A circumferential curved axial flow fan and design method thereof

Abstract

The present invention belongs to the field of fans, and specifically discloses a circumferential curved axial flow fan and a design method thereof. The method is specifically as follows: the leading edge inlet angle β1 of each axial flow blade is 18.0° to 26.0°, the trailing edge outlet angle β2 is 18.0° to 30.0°, and the relative curvature f of the blade is 0.06 to 0.10; when (r-R H ) / (R T ‑R H )=0%, the blade installation angle β is 37.0°~42.0°, and the blade chord l is 70.0mm~80.0mm; when (r-R H ) / (R T ‑R H )=100%, the blade installation angle β is 21.0°~26.0°, and the blade chord l is 315.0mm~335.0mm; the cross-sectional profile of the axial flow blade is determined by using the above parameters, and then the shape of the axial flow blade is determined. The present invention can adapt to the flow conditions of the outdoor unit of the air conditioner, reduce flow loss, enhance pressure resistance, improve efficiency and reduce noise at the same time.

Description

Technical Field

[0001] The present invention belongs to the field of fans, and more specifically, relates to a circumferential curved axial flow fan and a design method thereof. Background Art

[0002] With the improvement of people's living standards, air conditioning equipment has been widely used in residential, shopping malls, offices and other areas, and the demand is still increasing. How to produce air conditioners with high energy efficiency and low operating noise has always been a problem that air conditioner manufacturers need to solve.

[0003] The semi-open axial fan used in the outdoor unit of the air conditioner is different from the common closed fan in that its guide ring only covers the local area near the trailing edge, resulting in an extremely complex eddy field in this area. At the same time, due to the influence of the motor bracket and the heat exchanger, its air intake includes the front and side parts, making the air intake conditions more complex and uneven, resulting in low flow efficiency.

[0004] Experiments have shown that axial fans with backward-bending blade roots and forward-bending blade tips can improve their compressive performance and thus efficiency, and are particularly suitable for air conditioner outdoor units with complex structures and large air duct resistance. The existing axial fan design method uses a projection method, which has a small design space and low efficiency. Summary of the invention

[0005] In response to the above defects or improvement needs of the prior art, the present invention provides a circumferential curved axial flow fan and a design method thereof, wherein the design method can better adapt to the flow conditions, reduce flow losses, enhance the pressure resistance of the axial flow fan, effectively improve the efficiency of the axial flow fan and reduce noise by determining the cross-sectional profile and shape of the axial flow blades.

[0006] To achieve the above object, according to one aspect of the present invention, a design method for a circumferential curved axial flow fan is proposed, and the method is specifically as follows:

[0007] S1 The circumferential curved axial flow fan comprises a plurality of axial flow blades of the same shape and evenly distributed along the central cylinder. The axis of the central cylinder is denoted as the Z axis, and the radii of the cylinders corresponding to the blade top curved surface and the blade root curved surface of the axial flow blade are denoted as R T and R H , R H Point to R T The direction is recorded as the Y axis, O is the origin, and the axis perpendicular to the YOZ plane is recorded as the X axis, so as to establish the spatial rectangular coordinate system of the axial flow blade;

[0008] S2 takes the cross section of the axial flow blade and the cylinder as a blade profile, the mid-camber line of the blade profile is composed of P0, P1, P2 and P3, wherein P0 is the leading edge point, P3 is the trailing edge point, the straight line P0P3 is recorded as the blade chord l, the angle between the tangent P0P1 of the mid-camber line at point P0 and the blade chord l is recorded as the leading edge inlet angle β1, the angle between the tangent P2P3 of the mid-camber line at point P3 and the blade chord l is recorded as the trailing edge outlet angle β2, the angle between the negative direction of the X-axis and the blade chord l is recorded as the blade profile installation angle β, the maximum distance between the mid-camber line and the blade chord l is recorded as the camber F, and the ratio of the camber F to the blade chord l is recorded as the blade profile relative camber f; the leading edge inlet angle β1 is 18.0° to 26.0°, the trailing edge outlet angle β2 is 18.0° to 30.0°, and the blade profile relative camber f is 0.06 to 0.10;

[0009] S3 selects a preset number of equidistant sections along the blade height direction, and the distance from each section to the origin O is recorded as r. When (rR H ) / (R T -R H )=0%, the blade profile installation angle β of the corresponding cross section is 37.0°~42.0°; when (rR H ) / (R T -R H )=100%, the blade profile installation angle β of the corresponding cross section is 21.0°~26.0°, and the blade profile installation angle β of other cross sections is calculated according to the linear relationship;

[0010] S4Dang(rR H ) / (R T -R H )=0%, the blade chord l of the corresponding cross section is 70.0mm~80.0mm; when (rR H ) / (R T -R H )=100%, the blade chord l of the corresponding cross section is 315.0mm~335.0mm, and the blade chord l of other cross sections is calculated according to the exponential function relationship;

[0011] S5 uses the above parameters to determine the cross-sectional profile of the axial flow blade, and then determines the shape of the axial flow blade, thereby completing the design of the circumferential curved axial flow fan.

[0012] As a further preferred embodiment, the median arc line of step S2 is generated by a cubic B-spline curve controlled by P0, P1, P2 and P3.

[0013] As a further preferred embodiment, in step S3, the blade profile installation angle β of other cross sections is calculated according to the following formula:

[0014]

[0015] In the formula, β H for (rR H ) / (R T -R H ) = 0% blade installation angle, β T for (rR H ) / (R T -R H ) = 100% of the blade installation angle.

[0016] As a further preferred embodiment, in step S4, the blade chord l of other cross sections is calculated according to the following formula:

[0017]

[0018] In the formula, l H for (rR H ) / (R T -R H ) = 0% of the leaf chord, l T for (rR H ) / (R T -R H ) = 100% of leaf chord.

[0019] As a further preferred embodiment, determining the shape of the axial flow blade in step S5 specifically includes the following sub-steps:

[0020] S51: taking the midpoint of the blade chord l as the stacking point, forming a spatial stacking line according to the stacking points of each cross section, and projecting the spatial stacking line onto the XOY plane to obtain a curved stacking line;

[0021] S52 is on the XOY plane, when (rR H ) / (R T -R H )=100%, the angle between the line connecting the origin O and the superposition point of the cross section and the positive direction of the Y axis is recorded as the bending angle δ, and the value of the bending angle δ is 20.0°~30.0°;

[0022] S53 records the midpoint of the chord length of the blade root surface (2) as the blade root control point N, records the midpoint of the chord length of the blade tip surface (1) as the blade tip control point M, and records the angle between the tangent line of the curved overlap line at the blade root control point N and the positive direction of the Y axis as the blade root curved control angle δ H The angle between the tangent line at the blade tip control point M and the positive direction of the Y axis is recorded as the blade tip bending control angle δ T The ratio of the maximum curvature F1 of the curved stack line to the length of the line MN connecting the blade root and blade tip control points is recorded as the relative curvature f1 of the curved stack line; the blade root curvature control angle δ H The value of is 30.0°~40.0°, and the blade tip bending control angle δT The value of is 70.0°~80.0°, and the value of the relative curvature f1 of the curved stack line is 0.06~0.10.

[0023] As a further preferred embodiment, in step S51, the curved product curve is a cubic B-spline curve.

[0024] As a further preferred embodiment, the value of the blade profile trailing edge thickness ΔTE is 2.0 mm to 4.0 mm.

[0025] As further preferred, when (rR H ) / (R T -R H )=0%, the value of the blade leading edge thickness ΔLE of the corresponding cross section is 7.0mm~9.0mm; when (rR H ) / (R T -R H )=100%, the leading edge thickness ΔLE of the corresponding cross section is 2.0 mm to 4.0 mm, and the leading edge thickness ΔLE of other cross sections is calculated according to a linear relationship.

[0026] As a further preferred embodiment, the leading edge thickness of the blade profile of other cross sections is calculated according to the following formula:

[0027]

[0028] In the formula, ΔLE H for (rR H ) / (R T -R H ) = 0% of the leading edge thickness, ΔLE T for (rR H ) / (R T -R H ) = 100% of the leading edge thickness of the airfoil.

[0029] According to another aspect of the present invention, there is provided a circumferential curved axial flow fan obtained by using the above-mentioned design method.

[0030] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0031] 1. The present invention provides a circumferential curved axial flow fan, wherein the cross-sectional profile of the axial flow blade is determined by optimizing the values ​​of the leading edge inlet angle, the trailing edge inlet angle, the relative curvature of the blade, the blade installation angle and the blade chord of the axial flow blade, and then the shape of the axial flow blade is determined, thereby completing the design of the circumferential curved axial flow fan, so that it can better adapt to the flow conditions, reduce flow losses, enhance the pressure resistance of the axial flow fan, effectively improve the efficiency of the axial flow fan and reduce noise;

[0032] 2. In particular, the present invention designs the shape of the axial flow blades to obtain an axial flow fan with a backward curved blade root and a forward curved blade tip, which helps to reduce the aggregation of low-energy fluids in the boundary layer of the blade root and the blade tip, so that the boundary layer is thinned and the flow loss is reduced, thereby improving the pressure resistance and efficiency of the axial flow fan; at the same time, it prevents a large amount of low-energy fluid from gathering in the middle of the blade, causing increased losses;

[0033] 3. In addition, since the chord length of the root of the axial flow blade is small, its strength needs to be improved by increasing the thickness. The present invention optimizes the values ​​of the thickness of the trailing edge of the blade and the thickness of the leading edge of the blade, which can effectively improve the strength of the circumferential curved axial flow fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a three-dimensional schematic diagram of a circumferential curved axial flow fan provided by a preferred embodiment of the present invention;

[0035] Figure 2 is a front view of a circumferential curved axial flow fan provided by a preferred embodiment of the present invention;

[0036] Figure 3 is a top view of a circumferential curved axial flow fan provided by a preferred embodiment of the present invention;

[0037] Figure 4 is a bottom view of a circumferential curved axial flow fan provided by a preferred embodiment of the present invention;

[0038] Figure 5 Schematic diagram of the three-dimensional curved surface structure of the axial flow blade in the preferred embodiment of the present invention;

[0039] Figure 6 yes Figure 5 Schematic diagram of the cross-sectional shape of the blade root of the mid-axial flow blade;

[0040] Figure 7 yes Figure 5 Schematic diagram of the circumferential bend of the mid-axial flow blade.

[0041] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0042] 1-blade tip surface, 2-blade root surface, 3-leading edge surface, 4-trailing edge surface, 5-pressure surface, 6-suction surface. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] like Figure 1 As shown, an embodiment of the present invention provides a design method for a circumferential curved axial flow fan, and the method is specifically as follows:

[0045] The S1 circumferential curved axial flow fan includes a plurality of axial flow blades of the same shape and evenly distributed along the central cylinder. The surface of the axial flow blades is a three-dimensional curved surface in space, such as Figure 1-4 As shown, it includes a blade top curved surface 1, a blade root curved surface 2, a leading edge curved surface 3, a trailing edge curved surface 4, a pressure curved surface 5, and a suction curved surface 6;

[0046] like Figure 5 As shown, the blade tip surface 1 and the blade root surface 2 coincide with the sides of two coaxial cylinders. The axis of the central cylinder is recorded as the Z axis, and the radius of the cylinder corresponding to the blade tip surface 1 and the blade root surface 2 of the axial flow blade is recorded as R T and R H , and R T >R H , R H Point to R T The direction is recorded as the Y axis, O is the origin, and the axis perpendicular to the YOZ plane is recorded as the X axis, so as to establish the spatial rectangular coordinate system of the axial flow blade;

[0047] S2 uses the cross section of the axial flow blade and the cylinder as the blade profile. The center arc line of the blade profile is generated by a cubic B-spline curve controlled by P0, P1, P2 and P3, where P0 is the leading edge point, P3 is the trailing edge point, the straight line P0P3 is recorded as the blade chord l, the angle between the tangent line P0P1 of the center arc line at point P0 and the blade chord l is recorded as the leading edge inlet angle β1, the angle between the tangent line P2P3 of the center arc line at point P3 and the blade chord l is recorded as the trailing edge outlet angle β2, the angle between the negative direction of the X-axis and the blade chord l is recorded as the blade profile installation angle β, the maximum distance between the center arc line and the blade chord l is recorded as the curvature F, and the ratio of the curvature F to the blade chord l is recorded as the blade profile relative curvature f; the leading edge inlet angle β1 is 18.0°~26.0°, the trailing edge outlet angle β2 is 18.0°~30.0°, and the blade profile relative curvature f is 0.06~0.10;

[0048] S3 selects a preset number of equidistant sections along the blade height direction, and the distance from each section to the origin O is recorded as r. When (rR H ) / (R T -R H )=0%, the blade profile installation angle β of the corresponding cross section is 37.0°~42.0°; when (rR H ) / (R T -R H )=100%, the blade profile installation angle β of the corresponding cross section is 21.0°~26.0°, and the blade profile installation angle β of other cross sections is calculated according to the following formula:

[0049]

[0050] In the formula, β H for (rR H ) / (R T -R H ) = 0% blade installation angle, β T for (rR H ) / (R T -R H ) = 100% blade installation angle;

[0051] S4Dang(rR H ) / (R T -R H )=0%, the blade chord l of the corresponding cross section is 70.0mm~80.0mm; when (rR H ) / (R T -R H )=100%, the blade chord l of the corresponding section is 315.0mm~335.0mm, and the blade chord l of other sections is calculated according to the following formula:

[0052]

[0053] In the formula, l H for (rR H ) / (R T -R H ) = 0% of the leaf chord, l T for (rR H ) / (R T -R H ) = 100% of the leaf chord;

[0054] S5 uses the above parameters to determine the cross-sectional profile of the axial flow blade, and then determines the shape of the axial flow blade, thereby completing the design of the circumferential curved axial flow fan.

[0055] Specifically, the specific process of obtaining the blade profile in step S2 is:

[0056] The pressure surface 5 intersects with the blade tip surface 1 and the blade root surface 2, and the intersection line is the pressure surface curve ab. The suction surface 6 intersects with the blade tip surface 1 and the blade root surface 2, and the intersection line is called the suction surface curve cd. The center line between the pressure surface curve ab and the suction surface curve cd is called the mid-arc line. All three lines are cubic B-spline curves. The positive direction of the Z axis points from the suction surface to the pressure surface, which is the airflow direction.

[0057] The leading edge surface 3 intersects with the blade top surface 1 and the blade root surface 2, and the intersection line is called the leading edge curve ac. The trailing edge surface 4 intersects with the blade top surface 1 and the blade root surface 2, and the intersection line is called the trailing edge curve bd. The positive direction of the X-axis points from the leading edge surface 3 to the trailing edge surface 4.

[0058] With radius r from R H to R T A series of coaxial cylinder sides intersect with the axial flow blades to obtain a series of cross sections, which are then unfolded along the XOZ plane. Each cross section consists of a pressure surface curve ab, a suction surface curve cd, a leading edge curve ac and a trailing edge curve bd.

[0059] Further, determining the shape of the axial flow blade in step S5 specifically includes the following sub-steps:

[0060] S51 Figure 7 As shown, the midpoint of the leaf chord l is taken as the accumulation point, a space accumulation line is formed according to the accumulation point of each section, and the space accumulation line is projected to the XOY plane to obtain a curved accumulation line, which is a cubic B-spline curve;

[0061] S52 is on the XOY plane, when (rR H ) / (R T -R H )=100%, the angle between the line connecting the origin O and the superposition point of the cross section and the positive direction of the Y axis is recorded as the bending angle δ, and the value of the bending angle δ is 20.0°~30.0°;

[0062] S53 records the midpoint of the chord length of the blade root surface 2 as the blade root control point N, records the midpoint of the chord length of the blade tip surface 1 as the blade tip control point M, and records the angle between the tangent of the curved overlap line at the blade root control point N and the positive direction of the Y axis as the blade root bend control angle δ H The angle between the tangent line at the blade tip control point M and the positive direction of the Y axis is recorded as the blade tip bending control angle δ T The ratio of the maximum curvature F1 of the curved stack line to the length of the line MN connecting the blade root and blade tip control points is recorded as the relative curvature f1 of the curved stack line; the blade root curvature control angle δ HThe value of is 30.0°~40.0°, the value of the blade tip bending control angle is 70.0°~80.0°, and the value of the relative camber f1 of the bending stack line is 0.06~0.10.

[0063] More specifically, when the blade root bending control angle δ H When the angle is 0°, the axial flow blade is forward curved along the entire radial line. H When the angle is a certain one, the blade is backward curved at the root and forward curved at the tip. Axial flow fans with backward curved blade roots and forward curved blade tips can help reduce the accumulation of low-energy fluids in the boundary layer at the root and tip of the blades, thin the boundary layer, reduce flow losses, and improve the pressure resistance and efficiency of the axial flow fan. However, excessive backward curvature of the blade root and forward curvature of the blade tip cause a large amount of low-energy fluid to gather in the middle of the blade, increasing the loss. In addition, for axial flow fans whose guide shrouds only cover a portion of the blades, the forward curvature design has a greater impact on the radial inflow flow of the axial flow fan, so choosing the right parameters is crucial.

[0064] Furthermore, since the chord length of the blade root is small, its strength needs to be improved by increasing the thickness. Figure 6 As shown, the length of the straight line ac is the leading edge thickness ΔLE of the blade, and the length of the straight line bd is the trailing edge thickness ΔTE of the blade. The value of the trailing edge thickness ΔTE of the blade is 2.0mm~4.0mm; when (rR H ) / (R T -R H )=0%, the value of the blade leading edge thickness ΔLE of the corresponding cross section is 7.0mm~9.0mm; when (rR H ) / (R T -R H )=100%, the leading edge thickness of the corresponding section is 2.0mm~4.0mm, and the leading edge thickness of the blade profile of other sections is calculated according to the following formula:

[0065]

[0066] In the formula, ΔLE H for (rR H ) / (R T -R H ) = 0% of the leading edge thickness, ΔLE T for (rR H ) / (R T -R H ) = 100% of the leading edge thickness of the airfoil.

[0067] According to another aspect of the present invention, there is provided a circumferential curved axial flow fan obtained by using the above-mentioned design method.

[0068] The axial flow fan of the present invention is used for ventilation of the heat exchanger in the outdoor unit of the air conditioner. The material of the axial flow fan is ABS plastic, which is easy to shape and can be processed into fan blades of different shapes by injection molding, making the axial flow fan blades designed based on the primitive level method and circumferential bending technology easier to process.

[0069] In a preferred embodiment of the present invention, the diameter of the axial flow blade is 420 mm, the number of blades is 3, the blade chord l at 0% of the blade height is 70 mm, the blade chord l at 100% of the blade height is 320 mm, and the blade chord l of other sections changes in an exponential function relationship. The leading edge inlet angle β1 is 21°, the trailing edge outlet angle β2 is 21°, the blade profile relative curvature f is 0.06, the blade profile installation angle β at 0% of the blade height is 37°, the blade profile installation angle β at 100% of the blade height is 24°, the blade profile leading edge thickness ΔLE at 0% of the blade height is 7 mm, the blade profile leading edge thickness ΔLE at 100% of the blade height is 2 mm, the blade profile trailing edge thickness ΔTE is 2 mm, and the blade profile installation angle β and leading edge thickness of other sections change linearly. The bending angle δ is 20.0°, and the blade root bending control angle δ H is 35.0°, the blade tip bending control angle δ T It is 80.0°, and the relative curvature f1 of the bending stack line is 0.1.

[0070] Table 1 Comparison of numerical simulation results between prototype and embodiment (rotation speed 870 rpm)

[0071]

[0072] Table 1 shows the numerical simulation results of the prototype and the embodiment at a speed of 870 rpm. Under given different static pressure conditions, the flow rate of the embodiment is slightly reduced, which relatively reduces noise, reduces power, and improves efficiency, indicating that the axial flow fan designed by the method based on the combination of the elementary level and circumferential bend technology of the present invention can effectively improve the aerodynamic performance and acoustic performance of the fan.

[0073] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method for a circumferential curved axial flow fan, characterized in that: The method is as follows: The circumferential curved axial flow fan S1 comprises a plurality of axial flow blades of the same shape and uniformly distributed along a central cylinder. The axis of the central cylinder is denoted as the Z axis, and the radii of the cylinders corresponding to the blade top curved surface (1) and the blade root curved surface (2) of the axial flow blade are denoted as R T and R H , R H Point to R T The direction is recorded as the Y axis, O is the origin, and the axis perpendicular to the YOZ plane is recorded as the X axis, so as to establish the spatial rectangular coordinate system of the axial flow blade; S2 takes the cross section of the axial flow blade and the cylinder as a blade profile, the mid-camber line of the blade profile is composed of P0, P1, P2 and P3, wherein P0 is the leading edge point, P3 is the trailing edge point, the straight line P0P3 is recorded as the blade chord l, the angle between the tangent P0P1 of the mid-camber line at point P0 and the blade chord l is recorded as the leading edge inlet angle β1, the angle between the tangent P2P3 of the mid-camber line at point P3 and the blade chord l is recorded as the trailing edge outlet angle β2, the angle between the negative direction of the X-axis and the blade chord l is recorded as the blade profile installation angle β, the maximum distance between the mid-camber line and the blade chord l is recorded as the camber F, and the ratio of the camber F to the blade chord l is recorded as the blade profile relative camber f; the leading edge inlet angle β1 is 18.0° to 26.0°, the trailing edge outlet angle β2 is 18.0° to 30.0°, and the blade profile relative camber f is 0.06 to 0.10; S3 selects a preset number of equidistant sections along the blade height direction, and the distance from each section to the origin O is recorded as r. When (rR H ) / (R T -R H )=0%, the blade profile installation angle β of the corresponding cross section is 37.0°~42.0°; when (rR H ) / (R T -R H )=100%,the blade profile installation angle β of the corresponding cross section is 21.0°~26.0°,and the blade profile installation angle β of other cross sections is calculated according to the linear relationship; S4Dang(rR H ) / (R T -R H )=0%, the blade chord l of the corresponding cross section is 70.0mm~80.0mm; when (rR H ) / (R T -R H )=100%, the blade chord l of the corresponding cross section is 315.0mm~335.0mm, and the blade chord l of other cross sections is calculated according to the exponential function relationship; S5: using the above parameters to determine the cross-sectional profile of the axial flow blade, and then determining the shape of the axial flow blade, thereby completing the design of the circumferential curved axial flow fan; Wherein, determining the shape of the axial flow blade in step S5 specifically includes the following sub-steps: S51: taking the midpoint of the blade chord l as the stacking point, forming a spatial stacking line according to the stacking points of each cross section, and projecting the spatial stacking line onto the XOY plane to obtain a curved stacking line; S52 is on the XOY plane, when (rR H ) / (R T -R H )=100%, the angle between the line connecting the origin O and the superposition point of the cross section and the positive direction of the Y axis is recorded as the bending angle δ, and the value of the bending angle δ is 20.0°~30.0°; S53 records the midpoint of the chord length of the blade root surface (2) as the blade root control point N, records the midpoint of the chord length of the blade tip surface (1) as the blade tip control point M, and records the angle between the tangent line of the curved overlap line at the blade root control point N and the positive direction of the Y axis as the blade root curved control angle δ H The angle between the tangent line at the blade tip control point M and the positive direction of the Y axis is recorded as the blade tip bending control angle δ T The ratio of the maximum curvature F1 of the curved stack line to the length of the line MN connecting the blade root and blade tip control points is recorded as the relative curvature f1 of the curved stack line; the blade root curvature control angle δ H The value of is 30.0°~40.0°, and the blade tip bending control angle δ T The value of is 70.0°~80.0°, and the value of the relative curvature f1 of the curved stack line is 0.06~0.10; The value of the blade trailing edge thickness ΔTE is 2.0mm~4.0mm; When (rR H ) / (R T -R H )=0%, the value of the blade leading edge thickness ΔLE of the corresponding cross section is 7.0mm~9.0mm; when (rR H ) / (R T -R H )=100%, the leading edge thickness ΔLE of the corresponding cross section is 2.0 mm to 4.0 mm, and the leading edge thickness ΔLE of other cross sections is calculated according to a linear relationship.

2. The design method of the circumferential curved axial flow fan according to claim 1, characterized in that: The median arc of step S2 is generated by a cubic B-spline curve controlled by P0, P1, P2 and P3.

3. The design method of a circumferential curved axial flow fan according to claim 1, characterized in that: In step S3, the blade profile installation angle β of other sections is calculated according to the following formula: In the formula, β H for (rR H ) / (R T -R H ) = 0% blade installation angle, β T for (rR H ) / (R T -R H ) = 100% of the blade installation angle.

4. The design method of a circumferential curved axial flow fan according to claim 1, characterized in that: In step S4, the blade chord l of other sections is calculated according to the following formula: In the formula, l H for (rR H ) / (R T -R H ) = 0% of the leaf chord, l T for (rR H ) / (R T -R H ) = 100% of leaf chord.

5. The design method of a circumferential curved axial flow fan according to claim 1, characterized in that: In step S51, the curved product curve is a cubic B-spline curve.

6. The design method of a circumferential curved axial flow fan according to claim 1, characterized in that: The leading edge thickness of the blade profile of other cross sections is calculated according to the following formula: Where, △LE H for (rR H ) / (R T -R H ) = 0% of the blade leading edge thickness, △LE T for (rR H ) / (R T -R H ) = 100% of the leading edge thickness of the airfoil.

7. A circumferential curved axial flow fan obtained by using the design method of a circumferential curved axial flow fan as claimed in any one of claims 1 to 6.

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