Fan blade design method, fan blade, fan and range hood

Abstract

The invention discloses a fan blade design method, a fan blade, a fan and a range hood, the fan blade is arranged in a fan impeller, the design method comprises the following steps: taking a plane vertical to the rotation axis of the fan impeller as a characteristic plane, defining the blade profile of the fan blade on the characteristic plane as a characteristic curve, and setting the characteristic curve as a characteristic curve; the characteristic curve is a biarc curve; taking the blade profile of the single-arc blade on the characteristic plane as a first arc of a characteristic curve, and taking the inlet angle of the characteristic curve, the outlet angle of the characteristic curve and the radius of a second arc of the characteristic curve as three factors to obtain a linear regression equation about the fan flow and a linear regression equation about the total pressure efficiency; and taking the optimal solution as the size parameter of the fan blade. According to the design method of the fan blade, the design parameters of the double-arc curve are obtained on the basis of an existing single-arc blade, the internal flowing state of the fan is improved, and the aerodynamic performance of the fan is improved.

Description

Technical Field

[0001] The invention relates to the technical field of range hoods, and in particular to a design method for fan blades, a fan blade, a fan and a range hood. Background Art

[0002] In the fan system of the range hood, the multi-blade centrifugal fan has the characteristics of compact structure, high pressure coefficient, and large flow coefficient, which makes it widely used in range hoods. By rationally designing the blades of the centrifugal fan, the flow loss in the blade channel can be reduced and the working capacity of the impeller can be improved. At present, the blades usually adopt a single arc design. For example, the utility model patent with application number 202023122207.6 is based on concentric circles and adopts different arc radii and center angles to make the inlet and outlet angles of the first profile consistent with the second profile. This traditional single arc blade design is based on two-dimensional flow theory, and combined with the design conditions of the fan, various structural parameters are calculated. It lacks design targeting the axial differences of the internal flow field. Therefore, the blade structure of the current prior art is not optimal in terms of the aerodynamic performance of the fan and needs further improvement. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the defect that the blade structure of a multi-blade centrifugal fan in the prior art does not perform well in terms of the aerodynamic performance of the fan, and to provide a design method for fan blades, a fan blade, a fan and a range hood.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] A method for designing a fan blade, wherein the fan blade is arranged in a fan impeller, and the design method comprises the following steps:

[0006] S1. Taking a plane perpendicular to the rotation axis of the fan impeller as a characteristic plane, defining the blade profile of the fan blade on the characteristic plane as a characteristic curve, wherein the characteristic curve is a double arc curve;

[0007] S2, define the characteristic curve located on the side of the air inlet end as the first arc, and the characteristic curve located on the side of the air outlet end as the second arc, and take the inlet angle β of the characteristic curve as A , the outlet angle β of the characteristic curve B and the radius R of the second arc of the characteristic curve B As three factors, the linear regression equation about the fan flow rate and the linear regression equation about the total pressure efficiency are obtained;

[0008] S3. Taking the optimal solutions of the linear regression equation on the fan flow rate and the linear regression equation on the total pressure efficiency as the size parameters of the fan blades.

[0009] The design method of the fan blade selects a plane perpendicular to the rotation axis of the fan impeller as a characteristic plane, and on the basis of the current blade profile of a single arc blade, by keeping the outer diameter, inner / outer diameter ratio and blade height size parameters of the fan impeller unchanged, respectively calculates the inlet angle, outlet angle and the preferred parameters of the second arc radius of the double arc curve located on the air outlet side of the fan blade characteristic curve on the characteristic plane, so as to obtain the design parameters of the double arc curve on the basis of the current single arc blade, improve the internal flow state of the fan, and improve the aerodynamic performance of the fan.

[0010] Furthermore, the design method is designed on the basis of the current single arc blade, and the obtained fan blade is highly compatible with the current fan product structure.

[0011] Preferably, in step S1: the plane where the upper plate and the plane where the lower plate of the fan impeller are located are respectively used as the first characteristic plane and the second characteristic plane, and the blade profile of the fan blade on the first characteristic plane and the second characteristic plane is defined as a first characteristic curve and a second characteristic curve, and the first characteristic curve and the second characteristic curve are both double arc curves;

[0012] In step S2: the inlet angle β of the first characteristic curve is A1 , the outlet angle β of the first characteristic curve B1 and the radius R of the second arc of the first characteristic curve B1 As three factors, the linear regression equation of the fan flow rate of the first characteristic curve and the linear regression equation of the total pressure efficiency are obtained; at the same time, the inlet angle β of the second characteristic curve is used A2 , the outlet angle β of the second characteristic curve B2 and the radius R of the second arc of the second characteristic curve B2 As three factors, a linear regression equation of the fan flow rate on the second characteristic curve and a linear regression equation on the total pressure efficiency are obtained;

[0013] In step S3: the optimal solutions of the linear regression equation of the fan flow rate with respect to the first characteristic curve and the second characteristic curve and the linear regression equation with respect to the total pressure efficiency are taken as the size parameters of the fan blades.

[0014] The planes at both ends of the fan blade are selected as characteristic planes. On the basis of the current blade profile of the single arc blade, the outer diameter, the inner-outer diameter ratio and the blade height size parameters of the fan impeller are kept unchanged, and the inlet angle, outlet angle and the second arc radius optimal parameters of the fan blade on these two characteristic planes are calculated respectively, so as to obtain the design parameters of the double arc curve based on the current single arc blade, improve the internal flow state of the fan, and improve the aerodynamic performance of the fan.

[0015] Preferably, the design method further comprises the following steps:

[0016] S4, selecting a plane in which the axial flow rate of the fan blade accounts for the largest proportion as a third characteristic plane, defining the blade profile of the fan blade on the third characteristic plane as a third characteristic curve, and the third characteristic curve is a double arc curve;

[0017] S5, define the third characteristic curve located on the side of the air inlet end as the first arc, and the third characteristic curve located on the side of the air outlet end as the second arc, and define the inlet angle β of the third characteristic curve as A3 , the outlet angle β of the third characteristic curve B3 , the radius R of the second arc of the third characteristic curve B3 and the deflection angle α of the third characteristic curve as four factors, a linear regression equation of the fan flow rate on the third characteristic curve and a linear regression equation on the total pressure efficiency are obtained;

[0018] S6. Taking the optimal solutions of the linear regression equation of the fan flow rate with respect to the third characteristic curve and the linear regression equation with respect to the total pressure efficiency as the size parameters of the fan blades.

[0019] Preferably, the plane in which the axial flow rate in the fan blade accounts for the largest proportion is the plane where the center disk of the fan impeller is located.

[0020] Preferably, the value range of the deflection angle α of the third characteristic curve is 0°≤α≤6°.

[0021] Preferably, the inlet angle β of the characteristic curve A The value range is 65°≤β A ≤80°;

[0022] Preferably, the outlet angle β of the characteristic curve is B The value range is 165°≤β B ≤177°;

[0023] Preferably, the radius R of the second arc of the characteristic curve is B The value range is 11mm≤R B ≤14mm.

[0024] Preferably, the exit ends of the first arc and the second arc of the characteristic curve coincide with each other.

[0025] A fan blade, wherein the size parameters of the fan blade are obtained by the fan blade design method as described above.

[0026] A fan, wherein the fan impeller of the fan adopts the fan blades as described above, the fan has a main air inlet side and an auxiliary air inlet side, and the center disk of the fan impeller is located between the main air inlet side and the auxiliary air inlet side.

[0027] A range hood, wherein the fan system of the range hood adopts the fan as described above.

[0028] The positive and progressive effects of the present invention are:

[0029] In the design method of the fan blade, the fan blade, the fan and the range hood, the specific design method selects a plane perpendicular to the rotation axis of the fan impeller as a characteristic plane, uses the blade shape of the single arc blade as the first arc of the double arc curve on the corresponding characteristic plane, and respectively calculates the inlet angle, outlet angle and the second arc radius preferred parameters of the fan blade on these two characteristic planes, keeps the outer diameter, inner and outer diameter ratio and blade height size parameters of the fan impeller unchanged on the basis of the current single arc blade, obtains the design parameters of the double arc curve by calculation, improves the internal flow state of the fan, and improves the aerodynamic performance of the fan. In addition, the design method is designed on the basis of the current single arc blade, and the obtained fan blade has high compatibility with the current fan product structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The figure is a schematic structural diagram of a fan impeller according to an embodiment of the present invention.

[0031] Figure 2 This is an axial flow diagram of the outlet of a fan impeller according to an embodiment of the present invention.

[0032] Figure 3 It is a schematic structural diagram of a fan blade according to an embodiment of the present invention.

[0033] Figure 4 FIG. 4 is a schematic diagram of the distribution position of the characteristic plane according to an embodiment of the present invention.

[0034] Figure 5a FIG1 is a schematic diagram of a double arc curve of a fan blade according to an embodiment of the present invention (I).

[0035] Figure 5b FIG. 4 is a schematic diagram of a setting range of a connection point e according to an embodiment of the present invention.

[0036] Figure 6 Schematic diagram of a double arc curve of a fan blade according to an embodiment of the present invention (II).

[0037] Figure 7a This is an effect diagram of the level of each factor and the air volume of the first characteristic curve according to an embodiment of the present invention.

[0038] Figure 7b This is an effect diagram of each factor level and total pressure efficiency of the first characteristic curve according to an embodiment of the present invention.

[0039] Fan impeller 10, rotation axis A

[0040] Fan blade 1, curve f of the first arc, curve e of the second arc

[0041] Upper plate 2

[0042] Lower plate 3

[0043] Middle Plate 4 DETAILED DESCRIPTION

[0044] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0045] The present invention provides a double-inlet multi-blade centrifugal impeller and a design method for its fan blades. Figure 1 As shown, the fan impeller 10 includes a fan blade 1, an upper plate 2, a lower plate 3 and a middle plate 4. The upper plate 2 and the lower plate 3 are respectively arranged corresponding to the main air inlet side and the secondary air inlet side of the fan impeller 10, the middle plate 4 is located between the main air inlet side and the secondary air inlet side, the fan blade 1 is installed between the upper plate 2, the middle plate 4 and the lower plate 3, and the structural feature of the fan blade 1 is a three-dimensional space curved surface design.

[0046] like Figure 2 As shown, based on the setting of the main air inlet side and the auxiliary air inlet side of the double-inlet multi-blade centrifugal impeller, the flow rate of the fan blade 1 increases from the upper plate 2 to the middle plate 4 and from the lower plate 3 to the middle plate 4 in the axial direction, and the flow rate gradually increases. At the same time, due to the presence of the motor and related components on the auxiliary air inlet side, the flow rate ratio and its growth rate on this side are relatively small. Therefore, in this scheme, the upper plate 2, the lower plate 3 and the middle plate 4 are used as characteristic planes, and the blade profile of the fan blade 1 on the characteristic plane is designed in a targeted manner.

[0047] Specifically, the specific steps of the fan blade design method are as follows:

[0048] S1, taking the upper plate 2, the lower plate 3 or the middle plate 4 as a characteristic plane, defining the blade profile of the fan blade 1 on the characteristic plane as a characteristic curve, which is a double arc curve;

[0049] S2. Define the characteristic curve located on the inlet side as the first arc, and the characteristic curve located on the outlet side as the second arc. A , the outlet angle β of the characteristic curve B and the radius R of the second arc of the characteristic curve B As three factors, the linear regression equation about the fan flow (air volume) and the linear regression equation about the total pressure efficiency are obtained;

[0050] S3. Taking the optimal solutions of the linear regression equation on the fan flow rate and the linear regression equation on the total pressure efficiency as the size parameters of the fan blade 1.

[0051] This fan blade design method selects the upper plate 2, lower plate 3 and middle plate 4 of the fan impeller 10 as the characteristic plane, and on the basis of the current single arc blade blade profile, by keeping the outer diameter, inner and outer diameter ratio and blade height size parameters of the fan impeller 10 unchanged, respectively calculates the inlet angle, outlet angle and the second arc radius of the fan blade 1 on this characteristic plane, so as to obtain the design parameters of the double arc curve on the basis of the current single arc blade, improve the internal flow state of the fan, and improve the aerodynamic performance of the fan. In addition, this design method is designed on the basis of the current single arc blade, and the obtained fan blade 1 has high compatibility with the current fan product structure.

[0052] Of course, in other embodiments, other planes perpendicular to the rotation axis A of the fan impeller 10 may be selected as feature planes to calculate the size parameters of the fan blades 1 located on the corresponding planes and optimize the blade profile of the fan blades 1 .

[0053] like Figure 3 and Figure 4 As shown, specifically in this embodiment, the upper disk 2 of the fan impeller 10 is selected as the first characteristic plane, and the blade profile on the first characteristic plane is called the first characteristic curve. The lower disk 3 of the fan impeller 10 is selected as the second characteristic plane, and the blade profile on the second characteristic plane is called the second characteristic curve. The middle disk 4 of the fan impeller 10 is selected as the third characteristic plane, and the blade profile on the third characteristic plane is called the third characteristic curve. In addition, in other embodiments, considering that some fan impeller 10 structural schemes do not have a middle disk 4 structure, the plane with the largest axial flow rate can be selected as the third characteristic plane, and the blade profile on the third characteristic plane is called the third characteristic curve.

[0054] When the fan is working, the flow direction of the gas (see Figure 4 The direction indicated by the arrows is to enter the main and auxiliary air inlets of the fan respectively, and then flow to the middle area of ​​the fan impeller 10 (the area where the middle disk 4 is located). In order to reflect the timing of the axial flow of the gas, the first characteristic curve, the second characteristic curve and the third characteristic curve are designed in sequence in the design method of the fan blade. Specifically, the first characteristic curve and the second characteristic curve are designed first, and finally the third characteristic curve is designed.

[0055] Specifically, in order to obtain an optimal blade structure solution and promote the performance improvement of a multi-blade centrifugal fan, this embodiment provides a fan blade design method. Taking a multi-blade centrifugal fan with a single arc blade as a prototype, under the condition of keeping the volute parameters unchanged and the impeller outer diameter B, inner diameter C and inner and outer diameter ratio unchanged, an orthogonal test is used to test the inlet angle β of the double arc curve. A , outlet angle β B , the radius of the second arc RB The multi-parameter collaborative optimization design is carried out based on the second arc deflection angle α of the characteristic curve to obtain the optimal parameter level combination of the double arc blades, improve the internal flow state of the fan, and improve the aerodynamic performance of the fan.

[0056] Specifically, in view of the flow state of the fan blades 1 in the upper disk 2 area, the flow channel between the fan blades 1 in this area is made to be more consistent with the flow characteristics of the airflow in the upper disk 2 area of ​​the fan impeller 10, and the parameters of the first characteristic curve of the fan blade 1 are optimized based on the current conventional single arc blades. According to the flow field law of the multi-blade centrifugal fan, the air intake volume in the upper disk 2 area close to the fan impeller 10 is relatively small, and the circumferential working capacity of the blades is weakened. Considering that the other components of the fan such as the volute and collector remain unchanged, the prototype impeller is replaced. At the position of the upper disk 2, the impeller outer diameter B, inner diameter C, inner and outer diameter ratio and blade height are limited to remain unchanged, and the double arc curve is used to perform orthogonal optimization design of the blade shape. Therefore, the inlet angle β of the first characteristic curve is adopted. A1 and outlet angle β B1 For the sake of two factors and to facilitate parametric design, the radius of the second arc R of the double arc curve is selected B1 For the third factor.

[0057] Furthermore, in order to calculate and obtain a more preferred first characteristic curve, a three-factor three-level orthogonal test was conducted in combination with the prototype blade structure and design experience, and its design level was coded and described. A1 The design range is generally 65°~80°, and the specific inlet angle β is selected here. A1 The three design levels are: 65°, 72.5° and 80°; the fan blade outlet angle β B1 The design range is generally 165°~177°, and the specific outlet angle β is selected here. B1 The three design levels are: 165°, 171° and 177°; the design range of the blade radius is generally: 11mm~14mm, here we choose the second arc radius R B1 The three design levels are: 11mm, 12.5mm, and 14mm. In addition, based on the range hood model, the air volume Q and total pressure efficiency η are used as response values, and the orthogonal test table L9 (3^2) is combined to carry out geometric modeling and numerical simulation calculations. On the first characteristic plane, the air outlet end of the single arc blade line of the prototype is used as the reference point to draw the second arc, whose radius is R B1 , and the outlet angle is β B1 Since the technical solution is optimized under the condition that the inner and outer diameter parameters of the fan impeller 10 remain unchanged, the intersection of the second arc and the original impeller inner diameter is the air inlet end of the second arc.

[0058] like Figure 5a As shown, e is the connection point of the first arc and the second arc of the first characteristic curve. The air inlet end of the first arc is located on the inner diameter C of the fan impeller 10, and its inlet angle is β A1 The radius R is obtained by the above method. A1 The curve of the first arc (the radius of the first arc R A1 The radius of the corresponding single arc blade is consistent with that of the single arc blade of the corresponding single arc blade, and the single arc blade profile of the prototype is projected on the second and third characteristic planes. The blade profile optimized for the first characteristic curve is obtained by boundary blending, and the simulation calculation is performed in combination with the range hood whole machine model. The calculation results are shown in Table 1:

[0059] Table 1 The first characteristic curve test design and calculation results

[0060] Serial number <![CDATA[β A1 / °]]> <![CDATA[β B1 / °]]> <![CDATA[R B1 / mm]]> <![CDATA[Q A / (m 3 / min)]]> <![CDATA[η A / %]]> Prototype 74.7 173 12.5 19.68 41.02 1 65 165 11 19.61 41.53 2 65 171 12.5 19.55 41.26 3 65 177 14 19.68 41.19 4 72.5 165 12.5 19.68 42.04 5 72.5 171 14 19.58 41.32 6 72.5 177 11 19.62 41.22 7 80 165 14 19.46 41.09 8 80 171 11 19.66 41.37 9 80 177 12.5 19.58 41.07

[0061] Based on the first characteristic curve test design scheme and calculation results in the above table, the optimal combination scheme for orthogonal test is No. 4, that is, the inlet angle β of the first characteristic curve A1 =72.5°, outlet angle β B1 =165°, and the second arc radius R of the first characteristic curve B1 =12.5mm, the calculated air volume of the optimized solution is the same as that of the prototype, and the total pressure efficiency is increased by 1.02% compared with the prototype. And the influence relationship between the level of each factor in the first characteristic curve and the air volume Q and the total pressure efficiency η is obtained as follows Figure 7a , Figure 7b As shown, and the air volume Q is obtained through variance analysis A The ranking of significant factors is β A1 , R B1 and β B1 , and the total pressure efficiency η A The ranking of significant factors is β B1 , β A1 and R B1 .

[0062] Among them, Figure 5a and 5b As shown, in this embodiment, the connection point e of the first arc and the second arc is located at the midpoint of the entire first characteristic curve, that is, the arc length of the first arc and the second arc is the same. The purpose of using the midpoint as the connection point e in this embodiment is to ensure that the airflow has a relatively large center angle to turn and flow in the flow channel formed by the double arc blades, thereby reducing flow separation. Of course, in other embodiments, other positions can also be selected as the connection point of the first arc and the second arc.

[0063] For example, in other embodiments, the connection point e can be located relatively close to the air inlet end of the first arc, but the connection point e cannot be too close to the air inlet end of the first arc, because this will cause the curvature of the first arc to become very large, resulting in an unreasonable blade shape. Figure 5b As shown, the connection point e is preferably referenced to the midpoint of the single arc blade profile and is located within a range where the offset γ on both sides is less than or equal to 15° to achieve the purpose of reasonable design.

[0064] like Figure 6 As shown, in order to simplify the design process, the second characteristic curve of the fan blade 1 in this embodiment is the same as the first characteristic curve. For a multi-blade centrifugal fan with double air intake, the flow laws of the main air inlet and the auxiliary air inlet are similar, that is, the air intake gradually increases along the axial direction from the lower disk 3 to the middle disk 4 of the impeller. Therefore, the second characteristic curve is obtained by projecting the first characteristic curve to the second characteristic plane. Based on the above design method and optimization results, the optimal blade structure 1 with respect to the first and second characteristic curves is obtained. Of course, in other embodiments, the inlet angle β of the second characteristic curve can also be adjusted based on the above calculation design scheme. A2 , the outlet angle β of the second characteristic curve B2 and the radius R of the second arc of the second characteristic curve B2 As three factors, a linear regression equation for the fan flow rate regarding the second characteristic curve and a linear regression equation for the total pressure efficiency are obtained, and the optimal solutions of the linear regression equation for the fan flow rate regarding the first characteristic curve and the second characteristic curve and the linear regression equation for the total pressure efficiency are taken as the size parameters of the fan blade 1.

[0065] Furthermore, in order to improve the airflow state in the middle disk 4 area of ​​the fan impeller 10 and make the inter-blade flow channel of the fan blade 1 in this area more consistent with the flow characteristics of the airflow in the upper disk 2 area of ​​the impeller, based on the blade structure, the third characteristic curve is optimized by a method similar to the parametric drawing method of the first characteristic curve mentioned above. Figure 2 As shown, according to the flow field law of the multi-blade centrifugal fan, the air intake near the middle disk 4 is relatively large, and the circumferential working capacity of the fan blades 1 is enhanced. In addition, due to the axial flow of the gas and the rotation of the fan impeller 10, there is a certain phase difference between the airflow in the upper disk 2 and lower disk 3 and the airflow in the middle disk 4 in the circumferential direction. Therefore, when the inlet angle β of the third characteristic curve is A3 , outlet angle β B3 , the second arc radius R of the third characteristic curve B3 On the basis of the three factors, a third characteristic curve deflection angle α is added, which represents the angle formed by the deflection of the third characteristic curve relative to the first or second characteristic curve at the outlet end along the impeller installation direction.

[0066] Furthermore, in order to obtain the preferred third characteristic curve, the inlet angle β is selected A3 The value range of is 65° to 80°, and the outlet angle β B3 The value range is 165° to 177°, and the second arc radius R of the third characteristic curve is selected B3 The value range of is 11mm to 14mm, and the value range of the third characteristic curve deflection angle α is selected to be 0° to 6°, more preferably 0° to 5.714°. The design scheme is constructed by Box-Beknken experimental design and its results are simulated and calculated. The number of center point tests is 3. The experimental design scheme and calculation results are listed in Table 2.

[0067] Table 2 The third characteristic curve test design and calculation results

[0068]

[0069]

[0070] The variance analysis was performed on the calculation results with a significance level of P = 0.05. The results showed that the inlet angle β A3 The third characteristic curve deflection angle α has a significant effect on the flow rate Q, and the outlet angle β B3 and the third arc radius R B3 It has a significant impact on the total pressure efficiency η. Further multivariate quadratic fitting of the calculation results can obtain the fitting regression equation of the design parameters on the fan flow Q and total pressure efficiency η.

[0071] Q=19.63-0.0608A-0.0042B-0.0158C-0.1092D

[0072] +0.0075AB+0.03AC-0.025AD+0.025BC+0.095BD+0.0375CD

[0073] +0.0112A 2 +0.0062B 2 -0.387C 2 -0.0787D 2

[0074] η=41.43-0.2217A-1.19B-0.2633C-0.0733D

[0075] A, B, C, and D in the above fitting regression simulation are the design parameters β A3 , β B3 , R B3 , the encoding level of α.

[0076] Select the above four parameters as design variables and select the fan flow Q and total pressure efficiency η as optimization targets. The mathematical model is:

[0077]

[0078] Based on the hill climbing optimization algorithm, the best parameter combination is obtained as follows: A3 =65°, β B3 =165°, R B3 =11mm, α=0.03°, the fan flow rate Q B =19.889m 3 / min,η B =43.185%, 0.2m higher than the calculated air volume of the prototype 3 / min, while the total pressure efficiency is increased by 2.2%.

[0079] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for designing a fan blade, characterized in that: The fan blades are arranged in a fan impeller, and the design method comprises the following steps: S1. Taking a plane perpendicular to the rotation axis of the fan impeller as a characteristic plane, defining the blade profile of the fan blade on the characteristic plane as a characteristic curve, wherein the characteristic curve is a double arc curve; S2, define the characteristic curve located on the side of the air inlet end as the first arc, and the characteristic curve located on the side of the air outlet end as the second arc, and define the characteristic curve with the inlet angle β A , the outlet angle β of the characteristic curve B and the radius R of the second arc of the characteristic curve B As three factors, the linear regression equation about the fan flow rate and the linear regression equation about the total pressure efficiency are obtained; S3. Taking the optimal solutions of the linear regression equation on the fan flow rate and the linear regression equation on the total pressure efficiency as the size parameters of the fan blades.

2. The design method of a fan blade according to claim 1, characterized in that: In step S1: the plane where the upper plate and the plane where the lower plate of the fan impeller are located are respectively used as the first characteristic plane and the second characteristic plane, and the blade profiles of the fan blades on the first characteristic plane and the second characteristic plane are defined as the first characteristic curve and the second characteristic curve, and the first characteristic curve and the second characteristic curve are both double arc curves; In step S2: the inlet angle β of the first characteristic curve is A1 , the outlet angle β of the first characteristic curve B1 and the radius R of the second arc of the first characteristic curve B1 As three factors, the linear regression equation of the fan flow rate of the first characteristic curve and the linear regression equation of the total pressure efficiency are obtained; at the same time, the inlet angle β of the second characteristic curve is used A2 , the outlet angle β of the second characteristic curve B2 and the radius R of the second arc of the second characteristic curve B2 As three factors, a linear regression equation of the fan flow rate on the second characteristic curve and a linear regression equation on the total pressure efficiency are obtained; In step S3: the optimal solutions of the linear regression equation of the fan flow rate with respect to the first characteristic curve and the second characteristic curve and the linear regression equation with respect to the total pressure efficiency are taken as the size parameters of the fan blades.

3. The design method of a fan blade according to claim 2, characterized in that: The design method further comprises the following steps: S4, selecting a plane in which the axial flow rate of the fan blade accounts for the largest proportion as a third characteristic plane, defining the blade profile of the fan blade on the third characteristic plane as a third characteristic curve, and the third characteristic curve is a double arc curve; S5, define the third characteristic curve located on the side of the air inlet end as the first arc, and the third characteristic curve located on the side of the air outlet end as the second arc, and define the inlet angle β of the third characteristic curve as A3 , the outlet angle β of the third characteristic curve B3 , the radius R of the second arc of the third characteristic curve B3 and the deflection angle α of the third characteristic curve as four factors, a linear regression equation of the fan flow rate on the third characteristic curve and a linear regression equation on the total pressure efficiency are obtained; S6. Taking the optimal solutions of the linear regression equation of the fan flow rate with respect to the third characteristic curve and the linear regression equation with respect to the total pressure efficiency as the size parameters of the fan blades.

4. The design method of a fan blade according to claim 3, characterized in that: The plane with the largest proportion of axial flow in the fan blade is the plane where the center disk of the fan impeller is located.

5. The design method of a fan blade according to claim 3, characterized in that: The value range of the deflection angle α of the third characteristic curve is 0°≤α≤6°.

6. The design method of a fan blade according to claim 1, characterized in that: The inlet angle β of the characteristic curve A The value range is 65°≤β A ≤80°; and / or, the outlet angle β of the characteristic curve B The value range is 165°≤β B ≤177°; and / or, the radius R of the second arc of the characteristic curve B The value range is 11mm≤R B ≤14mm.

7. The method for designing a fan blade according to claim 1, characterized in that: An end of the first arc of the characteristic curve is connected to an end of the second arc.

8. A fan blade, characterized in that: The size parameters of the wind blade are obtained by the wind blade design method according to any one of claims 1-7.

9. A fan, characterized in that: The fan impeller of the fan adopts the fan blade as claimed in claim 8, the fan has a main air inlet side and an auxiliary air inlet side, and the center disk of the fan impeller is located between the main air inlet side and the auxiliary air inlet side.

10. A range hood, characterized in that: The fan system of the range hood adopts the fan as claimed in claim 9.

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