An axial flow fan

Abstract

The application relates to the field of blade fluid machinery design, in particular to an axial flow fan, which comprises a hub and a plurality of blades arranged at one end of the hub in the circumferential direction of the hub, the number of the blades is multiple, the multiple blades are composed of two groups of centrosymmetric sub-blade groups, the interval angles between the blades in each sub-blade group are different, in the same rotating direction, the interval angle between two adjacent blades in the same sub-blade group first increases and then decreases, and the interval angle between the two blades at the rotating end is the minimum, and the interval angle between the two blades at the rotating end increases again. Through the grouping of the non-uniform interval design, the blade passing frequency noise is effectively reduced, the dynamic balance performance of the impeller is ensured, the vibration problem caused by the non-uniform arrangement is avoided, and the balance of the aerodynamic performance and the acoustic performance is excellent.

Description

Technical Field

[0001] This application relates to the field of bladed fluid machinery design, and in particular to an axial flow fan. Background Technology

[0002] As a core piece of equipment in the field of fluid machinery, axial flow fans have been widely used in many key areas such as ventilation, HVAC (heating, ventilation and air conditioning) systems, industrial refrigeration, and thermal management of power electronic equipment due to their large flow rate and low air pressure. Their operational stability and acoustic performance directly determine the user experience and long-term reliability of the terminal equipment.

[0003] In existing technologies, traditional axial flow fan impellers generally employ a uniformly spaced blade arrangement. While this design offers advantages such as simple manufacturing processes and low initial design costs, the equidistant blade distribution results in highly consistent time intervals for airflow impacts, causing BPF noise energy to be highly concentrated on a single frequency and its harmonic bands, forming strong noise peaks. To address this issue, the industry has gradually explored non-uniformly spaced blade arrangement schemes. By breaking the periodicity of blade distribution, these schemes achieve spectral dispersion of noise energy, thereby reducing BPF peak noise. However, existing non-uniformly spaced designs still have significant technical drawbacks, making it difficult to simultaneously meet the dual requirements of noise suppression and dynamic balance performance. Firstly, some patent documents disperse noise energy through completely random circumferential blade distribution. While this can reduce BPF peaks to some extent, the random arrangement disrupts the impeller's mass symmetry, leading to significant unbalanced inertial forces during rotation. This problem not only causes severe fan vibration, exacerbates bearing wear, and shortens equipment lifespan, but may also secondary generate noise through structural sound transmission, thus weakening the noise suppression effect. Secondly, some patents propose non-uniform spacing designs based on sinusoidal modulation. While optimizing blade spacing distribution through a sinusoidal function improves the disorder of random arrangement to some extent, this approach doesn't consider the grouping symmetry of the impellers. The modulation pattern of the blade spacing still cannot completely offset the eccentricity error of the rotating mass. In actual operation, this design still experiences periodic vibrations due to uneven mass distribution, especially at high speeds where the vibration amplitude increases significantly, severely limiting its application in aerospace, precision electronics, and other fields with stringent dynamic balance requirements.

[0004] In summary, existing non-uniform pitch impeller designs for axial flow fans generally suffer from a technical bottleneck where noise suppression and dynamic balance performance are mutually constrained. With downstream applications demanding increasingly higher levels of quietness and stability from equipment, developing an impeller structure that can effectively suppress BPF noise through a reasonable non-uniform pitch design while ensuring excellent dynamic balance performance through precise mass symmetry design has become a critical technical problem urgently needing to be solved in the industry. Utility Model Content

[0005] The purpose of this application is to provide an axial flow fan to address the problems of high blade noise and poor dynamic balance performance in the prior art.

[0006] The embodiments of this application can be implemented through the following technical solutions: An axial flow fan includes a hub and a plurality of blades arranged circumferentially at one end of the hub, wherein the plurality of blades are composed of two sets of centrally symmetrical sub-blades. The spacing angle between the blades in each sub-blade group is different. Along the same rotation direction, the spacing angle between two adjacent blades in the same sub-blade group first increases and then decreases until the spacing angle between two blades at the end of the rotation increases again.

[0007] Furthermore, the angle between the two blades at the end of the rotation is greater than the angle between the two blades at the beginning of the rotation.

[0008] Furthermore, no two interval angle values ​​within each of the sub-blade groups are equal.

[0009] Furthermore, the number of blades is 22, and the 22 blades are synchronously divided into two groups of 11 corresponding intervals.

[0010] Furthermore, the minimum interval angle between two adjacent blades is greater than or equal to 14 degrees.

[0011] Furthermore, along the same rotation direction, the angular interval values ​​within each of the sub-blade groups are successively 14.86 degrees, 16.19 degrees, 17.31 degrees, 18.03 degrees, 18.34 degrees, 17.93 degrees, 17.01 degrees, 15.78 degrees, 14.65 degrees, 14.34 degrees, and 15.56 degrees.

[0012] Furthermore, the impeller has a hub ratio of 0.708 and an impeller diameter of 1050 mm.

[0013] The axial flow fan provided by the embodiments of this application has at least the following beneficial effects: (1) In terms of noise reduction, this application relies on the non-uniform spacing design of "different spacing angles within the sub-blade group, which first increases and then decreases along the rotation direction, and then increases again at the end", which completely breaks the periodicity of the traditional uniform arrangement of blades. This design makes the time difference of airflow being cut by the blades completely disordered, and efficiently disperses the blade passing frequency (BPF) noise energy, which was originally concentrated in a single frequency band, to multiple sidebands, greatly reducing the sharpness of pure tone noise and improving the sound quality of the fan operation from the root.

[0014] (2) Regarding dynamic balance performance, this application employs a "two-set blades in a centrally symmetrical" grouping design to precisely offset the mass eccentricity problem that may be caused by non-uniform spacing. The two sets of sub-blades form a mirror-symmetrical structure in the circumferential direction of the hub, ensuring that the overall center of mass of the impeller is strictly coincident with the axis of rotation, effectively avoiding eccentric inertial forces caused by non-uniform arrangement, and fundamentally solving the vibration hazard. This not only improves the stability and reliability of the fan operation, but also reduces bearing wear, significantly extends the service life of the equipment, and reduces subsequent maintenance costs.

[0015] (3) While optimizing noise reduction and dynamic balance, a high degree of adaptation to airflow characteristics is achieved through a refined interval angle change law (increasing first and then decreasing, and increasing again at the end). "Increasing first" avoids airflow congestion between blades, "decreasing later" prevents the generation of local turbulence, and "increasing again at the end" avoids the accumulation of vortices in the airflow at the tail of the blades, so that the aerodynamic drag loss is controlled within a very small range and the stability of aerodynamic performance is improved.

[0016] (4) In terms of practicality, the two sets of centrally symmetrical simplified structures reduce the difficulty of assembly and positioning. They can be compatible with the existing mass production system of axial flow fans without the need for customized special high-precision equipment, which greatly reduces the threshold for industrialization and has strong engineering feasibility and promotion value. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an axial flow fan according to this application; Figure 2 This is a schematic diagram of the blade distribution on the hub in this application; Figure 3 This is a schematic diagram of the blade spacing distribution in this application.

[0018] Numbers in the diagram 1-Hub; 2-Blade. Detailed Implementation

[0019] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0020] Furthermore, for ease of understanding, various components on the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application.

[0021] Singular forms of words also include plural meanings, and vice versa.

[0022] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, in the description of this application, in order to distinguish different units, the terms "first," "second," etc. are used in this specification, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application.

[0023] The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise expressly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this application.

[0024] An axial flow fan includes a hub 1 and a plurality of blades 2 arranged circumferentially at one end of the hub 1. The plurality of blades 2 are composed of two sets of centrally symmetrical sub-blades. The centrally symmetrical arrangement of the two sets of sub-blades enables the circumferential mass distribution of the impeller to be mirror symmetrical, effectively counteracting the eccentric inertial force that may be generated by a single non-uniform sub-blade set, and avoiding the accumulation of vibration energy during rotation.

[0025] Furthermore, the spacing angle between the blades 2 in each sub-blade group is not the same. Along the same rotation direction, the spacing angle between two adjacent blades 2 in the same sub-blade group first increases and then decreases until the spacing angle between two blades 2 at the end of the rotation increases again. Through the non-uniform interval of "increasing first and then decreasing, and then increasing the end angle value again", the rhythm of airflow cutting can be disrupted, the originally concentrated noise energy can be dispersed to multiple frequency bands, the sharpness can be greatly reduced, and the airflow speed changes during impeller rotation can be adapted to reduce airflow separation on the blade surface.

[0026] In some preferred embodiments, the angle between the two blades 2 at the end of the rotation is greater than the angle between the two blades 2 at the beginning of the rotation. The larger end spacing design can also prevent airflow from accumulating at the tail of the blades and forming vortices, thereby reducing noise and improving the air output efficiency and stability of the fan.

[0027] In some preferred embodiments, the number of blades 2 is 22. Since the blades 2 are arranged continuously along the circumference and are centrally symmetrical, the 22 blades 2 are synchronously divided into two corresponding intervals (each group contains 11 intervals). The sum of the angle values ​​of the 11 intervals in each group is strictly equal to 180°, and the angle values ​​of any two intervals are not equal, ensuring the elimination of any "local hidden dangers" that may lead to noise concentration or airflow turbulence, so that noise reduction and aerodynamic performance can reach a better state.

[0028] In some preferred embodiments, the minimum interval angle between two adjacent blades 2 is greater than or equal to 14 degrees to avoid geometric interference between the blades.

[0029] In some preferred embodiments, along the same rotation direction, the angular interval values ​​within each sub-blade group are sequentially 14.86 degrees, 16.19 degrees, 17.31 degrees, 18.03 degrees, 18.34 degrees, 17.93 degrees, 17.01 degrees, 15.78 degrees, 14.65 degrees, 14.34 degrees, and 15.56 degrees. During installation, the blades 2 in the first sub-blade group are installed sequentially starting from the 0-degree position according to the above spacing sequence, and the blades in the second sub-blade group are installed starting from the 180-degree position according to the same spacing sequence.

[0030] CFD analysis and experimental tests show that, compared with the uniformly spaced fan, the axial flow fan of this application reduces the peak noise level at the blade passage frequency by 10-15 dB, the total sound pressure level by 1-3 dB, and the aerodynamic efficiency change is within 1%. The mechanical vibration level is comparable to that of the uniformly spaced fan.

[0031] In some preferred embodiments, the impeller has a hub ratio of 0.708 and an impeller diameter of 1050 mm. This allows for both a large flow rate output (meeting the air volume requirements of large space ventilation, industrial refrigeration, and other scenarios) through the larger impeller diameter, and an improved impeller pressurization capability by taking advantage of the structural characteristics of a medium-high hub ratio.

[0032] It should be added that the impeller diameter refers to the diameter of the circular trajectory formed by the outermost edge of the blades when the impeller rotates, and the hub ratio is equal to the ratio of the hub diameter to the impeller diameter. The above terms are technical terms in this field and will not be explained in further detail here.

[0033] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An axial flow fan, comprising a hub (1) and a plurality of blades (2) arranged circumferentially at one end of the hub (1), characterized in that: The number of blades (2) is multiple, and the multiple blades (2) are composed of two groups of sub-blades that are centrally symmetrical; The interval angle between the blades (2) in each sub-blade group is different. Along the same rotation direction, the interval angle between two adjacent blades (2) in the same sub-blade group first increases and then decreases until the interval angle between the two blades (2) at the end of the rotation increases again.

2. An axial flow fan according to claim 1, characterized in that: The angle between the two blades (2) at the end of the rotation is greater than the angle between the two blades (2) at the beginning of the rotation.

3. An axial flow fan according to claim 1, characterized in that: No two interval angle values ​​within each of the aforementioned sub-blade groups are equal.

4. An axial flow fan according to claim 1, characterized in that: The number of blades (2) is 22, and the 22 blades (2) are synchronously divided into two groups of 11 intervals.

5. An axial flow fan according to claim 4, characterized in that: The minimum interval angle between two adjacent blades (2) is greater than or equal to 14 degrees.

6. An axial flow fan according to claim 4, characterized in that: Along the same rotation direction, the angular intervals within each of the sub-blade groups are 14.86 degrees, 16.19 degrees, 17.31 degrees, 18.03 degrees, 18.34 degrees, 17.93 degrees, 17.01 degrees, 15.78 degrees, 14.65 degrees, 14.34 degrees, and 15.56 degrees, respectively.

7. An axial flow fan according to claim 1, characterized in that: The impeller has a hub ratio of 0.708 and an impeller diameter of 1050 mm.

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