Low noise impeller applied to multi-blade centrifugal fan

Abstract

The application relates to a low-noise impeller applied to a multi-wing centrifugal fan and belonging to the mechanical technical field. The symmetry of the circumferential distribution of airflow at the outlet of the blade flow channel is changed by changing the shape of the fan blade, the periodicity of the impact strength of airflow on the volute tongue at the outlet of the impeller flow channel is changed, the rotating noise of the multi-wing centrifugal fan is reduced, and the noise of the multi-wing centrifugal fan is reduced. The low-noise impeller is composed of a hub, a front disc and blades. The blades installed in the circumferential direction of the impeller hub are distributed in a circle, are distinguished according to the size and shape of the adjacent blades, the blades are divided into multiple periods along the circumferential direction, the sizes of the blades in each period are different, but the sizes and shapes of the blades in the adjacent periods are the same. The aerodynamic noise of the multi-wing centrifugal fan is reduced by the design of the asymmetric blade shape without affecting the performance of the fan, and the processing is simple.

Description

Technical Field

[0001] This invention relates to a low-noise impeller for use in multi-blade centrifugal fans, belonging to the field of mechanical technology. Background Technology

[0002] With the increasing level of industrialization, noise pollution has become a significant environmental problem facing humanity.

[0003] As a general-purpose machine, fans are mainly used for ventilation in mines and underground engineering projects, boiler ventilation and induced draft, exhaust of high-temperature corrosive gases in chemical plants, and ventilation in air conditioning and protective equipment. Multi-blade centrifugal fans are a type of centrifugal fan. The main characteristics of this type of fan impeller are the use of forward-curved blades with a large diameter-to-width ratio and a large relative width, and a large number of blades. Multi-blade centrifugal fans have advantages such as high flow coefficient, high pressure coefficient, low noise, and small size, and are widely used in range hoods, air conditioners, etc. With the rapid development of the domestic home appliance industry, increasingly higher demands are being placed on the miniaturization, low noise, and high efficiency of fans. As people's living standards continue to improve, the requirements for the quality of home appliances, including both functional performance and noise levels, are also increasing. Multi-blade centrifugal fans are a key factor affecting the noise quality of home appliances such as dryers and air conditioners; their performance inevitably has a significant impact on the overall quality of these products.

[0004] Aerodynamic noise is the dominant component of fan noise, primarily composed of rotational noise and turbulent noise. Rotational noise is a discrete noise, with its frequency being the blade passage frequency and its harmonics, while turbulent noise is a broadband noise with a wide continuous spectrum. Generally, discrete noise exceeds the continuous portion by 5-10 dB, especially with small volute clearances and high speeds. Therefore, rotational noise constitutes the most significant component of fan noise. The root cause of rotational noise lies in the presence of a wake at the impeller outlet, resulting in uneven distribution of airflow velocity and pressure. This uneven airflow acts on the volute, creating pulsating forces that vary over time, leading to rotational noise. Previous low-noise designs for multi-blade centrifugal fans often resulted in significant performance losses and increased difficulties in impeller manufacturing. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a low-noise impeller for multi-blade centrifugal fans. Through the circumferential distribution design of asymmetrical blades, the aerodynamic noise of multi-blade centrifugal fans is reduced without significantly affecting the performance of the fans.

[0006] The technical solution of this invention is: a low-noise impeller for multi-blade centrifugal fans, comprising:

[0007] The hub has a through hole in the center for fixing and mounting the impeller;

[0008] The front disc is arranged coaxially with the wheel hub;

[0009] Multiple blades are evenly distributed circumferentially between the hub and the front disc. The multiple blades are divided into multiple equally distributed periodic arc segments along the circumferential direction of the hub. Adjacent periodic arc segments share a blade at the connection point. The radial length of the blades in each periodic arc segment is distributed from large to small and then from small to large.

[0010] Furthermore, the length of the exit segment arc of the blade within each periodic arc segment is distributed from large to small and then from small to large.

[0011] Furthermore, within one cycle arc, the exit section arc lengths of the blades at both ends are the same.

[0012] Furthermore, within one periodic arc segment, the maximum difference in blade arc length ranges from 0 to 0.3. L ,in, L This is the longest arc length of the blade.

[0013] Furthermore, ,in, Pi is a constant. The radius of the arc. It represents the angle of the arc containing the circular arc.

[0014] Furthermore, by changing the arc length of the blade exit section, the circumferential asymmetry of the blade shape is achieved, thereby enabling different exit flow field parameters between the exit channels of each blade within a single cycle.

[0015] Furthermore, within one periodic arc, the radial lengths of the blades at both ends are the same.

[0016] Furthermore, the number of blades within each periodic arc segment is an odd number greater than 4.

[0017] Furthermore, the number of periodic arc segments is not less than 3 and not greater than 8.

[0018] The advantages of this invention compared to the prior art are:

[0019] (1) The low-noise impeller involved in this invention mainly includes three parts: hub, front plate and blades, wherein the impeller is installed in the volute of the centrifugal fan. In order to ensure the installation strength of the blades and the reliability of the impeller during processing, the three parts can be processed as a whole or assembled, which has the advantage of universal processing.

[0020] (2) In the blade processing of this invention, the blade material may include metal or other non-metal materials, and has the characteristic of material universality;

[0021] (3) The circumferential asymmetry of the flow field in this invention is achieved by changing the size of the blade exit profile, thereby changing the exit angle and shape of the blade, and thus realizing the asymmetry of the blade in a single cycle. This flow field change caused by the change of the local structure of the blade does not require high precision in blade installation or processing, and has the characteristics of simple processing and convenient assembly.

[0022] (4) In this invention, the blades have no effect on the blade inlet flow channel and circumferential installation angle, so the circumferential installation angle of the blades is uniformly distributed. The impeller hub and front plate have good versatility and are characterized by simple processing and low cost.

[0023] (5) The blade shape in this invention is periodically distributed on the hub. Since the blade shape and distribution are the same in different periods, the dynamic balance of the impeller is guaranteed when it rotates at high speed.

[0024] (6) The low-noise impeller of the present invention has a simple structure, is easy to process, and has low aerodynamic loss. It can reduce the aerodynamic noise of multi-blade centrifugal fans and improve the sound quality without having much impact on the performance of the fan. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0026] Figure 1 This is a schematic diagram of the asymmetric low-noise fan impeller structure described in this invention;

[0027] Figure 2 This is a schematic diagram of the asymmetric low-noise fan impeller and centrifugal fan structure assembly described in this invention.

[0028] Figure 3 This is a schematic diagram of the asymmetric low-noise fan impeller centrifugal fan structure described in this invention;

[0029] Figure 4 This is a schematic diagram of the asymmetric blade distribution within a single cycle of the low-noise impeller described in this invention. Detailed Implementation

[0030] To better understand the above technical solutions, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0031] The following description, in conjunction with the accompanying drawings, provides a detailed explanation of a low-noise impeller for a multi-bladed centrifugal fan provided by an embodiment of the present invention. The specific implementation may include: a hub 1 with a through hole at its center for fixing and mounting the impeller; a front disc 2, coaxially arranged with the hub; multiple blades 3, evenly distributed circumferentially between the hub and the front disc; the multiple blades are divided into multiple equally distributed periodic arc segments along the circumference of the hub, with adjacent periodic arc segments sharing a blade at the connection point; the radial length of the blades within each periodic arc segment is distributed from largest to smallest and then from smallest to largest.

[0032] The length of the exit segment arc of the blade within each periodic arc segment is distributed from largest to smallest and then from smallest to largest.

[0033] Within one cycle arc, the exit section arc lengths of the blades at both ends are the same.

[0034] All blades of the impeller have the same inlet angle and shape. The exit angle and shape of the blades are mainly changed by altering the blade profile, thus achieving asymmetry within a single cycle. The blade shape and size decrease from a maximum value to a minimum value within each cycle, and then increase back to a maximum value, achieving a gradual change in blade shape within a single cycle and thus achieving circumferential asymmetry. Adjacent blades in adjacent cycles have the same shape and size, avoiding aerodynamic and vibration problems caused by excessive differences in adjacent blade shapes. Within a single cycle, the maximum difference in the arc length of different blades is between 0 and 0.3L, where L is the maximum blade arc length. The difference in the arc length of adjacent blades exhibits a sine or cosine relationship with the maximum difference.

[0035] In the solution provided by the embodiments of the present invention, the outlet angle and shape of the blades are changed by altering the size of the outlet arc of the blades uniformly distributed circumferentially on the impeller, thereby achieving symmetry in the circumferential distribution of the airflow at the blade channel outlet and changing the periodicity of the impact of the outlet airflow on the volute tongue 6 of the fan, thus reducing the rotational noise of the centrifugal fan. The low-noise impeller 4 is characterized by blades 3 uniformly distributed circumferentially along the hub 1, which are divided into multiple cycles according to different blade shapes, achieving asymmetry in the blade shape along the hub 1 within a single cycle, as well as asymmetry in the entire hub 1 circumferentially; the blade shape size in each cycle decreases from the initial maximum value to the minimum value, and then increases back to the maximum value, thus achieving a gradual change in the blade shape within a single cycle, and achieving circumferential asymmetry in the blade shape within a single cycle; adjacent blades 3 in adjacent cycles have the same shape and size, avoiding aerodynamic and vibration problems caused by excessive differences in the shapes of adjacent blades; within a cycle, the maximum difference in the arc length of different blades is between 0 and 0.3L, where L is the maximum blade arc length. The difference in the arc length of adjacent blades and the maximum difference exhibit a sine or cosine relationship.

[0036] The working principle is as follows:

[0037] This invention discloses a low-noise impeller for a multi-blade centrifugal fan, mainly comprising a hub 1, a front disc 2, and blades 3. Through the circumferential distribution design of the asymmetric blades 3, the aerodynamic noise of the multi-blade centrifugal fan is reduced with minimal impact on fan performance. It also features simple processing, good material versatility, and convenient assembly. Figures 1-3 As shown;

[0038] The outlet angle and shape of the blades can be changed by altering the size of the outlet arc of the circumferentially distributed blades of the wind turbine impeller. Figure 4 As shown.

[0039] To achieve the circumferential distribution design of the asymmetric blades 3, the blades are divided into m equal periodic arc segments along the circumference of the hub 1 according to their different shapes. The length of the exit arc of the blade profile is different in each periodic arc segment, and the circumferential angle corresponding to each periodic arc segment is... ,like Figure 4 As shown.

[0040] Along the circumferential direction of hub 1, the number of blades in each arc segment is an odd number greater than 4, and the number of equally divided periodic arc segments m is an integer, and 3≤m≤8.

[0041] The shape and size of the leaves vary within each cycle, decreasing from the maximum value at both ends to the minimum value in the middle, and then increasing back to the maximum value, thus achieving a gradual change in the leaf shape within a single cycle.

[0042] The gradual change of the blade within a single cycle achieves circumferential asymmetry of the blade shape within a single cycle, as well as circumferential asymmetry throughout the entire hub.

[0043] The shape and size of adjacent blades 3 in adjacent cycles are the same, which avoids aerodynamic and vibration problems caused by excessive differences in the shape of adjacent blades;

[0044] Within a single cycle, the maximum difference in the arc length of different blades ranges from 0 to 0.3L, where L is the maximum arc length of the blade. The difference in arc length between adjacent blades exhibits a sine or cosine relationship with the maximum difference.

[0045] In this invention, the blades have no effect on the blade inlet flow channel and circumferential installation angle, so the circumferential installation angle of the blades is uniformly distributed. The impeller hub and front disc have good versatility and are characterized by simple processing and low cost.

[0046] The blade processing in this invention can use metal or other non-metallic materials, which has the characteristic of material universality.

[0047] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0048] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A low noise impeller for use in a multi-bladed centrifugal fan, characterized by, The impeller comprises: a hub with a through hole in the center for fixing and mounting an impeller; a front disc coaxially arranged with the hub; a plurality of blades evenly distributed between the hub and the front disc; the plurality of blades are divided into a plurality of periodically-arranged arc segments with the same distribution along the circumference of the hub, adjacent periodically-arranged arc segments share one blade at the connecting position, the radial length of the blades in each periodically-arranged arc segment is first distributed from large to small and then from small to large; the difference between the arc length of adjacent blades and the maximum difference presents a sine or cosine relationship; the arc length of the outlet section of the blades in each periodically-arranged arc segment is first distributed from large to small and then from small to large.

2. A low noise impeller for use in a multi-bladed centrifugal fan according to claim 1, wherein In one periodically-arranged arc, the arc length of the outlet section of the blades at both ends is the same.

3. A low noise impeller for use in a multi-bladed centrifugal fan according to claim 1, wherein The maximum difference of the blade arc length in one cycle arc segment is between 0~0.3 L wherein, L is the longest arc length of the blade.

4. A low noise impeller for use in a multi-bladed centrifugal fan according to claim 1, wherein wherein, is the constant of the circle, is the radius of the circle, is the angle of the circle.

5. A low noise impeller for use in a multi-bladed centrifugal fan according to claim 1, wherein The asymmetry of the shape of the blades along the circumference is realized by changing the arc length of the outlet section of the blades, and then the outlet flow field parameters between the outlet sections of each blade in a single period are different.

6. A low noise impeller for use in a multi-bladed centrifugal fan according to claim 1, wherein In one periodically-arranged arc, the radial length of the blades at both ends is the same.

7. A low noise impeller for use in a multi-bladed centrifugal fan according to claim 1, wherein The number of blades in each periodically-arranged arc segment is an odd number greater than 4.

8. A low noise impeller for use in a multi-bladed centrifugal fan according to claim 1, wherein The number of periodically-arranged arc segments is not less than 3 and not more than 8.

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