axial direction, and may even be bent forward, which will make the flow channel at the trailing edge 120 of the blade 100 abnormally narrow and rapid, increasing the frictional resistance and pressure resistance of the airflow. The airflow will be difficult to merge smoothly when leaving the blade 100, and a large-scale, unstable vortex street will easily be generated behind the trailing edge 120.
[0091] In this application, a first parameter is introduced to evaluate the middle arc. The first parameter is the ratio w of the y-coordinate to the z-coordinate of point C on the middle arc 105 in the rectangular coordinate system.
[0092] In this application, the leaf shape parameters include at least the first included angle α1, the second included angle α2, the fourth included angle β1, the fifth included angle β2, and the first parameter.
[0093] In this application, the geometric features of the blade and the blade shape parameters are related as "design object" and "mathematical description tool". It can be considered that the geometric features are the specific manifestation of the physical shape of the blade and are the objects that need to be described and optimized. The blade shape parameters are the result of quantifying, digitizing and parameterizing these complex and continuous geometric features and are the variables used to establish the optimization matrix.
[0094] For the same airfoil parameter, the specific value of the airfoil parameter is different at different positions of the sample point on the initial blade. The range of values for each airfoil parameter is divided into multiple intervals, and a value is randomly selected in each interval so that each airfoil parameter includes multiple specific values. This ensures that the sample points evenly cover the entire possible range of variation of the airfoil parameter, rather than just being concentrated in a certain local area.
[0095] This Latin hypercube sampling method increases the likelihood of finding the optimal solution, making the optimization results more reliable and accurate, and better able to adapt to the actual situation where the leaf shape parameter values are different at different positions of the initial leaf.
[0096] The leaf shape parameters include n categories, and each category includes m sample points. Therefore, the optimization matrix includes m×n data points. For ease of description, each category is also referred to as each leaf shape parameter. In this application, each leaf shape parameter refers to the category of leaf shape parameters, not the specific value of the leaf shape parameter.
[0097] That is, the range of each leaf shape parameter is [ The sample size determines the coverage density of the leaf shape parameter space. The value range of each leaf shape parameter is divided into m equally probable intervals, with an interval width of... Randomly select a value from each interval. To ensure that each interval is sampled only once in each dimension, the intervals are arranged in order to generate a matrix of m sample points. Each sample point is a vector containing n airfoil parameters. The generated samples are then converted into airfoil parameter settings that can be used in CST simulation.
[0098]
[0099] Where m is the number of leaf shape parameters, n is the specific category of leaf shape parameters, and a is the lower bound vector of leaf shape parameters, a=[a1,a2,~a... n b is the upper bound vector of the leaf shape parameters, b = [b1, b2, ~b] n X is the generated optimization matrix, with a size of m×n, where each row represents a sample point.
[0100] It should be noted that the sample points are points on the blade, and each sample point may correspond to more than one blade profile parameter. For example, the blade profile parameters corresponding to the point on the leading edge 110 include the blade's forward bend angle and the blade's inlet angle.
[0101] It should also be noted that the range of values for different blade types is different.
[0102] In some embodiments, such as Figure 6 and Figure 13 As shown, the blade 100 is divided into five sections along its radial direction, and the mid-arc line is the curve connecting the centers of the inscribed circles of the airfoil in each section; that is, the blade 100 includes five mid-arc lines, and the directions of the five mid-arc lines from the blade root 140 to the blade tip 130 are respectively called: the first mid-arc line 106, the second mid-arc line 107, the third mid-arc line 108, the fourth mid-arc line 109 and the fifth mid-arc line 1010.
[0103] like Figure 6 As shown, among the five intermediate arcs, by adjusting the fourth intermediate arc 109 to a straight line and designing the upward curves at both ends of the fifth intermediate arc 1010, the blade tip 130 is flanged, achieving a maximum deflection of approximately 55% of the blade chord length. When the fourth intermediate arc becomes a straight line, the geometric angle of attack distribution from the leading edge 110 to the trailing edge 120 of the blade 100 is reconstructed. The straight intermediate arc forms a quasi-symmetrical airfoil with near-zero curvature at the blade tip 130, significantly reducing the local aerodynamic angle of attack in this region and suppressing the airflow separation originally caused by excessive curvature of the intermediate arc. The upward curves at both ends of the fifth intermediate arc form a high-pressure barrier on the blade back side, suppressing the lateral migration of the leaked flow. After the intermediate arc optimization, the vortex intensity at the fan blade tip 130 is significantly reduced.
[0104] like Figure 6As shown, the projections of the five mid-arc lines on the xOy plane are the first projected mid-arc line, the second projected mid-arc line 1011, the third projected mid-arc line 1012, the fourth projected mid-arc line 1013, and the fifth projected mid-arc line, respectively. The first projected mid-arc line, the second projected mid-arc line 1011, the third projected mid-arc line 1012, the fourth projected mid-arc line 1013, and the fifth projected mid-arc line are arranged radially along the blade 100. The first projected mid-arc line coincides with the first blade root curve 141, and the fifth projected mid-arc line coincides with the first blade tip curve 131.
[0105] In some embodiments, the endpoints of the five intermediate arcs on the leading edge 110 are selected to calculate the specific value of the first included angle α1, that is, the first included angle α1 has five specific values.
[0106] The specific values of the second included angle α2 are calculated by selecting the endpoints of the five intermediate arcs on the trailing edge 120, that is, the second included angle α2 has five specific values.
[0107] The specific value of the fourth included angle β1 is calculated by selecting the endpoints of the five middle arcs on the leading edge 110, that is, the fourth included angle β1 has five specific values.
[0108] The specific value of the fifth included angle β2 is calculated by selecting the endpoints of the five intermediate arcs on the trailing edge 120, that is, the fifth included angle β2 has five specific values.
[0109] Calculate the specific value of the first parameter by taking any point on each of the five mid-arcs; that is, the first parameter has five specific values.
[0110] In some embodiments of this application, the evaluation metrics include at least fan flow rate, static pressure efficiency, and noise, so that the objective function can better characterize the overall performance of the axial fan and ensure the accuracy of the blade design. At least some blade profile parameters affect the flow rate of the axial fan, at least some blade profile parameters affect the static pressure efficiency of the axial fan, and at least some blade profile parameters affect the noise of the axial fan.
[0111] Using blade profile parameters as independent variables and fan flow rate as the dependent variable, an optimization function for fan flow rate is established:
[0112] Using airfoil parameters as independent variables and static pressure efficiency as the dependent variable, an optimization function for static pressure efficiency is established:
[0113] Using the airfoil parameter as the independent variable and noise as the dependent variable, an optimization function for noise is established:
[0114] Where a is the CST airfoil parameter vector, ni is the combination of different airfoil parameter levels, P, Q, W, A, and u are the corresponding pressure, flow rate, power, area, and circumferential velocity, respectively, and f( ) is the efficiency optimization function, f( f(LP) is the optimization function for the flow coefficient, and f(LP) is the optimization function for the noise.
[0115] In some embodiments, the expression for the objective function Y is:
[0116] Where β0, β1, β2, and β3 are model weight coefficients used to balance the importance of each objective function; f( ) is the airfoil parameter characterizing static pressure efficiency, f( ) represents the airfoil parameter characterizing flow rate, f(LP) represents the airfoil parameter characterizing noise, and ε represents the error term.
[0117] It should be noted that the blade profile parameters affecting fan flow rate, static pressure efficiency, and noise are not mutually exclusive. For example, the first included angle α1 and the second included angle α2 affect both fan flow rate and noise, but the impact of the first included angle α1 and the second included angle α2 on flow rate is greater than its impact on noise. Therefore, the first included angle α1 and the second included angle α2 are more sensitive in the flow rate optimization function than in the noise optimization function.
[0118] The sensitivity of the same airfoil parameter varies across different evaluation indicators. To ensure that each airfoil parameter has an appropriate weight in different performance dimensions, the evaluation indicators such as air volume, efficiency, and noise can be evaluated based on their own variation patterns and the true extent to which they are affected by the airfoil parameter, thus guaranteeing the accuracy of different evaluation indicators.
[0119] In some embodiments, orthogonal experiments are used to perform sensitivity analyses on airfoil parameters affecting fan flow rate, airfoil parameters affecting static pressure efficiency, and airfoil parameters affecting noise, respectively, in order to efficiently determine the degree of influence of each airfoil parameter on different evaluation indicators. The orthogonal experimental method can obtain more comprehensive airfoil parameter information with fewer experiments, reducing experimental workload and cost, and improving the efficiency of sensitivity analysis.
[0120] During iterative optimization, the iteration step size is determined based on the sensitivity of the airfoil parameters. For highly sensitive airfoil parameters, a small step size is used to finely adjust the parameters and avoid missing the optimal solution due to excessively large step sizes. For less sensitive airfoil parameters, a large step size is used to improve optimization efficiency and reduce unnecessary computation. This differentiated step size strategy minimizes the number of iterations required while ensuring the accuracy of the results, thus accelerating the optimization process and improving computational efficiency.
[0121] It should be noted that the iterative method is a conventional technique in this field, and will not be elaborated upon here.
[0122] It should also be noted that Pareto charts are generated from several calculation samples, and high-efficiency, low-noise airfoil parameters are selected within a large flow coefficient range until the target is achieved.
[0123] Furthermore, it should be noted that there may not be a single optimal solution to the objective function, and different solutions correspond to different fan flow rates, static pressure efficiency, and noise levels. The final solution can be selected based on the preferences for fan flow rate, static pressure efficiency, and noise. If noise performance is preferred, the solution with the best noise performance is selected from multiple optimal solutions; if flow rate performance is preferred, the solution with the largest flow rate is selected from multiple optimal solutions; if static pressure efficiency performance is preferred, the solution with the highest static pressure efficiency is selected from multiple optimal solutions.
[0124] The aforementioned design method for axial flow fans establishes an optimization matrix based on the blade profile parameters of the initial blades. Iterative optimization of the objective function characterizing the overall performance of the blades is performed within the optimization matrix to obtain the specific values of each blade profile parameter when the overall performance of the initial blades is optimal. Optimizing the initial blades based on these specific values not only scientifically coordinates the coupling relationship between multiple blade profile parameters, reducing blindness and uncertainty in the design process, thus achieving more efficient synergistic optimization of multiple objectives such as airflow, efficiency, and noise in axial flow fans, but also shortens the design cycle, reduces manpower and experimental costs, and achieves synergistic optimization of multiple performance objectives that is difficult to achieve with traditional methods.
[0125] The above-mentioned design method for axial flow fans can optimize the blade parameters on a full scale, is less likely to get trapped in local optima, and has a fast calculation process, resulting in axial flow fans with good overall performance.
[0126] Based on the above-described design method for axial fans, this application also provides an axial fan designed using the above-described design method.
[0127] like Figures 3-4As shown, the axial fan includes a hub 200, which is connected to the rotating shaft of a motor so that the motor drives the axial fan to rotate; the hub 200 defines a central axis, and the axial fan rotates about the central axis.
[0128] like Figures 3-4 As shown, the axial fan includes blades 100, one end of which is connected to the hub 200, and the other end of which extends away from the hub 200; multiple blades 100 are provided, and the multiple blades 100 are arranged along the outer periphery of the hub 200.
[0129] To ensure the stability of the axial fan during rotation, multiple blades 100 are evenly distributed along the circumference of the hub 200 to ensure that the axial fan is subjected to uniform force and to prevent tilting and shaking during rotation.
[0130] In some embodiments, the axial fan includes six blades 100, which are evenly distributed around the outer periphery of the hub 200.
[0131] In the axial fan provided in this application, the first included angle α1 satisfies: ; Where A1, B1, and C1 are constants, and r1 is the distance from point A to point O.
[0132] The range of values for A1 is: A1≥0.85, A1≤1.15; the range of values for B1 is: B1≥0.2, B1≤0.3; the range of values for C1 is: C1≥60, C1≤75.
[0133] In some embodiments, A1 is 1, B1 is 0.229, and C1 is 69, that is... This improves the intake conditions of the leading edge 110, increases the working efficiency of the blade 100, and reduces intake noise. It ensures that the airflow can contact the leading edge 110 at appropriate angles of attack at different radii from the blade root 140 to the blade tip 130, thereby efficiently transferring rotational kinetic energy to the air. This avoids sudden separation of the airflow or the generation of turbulence at the leading edge 110 due to improper angles of attack, and reduces impact noise and flow loss.
[0134] The second included angle α2 satisfies: ; Where A2, B2, D1, and C2 are constants, and r2 is the distance from point B to point O.
[0135] The range of values for A2 is: A2≥2.5, A2≤3.5; the range of values for B2 is: B2≥0.0015, B2≤0.0025; the range of values for D1 is: D1≥0.45, D1≤0.55; the range of values for C2 is: C2≥15, C2≤25.
[0136] In some embodiments, A2 is 3, B2 is 0.0021, D1 is 0.4872, and C2 is 21, that is... This design allows the airflow from the upper and lower surfaces of the blade 100 to smoothly converge at the trailing edge 120, weakening the intensity and size of the vortex at the trailing edge 120 and effectively suppressing the generation of high-frequency noise. Simultaneously, it reduces airflow resistance, further lowering the fan's power consumption; it also improves airflow exit conditions on the blade 100, reducing vortex shedding and thus lowering wake noise.
[0137] It should be noted that, as Figure 7 As shown, the projection curve of the leaf tip 130 onto the xOy plane is the first leaf tip curve 131, and the projection curve of the leaf root 140 onto the xOy plane is the first leaf root curve 141. On the xOy plane, the point on the first leaf tip curve 131 has the largest distance r0 from the origin O, and the point on the first leaf root curve 141 has the largest distance r from the origin O. t Therefore, the range of values for r1 is minimized, and thus, r1 ≥ r0. t The range of values for r2 satisfies: r2 ≤ r0, r2 ≥ r t .
[0138] In some embodiments, the distance r0 from the first leaf tip curve 131 to the origin O is 372, and the distance r from the first leaf root curve 141 to the origin O is... t The value is 115, that is, r1≤115, r1≥372; r2≤115, r2≥372.
[0139] like Figure 8 As shown, the projection of the blade onto the yOz plane includes a third curve 103, which is the projection of the leading edge 110 onto the yOz plane. The coordinates of any point on the third curve 103 are (y1, z1). The third curve 103 can be represented as: ; A3, B3, D2, E1, and C3 are constants.
[0140] The range of values for A3 is: A3≥0.5, A3≤3.5; the range of values for B3 is: B3≥0, B3≤3.2; the range of values for D2 is: D2≥-0.1, D2≤0.3; the range of values for E1 is: E1≥-1, E1≤26; the range of values for C3 is: C3≥-1, C3≤913.
[0141] In some embodiments, the third curve 103 is To improve the static pressure resistance of blade 100.
[0142] In other embodiments, the third curve 103 is not entirely represented by a single functional relationship, but rather by different functional expressions corresponding to the numerical range of the distance y1 from a point on the third curve 103 to the z-axis. That is, the third curve 103 can be considered as a piecewise function.
[0143] Specifically, when y1≥115 and y1≤126, When y1 > 126 and y1 ≤ 372, .
[0144] Right now By using different function expressions corresponding to the distance y1 from the point on the third curve 103 to the z-axis, the flow path of the airflow in the axial and radial directions of the blade 100 is optimized, the impact and separation of the airflow at the leading edge 110 are reduced, the airflow noise is reduced, and the ability of the blade 100 to guide and drive the airflow is enhanced, the commutation speed is increased, thereby improving the heat exchange efficiency and reducing the fan power.
[0145] like Figure 8 As shown, the projection of the blade onto the plane yOz includes the fourth curve 104, which is the projection of the trailing edge 120 onto the plane yOz. The coordinates of any point on the fourth curve 104 are (y2, z2). The fourth curve 104 can be represented as: ; Among them, A4, B4, D3, E2, and C4 are constants.
[0146] The range of values for A4 is: A4≥0.5, A4≤4.5; the range of values for B4 is: B4≥0, B4≤4; the range of values for D3 is: D3≥-1, D3≤2; the range of values for E2 is: E2≥-1, E2≤202; the range of values for C4 is: C4≥220, C4≤4660.
[0147] In some embodiments, the fourth curve 104 is This reduces the torque of the axial fan and improves its efficiency.
[0148] In other embodiments, the fourth curve 104 is not entirely represented by a single functional relationship, but rather by different functional expressions corresponding to the numerical range of the distance y2 from a point on the fourth curve 104 to the z-axis. That is, the fourth curve 104 can be considered as a piecewise function.
[0149] Specifically, when y2≥115 and y2≤130, When y2 > 130 and y2 ≤ 340, When y2 > 340 and y2 ≤ 372, .
[0150] Right now This optimizes the airflow path in the axial and radial directions of the blade 100, reduces the impact and separation of airflow at the trailing edge, lowers airflow noise, and enhances the guiding and driving ability of the blade 100 to improve the commutation speed, thereby improving heat exchange efficiency and reducing fan power.
[0151] The fourth included angle β1 satisfies: ; Where A5, B5, D4, and C5 are constants, and r3 is the distance from point O to point D', the projection point of point D on the plane xOy; the range of A5 is: A5≥-1.5, A5≤-0.56; the range of B5 is: B5≥0, B5≤0.01; the range of D4 is: D4≥1, D4≤2; and the range of C5 is: C5≥140, C5≤150.
[0152] In some embodiments, This design aims to make the airflow smoother when it enters the blades 100, reduce the noise generated by the airflow impact, improve the efficiency of the blades 100 in capturing and driving the airflow, reduce the operating power of the axial fan, and increase the exchange speed and heat exchange efficiency of the outdoor heat exchanger.
[0153] like Figure 14 As shown, the vorticity loss at the blade tip 130° is relatively large in related technologies; for example... Figure 15 As shown, the vortex loss at the blade tip 130 is small in this application.
[0154] The fifth included angle β2 satisfies: ; Where A6, B6, D5, E3, and C6 are constants, and r4 is the distance from point O to point E', the projection point of point E on the plane xOy.
[0155] In some embodiments, the fifth included angle β2 satisfies: This design aims to improve the coordination between the blades 100 and the airflow, reduce noise caused by airflow disturbance, enhance the aerodynamic performance of the axial fan, reduce power consumption, and increase the heat exchange efficiency of the outdoor heat exchanger.
[0156] like Figure 10As shown, the maximum deflection point F of the middle arc 105 is set close to the leading edge 110. The distance L1 from point F to point D and the distance L2 from point D to point E satisfy: L1=55%L2, in order to optimize the airflow velocity distribution on the surface of the blade 100, so that the airflow forms a reasonable flow state near the leading edge 110 of the blade 100, reducing eddies and airflow separation, reducing the noise generated when the blade 100 is running, and also improving the lift characteristics of the blade 100, improving the efficiency of the axial fan, and reducing power consumption.
[0157] The projection of point C on the middle arc 105 onto the plane xOy is C', which forms a line OC' with point O. A third angle γ is formed between the line OC' and the line OA.
[0158] In some embodiments, γ ≥ 4°, γ ≤ 55°.
[0159] The ratio w of the y-coordinate to the z-coordinate of point C in a rectangular coordinate system satisfies: ; Where A7, B7, D6, and C7 are constants, and d is the radian of the third included angle γ.
[0160] The range of values for A7 is: A7≥0, A7≤0.55; the range of values for B7 is: B7≥-0.65, B7≤0.9; the range of values for D6 is: D6≥-0.45, D6≤1.2; the range of values for C7 is: C7≥0, C7≤0.5.
[0161] On the plane xOy, the distance between point C' and point O is r', where r' ≥ r0 and r' ≤ r t .
[0162] The relationship between the ratio w and the radian d is a piecewise function of the distance r' between point C' and point O. Based on the airflow characteristics of the blade 100 at different radius positions, the shape of the middle arc is adjusted so that the shape of each part of the blade 100 is adapted to the airflow characteristics, reducing local airflow turbulence, reducing the operating noise of the axial fan, improving the aerodynamic efficiency of the fan, reducing power loss, and improving the overall performance of the outdoor unit of the air conditioner.
[0163] Specifically, when r'≥r0 and r'<0.48r, ; When r'≥0.48r, r'<0.65r, ; When r'≥0.65r, r'<0.83r, ; When r'≥0.83r, r'≤r t hour, .
[0164] By considering different cases of the distance r' from point C' on the middle arc to the origin O, a specific functional expression for the ratio w and the radian d is given. This allows for adjustment of the middle arc shape according to the airflow characteristics of the blade 100 at different radius positions, so that the shape of each part of the blade 100 is adapted to the airflow characteristics, reducing local airflow turbulence, lowering the operating noise of the axial fan, improving the aerodynamic efficiency of the fan, reducing power loss, and enhancing the overall performance of the outdoor unit of the air conditioner.
[0165] like Figure 16 As shown, compared with the six-blade axial fan in this application and the four-blade axial fan in related technologies, the static pressure efficiency of the axial fan in this application is improved by 5% in the flow coefficient range of [0.275-0.35].
[0166] like Figure 17 As shown, comparing the six-blade axial fan in this application with the four-blade axial fan in related technologies, within the flow coefficient range of [0.275-0.35], the noise of the axial fan in this application is the same or slightly lower than that of the four-blade axial fan in related technologies. When rotating at the same speed, the motor power decreases by 6.8%.
[0167]
[0168] It should be noted that in this embodiment, the axial fan is mainly used in the outdoor unit of the top-discharge air conditioner. Therefore, in the design, the preference for static pressure efficiency is greater than the preference for noise, and the preference for noise is greater than the preference for air volume.
[0169] In the aforementioned axial flow fan, the airflow can flow in and out more smoothly and efficiently, thereby effectively reducing the aerodynamic noise caused by airflow separation and vortex shedding, and reducing the extra power consumed by the axial flow fan to overcome poor airflow. This allows the blades to better conform to the airflow trajectory when rotating 100°, reducing airflow impact and separation. The fan has a balanced performance in terms of air volume, static pressure efficiency, and noise, and has good overall performance. Moreover, it has a short design cycle and low design cost.
[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
[0171] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.
Claims
1. A design method for an axial flow fan, characterized in that, Includes the following steps: Select an initial blade to be optimized, and perform geometric parameterization on the geometric features of the initial blade to obtain the blade shape parameters corresponding to the geometric features. Then, establish an optimization matrix based on the blade shape parameters. Evaluation indicators for axial flow fans are selected, the relationship between blade profile parameters and evaluation indicators is established, and sensitivity analysis is performed on blade profile parameters that affect evaluation indicators to determine the optimization step size for each blade profile parameter. An objective function is established using evaluation indicators, and the optimal solution of the objective function is found in the optimization matrix using an iterative method. And obtain the specific values of the leaf shape parameters when the objective function is optimal; The initial blade is optimized based on the specific values of the blade shape parameters to obtain the final blade.
2. The design method of the axial flow fan according to claim 1, characterized in that, The blade is connected to the hub, and the blade includes: Leading edge, the leading edge being connected to the hub; the leading edge being located at the front end in the direction of blade rotation; Trailing edge, the trailing edge being connected to the hub; the trailing edge being located at the tail end in the direction of blade rotation; Define a first straight line that passes through the connection point between the trailing edge and the hub and is perpendicular to the center axis of the hub; Define a second straight line, which is perpendicular to the first straight line and the center axis of the wheel hub, respectively; A rectangular coordinate system is established with the first straight line as the x-axis, the second straight line as the y-axis, the central axis of the hub as the z-axis, and the intersection point O of the first straight line, the second straight line, and the central axis of the hub as the origin, in order to obtain the blade profile parameters of the initial blade in the axial and radial directions of the axial flow fan.
3. The design method of the axial flow fan according to claim 2, characterized in that, The CST method is used to obtain the leaf shape curve of the initial blade, so as to obtain the leaf shape parameters of the initial blade on the leaf shape surface.
4. The design method of the axial flow fan according to claim 3, characterized in that, The parameter samples of CST are obtained using Latin hypercube sampling; The value range of each of the aforementioned leaf shape parameters is divided into m intervals, and a value is randomly selected in each interval, so that each of the aforementioned leaf shape parameters includes m specific values. The leaf shape parameters include n categories, so that the optimization matrix is a matrix including m×n data.
5. The design method of the axial flow fan according to claim 1, characterized in that, The geometric features of the initial blade include at least the forward bend angle of the initial blade, the wrap angle of the initial blade, and the projection pattern of the initial blade onto the meridional plane.
6. The design method of the axial flow fan according to claim 1, characterized in that, The evaluation indicators include at least flow rate, static pressure efficiency, and noise.
7. The design method of the axial flow fan according to claim 1, characterized in that, When conducting sensitivity analysis, the sensitivity of leaf shape parameters that are common to different evaluation indicators is independent of each other.
8. The design method of the axial flow fan according to claim 1, characterized in that, Sensitivity analysis of the airfoil parameters affecting the evaluation index was conducted using orthogonal experiments.
9. The design method of the axial flow fan according to claim 1, characterized in that, When iteratively searching for the optimal solution of the objective function, the iteration step size of the air profile parameter with high sensitivity is small, while the iteration step size of the air profile parameter with low sensitivity is large.
10. An axial flow fan, characterized in that, It is designed using the design method described in any one of claims 1-9.