Multi-blade centrifugal fan blade and multi-blade centrifugal fan

Abstract

The utility model discloses a kind of multi-wing centrifugal fan blade and multi-wing centrifugal fan, it includes: elliptic arc section, the elliptic arc section is located the air inlet end of the blade;Linear section, the linear section is located the air outlet end of the blade;Middle circular arc section, the circular arc section is located the intermediate position of the blade, the circular arc section is connected respectively the linear section and the elliptic arc section.The blade profile is divided into the three-section composite structure of elliptic arc section, middle circular arc section and linear section, different area characteristics of air flow in blade channel are optimized respectively.Elliptic arc section optimizes inlet region air flow angle deviation, reduces inlet impact loss;Middle circular arc section realizes air flow steady turning, reduces flow separation caused by inverse pressure gradient in blade channel;Linear section suppresses outlet cross section vortex area, reduces outlet flow loss.Three-section synergistic effect significantly reduces aerodynamic loss, improves fan system efficiency, solves the defect that single circular arc blade cannot consider inlet impact and passage separation.

Description

Technical Field

[0001] This utility model relates to the field of fans, and in particular to a multi-blade centrifugal fan blade and a multi-blade centrifugal fan. Background Technology

[0002] Currently, the blade profile of multi-blade centrifugal fans used in household range hoods is still dominated by a single circular arc. This design only requires a single circular arc parameter for forming, resulting in simple processing and low mold costs. After a few iterations with the aid of an experience database or simplified CFD, "acceptable" aerodynamic performance can usually be obtained, hence its widespread adoption. Some high-end models also use double circular arc blades, with the inlet and outlet sections composed of circular arcs with different radii of curvature, in order to geometrically adapt to the incoming flow impact and diffusion requirements respectively.

[0003] However, single-circular-arc blades, with only a constant curvature, cannot match the varying airflow velocity field and pressure gradient along the impeller channel: in the inlet region, the fixed curvature easily leads to significant incident impact losses; in the middle and outlet regions of the channel, it is difficult to suppress flow separation under adverse pressure gradients. Because a single geometric parameter has an inverse relationship with both types of losses, the traditional single-circular-arc design cannot simultaneously reduce both inlet impact losses and channel separation losses, thus limiting further improvements in overall aerodynamic efficiency. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the defect that the traditional single circular arc scheme in the prior art cannot simultaneously reduce the inlet impact loss and the separation loss in the channel, thus limiting the further improvement of the overall aerodynamic efficiency. This utility model provides a double circular arc profile design method for multi-blade centrifugal fan blades and the blades themselves.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] A multi-blade centrifugal fan blade, characterized in that it comprises:

[0007] An elliptical arc segment, wherein the elliptical arc segment is located at the air intake end of the blade;

[0008] A straight segment, wherein the straight segment is located at the air outlet end of the blade;

[0009] The circular arc segment is located in the middle of the blade and connects the straight line segment and the elliptical arc segment.

[0010] In this design, the aforementioned structure is adopted, employing a three-segment composite structure consisting of an elliptical arc segment, a mid-circular arc segment, and a straight segment. These segments are optimized for different regions of the airflow within the blade passage. The elliptical arc segment optimizes the airflow angle deviation in the inlet region, reducing inlet impact losses; the mid-circular arc segment enables smooth airflow steering, reducing flow separation caused by the adverse pressure gradient within the blade passage; and the straight segment suppresses the vortex region at the outlet section, minimizing outlet flow losses. The synergistic effect of these three segments significantly reduces aerodynamic losses, improves the efficiency of the fan system, and overcomes the limitation of a single circular arc blade in simultaneously addressing inlet impact and passage separation.

[0011] Preferably, the two ends of the circular arc segment are tangent to the elliptical arc segment and the straight line segment, respectively.

[0012] In this design, the above-mentioned structure is adopted, with the medium circular arc segment connected tangentially to the elliptical arc segment and the straight line segment. This ensures a smooth transition of the blade profile, avoids local flow separation or vortices caused by geometric abrupt changes, further reduces additional flow losses, improves airflow stability, and thus enhances the overall aerodynamic performance of the impeller.

[0013] Preferably, the radius of curvature of the elliptical arc segment gradually increases from the air intake end to the middle circular arc segment.

[0014] In this design, the aforementioned structure is adopted, with the radius of curvature of the elliptical arc segment gradually increasing from the inlet end to the middle circular arc segment, so that the curvature change of the airflow entering the blade passage matches the velocity field distribution. The gradual curvature design can effectively mitigate the impact angle deviation between the airflow and the blade in the inlet region, reduce the risk of inlet airflow separation, thereby reducing impact losses and improving flow uniformity.

[0015] Preferably, the radius of the middle circular arc segment is R, the radius of curvature of the middle circular arc segment is k=1 / R, the major diameter of the elliptical arc segment is a, the minor diameter of the elliptical arc segment is b, and the radius of curvature K1 of the elliptical arc segment gradually increases from the air intake end to the middle circular arc segment.

[0016] The radius of curvature K1 of the elliptical arc segment is in the range of (1 / a, 1 / b), where 1 / R = 1 / b.

[0017] In this design, the aforementioned structure ensures a continuous transition in curvature between the elliptical arc segment and the mid-circular arc segment. This design seamlessly connects the curvature variation of the elliptical arc segment with the stable curvature of the mid-circular arc segment, adapting to the changing airflow angle requirements in the inlet region while ensuring the stability of airflow turning in the middle section, thus reducing energy loss caused by abrupt curvature changes.

[0018] Preferably, the ratio of the length of the major axis to the length of the minor axis of the elliptical arc segment is 3:1 to 10:1.

[0019] In this design, the above-mentioned structure and the optimized curvature distribution characteristics of the elliptical arc segment are achieved through the appropriate selection of the ratio of its major axis to minor axis (3:1 to 10:1). The ratio of the major axis to the minor axis determines the degree of curvature of the elliptical arc, ensuring both the gradual curvature characteristics of the inlet region and avoiding local velocity distortion caused by excessive curvature. This balances the inlet impact loss with the suppression of flow separation within the blade passage, thereby improving overall aerodynamic efficiency.

[0020] Preferably, the chord length of the elliptical arc segment accounts for 5% to 20% of the total chord length of the blade.

[0021] In this design, the aforementioned structure is adopted, with the elliptical arc segment accounting for 5% to 20% of the total chord length, ensuring the full realization of the inlet region optimization function. This proportion range guarantees sufficient front section length to reduce inlet impact, while avoiding an excessively long front section that would lead to an insufficient proportion of the middle arc segment, thereby maintaining the dominant role of airflow steering in the middle of the blade passage and minimizing aerodynamic losses.

[0022] Preferably, the chord length of the middle arc segment accounts for 60% to 90% of the total chord length of the blade.

[0023] In this design, the aforementioned structure is adopted, with the central arc segment accounting for 60% to 90% of the total chord length, ensuring that the airflow does not dominate the turning process in the middle of the blade passage. This proportion range is matched with the variation law of the pressure gradient within the blade passage through geometric parameters, enabling the airflow to turn smoothly, reducing flow separation caused by adverse pressure gradients, thereby significantly reducing energy loss within the passage and improving the fan's pressure rise capacity.

[0024] Preferably, the chord length of the straight segment accounts for 5% to 10% of the total blade chord length.

[0025] In this design, the aforementioned structure is adopted, with the straight section accounting for 5% to 10% of the total chord length. This extremely short straight section effectively eliminates the vortex region at the blade exit. This proportion ensures precise control of the exit cross-sectional area while avoiding a decrease in velocity in the exit region caused by excessively long straight sections, thereby suppressing the generation of separation vortices and improving exit flow efficiency.

[0026] Preferably, the chord length of the elliptical arc segment accounts for 13.6% of the total blade chord length; the chord length of the medium circular arc segment accounts for 79.6% of the total blade chord length; and the chord length of the straight line segment accounts for 6.8% of the total blade chord length.

[0027] In this scheme, the above-mentioned structure is adopted, and the specific chord length ratio (13.6% for the elliptical arc segment, 79.6% for the mid-circle arc segment, and 6.8% for the straight segment) is the optimal solution obtained through a multi-objective optimization algorithm (such as NSGA-II) combined with CFD simulation and experimental verification. This ratio combination ensures reduced inlet impact loss (13.6% for the elliptical segment) and stable flow in the middle (79.6% for the mid-circle arc segment), while precisely controlling the outlet vortex region through the 6.8% straight segment. Ultimately, this achieves improved total pressure efficiency of the fan, reduced total pressure loss, and stable aerodynamic performance under different operating conditions.

[0028] A multi-blade centrifugal fan, characterized in that it includes the aforementioned multi-blade centrifugal fan blades.

[0029] In this solution, the aforementioned structure and the use of a multi-blade centrifugal fan with three composite linear blades demonstrate significant performance advantages at the overall machine level. Compared to traditional single-arc blade fans, it improves total pressure efficiency, reduces energy consumption, and lowers noise levels. Furthermore, the geometric optimization of the blade structure reduces flow separation within the blade passage, improving the fan's stability under low Reynolds number conditions and meeting the high-efficiency, low-noise operation requirements of range hoods under complex operating conditions.

[0030] The significant advantages of this invention are as follows: This invention discloses a multi-blade centrifugal fan blade and a multi-blade centrifugal fan. By dividing the blade profile into a three-segment composite structure—an elliptical arc segment, a mid-circular arc segment, and a straight segment—it optimizes the airflow characteristics in different regions within the blade passage. The elliptical arc segment optimizes the airflow angle deviation in the inlet region, reducing inlet impact losses; the mid-circular arc segment achieves smooth airflow steering, reducing flow separation caused by the adverse pressure gradient within the blade passage; and the straight segment suppresses the vortex region at the outlet section, reducing outlet flow losses. The synergistic effect of these three segments significantly reduces aerodynamic losses, improves the efficiency of the fan system, and solves the defect of a single circular arc blade that cannot simultaneously address inlet impact and passage separation. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the multi-blade centrifugal fan blades in this embodiment.

[0032] Figure 2 This is a schematic diagram of the structure of the multi-blade centrifugal fan blades in this embodiment.

[0033] Figure 3 This is a schematic diagram of the structure of the multi-blade centrifugal fan in this embodiment.

[0034] Explanation of reference numerals in the attached figures:

[0035] Leaf 1

[0036] Straight segment 11

[0037] Mid-circle segment 12

[0038] Elliptical arc segment 13

[0039] Multi-blade centrifugal fan 100 Detailed Implementation

[0040] 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.

[0041] like Figure 1 , Figure 2 As shown, this embodiment discloses a multi-blade centrifugal fan blade 1, which includes an elliptical arc segment 13 located at the inlet end of the blade 1; a straight segment 11 located at the outlet end of the blade 1; and a mid-circular arc segment 12 located in the middle of the blade 1, connecting the straight segment 11 and the elliptical arc segment 13. By dividing the blade 1 profile into a three-segment composite structure of elliptical arc segment 13, mid-circular arc segment 12, and straight segment 11, the characteristics of airflow in different regions within the blade passage are optimized. The elliptical arc segment 13 optimizes the airflow angle deviation in the inlet region, reducing inlet impact loss; the mid-circular arc segment 12 achieves smooth airflow steering, reducing flow separation caused by the adverse pressure gradient within the blade passage; and the straight segment 11 suppresses the vortex region at the outlet section, reducing outlet flow loss. The synergistic effect of the three segments significantly reduces aerodynamic losses, improves the system efficiency of the multi-blade centrifugal fan 100, and solves the defect that a single circular arc blade cannot simultaneously address inlet impact and channel separation. The airflow is divided into three sections: Elliptical arc segment 13 (inlet end): located at the leading edge of blade 1, used to optimize the airflow angle deviation in the inlet region. Medium circular arc segment 12 (middle section): located in the middle of blade 1, used to achieve smooth airflow deflection. Straight segment 11 (outlet end): located at the trailing edge of blade 1, used to suppress the outlet vortex region. Specifically: Elliptical arc segment 13 is generated using an elliptical curve, and its major-to-minor axis ratio is optimized based on the airflow inlet angle deviation. Medium circular arc segment 12 uses a single circular arc radius, the radius of which is determined through numerical simulation to ensure smooth airflow deflection in the middle of the blade passage. Straight segment 11 connects medium circular arc segment 12 to the outlet end of blade 1 using a straight line, the length of which is designed according to the outlet vortex region control requirements.

[0042] like Figure 1 , Figure 2As shown, the front and rear ends of the intermediate circular arc segment 12 are tangent to the elliptical arc segment 13 and the straight segment 11, respectively. The tangential connection between the intermediate circular arc segment 12 and the elliptical arc segment 13 and the straight segment 11 ensures a smooth transition of the blade profile I, avoiding local flow separation or vortices caused by geometric abrupt changes, further reducing additional flow losses, improving airflow stability, and thus enhancing the overall aerodynamic performance of the impeller. The tangential connection eliminates local sharp angles or curvature abrupt changes in the blade profile I, reducing the risk of airflow separation in the profile transition zone, lowering additional flow losses by approximately 5% to 8%, and improving airflow stability. The tangential connection structure can be preferably achieved using CNC machine tools or die stamping technology to avoid geometric abrupt changes.

[0043] like Figure 1 , Figure 2 As shown, the radius of curvature of elliptical arc segment 13 gradually increases from the inlet end to the middle circular arc segment 12. This gradual increase in the radius of curvature of elliptical arc segment 13 ensures that the curvature change of the airflow entering the blade passage matches the velocity field distribution. This gradual curvature design effectively mitigates the impact angle deviation between the airflow and blade 1 in the inlet region, reduces the risk of inlet airflow separation, thereby reducing impact losses and improving flow uniformity. Specifically, the radius of the middle circular arc segment 12 is R, and its radius of curvature k = 1 / R. The major diameter of elliptical arc segment 13 is a, the minor diameter is b, and the radius of curvature K1 of elliptical arc segment 13 gradually increases from the inlet end to the middle circular arc segment 12. The range of the radius of curvature K1 of elliptical arc segment 13 is (1 / a, 1 / b), where 1 / R = 1 / b. This ensures a continuous transition in curvature between elliptical arc segment 13 and middle circular arc segment 12. This design connects the curvature variation of the elliptical arc segment 13 with the stable curvature of the middle circular arc segment 12, which not only adapts to the airflow angle variation requirements in the inlet region, but also ensures the stability of the airflow turning in the middle section, reducing energy loss caused by abrupt curvature changes.

[0044] In this embodiment, the curvature of the elliptical arc segment 13 changes uniformly and continuously.

[0045] like Figure 1 , Figure 2 As shown, the ratio of the major axis to the minor axis of elliptical arc segment 13 is 3:1 to 10:1. The appropriate selection of this ratio (3:1 to 10:1) optimizes the curvature distribution characteristics of elliptical arc segment 13. The ratio of the major axis to the minor axis determines the degree of curvature of the elliptical arc, ensuring both the gradual curvature characteristics of the inlet region and avoiding local velocity distortion caused by excessive curvature. This balances the inlet impact loss and the suppression effect of flow separation within the blade passage, thereby improving overall aerodynamic efficiency. The optimal value can be determined through wind tunnel experiments.

[0046] In this embodiment, the ratio of the major axis to the minor axis of the elliptical arc segment 13 is 5.3:1. The chord length of the elliptical arc segment 13 in this design accounts for 5% to 20% of the total chord length of blade 1. This 5% to 20% proportion of the elliptical arc segment 13 ensures the full realization of the inlet region optimization function. This ratio range guarantees sufficient front section length to reduce inlet impact while avoiding an excessively long front section that would lead to insufficient proportion of the mid-section arc segment, thus maintaining the dominant role of airflow steering in the middle of the blade passage and minimizing aerodynamic losses. CFD simulation analysis was used to analyze the aerodynamic performance under different chord length ratios, and four sets of parameters (5%, 10%, 15%, and 20%) were selected for comparative testing. This ensures reduced inlet impact losses while avoiding a decrease in steering capability due to compression of the mid-section arc segment 12.

[0047] In this embodiment, simulation analysis shows that when the chord length of the elliptical arc segment 13 accounts for 13.6%, the inlet impact loss and the flow separation loss in the middle section achieve the optimal balance, resulting in a 7.2% improvement in total pressure efficiency. In this design, the chord length of the middle circular arc segment 12 accounts for 60% to 90% of the total chord length of blade 1. This 60% to 90% proportion of the middle circular arc segment 12 ensures that the airflow does not dominate the turning process in the middle of the blade passage. This range of proportions, through matching the variation law of the pressure gradient within the blade passage with geometric parameters, allows for smooth airflow turning, reducing flow separation caused by the adverse pressure gradient, thereby significantly reducing energy loss within the passage and improving the fan's pressure rise capability. Specific numerical values ​​are obtained through numerical simulations, such as those based on the Reynolds-averaged Navier-Stokes equations (RANS), simulating the flow characteristics of the blade passage under different lengths of the middle circular arc segment 12. Experimental verification is further supported by observing changes in the airflow separation region within the blade passage using particle image velocimetry (PIV) technology.

[0048] In this embodiment, analysis shows that when the proportion of the arc segment 12 is 79.6%, the flow separation area under the adverse pressure gradient in the middle of the blade passage is reduced by 40%, and the fan pressure rise capacity is increased by 12%. The chord length of the straight segment 11 in this scheme accounts for 5%~10% of the total blade chord length. This 5%~10% proportion of the straight segment 11 effectively eliminates the vortex region at the blade passage exit through its extremely short length. This proportion ensures precise control of the exit cross-sectional area while avoiding a decrease in outlet velocity caused by an excessively long straight segment 11, thereby suppressing the generation of separation vortices and improving outlet flow efficiency. The 5%~10% chord length of the straight segment 11 is specifically implemented by: analyzing the influence of the straight segment 11 length on the intensity of the outlet vortex region through CFD simulation and determining the optimal proportion based on experimental data; and further weakening the vortex region intensity by using a chamfered end to the straight segment 11.

[0049] In this embodiment, analysis shows that when the straight segment 11 accounts for 6.8%, the energy dissipation of the outlet vortex region is reduced by 18%, and the total pressure loss of the fan is reduced by 9.5%.

[0050] like Figure 1 As shown in the figure, in this embodiment, the chord length of the elliptical arc segment 13 accounts for 13.6% of the total blade chord length; the chord length of the mid-circular arc segment 12 accounts for 79.6% of the total blade chord length; and the chord length of the straight segment 11 accounts for 6.8% of the total blade chord length. The specific chord length ratios (elliptical arc segment 13.6%, mid-circular arc segment 12 79.6%, straight segment 11 6.8%) are the optimal solutions obtained through a multi-objective optimization algorithm (such as NSGA-II) combined with CFD simulation and experimental verification. This ratio combination ensures reduced inlet impact loss (elliptical segment 13.6%) and stable flow in the middle (mid-circular arc segment 12 79.6%), while precisely controlling the outlet vortex region through the straight segment 11 6.8%, ultimately achieving a 100% increase in total pressure efficiency and a reduction in total pressure loss for the multi-blade centrifugal fan, while maintaining stable aerodynamic performance under different operating conditions.

[0051] In this embodiment, as Figure 2 As shown, the exit angle of the straight segment is 165 degrees, the radius of the middle circular arc segment is 11.9 mm, and the radius of the arch circle of the arch point of the middle circular arc segment and the straight segment is 110 mm.

[0052] like Figure 3 As shown, this embodiment also provides a multi-blade centrifugal fan 100, which includes the aforementioned multi-blade centrifugal fan blades 1. The multi-blade centrifugal fan 100, employing the aforementioned three-section composite profile blades 1, exhibits significant performance advantages at the overall machine level. Compared to traditional single-arc blade fans, it improves total pressure efficiency, reduces energy consumption, and lowers noise levels. Furthermore, the geometric optimization of the blade structure 1 reduces flow separation within the blade passage, improving the stability of the multi-blade centrifugal fan 100 under low Reynolds number conditions, thus meeting the high-efficiency, low-noise operation requirements of range hoods under complex operating conditions.

[0053] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model 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 this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. A multi-blade centrifugal fan blade, characterized in that, It includes: An elliptical arc segment, wherein the elliptical arc segment is located at the air intake end of the blade; A straight segment, wherein the straight segment is located at the air outlet end of the blade; The circular arc segment is located in the middle of the blade and connects the straight line segment and the elliptical arc segment.

2. The multi-blade centrifugal fan blade as described in claim 1, characterized in that, The two ends of the circular arc segment are tangent to the elliptical arc segment and the straight line segment, respectively.

3. The multi-blade centrifugal fan blade as described in claim 1, characterized in that, The radius of curvature of the elliptical arc segment gradually increases from the air intake end to the middle circular arc segment.

4. The multi-blade centrifugal fan blade as described in claim 3, characterized in that, The radius of the middle circular arc segment is R, the radius of curvature of the middle circular arc segment is k=1 / R, the major diameter of the elliptical arc segment is a, the minor diameter of the elliptical arc segment is b, and the radius of curvature K1 of the elliptical arc segment gradually increases from the air intake end to the middle circular arc segment. The radius of curvature K1 of the elliptical arc segment is in the range of (1 / a, 1 / b), where 1 / R = 1 / b.

5. A multi-blade centrifugal fan blade as described in claim 4, characterized in that, The ratio of the length of the major axis to the length of the minor axis of the elliptical arc segment is 3:1 to 10:

1.

6. The multi-blade centrifugal fan blade as described in claim 1, characterized in that, The chord length of the elliptical arc segment accounts for 5% to 20% of the total chord length of the blade.

7. A multi-blade centrifugal fan blade as described in claim 1, characterized in that, The chord length of the middle circular arc segment accounts for 60% to 90% of the total chord length of the blade.

8. A multi-blade centrifugal fan blade as described in claim 1, characterized in that, The chord length of the straight segment accounts for 5% to 10% of the total blade chord length.

9. A multi-blade centrifugal fan blade as described in claim 1, characterized in that, The chord length of the elliptical arc segment accounts for 13.6% of the total chord length of the blade; The chord length of the middle circular arc segment accounts for 79.6% of the total blade chord length; The chord length of the straight segment accounts for 6.8% of the total blade chord length.

10. A multi-blade centrifugal fan, characterized in that, It includes the multi-blade centrifugal fan blades as described in any one of claims 1-9.

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