Design method of volute molded line, fan volute, fan system and range hood

Abstract

The invention discloses a volute molded line design method, a fan volute, a fan system and a range hood, the volute molded line design method is used for designing a volute molded line of the fan volute, and the volute molded line design method comprises the following steps that the volute molded line is divided into at least three sections of curves in the direction from an outlet of the volute molded line to a volute tongue; sequentially calculating the size parameters of each section of curve along the direction from the outlet of the volute molded line to the volute tongue, and performing an orthogonal test by taking the size parameter of each section of curve as a factor and taking the fan total pressure loss coefficient and the fan static pressure recovery coefficient as responses; based on an orthogonal test result, a linear regression equation about a fan total pressure loss coefficient and a linear regression equation about a fan static pressure recovery coefficient are obtained; and taking the optimal solution as a size parameter of each curve section. According to the design method of the volute molded line, basic data are obtained through an orthogonal test mode according to the size parameters of each curve section, then the basic data are fitted through a linear regression equation, and the calculation workload is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of range hoods, and particularly to a design method for a volute profile, a blower volute, a blower system, and a range hood. Background Art

[0002] Multi-wing centrifugal blowers have the characteristics of large suction force, low noise, and compact structure, and are applied to household range hoods. The volute is the core component of the centrifugal blower, and its function is to convert the kinetic energy of the gas at the impeller outlet into potential energy, overcome the flue resistance, and lead the flue gas out of the volute and finally discharge it outdoors. The profile of the volute not only determines the external dimensions of the centrifugal blower, but also has a great influence on the air volume, efficiency, and aerodynamic noise, and thus determines the aerodynamic performance and noise performance of the range hood.

[0003] The traditional design of the volute profile adopts the equal circulation method and the average velocity method. Among them, the equal circulation method is based on the assumption that the air flow is free and its moment of momentum remains unchanged, and it is obtained that the movement trajectory of the fluid particles in the volute conforms to the logarithmic spiral. The average velocity method first calculates the maximum opening with the following formula, and then calculates the volute profile according to the formula: This kind of volute profile with continuous derivatives is convenient for calculation. However, for a range hood, the external dimensions of the centrifugal blower are limited by the blower frame, its inlet is located inside the box, and the outlet is connected to the working pipe network. The traditional volute profile design does not conform to the gas flow law inside the volute of the range hood and cannot meet the state of optimal multi-condition operation performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defect of poor performance of the multi-wing centrifugal blower obtained by the existing volute profile design method, and to provide a design method for a volute profile, a volute, a blower system, and a range hood.

[0005] The present invention solves the above technical problem through the following technical solutions:

[0006] A design method for a volute profile, which is used to design the volute profile of a blower volute. The design method for the volute profile includes the following steps:

[0007] S1. Divide the volute profile into at least three sections of curves along the direction from the outlet of the volute profile to the volute tongue;

[0008] S2. Calculate the dimensional parameters of each section of the curve in turn along the direction from the outlet of the volute profile to the volute tongue. Among them, the calculation method for each section of the curve includes at least:

[0009] S21. Take the dimensional parameters of each section of the curve as factors and the total pressure loss coefficient of the blower and the static pressure recovery coefficient of the blower as responses, and conduct an orthogonal test;

[0010] S22. Based on the orthogonal test results, a linear regression equation for the total pressure loss coefficient of the fan and a linear regression equation for the static pressure recovery coefficient of the fan are obtained;

[0011] S23. Taking the optimal solutions of the linear regression equation about the total pressure loss coefficient of the fan and the linear regression equation about the static pressure recovery coefficient of the fan as the size parameters of each section of the curve.

[0012] The design method of the volute profile reflects the internal flow field characteristics of the fan through the total pressure loss coefficient of the fan and the static pressure recovery coefficient of the fan, and divides the volute profile into at least three curves along the direction from the outlet of the volute profile to the volute tongue and calculates them in sections, which can significantly reduce the calculation difficulty compared with the overall calculation. Among them, the size parameters of each curve are obtained by orthogonal test to obtain basic data, and then the linear regression equation is used to fit these basic data, and the optimal solution is obtained in a relatively simple calculation method, which effectively reduces the calculation workload.

[0013] In addition, the curve shape on the outlet side close to the volute profile has a relatively large influence on the internal flow field of the fan, so the calculation is performed sequentially starting from the curve close to the outlet side to match the internal flow field characteristics of the fan as much as possible.

[0014] Preferably, step S21 specifically includes:

[0015] The dimension parameters of the first section of the curve from the outlet of the volute profile to the volute tongue as factors of the orthogonal test include at least the outlet angle.

[0016] The outlet angle of the volute profile is used as a factor in the orthogonal test to objectively reflect the dimensional parameters of the volute profile and improve the performance of the fan using the volute profile.

[0017] Preferably, step S21 specifically includes:

[0018] The dimension parameters of the last section of the curve from the outlet of the volute profile to the volute tongue as factors of the orthogonal test at least include the volute tongue radius.

[0019] The volute tongue radius of the volute profile is used as a factor in the orthogonal test to objectively reflect the dimensional parameters of the volute profile and improve the performance of the fan using the volute profile.

[0020] Preferably, step S21 specifically includes: the number of factors of the orthogonal test for each curve segment is less than or equal to four.

[0021] By controlling the number of factors in each curve segment during orthogonal testing, we can avoid a significant increase in the number of tests due to excessive factors, and control the test cost and workload.

[0022] Preferably, the total pressure loss coefficient of the fan is obtained by weighting the total pressure loss coefficient of the fan under small flow conditions and the total pressure loss coefficient of the fan under large flow conditions; and / or,

[0023] The static pressure recovery coefficient of the fan is obtained by weighting the static pressure recovery coefficient of the fan under small flow conditions and the static pressure recovery coefficient of the fan under large flow conditions.

[0024] When optimizing the volute profile, by weighting the parameters of the fan under small flow conditions and large flow conditions, a volute profile that can take into account two mainstream working conditions and has better aerodynamic performance is obtained.

[0025] Preferably, in the total pressure loss coefficient of the fan and / or the static pressure recovery coefficient of the fan, the weighting ratio is 1:1; and / or,

[0026] The small flow condition is the working condition when the working air volume of the range hood is 12 m³ / min; and / or,

[0027] The large flow condition is the working condition when the working air volume of the range hood is 35 m³ / min.

[0028] Preferably, in step S21, it specifically includes:

[0029] Setting the factor levels in the orthogonal experiment based on the maximum volute profile.

[0030] The maximum volute profile usually refers to the largest volute shape that can be designed under given design constraints. In step S21 of the orthogonal experiment for each section of the curve, setting the factor levels in the orthogonal experiment based on the maximum volute profile to set a reasonable level range, and on the premise of ensuring that the level range is wide enough to cover possible optimal values, avoiding the level range exceeding the limit and obtaining size parameters that cannot be adopted.

[0031] Preferably, the maximum volute profile is calculated based on the width and depth of the fan frame, the outer diameter of the impeller, and the assembly clearance.

[0032] Calculating the maximum volute profile through these parameters, so that the size parameters of the volute profile obtained by this design method can meet the assembly requirements.

[0033] A fan volute, the size parameters of the fan volute are obtained by the design method of the volute profile as described above.

[0034] A fan system, the fan system adopts the fan volute as described above.

[0035] A range hood, the range hood adopts the fan system as described above.

[0036] The positive and progressive effects of the present invention are as follows:

[0037] In the design method of the volute profile, the volute, the fan system and the range hood, the internal flow field characteristics of the fan are reflected by the total pressure loss coefficient of the fan and the static pressure recovery coefficient of the fan, and the volute profile is divided into at least three sections of curves along the direction from the outlet of the volute profile to the volute tongue and calculated section by section, so that the calculation difficulty can be significantly reduced compared with the overall calculation.

[0038] Among them, the dimensional parameters of each section of the curve are used to obtain the basic data through the orthogonal test method, and then the linear regression equation is used to fit these basic data to obtain the optimal solution in a relatively simple calculation method, and the calculation workload is effectively reduced. Moreover, the curve shape near the outlet side of the volute profile has a relatively large influence on the internal flow field of the fan. Therefore, the calculation is carried out sequentially from the curve near the outlet side to match the internal flow field characteristics of the fan as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic structural diagram of the fan system according to an embodiment of the present invention.

[0040] Figure 2 It is a schematic diagram of the dimensional parameters of the volute profile according to an embodiment of the present invention.

[0041] Figure 3 It is a diagram showing the dimensional relationship between the volute profile and the fan frame according to an embodiment of the present invention.

[0042] Figure 4 It is a schematic diagram of the segmentation of the volute profile according to an embodiment of the present invention.

[0043] Figure 5 It is a schematic diagram of the optimized volute profile according to an embodiment of the present invention.

[0044] Figure 6 It is a comparative schematic diagram of the optimized volute profile according to an embodiment of the present invention and the volute profile of the conventional single expansion angle logarithmic spiral. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The present invention will be further described below by way of embodiments, but the present invention is not limited to the scope of the described embodiments.

[0046] Embodiment 1

[0047] The present invention provides a design method for a volute profile, which is used to design the volute profile of the fan volute 10 as shown in Figure 1 The fan volute 10 is used to accommodate a fan to form the fan system 1 of the range hood.

[0048] As shown in Figure 2As shown, it is the volute profile of the fan volute to be designed and determined in this embodiment. In order to obtain the spiral equation of this volute profile, according to the influence of the volute profile in different intervals on the fan performance, and combined with the flow field characteristics inside the volute under different operating conditions of the fan, 12 dimensional parameters as shown in Figure 2 are selected in the circumferential direction (the volute tongue radius R, the openings A1 - A10 at various positions of the volute profile, and the outlet angle θ) to achieve the description of the volute profile and the flow control inside the volute, and a segmented optimization design is carried out on these dimensional parameters in the direction from the outlet to the volute tongue along the volute profile, and the optimized volute profile is gradually obtained. In this embodiment, for the convenience of calculation, the volute profile corresponding to the fan volute outlet is set in the fourth quadrant. The opening A1 corresponds to the opening size at the volute tongue, and the openings A2, A4, A6, and A8 respectively correspond to the opening sizes at the X - axis and Y - axis.

[0049] Since when carrying out parameter optimization, conducting a design with 12 factors simultaneously will result in a relatively large number of test times and the occurrence of invalid test groups, which will affect the analysis of test results. Therefore, in combination with the flow field characteristics inside the fan, the above 12 dimensional parameters are optimized in batches.

[0050] As shown in Figure 3 , before starting the optimization design of specific dimensional parameters, first select the impeller outer diameter D2 according to the width W, depth L, and height H of the fan frame. The impeller outer diameter is related to the placement position of the fan in the fan frame. If the width direction of the volute is parallel to the width direction of the fan frame, then D2 = (0.58 - 0.72)W; if the width direction of the volute is parallel to the depth direction of the fan frame, then D2 = (0.58 - 0.72)L.

[0051] Generally speaking, a certain assembly gap d needs to be reserved between the width direction of the volute and the inner wall of the fan frame to avoid structural interference. Generally, d≥3.5mm. In this embodiment, d = 3.5mm, so W = M + 7mm, where M is the volute width dimension.

[0052] According to the above requirements for the volute width dimension, and combined with the logarithmic spiral equation , the maximum expansion angle is obtained, and the maximum volute profile under the limiting dimensions is drawn. Based on the maximum volute profile, the base values and approximate ranges of the 12 dimensional parameters of the volute profile are determined, and then an optimized design method is used to obtain an optimized volute profile scheme.

[0053] Among them, the specific design method of the volute profile includes the following steps:

[0054] S1. Along the direction from the outlet to the volute tongue of the volute profile, divide the volute profile into at least three curves;

[0055] S2. Calculate the dimensional parameters of each section of the curve in sequence along the direction from the outlet to the volute tongue of the volute profile. Among them, the calculation method for each section of the curve includes at least:

[0056] S21. Take the dimensional parameters of each section of the curve as factors and the total pressure loss coefficient of the fan and the static pressure recovery coefficient of the fan as responses to conduct an orthogonal experiment;

[0057] S22. Based on the results of the orthogonal experiment, obtain the linear regression equation for the total pressure loss coefficient of the fan and the linear regression equation for the static pressure recovery coefficient of the fan;

[0058] S23. Take the optimal solutions of the linear regression equation for the total pressure loss coefficient of the fan and the linear regression equation for the static pressure recovery coefficient of the fan as the dimensional parameters of each section of the curve.

[0059] The design method of this volute profile reflects the internal flow field characteristics of the fan through the total pressure loss coefficient of the fan and the static pressure recovery coefficient of the fan, and divides the volute profile into at least three sections of curves along the direction from the outlet to the volute tongue of the volute profile and calculates them section by section. Compared with the overall calculation, the calculation difficulty can be significantly reduced. Among them, the dimensional parameters of each section of the curve obtain the basic data through the orthogonal experiment method, and then use the linear regression equation to fit these basic data to obtain the optimal solution in a relatively simple calculation method, and the calculation workload is effectively reduced.

[0060] Moreover, the curve shape near the outlet side of the volute profile has a relatively large influence on the internal flow field of the fan. Therefore, calculate in sequence starting from the curve near the outlet side to match the internal flow field characteristics of the fan as much as possible.

[0061] Specifically, in this embodiment, as Figure 4 shown, for the convenience of calculation, along the direction from the outlet to the volute tongue of the volute profile, the volute profile is divided into three sections of curves (C1, C2, C3), namely the first section of the volute profile located in the fourth quadrant (including the parameter dimensions θ, A10, A9, A8), the second section of the volute profile located in the third and second quadrants (A8, A7, A6, A5, A4), and the third section of the volute profile located in the first quadrant and part of the fourth quadrant (A4, A5, A6, A1, R). Since each section of the curve is distinguished according to the quadrant, A8 is included in both the first section of the volute profile and the second section of the volute profile, and A4 is included in both the second section of the volute profile and the third section of the volute profile.

[0062] Since the volute profile of the fan in the outlet section has a relatively large influence on the aerodynamic performance of the fan, while the volute profile in the volute tongue area has a relatively small influence on the aerodynamic performance of the fan. Therefore, first optimize the first section of the volute profile, including the parameters A8, A9, A10, and θ.

[0063] Among them, the section from Design A9 to the outlet of the volute is a straight line segment, and A9 = (1 - 1.05)A8. In this embodiment, A8 = 97.5 mm, and A9 = 1.02 * A8 = 100.4 mm. Since the parameter A8 affects the width of the volute and it is currently the maximum volute profile, the adjustment coefficient of Design A8 is 0.92 - 1 to avoid the adjustment coefficient of A8 exceeding 1, which may result in a volute profile larger than the maximum volute profile obtained from previous calculations, making the manufactured fan volute unable to be assembled and used. In addition, according to the influence of parameters A10 and θ on the aerodynamic performance of the fan, Design A10 = (1.3 - 1.34) * A8, and 8° ≤ θ ≤ 12°.

[0064] Furthermore, in order to obtain an optimized volute profile, the parameters A8, A10, and θ are selected for a three-factor and three-level orthogonal experiment and optimization design, with A9 as an accompanying variable, and A9 = 1.02 * A8. Among them, the three factor levels of A8 are 0.92 * A8, 0.96 * A8, and A8; the three factor levels of A10 are 1.3 * A8, 1.34 * A8, and 1.38 * A8; and the three factor levels of θ are 8°, 10°, and 12°.

[0065] In this embodiment, the parameter outlet angle θ is selected as a factor in the orthogonal experiment to objectively reflect the dimensional parameters of the volute profile and improve the performance of the fan using this volute profile. Additionally, selecting the parameters A8, A10, and θ for a three-factor and three-level orthogonal experiment with A9 as an accompanying variable can avoid a significant increase in the number of experiments due to too many factors in the orthogonal experiment, and control the experimental cost and workload. In other embodiments, the parameters A8, A9, A10, and θ can also be selected for a four-factor and three-level orthogonal experiment according to the actual situation, or an orthogonal experiment with other numbers of factors can be used.

[0066] Furthermore, in order to obtain a volute solution with low total pressure loss and high static pressure recovery. The dimensionless parameters, namely the total pressure loss coefficient of the volute under two working conditions and the static pressure recovery coefficient are selected as the optimization objectives. Among them, and The formulas for are:

[0067]

[0068]

[0069] Among them, is the total pressure at the outlet of the fan impeller, is the static pressure at the outlet of the fan impeller, is the total pressure at the outlet of the volute, is the static pressure at the outlet of the volute, and the large flow rate working condition is and , the low-flow condition is and .

[0070] Furthermore, in order to take into account the performance of the fan under two operating conditions, a weighting coefficient is set to weight the optimization objectives and for the two operating conditions respectively. 0 < < 1, and the sum of the weighting coefficients for the two operating conditions is 1. Its value is determined by the maximum volute profile and the optimization objective, that is, the greater the performance distance of the maximum volute profile from the target of a certain operating condition, the greater the corresponding weighting coefficient. When optimizing the fan performance, it is often required to improve the aerodynamic performance of the two operating conditions simultaneously, or consider the optimization objectives of the two operating conditions equally important. Set the weighting coefficient for the low-flow condition to be equal to the weighting coefficient for the high-flow condition, both being 0.5. Then,

[0071]

[0072]

[0073] Specifically, in this embodiment, the air volume of the low-flow condition is set to correspond to the working air volume of 12 m³ / min in the national standard for the range hood using this fan system, and the air volume of the high-flow condition is set to correspond to the maximum air volume of 35 m³ / min of the range hood using this fan system. Due to the existence of the pipe network resistance in the working air volume condition, the total pressure loss in the volute is small. To simplify the objective function, the total pressure loss coefficient of the low-flow condition is ignored here, that is, .

[0074] In this embodiment, by weighting the parameters of the fan under the low-flow condition and the high-flow condition, a volute profile that can take into account two mainstream operating conditions and has better aerodynamic performance is obtained.

[0075] Furthermore, taking the weighted total pressure loss coefficient and the weighted static pressure recovery coefficient as responses, geometric modeling and numerical simulation calculations are carried out in combination with the orthogonal test table L9(3^2). In this embodiment, the orthogonal test results of the first-stage volute profile are shown in Table 1:

[0076] Table 1 Orthogonal test results of the first-stage volute profile

[0077]

[0078] Based on the above orthogonal test results, through range analysis and linear fitting regression, a regression equation about the weighted total pressure loss coefficient and A8, A10, and θ is obtained:

[0079]

[0080] and the weighted static pressure recovery coefficient and A8, A10, and The regression equation of:

[0081]

[0082] and with as the optimization objective, the parameter combination for the optimization of the first-stage volute profile is obtained. The specific parameter combination scheme is: A8 = 91.43 mm, A10 = 126.75 mm, θ = 12°.

[0083] Furthermore, after completing the optimization of the first stage of the volute profile, based on the first-stage volute profile, continue to optimize the second-stage volute profile.

[0084] Since the optimal value of the opening A8, 91.43 mm, is known, the opening parameters that still need to be calculated for the second-stage volute profile include A5, A6, and A7. Generally, the height dimension of the fan frame is relatively large. Therefore, the design space of the fan volute in this direction is also relatively large. When conducting the orthogonal experiment, the adjustment coefficients of the corresponding design opening parameters A5, A6, and A7 are all 1 to 1.12. Then, the three factor levels of A5 are A5, 1.06A5, and 1.12A5; the three factor levels of A6 are A6, 1.06A6, and 1.12A6; the three factor levels of A7 are A7, 1.06A7, and 1.12A7. Based on the optimization results of the first-stage volute profile above, with the weighted total pressure loss coefficient and the weighted static pressure recovery coefficient as the responses, combined with the orthogonal experiment table L9(3^2), carry out geometric modeling and numerical simulation calculations. In this embodiment, the orthogonal experiment results of the second-stage volute profile are shown in Table 2:

[0085] Table 2 Orthogonal experiment results of the second-stage volute profile

[0086]

[0087] Further, through range analysis and linear fitting regression, the regression equations of the weighted total pressure loss coefficient with A5, A6, and A7 are obtained:

[0088]

[0089] and the weighted static pressure recovery coefficient with A5, A6, and A7 are obtained:

[0090]

[0091] and with as the optimization objective, the optimal combination scheme of the parameters for the second-stage volute profile is: A5 = 60.38 mm, A6 = 76.65 mm, A7 = 86.1 mm.

[0092] Furthermore, after completing the optimization of the first and second stages of the volute profile, continue to optimize the last stage of the volute profile. The third-stage volute profile includes the parameters R, A1, A2, A3, and A4 in the first and fourth quadrants.

[0093] To simplify the optimization process, orthogonal experiments are conducted by selecting R, A1, and A4. Among them, R represents the radius of the volute tongue, and A1 represents the clearance at the radius-tongue position. Since the volute tongue diverts the flow and the radius-tongue clearance is relatively small, the air flow decelerates after passing through the volute tongue. Therefore, A2 is designed as (1 - 1.1)A1. In this embodiment, A2 = 1.05A1. Since the area near A3 in the volute flow channel is the intersection of the recirculating gas from the volute tongue and the air flow at the outlet of the fan impeller, the gas flow is relatively complex. Therefore, A3 is designed as (0.7 - 0.9)A4. In this embodiment, A3 = 0.8 * A4. Since the parameter A4 affects the width of the volute and it is currently the maximum volute profile, the adjustment coefficient of A4 is selected as 0.92 - 1. In this embodiment, A4 = 42.2 mm. In the orthogonal experiment, the three factor levels of the volute tongue radius R are 12, 16, and 20; the three levels of A1 are 12, 16, and 20; and the three levels of A4 are 0.92A4, 0.96A4, and A4. On the basis of the optimization of the first and second stages of the volute profile above, with the weighted total pressure loss coefficient and the weighted static pressure recovery coefficient as the responses, geometric modeling and numerical simulation calculations are carried out in combination with the orthogonal experiment table L9(3^2). In this embodiment, the orthogonal experiment results of the third-stage volute profile are shown in Table 3:

[0094] Table 3 Orthogonal experiment results of the third-stage volute profile

[0095]

[0096] Furthermore, through range analysis and linear fitting regression, the regression equations of the weighted total pressure loss coefficient with R, A1, and A4 are obtained:

[0097]

[0098] and the regression equations of the weighted static pressure recovery coefficient with R, A1, and A4 are obtained:

[0099]

[0100] and with Taking the optimization objective, the preferred parameter combination scheme for the third-stage volute profile is: R = 18.06 mm, A1 = 20 mm, A4 = 42.2 mm.

[0101] Based on the optimization results of the three curves, the optimized volute profile parameters are shown in the following table:

[0102]

[0103] Connecting each point through a spline curve for plotting, the optimized volute profile is as Figure 5 shown.

[0104] As Figure 6 shown, in order to verify the performance of the optimized volute profile, a volute profile H' composed of logarithmic spiral curves with a conventional single expansion angle is correspondingly plotted, and geometric modeling and simulation calculations are carried out for the optimized volute profile H. The calculation results are shown in the following table:

[0105]

[0106] It can be seen from the above table that the performance of the optimized volute profile H is improved compared with that of the conventional volute profile H' with a single expansion angle under two common working conditions. Among them, under the small-flow (air volume is 12 m 3 / min) working condition, the total pressure efficiency of the optimized volute profile H is increased by 1.79% compared with that of the conventional volute profile H'; under the large-flow (air volume is 35 m 3 / min) working condition, the total pressure efficiency of the optimized volute profile H is increased by 2.68% compared with that of the conventional volute profile H'.

[0107] Furthermore, after obtaining the above-mentioned relatively preferred volute profile scheme, according to the influence of each dimension parameter on the aerodynamic performance of the fan in the optimization results, combined with the optimization objective and spatial dimensions, by adjusting the weighting coefficients of the two working conditions , the optimized volute profile can be adjusted specifically.

[0108] The present invention also provides a fan system, and the fan system uses a fan volute manufactured with the dimension parameters obtained by the above-mentioned volute profile design method. In addition, the present invention also provides a range hood, and the range hood uses the above-mentioned fan system.

[0109] By using a fan volute manufactured with the dimension parameters obtained by the above-mentioned volute profile design method, the total pressure efficiency of the range hood and the fan system can be improved.

[0110] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principle and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for designing a volute profile, which is used to design a volute profile of a fan volute, characterized in that: The design method of the volute profile comprises the following steps: S1, along the direction from the outlet of the volute profile to the volute tongue, the volute profile is divided into at least three curves; S2. Calculate the size parameters of each curve segment in sequence along the direction from the outlet of the volute profile to the volute tongue, wherein the calculation method of each curve segment at least includes: S21. Taking the size parameters of each curve as factors and the fan total pressure loss coefficient and fan static pressure recovery coefficient as responses, an orthogonal test is conducted; S22. Based on the orthogonal test results, a linear regression equation for the total pressure loss coefficient of the fan and a linear regression equation for the static pressure recovery coefficient of the fan are obtained; S23. Taking the optimal solutions of the linear regression equation about the total pressure loss coefficient of the fan and the linear regression equation about the static pressure recovery coefficient of the fan as the size parameters of each curve segment.

2. The method for designing a volute profile as claimed in claim 1, characterized in that: Step S21 specifically includes: The dimension parameters of the first section of the curve along the outlet of the volute profile to the volute tongue as factors of the orthogonal test include at least the outlet angle; and / or, The dimension parameters of the last section of the curve from the outlet of the volute profile to the volute tongue as factors of the orthogonal test at least include the volute tongue radius.

3. The method for designing a volute profile as claimed in claim 1, characterized in that: Step S21 specifically includes: the number of factors of the orthogonal test for each curve segment is less than or equal to four.

4. The method for designing a volute profile as claimed in claim 1, characterized in that: The total pressure loss coefficient of the fan is obtained by weighting the total pressure loss coefficient of the fan under a small flow rate condition and the total pressure loss coefficient of the fan under a large flow rate condition; and / or, The fan static pressure recovery coefficient is obtained by weighting the fan static pressure recovery coefficient under a small flow rate condition and the fan static pressure recovery coefficient under a large flow rate condition.

5. The method for designing a volute profile as claimed in claim 4, characterized in that: In the fan total pressure loss coefficient and / or the fan static pressure recovery coefficient, the weighted ratio is 1:1; and / or, The low flow rate working condition is the working condition when the range hood has a working air volume of 12m³ / min; and / or, The high flow rate working condition refers to the working condition when the range hood has an operating air volume of 35m³ / min.

6. The method for designing a volute profile as claimed in claim 1, characterized in that: Step S21 specifically includes: The levels of each factor in the orthogonal experiment were set based on the maximum volute profile.

7. The method for designing a volute profile as claimed in claim 6, characterized in that: The maximum volute profile is calculated based on the width and depth of the fan frame, the outer diameter of the impeller and the assembly clearance.

8. A fan volute, characterized in that: The size parameters of the fan volute are obtained by the design method of the volute profile as described in any one of claims 1-7.

9. A fan system, characterized in that: The fan system adopts the fan volute as described in claim 8.

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

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