Design method of fan blade, fan blade, fan and extractor hood

Abstract

The application discloses a design method of a fan blade, the fan blade, a fan and an extractor hood. The fan blade is arranged in a fan impeller. The design method comprises the following steps: taking a plane perpendicular to the rotating 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 the characteristic curve is a double circular arc curve; taking the blade profile of a single circular arc blade on the characteristic plane as a first circular arc of the characteristic curve, taking the inlet angle of the characteristic curve, the outlet angle of the characteristic curve and the radius of a second circular arc of the characteristic curve as three factors, obtaining a linear regression equation about the flow of the fan and a linear regression equation about the total pressure efficiency, and taking the optimal solution as the size parameter of the fan blade. The design method of the fan blade obtains the design parameters of the double circular arc curve on the basis of the current single circular arc blade, improves the internal flow state of the fan and improves the aerodynamic performance of the fan.

Description

Technical Field

[0001] This invention relates to the field of range hood technology, and in particular to a design method for fan blades, fan blades, a fan, and a range hood. Background Technology

[0002] In the fan system of range hoods, multi-blade centrifugal fans are widely used due to their compact structure, high pressure coefficient, and large flow coefficient. Proper design of the centrifugal fan blades can reduce flow losses within the impeller channel and improve the impeller's work capacity. Currently, blades typically employ a single circular arc design. For example, utility model patent application number 202023122207.6 uses concentric circles with different arc radii and center angles to ensure that the inlet and outlet angles of the first and second profiles are consistent. This traditional single circular arc blade design is based on two-dimensional flow theory and calculates various structural parameters according to the fan's design conditions. However, it lacks a design tailored to the axial differences in the internal flow field. Therefore, the current blade structure does not perform optimally in terms of aerodynamic performance and requires further improvement. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defect of the blade structure of multi-blade centrifugal fans in the prior art in terms of poor aerodynamic performance, and to provide a design method for fan blades, fan blades, fans and range hoods.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] A method for designing wind turbine blades, wherein the wind turbine blades are disposed in a wind turbine impeller, the method comprising the following steps:

[0006] S1. Take the plane perpendicular to the rotation axis of the fan impeller as the feature plane, and define the blade shape of the fan blade on the feature plane as the feature curve, wherein the feature curve is a double circular arc curve;

[0007] S2. Define the characteristic curve located on the intake side as the first arc and the characteristic curve located on the exhaust side as the second arc, with the inlet angle β of the characteristic curve as the reference point. A The exit angle β of the characteristic curve B and the radius R of the second arc of the characteristic curve B Using three factors, linear regression equations for fan flow rate and total pressure efficiency were obtained;

[0008] S3. The optimal solutions of the linear regression equations for fan flow rate and total pressure efficiency are used as the size parameters of the fan blades.

[0009] The design method for this wind turbine blade selects a plane perpendicular to the rotation axis of the wind turbine impeller as the characteristic plane. Based on the current single-circular-arc blade airfoil, while keeping the outer diameter, inner-outer diameter ratio, and blade height of the wind turbine impeller unchanged, the inlet angle, outlet angle, and the optimal parameters of the second circular arc radius on the outlet side of the double-circular-arc curve of the wind turbine blade are calculated on this characteristic plane. This allows for the acquisition of design parameters for a double-circular-arc curve based on the current single-circular-arc blade, thereby improving the internal flow state of the wind turbine and enhancing its aerodynamic performance.

[0010] Furthermore, this design method is based on the current single circular arc blade design, and the resulting wind turbine blades have high compatibility with the current wind turbine product structure.

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

[0012] In step S2: using the inlet angle β of the first characteristic curve A1 The exit angle β of the first characteristic curve B1 The radius R of the second arc of the first characteristic curve B1 Using three factors, linear regression equations for fan flow rate and total pressure efficiency were obtained regarding the first characteristic curve; simultaneously, the inlet angle β of the second characteristic curve was used... A2 The exit angle β of the second characteristic curve B2 The radius R of the second arc of the second characteristic curve B2 Using three factors, we obtained the linear regression equations for the fan flow rate and the total pressure efficiency with respect to the second characteristic curve.

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

[0014] The planes at both ends of the fan blade are selected as characteristic planes. Based on the current single-circular-arc blade airfoil, while keeping the outer diameter, inner-outer diameter ratio, and blade height of the fan impeller unchanged, the optimal parameters of the inlet angle, outlet angle, and second arc radius of the arc curve of the fan blade on these two characteristic planes are calculated respectively. This is to obtain the design parameters of the double-circular-arc curve based on the current single-circular-arc blade, improve the internal flow state of the fan, and enhance the aerodynamic performance of the fan.

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

[0016] S4. Select the plane with the largest proportion of axial flow in the wind turbine blade as the third characteristic plane, and define the blade shape of the wind turbine blade on the third characteristic plane as the third characteristic curve, which is a double circular arc curve.

[0017] S5. Define the third characteristic curve located on the intake side as the first arc and the one located on the exhaust side as the second arc, with the inlet angle β of the third characteristic curve as the reference point. A3 The exit angle β of the third characteristic curve B3 The radius R of the second arc of the third characteristic curve B3 Using the deflection angle α of the third characteristic curve as four factors, we obtain the linear regression equations for the fan flow rate and the total pressure efficiency with respect to the third characteristic curve.

[0018] S6. The optimal solutions of the linear regression equations for the fan flow rate and the total pressure efficiency based on the third characteristic curve are used as the size parameters of the fan blades.

[0019] Preferably, the plane with the largest proportion of axial flow in the wind turbine blades is the plane where the middle disk of the wind turbine impeller is located.

[0020] Preferably, the deflection angle α of the third characteristic curve ranges from 0° to α to 6°.

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

[0022] Preferably, the exit angle β of the characteristic curve B The range of values ​​for β is 165° ≤ β B ≤177°;

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

[0024] Preferably, the first arc of the characteristic curve coincides with the exit end of the second arc.

[0025] A wind turbine blade, the dimensional parameters of which are obtained by the wind turbine blade design method described above.

[0026] A fan, wherein the fan impeller employs fan blades as described above, the fan has a main air intake side and a secondary air intake side, and the central disk of the fan impeller is located between the main air intake side and the secondary air intake side.

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

[0028] The positive and progressive effects of this invention are as follows:

[0029] In this design method for fan blades, the specific design method selects a plane perpendicular to the rotation axis of the fan impeller as the characteristic plane. The blade profile of a single circular arc blade is used as the first arc of a double circular arc curve on the corresponding characteristic plane. The optimal parameters for the inlet angle, outlet angle, and second arc radius of the double circular arc curve on these two characteristic planes are calculated. While maintaining the outer diameter, inner-outer diameter ratio, and blade height of the fan impeller unchanged from the current single circular arc blade design, the design parameters for the double circular arc curve are obtained through calculation, improving the internal flow state of the fan and enhancing its aerodynamic performance. Furthermore, this design method is based on the current single circular arc blade design, resulting in fan blades with high compatibility with current fan product structures. Attached Figure Description

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

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

[0032] Figure 3 This is a schematic diagram of the structure of a wind turbine blade according to an embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram showing the distribution of the feature planes according to an embodiment of the present invention.

[0034] Figure 5a This is a schematic diagram (a) of the double circular arc curve of a wind turbine blade according to an embodiment of the present invention.

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

[0036] Figure 6 This is a schematic diagram (II) of the double circular arc curve of a wind turbine blade according to an embodiment of the present invention.

[0037] Figure 7a This is a graph showing the effect of the level of each factor on the air volume on the first characteristic curve of an embodiment of the present invention.

[0038] Figure 7b This is a graph showing the effect of the level of each factor on the total pressure efficiency in the first characteristic curve of an embodiment of the present invention.

[0039] Fan impeller 10, rotation axis A

[0040] Wind turbine blade 1, curve f of the first circular arc, curve e of the second circular arc

[0041] Upper plate 2

[0042] Lower plate 3

[0043] Mid-game 4 Detailed Implementation

[0044] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0045] This invention provides a design method for a dual-inlet multi-blade centrifugal impeller and its fan blades. For example... Figure 1 As shown, the fan impeller 10 includes fan blades 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 set on the main air intake side and the auxiliary air intake side of the fan impeller 10. The middle plate 4 is located between the main air intake side and the auxiliary air intake side. The fan blades 1 are installed between the upper plate 2, the middle plate 4, and the lower plate 3. The structural feature of the fan blades 1 is a three-dimensional curved surface design.

[0046] like Figure 2 As shown, based on the main and auxiliary air intake sides of the dual-inlet multi-blade centrifugal impeller, the flow rate proportion of the fan blades 1 increases sequentially from the upper plate 2 to the middle plate 4 and from the lower plate 3 to the middle plate 4 along the axial direction, and the flow velocity gradually increases. Meanwhile, on the auxiliary air intake side, due to the presence of the motor and related components, the flow rate proportion and its growth rate are relatively small. Therefore, in this design, the upper plate 2, lower plate 3, and middle plate 4 are used as characteristic planes, and the blade shape of the fan blades 1 on these characteristic planes is specifically designed.

[0047] Specifically, the design steps for wind turbine blades are as follows:

[0048] S1. Take the upper plate 2, lower plate 3 or middle plate 4 as the characteristic plane, and define the blade shape of the fan blade 1 on the characteristic plane as the characteristic curve. The characteristic curve is a double circular 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, with the inlet angle β of the characteristic curve as the reference point. A The exit angle β of the characteristic curve B The radius R of the second arc of the characteristic curve B Using three factors, linear regression equations were obtained for fan flow rate (air volume) and total pressure efficiency.

[0050] S3. The optimal solutions of the linear regression equations for fan flow rate and total pressure efficiency are used as the size parameters of fan blade 1.

[0051] This method for designing wind turbine blades selects the upper plate 2, lower plate 3, and middle plate 4 of the wind turbine impeller 10 as characteristic planes. Based on the current single-circular-arc blade profile, while keeping the outer diameter, inner-outer diameter ratio, and blade height of the wind turbine impeller 10 constant, it calculates the optimal parameters for the inlet angle, outlet angle, and second arc radius of the arc curve of the wind turbine blade 1 on these characteristic planes. This allows for the acquisition of double-circular-arc design parameters based on the current single-circular-arc blade, improving the internal flow state of the wind turbine and enhancing its aerodynamic performance. Furthermore, this design method, based on the current single-circular-arc blade design, results in wind turbine blade 1 with high compatibility with current wind turbine product structures.

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

[0053] like Figure 3 and Figure 4 As shown, specifically in this embodiment, the upper plate 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 plate 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 plate 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. Alternatively, in other embodiments, considering that some fan impeller 10 structural designs do not include a middle plate 4, the plane with the largest axial flow ratio can be selected as the third characteristic plane, and the blade profile on the third characteristic plane is called the third characteristic curve.

[0054] Because the direction of gas flow (see...) is different when the fan is working. Figure 4 The arrows indicate the directions of the airflow entering the main and auxiliary air inlets of the fan, and then flowing into the middle region of the fan impeller 10 (the region where the central disk 4 is located). To reflect the sequential flow of the axial gas flow, the first characteristic curve, the second characteristic curve, and the third characteristic curve are designed sequentially in the fan blade design method. Specifically, the first and second characteristic curves are designed first, and the third characteristic curve is designed last.

[0055] Specifically, in order to obtain an optimal blade structure and improve the performance of multi-blade centrifugal fans, this embodiment provides a design method for fan blades. Using a multi-blade centrifugal fan with a single circular arc blade as a prototype, and keeping the volute parameters, impeller outer diameter B, inner diameter C, and inner-outer diameter ratio constant, an orthogonal experiment is conducted to determine the inlet angle β of the double circular arc curve. A , exit angle β B The radius of the second arc RB The second arc deflection angle α of the characteristic curve is used for multi-parameter collaborative optimization design to obtain the optimal parameter level combination of the double arc blades, which improves the internal flow state of the fan and enhances the aerodynamic performance of the fan.

[0056] Specifically, regarding the flow state of the fan blade 1 in the upper plate 2 region, to make the flow channel between the fan blades 1 in this region more consistent with the flow characteristics of the airflow in the upper plate 2 region of the fan impeller 10, the parameters of the first characteristic curve of the fan blade 1 are optimized based on the current conventional single circular arc blades. According to the flow field law of multi-blade centrifugal fans, the air intake volume in the upper plate 2 region near the fan impeller 10 is relatively small, and the circumferential work capacity of the blades is weakened. Considering that the impeller of the prototype can be replaced without changing other fan components such as the volute and collector, the outer diameter B, inner diameter C, inner diameter-to-outer diameter ratio, and blade height of the impeller are kept constant at the upper plate 2 position. The blade shape is orthogonally optimized using a double circular arc curve. Therefore, the inlet angle β of the first characteristic curve is adopted. A1 and exit angle β B1 For two factors, and to facilitate parametric design, the radius R of the second arc of the double circular arc curve is selected. B1 This is the third factor.

[0057] Furthermore, to obtain a more optimized first characteristic curve, a three-factor, three-level orthogonal experiment was conducted, combining the prototype blade structure and design experience, and the design levels were coded and explained. Currently, the inlet angle β of the multi-bladed centrifugal blade... A1 The design range is generally 65° to 80°, and the specific inlet angle β is selected here. A1 The three design levels are 65°, 72.5°, and 80°; the outlet angle β of the wind turbine blade 1 is... B1 The design range is generally 165° to 177°, and the specific exit angle β is selected here. B1 The three design levels are 165°, 171°, and 177°; while the design range for the blade radius is generally 11mm to 14mm. Here, the second arc radius R is selected. B1 The three design levels are 11mm, 12.5mm, and 14mm. Furthermore, based on the overall model of the range hood, geometric modeling and numerical simulation calculations are carried out using air volume Q and total pressure efficiency η as response values, combined with orthogonal experimental table L9(3^2). On the first characteristic plane, taking the outlet end of the prototype's single-circular-arc blade profile as the reference point, a second circular arc with radius R is drawn. B1 and the exit angle is β B1 Since this technical solution is optimized under the condition that the inner and outer diameter parameters of the 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 between the first and second arcs of the first characteristic curve. The 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 using the above method. A1 The curve of the first arc (radius R of the first arc) A1 (The radius of the corresponding single circular arc blade is consistent), and the single circular arc blade profile of the prototype is projected onto the second and third feature planes. The blade structure optimized with respect to the first feature curve is obtained through boundary blending. Simulation calculation is then performed using the whole model of the range hood. The calculation results are shown in Table 1.

[0059] Table 1. Experimental Design Scheme and Calculation Results for the First Characteristic Curve

[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 experimental design schemes and calculation results of the first characteristic curve in the table above, the optimal combination scheme for orthogonal experiments is number 4, which is the inlet angle β of the first characteristic curve. A1 =72.5°, exit angle β B1 =165°, and the radius R of the second arc of the first characteristic curve. B1 =12.5mm, the calculated air volume of the optimized scheme is the same as that of the prototype, and the total pressure efficiency is improved by 1.02% compared with the prototype. The influence relationship between the levels 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 through analysis of variance, the relationship between air volume Q and the air volume Q is obtained. A The significance of the factors is ranked as β. A1 R B1 and β B1 And regarding the total pressure efficiency η A The significance of the factors is ranked as β. B1 ,β A1 and R B1 .

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

[0063] For example, in other embodiments, the connection point e can be located relatively close to the air intake end of the first arc, but it cannot be too close to the air intake end of the first arc, as this would cause the curvature of the first arc to become too large, resulting in an unreasonable blade shape. Therefore, in other embodiments, such as Figure 5b As shown, the connection point e is preferably located within a range of offset γ less than or equal to 15° on both sides, with the midpoint of the single circular arc blade profile as a reference, in order to achieve the purpose of reasonable design.

[0064] like Figure 6 As shown, 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 dual-inlet multi-blade centrifugal fan, the flow patterns of the main inlet and the auxiliary inlet are similar, that is, the air intake gradually increases along the axial direction from the impeller lower plate 3 to the middle plate 4. Therefore, the second characteristic curve is obtained by projecting the first characteristic curve onto 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 calculated and designed based on the above-mentioned design scheme. A2 The exit angle β of the second characteristic curve B2 The radius R of the second arc of the second characteristic curve B2 As three factors, linear regression equations for fan flow rate and total pressure efficiency with respect to the second characteristic curve are obtained, and the optimal solutions of the linear regression equations for fan flow rate and total pressure efficiency with respect to the first and second characteristic curves are used as the size parameters of fan blade 1.

[0065] Furthermore, in order to improve the airflow state in the middle disk 4 region of the fan impeller 10, and to make the inter-blade flow channel of the fan blade 1 in this region more consistent with the flow characteristics of the airflow in the upper disk 2 region of the impeller, based on the blade structure, a method similar to the parametric plotting method of the first characteristic curve mentioned above is used to optimize the design of the third characteristic curve. For example... Figure 2 As shown, according to the flow field law of the multi-blade centrifugal fan, the air intake near the middle plate 4 is relatively large, and the circumferential work capacity of the fan blade 1 is enhanced. Furthermore, due to the axial flow of the gas and the rotation of the fan impeller 10, there is a certain phase difference in the circumferential direction between the airflow in the upper plate 2 and lower plate 3 regions and the airflow in the middle plate 4 region. Therefore, the inlet angle β of the third characteristic curve... A3 Exit angle β B3 The radius R of the second arc of the third characteristic curve B3 Based on 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 mounting direction.

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

[0067] Table 2. Experimental Design Scheme and Calculation Results for the Third Characteristic Curve

[0068]

[0069]

[0070] An analysis of variance was performed on the calculation results at a significance level of P = 0.05. The results showed that the inlet angle β A3 The deflection angle α of the third characteristic curve has a significant impact on the flow rate Q, as does the outlet angle β. B3 and the radius R of the third arc B3 The total pressure efficiency η has a significant impact. Further, by fitting the calculation results to a multivariate quadratic term, we can obtain the fitting regression equation of the design parameters on the fan flow rate Q and the 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] In the above regression simulation, A, B, C, and D are the design parameters β. A3 ,β B3 R B3 The coding level of α.

[0076] Choosing the above four parameters as design variables and selecting the fan flow rate Q and total pressure efficiency η as optimization objectives, the mathematical model is as follows:

[0077]

[0078] The optimal parameter combination obtained based on the hill-climbing optimization algorithm is: β A3 =65°, β B3 =165°, R B3 =11mm, α=0.03°, the fan flow rate Q at this time B =19.889m 3 / min, η B =43.185%, an increase of 0.2m³ in calculated airflow compared to the prototype. 3 / min, while the total pressure efficiency is improved by 2.2%.

[0079] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for designing wind turbine blades, characterized in that, The fan blades are disposed in the fan impeller, and the design method includes the following steps: S1. Take the plane perpendicular to the rotation axis of the fan impeller as the feature plane, and define the blade shape of the fan blade on the feature plane as the feature curve, wherein the feature curve is a double circular arc curve; S2. Define the characteristic curve located on the intake side as the first arc and the characteristic curve located on the exhaust side as the second arc. The radius R of the first arc of the characteristic curve is... A The radius of the single circular arc blade corresponding to the wind turbine blade is consistent with the inlet angle β of the characteristic curve. A The exit angle β of the characteristic curve B and the radius R of the second arc of the characteristic curve B Using three factors, linear regression equations for fan flow rate and total pressure efficiency were obtained; S3. The optimal solutions of the linear regression equations for fan flow rate and total pressure efficiency are used as the size parameters of the fan blades.

2. The wind turbine blade design method as described in claim 1, characterized in that, In step S1: the plane where the upper plate of the wind turbine impeller is located and the plane where the lower plate is located are respectively taken as the first characteristic plane and the second characteristic plane. The blade shape of the wind turbine blade on the first characteristic plane and the second characteristic plane is defined as the first characteristic curve and the second characteristic curve. The first characteristic curve and the second characteristic curve are both double circular arc curves. In step S2: using the inlet angle β of the first characteristic curve A1 The exit angle β of the first characteristic curve B1 The radius R of the second arc of the first characteristic curve B1 Using three factors, linear regression equations for fan flow rate and total pressure efficiency were obtained regarding the first characteristic curve; simultaneously, the inlet angle β of the second characteristic curve was used... A2 The exit angle β of the second characteristic curve B2 The radius R of the second arc of the second characteristic curve B2 Using three factors, we obtained the linear regression equations for the fan flow rate and the total pressure efficiency with respect to the second characteristic curve. In step S3: the optimal solutions of the linear regression equations for the fan flow rate and the linear regression equations for the total pressure efficiency with respect to the first and second characteristic curves are used as the size parameters of the fan blades.

3. The wind turbine blade design method as described in claim 2, characterized in that, The design method further includes the following steps: S4. Select the plane with the largest proportion of axial flow in the wind turbine blade as the third characteristic plane, and define the blade shape of the wind turbine blade on the third characteristic plane as the third characteristic curve, which is a double circular arc curve; S5. Define the third characteristic curve located on the intake side as the first arc and the one located on the exhaust side as the second arc, with the inlet angle β of the third characteristic curve as the reference point. A3 The exit angle β of the third characteristic curve B3 The radius R of the second arc of the third characteristic curve B3 Using the deflection angle α of the third characteristic curve as four factors, we obtain the linear regression equations for the fan flow rate and the total pressure efficiency with respect to the third characteristic curve. S6. The optimal solutions of the linear regression equations for the fan flow rate and the total pressure efficiency based on the third characteristic curve are used as the size parameters of the fan blades.

4. The wind turbine blade design method as described in claim 3, characterized in that, The plane with the largest proportion of axial flow in the wind turbine blades is the plane where the middle disk of the wind turbine impeller is located.

5. The wind turbine blade design method as described in claim 3, characterized in that, The deflection angle α of the third characteristic curve ranges from 0° to α to 6°.

6. The wind turbine blade design method as described in 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 exit angle β of the characteristic curve B The range of values ​​for β 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 wind turbine blade design method as described in claim 1, characterized in that, The end of the first arc of the characteristic curve is connected to the end of the second arc.

8. A wind turbine blade, characterized in that, The dimensional parameters of the wind turbine blades are obtained by the wind turbine blade design method as described in any one of claims 1-7.

9. A fan, characterized in that, The impeller of the fan adopts the fan blades as described in claim 8. The fan has a main air intake side and a secondary air intake side, and the central disk of the fan impeller is located between the main air intake side and the secondary air intake side.

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

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