Noise reduction cross-flow fan based on unequally-spaced inclined blade distribution

Abstract

The noise reduction cross-flow fan comprises a plurality of blades which are distributed in the circumferential direction at unequal intervals, and the blade stacking line of the blades and the axial direction of an impeller are obliquely arranged, so that an included angle is formed between the blade stacking line and the rotating axis direction of the fan. According to the noise reduction cross-flow fan, the cross-flow fan bodies which are distributed in the non-equidistant circumferential direction are utilized, so that the periodic time intervals of flapping airflow of the blades are unequal, noise superposition generated by resonance of the blades and surrounding air is improved, and the problem that the resonance peak value is too high is avoided; besides, the blades which are axially and obliquely arranged are utilized, so that the airflow flows through the blades more smoothly when the fan rotates, the airflow can be distributed more uniformly on the surfaces of the blades, local high-pressure and low-pressure areas are reduced, and vortex and noise of the airflow are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of crossflow fan blade optimization, in particular to a noise-reducing crossflow fan based on the distribution of unequally spaced oblique blades. Background Art

[0002] Crossflow fans are commonly used in household air conditioners. Their characteristics are that the air volume is very uniform and stable. However, there is still a lack of research on noise reduction of crossflow fan blades.

[0003] The traditional crossflow fan blades are arranged in an equidistant and vertical manner. This method has two unreasonable aspects: first, the traditional method arranges the blades in an equidistant manner, which makes the blades hit the airflow at equal intervals, resulting in resonance, which greatly increases the noise problem of the crossflow fan. Second, the traditional method arranges the blades in a vertical manner, which makes the airflow unevenly distributed on the blade surface, resulting in several high-pressure and low-pressure areas locally, which significantly increases the noise of the crossflow fan.

[0004] The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0005] In view of the shortcomings or defects of the above-mentioned prior art, a noise-reducing crossflow fan based on unequally spaced oblique blade distribution is provided. The crossflow fan with unequally spaced circumferential distribution is used to make the periodic time intervals of the blades hitting the airflow unequal, thereby improving the superposition of noise generated by the resonance of the blades with the surrounding air and avoiding the problem of excessively high resonance peak values. In addition, the axially inclined blades are used to make the airflow flow through the blades smoother when the fan rotates, and the airflow can be distributed more evenly on the blade surface, reducing local high-pressure and low-pressure areas, thereby reducing the vortex and noise of the airflow.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A noise-reducing crossflow fan based on unequally spaced oblique blade distribution comprises a plurality of blades unequally spaced along the circumferential direction, wherein the blade stacking line of the blades is arranged obliquely to the impeller axial direction so that the blade stacking line forms an angle with the direction of the fan rotation axis.

[0008] In the noise-reducing crossflow fan based on the unequally spaced oblique blade distribution, the angular spacings between the blades and adjacent blades are all different.

[0009] In the noise reduction crossflow fan based on the unequally spaced oblique blade distribution, the minimum angular spacing θ between the multiple blades is min is 5°.

[0010] In the noise reduction crossflow fan based on the unequally spaced oblique blade distribution, the blades meet the following requirements: ;in, is the angular distance between the mth blade and the first blade, and z is the number of blades.

[0011] In the noise-reducing crossflow fan based on the distribution of unequally spaced oblique blades, the angle is 5°.

[0012] In the noise-reducing crossflow fan based on the distribution of unequally spaced oblique blades, the blades are arranged in groups of two, and the angular spacing between two blades in a group is smaller than the angular spacing between two adjacent blades between groups.

[0013] In the noise-reducing crossflow fan based on unequally spaced oblique blade distribution, the total number of blades is 36, and the blades are divided into 18 groups of two, with an angular spacing of 20° between two adjacent groups and an angular spacing of 5° between two blades in a group.

[0014] In the noise reduction crossflow fan based on the unequally spaced oblique blade distribution, the noise source is arranged 1 m horizontally and 0.8 m vertically downward from the rotation origin of the noise reduction crossflow fan.

[0015] In the noise-reducing crossflow fan based on unequally spaced oblique blade distribution, Fourier transform is used to convert the normal fan pressure pulsation results to obtain the sound pressure level-frequency comparison of the noise-reducing crossflow fan based on unequally spaced oblique blade distribution to optimize the angular spacing between the blades.

[0016] In the noise reduction crossflow fan based on the distribution of unequally spaced oblique blades, the blades of the noise reduction crossflow fan based on the distribution of unequally spaced oblique blades form a centrally symmetrical structure.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention utilizes a cross-flow fan with unequal circumferential distribution to make the periodic time intervals of the airflow flapping by each blade unequal, thereby improving the superposition of noise caused by the resonance of the blade and the surrounding air and avoiding the problem of excessively high resonance peak value; the blades are arranged axially tilted to make the airflow flow through the blades smoother when the fan rotates, and the airflow can be distributed more evenly on the blade surface, reducing local high-pressure and low-pressure areas, thereby reducing the vortex and noise of the airflow. Under the same working conditions, the flow coefficient of the tilted unequally spaced blades is increased by 16% compared with traditional blades, the average sound pressure level is reduced by 9.87%, and the fan efficiency is increased by 26.75%.

[0019] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to achieve the extent that those skilled in the art can implement it according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0021] In the attached picture:

[0022] Figure 1 It is a schematic diagram of the unequally spaced distribution of leaves;

[0023] Figure 2 It is a schematic diagram of the oblique position of the blade;

[0024] Figure 3 This is a schematic diagram comparing the flow coefficients of different structures;

[0025] Figure 4 This is a schematic diagram comparing the sound pressure levels of different structures;

[0026] Figure 5 This is a schematic diagram comparing the efficiency of fans with different structures;

[0027] Figure 6 It is a schematic diagram of the optimization percentage of each structural performance indicator.

[0028] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0030] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0031] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0032] For a better understanding, Figures 1 to 6 As shown, a noise-reducing crossflow fan based on unequally spaced oblique blade distribution includes a plurality of blades unequally spaced along the circumferential direction, wherein the blade stacking line of the blades is arranged obliquely to the impeller axis so that the blade stacking line forms an angle with the direction of the fan rotation axis.

[0033] In a preferred embodiment of the noise-reducing crossflow fan based on the distribution of unequally spaced oblique blades, the angular spacing between the blades and adjacent blades is different.

[0034] In the preferred embodiment of the noise-reducing crossflow fan based on the unequally spaced oblique blade distribution, the minimum angular spacing θ between the multiple blades is min is 5°.

[0035] In a preferred embodiment of the noise reduction crossflow fan based on the unequally spaced oblique blade distribution, the blades meet the following requirements: ;in, is the angular distance between the mth blade and the first blade, and z is the number of blades.

[0036] In a preferred embodiment of the noise reducing crossflow fan based on the unequally spaced oblique blade distribution, the angle is 5°.

[0037] In a preferred embodiment of the noise-reducing crossflow fan based on the distribution of unequally spaced oblique blades, the blades are arranged in groups of two, and the angular spacing between two blades in a group is smaller than the angular spacing between two adjacent blades between groups.

[0038] In the preferred embodiment of the noise-reducing crossflow fan based on unequally spaced oblique blade distribution, the total number of blades is 36, and the blades are divided into 18 groups of two, with an angular spacing of 20° between two adjacent groups and an angular spacing of 5° between two blades in a group.

[0039] In the preferred embodiment of the noise reduction crossflow fan based on the unequally spaced oblique blade distribution, the noise source is arranged 1 m horizontally and 0.8 m vertically downward from the rotation origin of the noise reduction crossflow fan.

[0040] In the preferred embodiment of the noise reduction crossflow fan based on unequally spaced oblique blade distribution, Fourier transform is used to convert the normal fan pressure pulsation results to obtain the sound pressure level-frequency comparison of the noise reduction crossflow fan based on unequally spaced oblique blade distribution to optimize the angular spacing between the blades.

[0041] In a preferred embodiment of the noise reduction crossflow fan based on the distribution of unequally spaced oblique blades, the blades of the noise reduction crossflow fan based on the distribution of unequally spaced oblique blades form a centrally symmetrical structure.

[0042] In one embodiment, Figure 1 As shown, the noise reduction crossflow fan based on the unequally spaced oblique blade distribution includes blades distributed unequally along the circumference, and the blade stacking line is arranged obliquely with respect to the impeller axis; wherein, the angular spacing between the first blade 1 and the third blade 3 is θ1, and the angle between the first blade 1 and the adjacent second blade 2 is the minimum angular spacing θ2, so as to set a plurality of unequally spaced circumferentially distributed blades, and the blade oblique arrangement means that the blade stacking line has an angle with the direction of the fan rotation axis. Furthermore, the angular spacing θ2 between the first blade 1 and the second blade 2 is 5°, and the angular spacing θ1 between the first blade 1 and the sixteenth blade 3 is 20°.

[0043] In one embodiment, the blades satisfy the rotor automatic balancing theory: ;in, is the angular distance between the mth blade and the first blade, wherein one blade is set as the reference blade and is recorded as the third blade 3, then ; z is the number of impeller blades. Inclined blades refer to blades with an angle θ3=5° between the centerline of the leading edge and the center axis of the impeller.

[0044] In one embodiment, the total number of blades is 36, so the blades are divided into groups of two, a total of 18 groups, and the spacing between two adjacent groups is 20°, which is equivalent to an 18-blade impeller with an angular spacing of 20°. The angular spacing between the blades has a minimum value θ min =θ2=5° is called the minimum angular spacing. The method for measuring airflow noise uses Fourier transform (FFT) to convert the results of the pressure pulsation of the straight-state fan to obtain the sound pressure level-frequency comparison of the equidistant fan, the unequally spaced fan, and the unequally spaced helical fan. The design of the noise-reducing crossflow fan takes into account the air conditioner's own flow channel, the volute tongue and the volute.

[0045] In one embodiment, if Figure 2As shown in the figure, the unequally spaced blades are tilted so that the blade stacking line 5 and the fan rotation axis 4 are 5°, and a three-dimensional model of the flow field for aerodynamic noise analysis of unequally spaced tilted fans is established. The fan is placed in the air conditioning internal flow field for overall flow noise simulation. Figure 3 As shown in the figure, by comparing the flow coefficients of the three fans with different structures, it can be seen that the flow coefficient of the inclined unequally spaced blades is the largest, the inclined blades are the second, and the flow coefficient of the traditional blades is the smallest. This proves that the cross-flow fan designed with inclined unequally spaced blades can significantly improve the flow conditions of the flow field in the heat exchanger, which will further improve the flow and heat transfer conditions of the heat exchanger driven by the airflow.

[0046] In one embodiment, if Figure 4 As shown in the figure, by comparing the noise spectra of different fan structures, it can be seen that: the sound pressure level of traditional blades is the largest, and most of them have discrete characteristics, which can be verified by the flow coefficient. The airflow difference then hits the blades to produce discrete noise; on the other hand, the sound pressure level of inclined unequally spaced blades is the smallest, and the noise level is lower than that of traditional fans at most frequency points, especially in the low-frequency area, where the improvement is particularly significant.

[0047] In one embodiment, if Figure 5 As shown in the figure, by comparing the fan efficiency of different fan structures, it can be seen that the overall performance of the inclined unequal-pitch blade structure is better than the other two blade structures, indicating that the combined design of inclined and unequal-pitch blades helps to reduce the separation of airflow on the blade surface, which helps to reduce the generation of vortices and turbulence, thereby reducing energy losses and improving the overall efficiency of the fan.

[0048] In one embodiment, if Figure 6 As shown in the figure, taking the performance indicators of traditional blades as the standard, the flow coefficient of inclined unequal-pitch blades is improved by 16% compared with traditional blades, and the inclined blades are improved by 1.87% compared with traditional blades; the average sound pressure level of inclined unequal-pitch blades is reduced by 9.87% compared with traditional blades, and the inclined blades are reduced by 1.14% compared with traditional blades; the fan efficiency of inclined unequal-pitch blades is improved by 26.75% compared with traditional blades, and the inclined blades are improved by 2.136% compared with traditional blades; this shows that by simultaneously changing the inclination angle and spacing of the blades, the airflow angle entering and leaving the blades can be more effectively controlled, making the airflow between the blades smoother, reducing resistance and noise, and at the same time improving the pressure recovery capacity, significantly improving the performance of the equipment; it shows that the design structure can effectively drive the heat exchange of the heat exchanger to improve the heat exchange performance of the air conditioner.

[0049] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0050] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A noise-reducing crossflow fan based on unequally spaced oblique blade distribution, characterized in that: It comprises a plurality of blades which are unequally distributed along the circumferential direction, wherein the blade stacking line of the blades is arranged obliquely to the impeller axial direction so that the blade stacking line forms an angle with the direction of the fan rotation axis.

2. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: The angular spacings between the blades and adjacent blades are all different.

3. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: Minimum angular spacing θ between multiple blades min is 5°.

4. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: The blades satisfy: ;in, is the angular distance between the mth blade and the first blade, and z is the number of blades.

5. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: The angle is 5°.

6. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: The blades are arranged in groups of two, and the angular spacing between two blades in a group is smaller than the angular spacing between two adjacent blades in the group.

7. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: The total number of blades is 36, and the blades are divided into 18 groups of two each, with an angular spacing of 20° between two adjacent groups and an angular spacing of 5° between two blades in a group.

8. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: The noise source is arranged 1m horizontally and 0.8m vertically downward from the rotation origin of the noise reduction crossflow fan.

9. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 8, characterized in that: Fourier transform is used to convert the pressure pulsation results of the normal fan to obtain the sound pressure level-frequency comparison of the noise-reducing crossflow fan based on the unequally spaced oblique blade distribution to optimize the angular spacing between the blades.

10. The noise-reducing crossflow fan based on unequally spaced oblique blade distribution according to claim 1, characterized in that: The blades of the noise-reducing crossflow fan based on the unequally spaced oblique blade distribution form a centrally symmetrical structure.

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