Blade front edge sawtooth arrangement method, impeller, centrifugal fan and range hood thereof

Abstract

This application relates to the field of range hoods, specifically a method for arranging the leading edge serrations of blades on an impeller of a centrifugal fan, comprising: obtaining the pitch λ of the first serrations on the leading edge of the first blade. b ; Obtain the sawtooth pitch λ at λ b Empirical parameter values ​​K and i related to the relationship between the vortex size D and the vortex energy E in the vicinity of λ. b Nearby empirical parameter values ​​L and j are obtained; the pitch λ of the second serration on the leading edge of the second blade is obtained. xb The ratio N between the number of the first blade and the number of the second blade is used to obtain the average energy E of the vortex generated by the N+1 blades in a blade unit. ave According to E ave λ is derived b , λ xb The relationship between N and N. This application, through the above method, makes the flow of small-sized vortices more stable and the streamlines of small-sized vortices more ordered, thereby reducing the degree of chaos in turbulence and lowering energy dissipation.

Description

Technical Field

[0001] This application relates to the field of range hoods, and in particular to a method for arranging the leading edge serrations of blades, an impeller, a centrifugal fan, and a range hood thereof. Background Technology

[0002] Range hoods typically use centrifugal fans as their power system. Centrifugal fans offer advantages such as high static pressure, low noise, and compact structure. The blades are a crucial component of the centrifugal fan impeller; their shape, number, and angle all affect the impeller's efficiency, noise levels, and other performance characteristics. Adding shape features to the leading edge of the blades is a common method to improve airflow disturbance, reduce pulsating pressure, and lower aerodynamic noise.

[0003] In related technologies, the blades used in centrifugal fans have a first structure on the inner edge of the blade inlet side. This first structure has at least two structures spaced apart along the height of the blade, and its shape is an inverted airfoil head. A centrifugal fan using the aforementioned blades and a range hood using the same centrifugal fan are also disclosed. The inverted airfoil head on the inner edge of the blade reduces airflow offset loss and incoming flow impact loss, improving aerodynamic performance and efficiency. The outer edge of the blade uses a gradually changing wave or a positive airfoil curve to reduce dynamic and static interference of the airflow between the impeller outlet and the volute. The concave and convex parts control the local airflow flow to the left and right respectively, reducing losses caused by secondary crossflow after airflow exit, thereby improving efficiency and reducing noise. However, because the sawtooth shape of each blade is consistent, the size and energy of the vortices formed are similar. When these vortices collide in the confluence area, they generate highly random vortex motion, making the motion more complex and increasing the chaos and energy dissipation of the turbulence. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for arranging the leading edge serrations of blades, an impeller, a centrifugal fan, and a range hood that can solve the above-mentioned technical problems.

[0005] To address the aforementioned technical problems, this application provides the following technical solution:

[0006] A method for arranging the leading edge serrations of blades on a centrifugal fan impeller, wherein the centrifugal fan impeller includes multiple blade units arranged sequentially along the rotation direction of the impeller; each blade unit includes a first blade and a second blade, the leading edge of the first blade having a first serration, and the leading edge of the second blade having a second serration; the method for arranging the leading edge serrations of blades on the centrifugal fan impeller includes:

[0007] Obtain the pitch λ of the first serration on the leading edge of the first blade. b ;

[0008] Obtain the sawtooth pitch λ at λ bEmpirical parameter values ​​K and i for the relationship between the vicinity and the vortex diameter D are obtained. The value of K ranges from 0.1 to 0.5, and the value of i ranges from 0.4 to 1.2.

[0009] Obtain the vortex diameter D and vortex energy E in λ b Nearby empirical parameter values ​​L and j are obtained. The value of L ranges from 0.1 to 10, and the value of j ranges from 0.6 to 1.8.

[0010] Obtain the pitch λ of the second serration on the leading edge of the second blade. xb The ratio N between the number of the first blades and the number of the second blades is obtained, and the average energy E of the vortex generated by the N+1 blades in one blade unit is obtained. ave , ;

[0011] According to E ave The formula yields λ. b , λ xb The following relationship exists between N and N:

[0012] N > 4 and N is a positive integer

[0013] Among them, E b It is the energy of the large vortex generated by the first blade; E xb It is the energy of the small vortex generated by the second blade; D b It is the diameter of the vortex generated by the first blade; D xb It is the diameter of the vortex generated by the second blade.

[0014] In one implementation, E ave The values ​​of satisfy the following relationship: .

[0015] In one implementation, .

[0016] In one implementation, .

[0017] In one embodiment, the total number of blades on the impeller is M. The value is even.

[0018] In one embodiment, the impeller has a center point, and the first blades are provided in multiple sets, with the multiple sets of first blades arranged in a centrally symmetrical manner with the center point as the symmetry point.

[0019] In one implementation, 5 ≤ N ≤ 14.

[0020] This application also provides the following technical solutions:

[0021] An impeller for a centrifugal fan includes multiple blade units arranged along the rotation of the impeller; each blade unit includes a first blade and a second blade, the leading edge of the first blade having multiple first serrations, and the leading edge of the second blade having multiple second serrations; the serration pitch λ on the first blade. b pitch with the serrations on the second blade The blades are arranged using the aforementioned method of arranging the leading edge serrations on the impeller of the centrifugal fan.

[0022] This application also provides the following technical solutions:

[0023] A centrifugal fan, including the impeller for the centrifugal fan.

[0024] This application also provides the following technical solutions:

[0025] A range hood includes the centrifugal fan mentioned above.

[0026] Compared with the prior art, the centrifugal fan impeller blade leading edge serration arrangement method provided in this application rearranges the first and second blades within a blade unit, and the serration pitch λ of the first serration at the leading edge of the first blade is... b pitch with the serrations on the second blade This establishes a corresponding relationship, thereby adjusting the ratio of the production frequencies of large and small vortices. Thus, changes in the blade serration pitch periodically generate vortices of varying sizes (large and small vortices) within the centrifugal fan. During the interaction of these different vortex sizes, the dominant motion of the large vortex makes the flow of the small vortex more stable and its streamlines more ordered, reducing the chaos of the turbulence and minimizing energy dissipation. Simultaneously, as the large vortex mixes with the small vortex, energy is transferred from the large vortex to the small vortex, rapidly reducing the energy of the large vortex. This allows newly generated large vortices to also guide previously generated large vortices. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the centrifugal fan impeller provided in this application.

[0029] Figure 2 A three-dimensional schematic diagram of the first blade provided for this application.

[0030] Figure 3 A side view of the first blade provided for this application.

[0031] Figure 4 A partial structural schematic diagram of the first blade provided in this application.

[0032] Figure 5 A three-dimensional schematic diagram of the second blade provided in this application.

[0033] Figure 6 A side view of the second blade provided in this application.

[0034] Figure 7 A partial structural diagram of the second blade provided in this application.

[0035] Reference numerals: 100, impeller; 10, blade unit; 11, first blade; 111, first serration; 12, second blade; 121, second serration. Detailed Implementation

[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0037] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0041] like Figure 1 As shown, this application provides an impeller 100 for a centrifugal fan (hereinafter referred to as impeller 100). The impeller 100 includes a plurality of blade units 10, which are arranged sequentially along the rotation direction of the impeller 100. Each blade unit 10 includes a first blade 11 and a second blade 12, and the ratio between the first blade 11 and the second blade 12 is configured as N. The leading edge of the first blade 11 has a plurality of first serrations 111, and the leading edge of the second blade 12 has a plurality of second serrations 121. Thus, the first serrations 111 and the second serrations 121 improve the airflow disturbance of the impeller 100 and reduce pulsating pressure.

[0042] While the serrations can improve airflow disturbance and allow the laminar boundary layer on the blades to transition to turbulence earlier, thus preventing vortex separation caused by unstable waves in the laminar boundary layer, related technologies often feature serrations with the same pitch on the leading edge of each blade. However, because the serrations on each blade have the same shape, the size and energy of the vortices they form are relatively similar. When these vortices collide in the confluence area, they generate highly random vortex motion, making the motion more complex and increasing the degree of chaos and energy dissipation in the turbulence.

[0043] Therefore, this application proposes a method for arranging the leading edge serrations of blades on impellers for centrifugal fans, thereby solving the above problems by combining the arrangement of blade serrations with the design of the serration pitch on the blades.

[0044] like Figures 1 to 7 As shown, the method for arranging the leading edge serrations of the blades on the centrifugal fan impeller provided in this application includes:

[0045] Step S1: Obtain the pitch λ of the first serration 111 on the leading edge of the first blade 11. b ;

[0046] Step S2: Obtain the sawtooth pitch λ. b Empirical parameter values ​​K and i for the relationship between the vicinity and the vortex size D are obtained. The value of K ranges from 0.1 to 0.5, and the value of i ranges from 0.4 to 1.2.

[0047] Step S3: Obtain the vortex size D and vortex energy E in λ b Nearby empirical parameter values ​​L and j are obtained. The value of L ranges from 0.1 to 10, and the value of j ranges from 0.6 to 1.8.

[0048] Step S4: Obtain the pitch λ of the second serration 121 on the leading edge of the second blade 12. xb The ratio N between the number of the first blade (11) and the number of the second blade is used to obtain the average energy E of the vortex generated by N+1 blades. ave , ;

[0049] Step S5, according to E ave The formula yields λ. b , λ xb The following relationship exists between N and N:

[0050] N > 4 and N is a positive integer

[0051] Among them, E b It is the energy of the large vortex generated by the first blade 11; E xb It is the energy of the small vortex generated by the second blade; D b It is the diameter of the vortex generated by the first blade 11; D xb It is the diameter of the vortex generated by the second blade.

[0052] Understandably, the diameter of large vortices can be adjusted by the sawtooth pitch λ, and the generation frequency ratio of large and small vortices can be controlled by the ratio of the number of first blades 11 to second blades 12. And through the method described above, the first pitch can be adjusted... Second pitch A reasonable relationship is satisfied; simultaneously, the ratio of the number of first blades 11 and second blades 12 within a blade unit is obtained, allowing the size (diameter) of the large vortex to be sufficiently large, thus guiding the small vortex and enabling the serrations to function properly in reducing intake obstruction. Furthermore, the generation frequency ratio of large to small vortices is within a reasonable range, preventing excessively high generation frequency of large vortices and insufficient energy reduction, allowing the collision turbulence of new and old large vortices to become dominant. In other words, the centrifugal fan blades designed using the above method, under the dominant motion of large vortices, will make the flow of small vortices more stable and the streamlines of small vortices more orderly, thereby reducing the degree of turbulence chaos and lowering energy dissipation. Simultaneously, after large vortices mix with small vortices, energy is transferred from the large vortex to the small vortex, causing the energy of the large vortex to decrease rapidly, allowing newly generated large vortices to also guide previously generated large vortices.

[0053] Here, "size" refers to the diameter of the vortex; a large-size vortex is a large-diameter vortex, and a small-size vortex is a small-diameter vortex. Of course, "large-size" and "small-size" are relative concepts. A vortex with a larger size than a vortex with a smaller size is called a large-size vortex.

[0054] It should also be noted that the first pitch It is greater than the second pitch. Therefore, the serrations on the first blade 11 are sparsely distributed, while those on the second blade 12 are densely distributed; hence, the first blade 11 is also called a sparsely toothed blade, and the second blade is also called a densely toothed blade. In this application, the ratio of sparsely toothed blades to densely toothed blades is set in a blade unit 10, and different pitches are constructed to ensure that the generation frequency of large-sized vortices is within a suitable range, thereby enabling small-sized vortices to always move in an orderly manner under the dominance of large-sized vortices, reducing the degree of chaos in turbulence and lowering energy consumption.

[0055] Further, in step S1, . The value of is related to the size of the large vortex, and if the size of the large vortex is too large, it will affect the serrations' ability to reduce intake obstruction. Here, The weights can be 3mm, 4mm, 5mm, etc. It should be noted that... The value of cannot be too small; if it is too small, it will be impossible to generate large vortices near the sawtooth pattern to guide the movement of small vortices. Therefore, here... .

[0056] In step S2, . If the value is too small, the overall machining precision of the saw teeth will be high, making machining difficult or costly. If it is too large, it will... and The proximity results in vortices of similar size, failing to reduce the chaos of the turbulence and thus the energy dissipation. Therefore, here... The value and N and N are interrelated. When After the value of N is set to a constant, the larger N is, the better. It will also increase accordingly. Here, .For example, The values ​​can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc. Of course, The value can be designed and set according to actual needs.

[0057] Furthermore, in step S2, the specific values ​​of the empirical parameters K and i depend on multiple factors such as blade design and operating environment. Empirically, the value of K generally ranges from 0.1 to 0.5, meaning K can be 0.1, 0.2, 0.3, 0.4, 0.5, etc. The value of i ranges from 0.4 to 1.2, meaning i can be 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, etc. Of course, the value of i is an empirical range, and the specific data needs to be adjusted based on experimental data.

[0058] In step S3, the empirical parameter values ​​L and j depend on factors such as airflow shear and vortex intensity. Empirically, L generally ranges from 0.1 to 10, meaning values ​​of L can be 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. The value of j ranges from 0.6 to 1.8, meaning values ​​of j can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, etc. Of course, the value of j is an empirical range, and specific values ​​need to be adjusted based on experimental data.

[0059] In step S4, the average energy E ave The values ​​of satisfy: That is, average energy. It should be greater than or equal to One-eighth of this is to ensure that the old large vortex continues to guide the smaller vortex before a new large vortex forms. Meanwhile, the average energy... It should be less than or equal to One-fifth of the total, to ensure the dominant role of the newly formed large vortex cluster.

[0060] Furthermore, the total number of blades 10 on the impeller 100 is M. The value of N must be even. For example, if the total number of blades M = 60 in impeller 100, then to ensure that the ratio of the total number of blades M to (N+1) is even, N can obviously be 5, 9, or 14, and the corresponding N+1 is 6 (10 groups), 10 (6 groups), or 15 (4 groups). Similarly, if the total number of blades n = 70 in impeller 100, then to ensure that the ratio of the total number of blades to (N+1) is even, N can only be 6, 9, or 13, and the corresponding N+1 is 7 (10 groups), 10 (6 groups), or 14 (5 groups).

[0061] Preferably, the total number of blades in the impeller 100 is limited. Therefore, the value of N is generally no greater than 14. Thus, in this embodiment, 5 ≤ N ≤ 14. Here, the value of N can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, etc. Of course, the specific value of N can be selected according to actual needs.

[0062] Furthermore, the impeller 100 has a center point, and multiple sets of first blades 11 are provided. The multiple sets of first blades 11 are arranged in a centrally symmetrical manner with the center point as the symmetry point, so as to ensure the dynamic balance of the impeller 100.

[0063] In one embodiment, taking M=60 as an example, to ensure that the ratio of the total number of impeller blades to (N+1) is even, N can only be 5, 9, or 14, corresponding to N+1 of 6 (10 groups), 10 (6 groups), and 15 (4 groups). Therefore, when N=5, within blade unit 10, the number of first blades 11 is 1, the number of second blades 12 is 5, and blade unit 10 has 10 groups. When N=9, within blade unit 10, the number of first blades 11 is 1, the number of second blades 12 is 9, and blade unit 10 has 6 groups. When N=14, within blade unit 10, the number of first blades 11 is 1, the number of second blades 12 is 15, and blade unit 10 has 4 groups.

[0064] Next, take The thickness is 5mm, and testing showed that the structure of this range hood... The ratio is approximately 0.5; and taking N values ​​of 5, 9, and 14 as examples, the following values ​​are obtained: The weight range is as follows:

[0065] When N=5 =1mm, Meaningless, therefore .

[0066] When N=9 1.66mm, , .

[0067] When N=14, 1.88mm, 1.25mm, therefore .

[0068] Meanwhile, tests were conducted on the range hood, including the impeller provided in this application. The People's Republic of China National Standard GB / T 17713-2022 (Range Hoods and Cooking Smoke Extraction Devices) was used as the testing standard. The data obtained from the tests are as follows:

[0069]

[0070] It is understandable that, as demonstrated by the above experiments, under the same operating airflow conditions, the embodiment provided in this application shows improvements in both operating noise and maximum total pressure efficiency compared to the control group. The reduction in operating noise and the increase in maximum total pressure efficiency indicate that, during operation, the blades 10 of the centrifugal fan designed using this method, under the dominant motion of large-sized vortices, make the flow of small-sized vortices more stable and the streamlines of small-sized vortices more orderly, thereby reducing the degree of turbulence chaos and lowering energy dissipation.

[0071] This application also provides a centrifugal fan, including the centrifugal fan impeller 100 described above.

[0072] This application also provides a range hood, including a centrifugal fan.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A method for arranging the leading edge serrations of blades on an impeller for a centrifugal fan, wherein the centrifugal fan impeller comprises multiple blade units arranged sequentially along the rotation direction of the impeller; each blade unit comprises a first blade and a second blade, the leading edge of the first blade having a first serration, and the leading edge of the second blade having a second serration; characterized in that, The method for arranging the leading edge serrations of the blades on the impeller of the centrifugal fan includes: Obtain the pitch λ of the first serration on the leading edge of the first blade. b ; Obtain the sawtooth pitch λ at λ b Empirical parameter values ​​K and i for the relationship between the vicinity and the vortex diameter D are obtained. The value of K ranges from 0.1 to 0.5, and the value of i ranges from 0.4 to 1.

2. Obtain the vortex diameter D and vortex energy E in λ b Nearby empirical parameter values ​​L and j are obtained. The value of L ranges from 0.1 to 10, and the value of j ranges from 0.6 to 1.

8. Obtain the pitch λ of the second serration on the leading edge of the second blade. xb The ratio N between the number of the first blades and the number of the second blades is used to obtain the average energy E of the vortex generated by the N+1 blades in one blade unit. ave , ; According to E ave The formula yields λ. b , λ xb The following relationship exists between N and N: N > 4 and N is a positive integer Among them, E b It is the energy of the large vortex generated by the first blade; E xb It is the energy of the small vortex generated by the second blade; D b It is the diameter of the vortex generated by the first blade; D xb It is the diameter of the vortex generated by the second blade.

2. The method for arranging the leading edge serrations of the blades on the impeller of a centrifugal fan according to claim 1, characterized in that, E ave The values ​​of satisfy the following relationship: 。 3. The method for arranging the leading edge serrations of the blades on the impeller of a centrifugal fan according to claim 1, characterized in that, 。 4. The method for arranging the leading edge serrations of the blades on the impeller of a centrifugal fan according to claim 1, characterized in that, 。 5. The method for arranging the leading edge serrations of the blades on the impeller of a centrifugal fan according to claim 1, characterized in that, The total number of blades on the impeller is M. The value is even.

6. The method for arranging the leading edge serrations of the blades on the impeller of a centrifugal fan according to claim 5, characterized in that, The impeller has a center point, and the first blades are arranged in multiple sets, with the multiple sets of first blades arranged in a centrally symmetrical manner with the center point as the symmetry point.

7. The method for arranging the leading edge serrations of the blades on an impeller for a centrifugal fan according to claim 1 or 6, characterized in that, 5≤N≤14。 8. An impeller for a centrifugal fan, characterized in that, The impeller comprises multiple blade units arranged along its rotation; each blade unit includes a first blade and a second blade, the leading edge of the first blade having multiple first serrations, and the leading edge of the second blade having multiple second serrations; the serration pitch λ on the first blade is... b pitch with the serrations on the second blade The blades of the centrifugal fan impeller are arranged using the serrated leading edge arrangement method described in any one of claims 1-7.

9. A centrifugal fan, characterized in that, Includes the centrifugal fan impeller as described in claim 8.

10. A range hood, characterized in that, Includes the centrifugal fan as described in claim 9.

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