Design method for pneumatic blade profile of high-performance straight blade axial flow fan

Abstract

A design method of a pneumatic blade profile of a high-performance straight blade axial flow fan belongs to the technical field of axial flow fans, and comprises a blade profile reference scheme, a blade profile automation scheme and a blade profile optimization scheme of the axial flow fan. The method comprises the steps that firstly, an axial flow fan blade profile reference scheme is selected, and a lift coefficient reference value and a resistance coefficient reference value are obtained through lift coefficients and resistance coefficients under multiple working conditions; secondly, full-process automation of the blade profile under given input parameters is achieved through a blade profile automation scheme; finally, based on the blade profile optimization scheme, the lift coefficient reference value, the resistance coefficient reference value and the blade profile automation scheme are combined, large-scale screening and optimization are conducted on the axial flow fan through an optimization algorithm, and finally the pneumatic blade profile of the high-performance straight-blade axial flow fan is determined. According to the method, the number of control points can be reduced, the parametric modeling efficiency is improved while the blade profile is accurately described, the calculation efficiency can be greatly improved, the optimized blade profile can adapt to more working conditions, and the pneumatic blade profile of the high-performance straight-blade axial flow fan is screened.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flow fans and relates to a design method for an aerodynamic blade profile of a high-performance straight-blade axial flow fan. Background Art

[0002] The design goal of axial flow fans is to improve efficiency and reduce energy consumption. In order to reduce energy consumption, fan manufacturers and research institutions are constantly improving the design and aerodynamic characteristics of axial flow fan blades to improve the efficiency of the fan. Because straight-blade fans have a natural advantage in manufacturing costs, the aerodynamic blade shape of high-performance straight-blade axial flow fans has been a key area of ​​research for fan manufacturers. Axial flow fans have a large outer diameter and a relatively small hub, generally below 0.3. If straight blades are used, the aerodynamic parameters change dramatically along the blade height direction, and the blade shape has large differences in working conditions at multiple blade height sections. The blade shape needs to have a high lift coefficient, a low loss coefficient, and good variable working condition performance, making blade shape design difficult.

[0003] In view of the above problems, the present invention provides a fan blade profile obtained by using a CFD numerical method combined with an optimization algorithm. This blade profile has higher aerodynamic efficiency when applied to an axial flow fan with straight blades. Summary of the invention

[0004] The problem to be solved by the present invention is to provide a design method for the aerodynamic blade profile of a high-performance straight-blade axial flow fan in view of the defects involved in the background technology. The method utilizes the CFD numerical calculation method and combines it with the optimization algorithm. The obtained fan blade profile has the characteristics of good variable operating condition aerodynamic performance, small air resistance, and fast design speed.

[0005] To achieve the above object, the technical solution adopted in the present invention is:

[0006] A method for designing a high-performance straight-blade axial fan aerodynamic blade profile, the design method includes an axial fan blade profile reference scheme, a blade profile automation scheme, and a blade profile optimization scheme; the axial fan blade profile reference scheme includes two parts: CFD calculation of lift coefficient and drag coefficient under multiple working conditions, and weighted coefficient merging; the automation scheme includes three parts: blade profile parameter modeling, automated numerical calculation, and automated flow field analysis, which respectively realize the automation of blade profile generation, the automation of blade profile flow field calculation, and the automation of blade profile flow field post-processing; the blade profile optimization scheme is a multi-objective optimization algorithm scheme. The design method first selects an axial fan blade profile reference scheme, that is, determines the lift coefficient and drag coefficient under multiple working conditions by the CFD method, merges the lift coefficient under multiple working conditions into a lift coefficient reference value by the weighted coefficient, and merges the drag coefficient under multiple working conditions into a drag coefficient reference value by the weighted coefficient. Secondly, the blade profile automation scheme is used to realize the full process automation of the blade profile under given input parameters. Finally, based on the blade optimization scheme, combined with the lift coefficient reference value and drag coefficient reference value of the blade reference scheme, and the blade automation scheme, the axial flow fan is screened and optimized on a large scale through the optimization algorithm, and the aerodynamic blade profile of the high-performance straight-blade axial flow fan is finally determined. The specific steps include:

[0007] The first step is to select the reference blade scheme of the axial fan and obtain the reference values ​​of the lift coefficient and the drag coefficient. Specifically:

[0008] Step 1) The lift coefficient and drag coefficient of the original blade under multiple working conditions are obtained through CFD calculation.

[0009] Step 2) The lift coefficients under multiple working conditions are combined into a lift coefficient reference value through a weighted coefficient, and the drag coefficients under multiple working conditions are combined into a drag coefficient reference value through a weighted coefficient.

[0010] The second step is to achieve full process automation of blade profiling under given input parameters through blade profiling automation solution, specifically:

[0011] Step 3) Parametric modeling of the original leaf shape is performed as follows:

[0012] Step 3.1) Describe the standard mid-camber curve in the original blade profile through a five-point fourth-order Bezier curve, such as Figure 4 As shown, the details are as follows:

[0013] The five points are P1, P2, P3, P4, and P5, of which the coordinates of the starting point P1 and the end point P5 are known as reference points, and the three control points P2, P3, and P4 in the middle are to be determined. Through dimensionless processing, the points to be determined are converted into the inlet geometric angle X1, the outlet geometric angle X2, and four dimensionless parameters m1, m2, m3, and m4. These six parameters will be used to optimize the shape of the middle arc. The specific meanings and sources of parameters m1, m2, m3, m4, X1, and X2 are as follows: the inlet geometry angle X1 is the angle between the tangent of the standard mid-arc curve at point P1 and the x-axis, and the outlet geometry angle X2 is the angle between the tangent of the standard mid-arc curve at point P5 and the X-axis. By calculating the tangent extension line PA of the inlet geometry angle and the outlet geometry angle, the control point P2 is obtained between (P1, PA) by the linear difference of the dimensionless parameter m1, the control point P4 is obtained between (P5, PA) by the linear difference of the parameter dimensionless m2, the control point PB is obtained between (P2, P4) by the linear difference of the dimensionless parameter m3, and finally the control point P3 is obtained between (PA, PB) by the linear difference of the dimensionless parameter m4.

[0014] Step 3.2) The standard thickness distribution curve is described by two four-point third-order Bezier curves, such as Figure 5 As shown, the details are as follows:

[0015] In the two four-point third-order Bezier curves, the control points describing the first Bezier curve are Q1, Q2, Q3, Q4, and the control points describing the second Bezier curve are Q4, Q5, Q6, Q7. c 、x c 、r cLE 、r cTE ,θ LE ,θ TE , and obtain the standard thickness distribution curve, whose specific meaning and source are as follows:

[0016] t1, t2, t3, t4 are four dimensionless parameters ranging from 0 to 1, y c is the maximum relative thickness, that is, the y-axis coordinate corresponding to the maximum value point of the standard thickness distribution curve of the original blade in the coordinate system, x c is the x-axis coordinate of the maximum point of the standard thickness distribution curve of the original blade in the coordinate system, r cLE is the relative radius of the leading edge of the aerodynamic blade of the straight blade axial flow fan, r cTE is the relative radius of the trailing edge of the aerodynamic blade of the straight blade axial flow fan, θ LE is the leading edge wedge angle, θ TE is the trailing edge wedge angle. Control point Q1(0, r cLE )、Q4(x c ,yc )、Q7(1,r cTE ) is a fixed point, and control point Q4 is the connection point of the two Bezier curves. The connection point is used to determine the maximum relative thickness of the blade. The coordinates of point QC are (0, y c ), the coordinates of point QD are (1, y c ), the coordinates of point QE are (x c , r cLE ), the extension line of the leading edge wedge angle intersects with the line connecting point QC and control point Q4 at point QA, the extension line of the trailing edge wedge angle intersects with the line connecting point QE and control point Q4 at point QB, the control point Q2 is obtained by linear difference of dimensionless parameter t1 between (Q1, QA), the control point Q3 is obtained by linear difference of dimensionless parameter t3 between (Q4, QC), the control point Q6 is obtained by linear difference of dimensionless parameter t2 between (Q7, QB), and the control point Q5 is obtained by linear difference of dimensionless parameter t4 between (Q4, QD).

[0017] Step 3.3) The leading edge curve and trailing edge curve of the aerodynamic blade of the straight blade axial flow fan are described by elliptical equations, as follows:

[0018] The parameterized equation of the standard elliptic equation and its derivative equation are shown in (1) and (2).

[0019]

[0020] In the formula, a represents the length of the major axis of the ellipse, b represents the length of the minor axis of the ellipse, k represents the aspect ratio of the ellipse, x represents the horizontal coordinate of a point on the ellipse, and y represents the vertical coordinate of a point on the ellipse. is the angle parameter, the value range is 0~2π, x ′ Represents x with respect to the parameter The derivative of y ′ Represents y with respect to the parameter The derivative of .

[0021] The leading edge curve, the trailing edge curve, the pressure side curve, and the suction side curve are guaranteed to be first-order continuous at the connection point, that is, the slopes of the leading edge curve, the trailing edge curve, the pressure side curve, and the suction side curve at the connection point are the same. Subscript LE is defined to represent the leading edge, and subscript TE is defined to represent the trailing edge; by giving the leading edge ellipse equation the aspect ratio k LE The value of the leading edge wedge angle θ LE , the leading edge curve parameters can be obtained The range of the trailing edge ellipse equation is given by the aspect ratio k TE The value of the trailing edge wedge angle θ TE , the trailing edge curve parameters can be obtained The specific formula is as described in (3). Given uniform parameters within the range, the leading edge curve can be obtained by coordinate transformation, and the trailing edge curve parameters The parameters are given uniformly within the range, and the trailing edge curve can be obtained through coordinate transformation.

[0022]

[0023] Step 3.4) superimposes the standard thickness distribution of the original blade along the positive and negative directions of the normal direction of the standard mid-camber line in step 3.1) to obtain the pressure side curve and the suction side curve. Then, the leading edge curve obtained in step 3.3) is spliced ​​to the front end of the pressure side and the suction side, and the trailing edge curve obtained in step 3.3) is spliced ​​to the rear end of the pressure side and the suction side, thereby obtaining a complete standardized blade profile.

[0024] Step 4) The standardized blade profile is transformed into a parameterized blade profile by coordinate transformation, and then a specific blade profile geometry file is obtained.

[0025] The third step is to conduct large-scale screening and optimization of axial flow fans based on the blade optimization scheme, combined with the lift coefficient reference value and drag coefficient reference value of the blade reference scheme, and the blade automation scheme through the optimization algorithm, and finally determine the aerodynamic blade profile of high-performance straight-blade axial flow fans, as follows:

[0026] Step 5) The grid drawing script program written in Python calls the Autogrid5 software to draw a grid for the blade geometry file in step 4).

[0027] Step 6) Call the Fine software through the solution setting script program written in Python to set the boundary conditions of the blade fluid domain and perform numerical calculations.

[0028] Step 7) Call CFview software to perform flow field post-processing through a post-processing script program written in Python to obtain numerical calculation results.

[0029] Step 8) The NSGA-II multi-objective optimization algorithm in the Modefrontier software is used to optimize the aerodynamic blade profile of the axial flow fan with high-performance straight blades by combining the results of the type automation scheme with the reference values ​​of the lift coefficient and the drag coefficient of the blade profile reference scheme.

[0030] Compared with the prior art, the present invention adopts the above technical solution and has the following beneficial effects:

[0031] (1) Compared with the traditional modeling method, the parametric modeling method adopted by the present invention can reduce the number of control points by selecting the parametric method of the mid-arc superimposed thickness, thereby improving the efficiency of the parametric modeling while accurately describing the blade shape.

[0032] (2) Compared with the traditional manual numerical calculation and flow field analysis, the automated numerical calculation and flow field analysis method adopted in the present invention can realize the automation of the whole process from generating blade data points, generating calculation domain and grid, CFD calculation and data post-processing, by using the convenient Python interface and automatic structured grid generation module Autogrid5 provided by NUMECA, which can greatly improve the calculation efficiency.

[0033] (3) The present invention adopts a multi-point optimization method. Compared with the traditional single-point optimization method, the multi-point optimization can simultaneously optimize the working state of the blade profile under different angles of attack, so that the optimized blade profile can adapt to more working conditions, and then determine the comprehensive aerodynamic performance of the fan blade profile under a wide range of variable working conditions, so as to screen the aerodynamic blade profile of high-performance straight-blade axial flow fans. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Flow chart of the aerodynamic blade design method for high-performance straight-blade axial fans.

[0035] Figure 2 Flowchart of the parametric design method for blade profiles.

[0036] Figure 3 This is the aerodynamic blade profile of a high-performance straight-blade axial flow fan.

[0037] Figure 4 is the standardized median arc curve in step 3.1).

[0038] Figure 5 is the normalized thickness distribution curve in step 3.2).

[0039] Figure 6 This is a comparison of the blade profiles before and after optimization. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings:

[0041] The present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. On the contrary, these embodiments are provided to make the present invention disclosed thoroughly and completely, and will fully express the scope of the present invention to those skilled in the art. In the accompanying drawings, components are enlarged for clarity.

[0042] It should be understood that although the terms first, second, third, etc. can be used here to describe various elements, components and / or parts, these elements, components and / or parts are not limited by these terms. These terms are only used to distinguish elements, components and / or parts from each other. Therefore, the first element, component and / or part discussed below can become the second element, component or part without departing from the teaching of the present invention.

[0043] A method for designing a high-performance straight-blade axial flow fan aerodynamic blade profile according to the present invention comprises the following steps:

[0044] Step 1) The lift coefficient and drag coefficient of the original blade under multiple working conditions are obtained through CFD calculation.

[0045] Step 2) The lift coefficient and the drag coefficient are combined into reference values ​​through weighting coefficients.

[0046] Step 3) Parametric modeling of the original leaf shape, the specific steps are as follows:

[0047] Step 3.1) Describe the standard mid-arc curve using a five-point fourth-order Bezier curve, such as Figure 4 As shown, the control points are P1, P2, P3, P4, and P5, the starting point P1 and the end point P5 are fixed, and the dimensionless parameters m1, m2, m3, and m4 are all 0.5, X1 = 5°, and X2 = 40°. The extension lines of the exit geometry angle and the entrance geometry angle intersect at point PA, and the control point P2 is obtained by linear difference of the dimensionless parameter m1 between (P1, PA), and the control point P4 is obtained by linear difference of the dimensionless parameter m2 between (P5, PA), and the control point PB is obtained by linear difference of the dimensionless parameter m3 between (P2, P4), and finally the control point P3 is obtained by linear difference of the dimensionless parameter m4 between (PA, PB).

[0048] Step 3.2) The standard thickness distribution curve is described by two four-point third-order Bezier curves, such as Figure 5 As shown, it is known that t1 = 0.31939, t2 = 0.70995, t3 = 0.51721, t4 = 0.5751, y c =0.07448m,x c =0.22m, r cLE =0.02m, r cTE =0.003m,θ LE =35.857°,θ TE=1.0293°. Control points Q1 (0, 0.02), Q4 (0.22, 0.07448), and Q7 (1, 0.003) are fixed points. The coordinates of point QC are (0, 0.07448), the coordinates of point QD are (1, 0.07448), and the coordinates of point QE are (0.22, 0.02). The extension line of the leading edge wedge angle intersects the line connecting point QC and control point Q4 at point QA. The extension line of the trailing edge wedge angle intersects the line connecting point QC and control point Q4 at point QA. The line connecting QE and control point Q4 intersects at point QB. The control point Q2 is obtained by linear difference of dimensionless parameter t1 between (Q1, QA), the control point Q3 is obtained by linear difference of dimensionless parameter t3 between (Q4, QC), the control point Q6 is obtained by linear difference of dimensionless parameter t2 between (Q7, QB), and the control point Q5 is obtained by linear difference of dimensionless parameter t4 between (Q4, QD).

[0049] Step 3.3) Both the leading edge curve and the trailing edge curve are described by ellipse equations.

[0050] The length-to-width ratio k of the leading edge ellipse equation is known LE =1.0855, the length-to-width ratio k of the trailing edge ellipse equation TE =0.89165, leading edge wedge angle θ LE =35.857°, trailing edge wedge angle θ TE =1.0293°. LE =1.0855 and leading edge wedge angle θ LE =35.857°Substitute into equation (3) and obtain the leading edge ellipse equation parameters The range is 128.115°~231.885°. TE =0.89165 and leading edge wedge angle θ TE =1.0293°Substitute into equation (3) and obtain the leading edge ellipse equation parameters The range is 90.918°~269.082°.

[0051]

[0052]

[0053]

[0054] Step 3.4) Superimpose the standard thickness distribution of the original blade along the positive and negative directions of the normal direction of the standard mid-camber line in step 3.1) to obtain the pressure side curve and the suction side curve. Then, splice the leading edge curve to the front end of the pressure side and the suction side, and splice the trailing edge curve to the rear end of the pressure side and the suction side, so as to obtain a complete standardized blade profile.

[0055] Step 4) The standardized blade profile is transformed into a parameterized blade profile by coordinate transformation, and then a specific blade profile geometry file is obtained.

[0056] Step 5) The grid drawing script program written in Python calls the Autogrid5 software to draw a grid for the blade geometry file in step 4).

[0057] Step 6) Call the Fine software through the solution setting script program written in Python to set the boundary conditions of the blade fluid domain and perform numerical calculations.

[0058] Step 7) Call CFview software to perform flow field post-processing through a post-processing script program written in Python to obtain numerical calculation results.

[0059] Step 8) The NSGA-II multi-objective optimization algorithm in the Modefrontier software is used to optimize the aerodynamic blade profile of the axial flow fan with high performance straight blades by combining the results of the automatic scheme with the reference values ​​of the lift coefficient and the drag coefficient of the blade profile reference scheme. Figure 6 shown.

[0060] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for designing a high-performance straight-blade axial fan aerodynamic blade profile, characterized in that: The design method includes an axial fan blade profile reference scheme, a blade profile automation scheme, and a blade profile optimization scheme; the axial fan blade profile reference scheme includes two parts: CFD calculation of lift coefficient and drag coefficient under multiple working conditions, and weighted coefficient merging; the automation scheme includes three parts: blade profile parameter modeling, automated numerical calculation, and automated flow field analysis, which respectively realize automated blade profile generation, automated blade profile flow field calculation, and automated blade profile flow field post-processing; The blade profile optimization scheme is a multi-objective optimization algorithm scheme; The design method firstly selects a reference blade scheme of an axial flow fan, and obtains a reference value of a lift coefficient and a reference value of a drag coefficient respectively through lift coefficients and drag coefficients under multiple working conditions; Secondly, the blade profile automation solution is used to achieve full-process automation of blade profile under given input parameters; finally, based on the blade profile optimization solution, combined with the lift coefficient reference value and drag coefficient reference value of the blade profile reference solution, and the blade profile automation solution, the axial flow fans are screened and optimized on a large scale through the optimization algorithm, and finally the aerodynamic blade profile of high-performance straight-blade axial flow fans is determined.

2. The method for designing a high-performance straight-blade axial fan aerodynamic blade profile according to claim 1, characterized in that: The specific steps include: The first step is to select a reference blade scheme for an axial flow fan and obtain reference values ​​for the lift coefficient and the drag coefficient. Specifically, step 1) obtain the lift coefficient and the drag coefficient of the original blade under multiple working conditions through CFD calculation; Step 2) combining the lift coefficients under multiple working conditions into a lift coefficient reference value through a weighted coefficient, and combining the drag coefficients under multiple working conditions into a drag coefficient reference value through a weighted coefficient; The second step is to achieve full process automation of blade profiling under given input parameters through blade profiling automation solution, specifically: Step 3) Parametric modeling of the original leaf shape is performed as follows: Step 3.1) describing the standard mid-camber curve in the original blade profile by a five-point fourth-order Bezier curve; Step 3.2) describing the standard thickness distribution curve by two four-point third-order Bezier curves; Step 3.3) The leading edge curve and the trailing edge curve of the aerodynamic blade of the straight blade axial flow fan are described by an elliptical equation to obtain the leading edge curve and the trailing edge curve respectively; Step 3.4) superimposes the standard thickness distribution of the original blade profile along the positive and negative directions of the normal direction of the standard mid-camber line in step 3.1) to obtain a pressure side curve and a suction side curve; then, the leading edge curve obtained in step 3.3) is spliced ​​to the front ends of the pressure side and the suction side, and the trailing edge curve obtained in step 3.3) is spliced ​​to the rear ends of the pressure side and the suction side, thereby obtaining a complete standardized blade profile; Step 4) The standardized blade profile is transformed into a parameterized blade profile by coordinate transformation, and then a specific blade profile geometry file is obtained; The third step is to conduct large-scale screening and optimization of axial flow fans based on the blade optimization scheme, combined with the lift coefficient reference value and drag coefficient reference value of the blade reference scheme, and the blade automation scheme through the optimization algorithm, and finally determine the aerodynamic blade profile of high-performance straight-blade axial flow fans, as follows: Step 5) calling the Autogrid5 software through a grid drawing script program written in Python to draw a grid for the blade geometry file in step 4); Step 6) calling Fine software through a solution setting script program written in Python to set the boundary conditions of the blade fluid domain and perform numerical calculations; Step 7) Calling CFview software to perform flow field post-processing through a post-processing script program written in Python to obtain numerical calculation results; Step 8) The NSGA-II multi-objective optimization algorithm in the Modefrontier software is used to optimize the aerodynamic blade profile of the axial flow fan with high-performance straight blades by combining the results of the type automation scheme with the reference values ​​of the lift coefficient and the drag coefficient of the blade profile reference scheme.

3. The method for designing a high-performance straight-blade axial flow fan aerodynamic blade profile according to claim 2, characterized in that: The step 3.1) is as follows: The five points are P1, P2, P3, P4, and P5, where the starting point P1 and the end point P5 are used as reference point coordinates, and the three control points P2, P3, and P4 in the middle are to be determined; through dimensionless processing, the points to be determined are converted into the inlet geometry angle X1, the outlet geometry angle X2, and four dimensionless parameters m1, m2, m3, and m4. These six parameters will be used to optimize the shape of the mid-arc line; the specific meanings and sources of the parameters m1, m2, m3, m4, X1, and X2 are as follows: The inlet geometry angle X1 is the angle between the tangent of the standard mid-arc curve at point P1 and the x-axis. Angle, the exit geometry angle X2 is the angle between the tangent of the standard mid-arc curve at point P5 and the X-axis. By calculating the tangent extension line PA of the inlet geometry angle and the exit geometry angle, the control point P2 is obtained between (P1, PA) by the linear difference of the dimensionless parameter m1, the control point P4 is obtained between (P5, PA) by the linear difference of the dimensionless parameter m2, the control point PB is obtained between (P2, P4) by the linear difference of the dimensionless parameter m3, and finally the control point P3 is obtained between (PA, PB) by the linear difference of the dimensionless parameter m4.

4. The method for designing a high-performance straight-blade axial flow fan aerodynamic blade profile according to claim 2, characterized in that: The step 3.2) is as follows: In the two four-point third-order Bezier curves, the control points describing the first Bezier curve are Q1, Q2, Q3, Q4, and the control points describing the second Bezier curve are Q4, Q5, Q6, Q7; through the four dimensionless parameters t1, t2, t3, t4 and the parameter y c 、x c 、r cLE 、r cTE ,θ LE ,θ TE , the standard thickness distribution curve is obtained, and its specific meaning and source are as follows: t1, t2, t3, t4 are four dimensionless parameters ranging from 0 to 1, y c is the maximum relative thickness, that is, the y-axis coordinate corresponding to the maximum value point of the standard thickness distribution curve of the original blade in the coordinate system, x c is the x-axis coordinate of the maximum point of the standard thickness distribution curve of the original blade in the coordinate system, r cLE is the relative radius of the leading edge of the aerodynamic blade of the straight blade axial flow fan, r cTE is the relative radius of the trailing edge of the aerodynamic blade of the straight blade axial flow fan, θ LE is the leading edge wedge angle, θ TE is the trailing edge wedge angle; control point Q1(0, r cLE )、Q4(x c ,y c )、Q7(1,r cTE ) is a fixed point, and the control point Q4 is the connection point of the two Bezier curves. The connection point is used to determine the maximum relative thickness of the blade. The coordinates of point QC are (0, y c ), the coordinates of point QD are (1, y c ), the coordinates of point QE are (x c , r cLE ), the extension line of the leading edge wedge angle intersects with the line connecting point QC and control point Q4 at point QA, the extension line of the trailing edge wedge angle intersects with the line connecting point QE and control point Q4 at point QB, the control point Q2 is obtained by linear difference of dimensionless parameter t1 between (Q1, QA), the control point Q3 is obtained by linear difference of dimensionless parameter t3 between (Q4, QC), the control point Q6 is obtained by linear difference of dimensionless parameter t2 between (Q7, QB), and the control point Q5 is obtained by linear difference of dimensionless parameter t4 between (Q4, QD).

5. The method for designing a high-performance straight-blade axial flow fan aerodynamic blade profile according to claim 2, characterized in that: The step 3.3) is as follows: The parameterized equation of the standard elliptic equation and its derivative equation are shown in (1) and (2); In the formula, a represents the length of the major axis of the ellipse, b represents the length of the minor axis of the ellipse, k represents the aspect ratio of the ellipse, x represents the horizontal coordinate of a point on the ellipse, and y represents the vertical coordinate of a point on the ellipse. is the angle parameter, the value range is 0~2π, x ′ Represents x with respect to the parameter The derivative of y ′ Represents y with respect to the parameter The derivative of The leading edge curve, the trailing edge curve, the pressure side curve, and the suction side curve are guaranteed to be first-order continuous at the connection point, that is, the slopes of the leading edge curve, the trailing edge curve, the pressure side curve, and the suction side curve at the connection point are the same; the subscript LE is defined to represent the leading edge, and the subscript TE is defined to represent the trailing edge; by giving the leading edge ellipse equation the aspect ratio k LE The value of the leading edge wedge angle θ LE , find the leading edge curve parameters The range of the trailing edge ellipse equation is given by the aspect ratio k TE The value of the trailing edge wedge angle θ TE , and obtain the trailing edge curve parameters The specific formula is as described in (3); in the leading edge curve parameter The parameters are uniformly given within the range, and then the leading edge curve is obtained by coordinate transformation. Given parameters uniformly within the range, the trailing edge curve is obtained through coordinate transformation;

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