Low-noise impeller applied to multi-wing centrifugal fan

Abstract

The invention discloses a low-noise impeller applied to a multi-wing centrifugal fan, and belongs to the technical field of machinery. According to the multi-blade centrifugal fan, the shape of the fan blade is changed, so that the symmetry of airflow in the blade flow channel outlet in the circumferential direction is changed, the periodicity of the impact strength of the airflow on the volute tongue at the impeller flow channel outlet is changed, and therefore the rotation noise of the multi-blade centrifugal fan is lowered, and the noise of the multi-blade centrifugal fan is lowered. The low-noise impeller is composed of a hub, a front disc and blades. Blades installed in the circumferential direction of an impeller hub are distributed in a circumferential mode, the blades are distinguished according to the sizes and the shapes of the adjacent blades, the blades are divided into a plurality of periods in the circumferential direction, the sizes of the blades in each period are different, but the sizes and the shapes of the blades in the adjacent periods are the same. Through the design of the asymmetric blade shape, under the condition that the performance of the fan is not greatly influenced, the aerodynamic noise of the multi-blade centrifugal fan is reduced, and machining is easy.

Description

Technical Field

[0001] The present invention relates to a low-noise impeller applied to a multi-wing centrifugal fan, belonging to the field of mechanical technology. Background Art

[0002] With the improvement of industrialization level, noise pollution has become an important environmental problem faced by mankind. Noise not only affects people's normal rest, study and work, but also can seriously endanger human health and induce various diseases. Noise can cause hearing damage to people, affect people's nervous system, and can affect the intellectual development of children.

[0003] As a general-purpose machine, the fan is mainly used in the ventilation of mines and underground projects, the ventilation and induced draft of boilers, the exhaust of high-temperature corrosive gases in chemical plants, the ventilation of air conditioners and protective equipment, etc. The multi-wing centrifugal fan is a kind of centrifugal ventilator. The main characteristics of the impeller of this kind of fan are the use of forward blades with a large diameter ratio and a large relative width, and a large number of blades. The multi-wing centrifugal fan has the characteristics of large flow coefficient, high pressure coefficient, low noise, small size, etc., and is widely used in range hoods, air conditioners, etc. With the rapid development of the domestic household appliance industry, higher and higher requirements are put forward for the miniaturization, low noise and high efficiency of the fan. With the increasing improvement of people's living standards, the requirements for the quality of household appliances, including the two indicators of functional performance and noise, are also getting higher and higher. The multi-wing centrifugal ventilator is the key factor affecting the sound quality of household appliances such as dryers and air conditioners. The quality of its performance will inevitably have a significant impact on the overall quality of household appliance products.

[0004] The main part of the fan noise is the aerodynamic noise, and the aerodynamic noise is mainly composed of two parts: rotational noise and turbulent noise. Rotational noise is a discrete noise, and its frequency is the blade passing frequency and its harmonics. Turbulent noise is a broadband noise, and its spectrum is a broadband continuous spectrum. Generally speaking, the discrete noise exceeds the continuous part by 5-10 dB, especially for the case of small volute tongue clearance and high rotational speed. Therefore, the rotational noise accounts for the main component in the fan noise. The root cause of the rotational noise is mainly that there is a wake at the impeller outlet, and the velocity and pressure distribution of the air flow are uneven. This uneven air flow acts on the volute tongue, forming a pulsating force that changes with time, resulting in the generation of rotational noise. In the past, the low-noise design of multi-wing centrifugal fans mostly brought great losses to the performance of the fans, and at the same time brought difficulties to the processing of the impeller structure. Summary of the Invention

[0005] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, providing a low-noise impeller applied to a multi-wing centrifugal fan, and reducing the aerodynamic noise of the multi-wing centrifugal fan through the circumferential distribution design of asymmetric blades with little influence on the performance of the fan.

[0006] The technical solution of the present invention is: a low-noise impeller applied to a multi-wing centrifugal fan, comprising:

[0007] a hub with a through hole at the center for fixedly installing the impeller;

[0008] a front disc coaxially arranged with the hub;

[0009] a plurality of blades evenly distributed circumferentially between the hub and the front disc; the plurality of blades are divided into a plurality of identical distributed periodic arc segments along the circumferential direction of the hub, and one blade at the joint is shared by adjacent periodic arc segments, and the radial lengths of the blades within each periodic arc segment are first from large to small and then from small to large.

[0010] Further, the arc length of the outlet section of the blades within each periodic arc segment is first from large to small and then from small to large.

[0011] Further, within one periodic radian, the arc lengths of the outlet sections of the blades at both ends are the same.

[0012] Further, within one periodic arc segment, the maximum difference in the arc length of the blades is between 0 and 0.3L, where L is the longest arc length of the blades.

[0013] Further, L = 2*Pi*R*θ 1 / 360, where Pi is the constant of pi, R is the radius of the arc, and θ 1 is the arc angle where the arc is located.

[0014] Further, by changing the arc length of the outlet section of the blades, the circumferential asymmetry of the blade shape is realized, and further the difference in the outlet flow field parameters between the outlets of each blade flow passage within a single period is realized.

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

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

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

[0018] The advantages of the present invention compared with the prior art are as follows:

[0019] (1) The low-noise impeller involved in the present invention mainly includes three parts: a hub, a front disc and blades, and the impeller is installed in the volute of the centrifugal fan. During processing, in order to ensure the installation strength of the blades and the reliability of the impeller, the three can be processed in an integral manner or in an assembled manner, which has the advantage of processing universality;

[0020] (2) In the blade processing of the present invention, the blade material can include metals or other non-metallic materials, featuring material universality.

[0021] (3) The circumferential asymmetry of the flow field in the present invention is achieved by changing the profile size at the blade outlet, which changes the outlet angle and shape of the blade, and further realizes the asymmetry of the blade within a single cycle. This flow field change caused by the local structure change of the blade has low requirements for blade installation or processing accuracy, and features simple processing and convenient assembly.

[0022] (4) In the present invention, the blade has no influence on the blade inlet flow passage and the circumferential installation angle, so the circumferential distribution of the circumferential installation angle of the blade is evenly distributed. The hub and the front disc of the impeller have good versatility, featuring simple processing and low cost.

[0023] (5) The circumferential distribution of the blade shape on the hub in the present invention shows periodicity. Since the blade shapes and distributions in different cycles are the same, it ensures the dynamic balance of the impeller during high-speed rotation.

[0024] (6) The low-noise impeller structure involved in the present invention is simple in structure, convenient to process, and has low aerodynamic loss. It can reduce the aerodynamic noise of the multi-wing centrifugal fan and improve the sound quality with little impact on the fan performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered as limiting the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0026] Figure 1 is a schematic structural diagram of the asymmetric low-noise fan impeller according to the present invention;

[0027] Figure 2 is a schematic assembly diagram of the asymmetric low-noise fan impeller and the centrifugal fan structure according to the present invention

[0028] Figure 3 is a schematic structural diagram of the asymmetric low-noise fan impeller centrifugal fan structure according to the present invention;

[0029] Figure 4 is a schematic diagram of the asymmetric distribution of the blades within a single cycle of the low-noise impeller according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[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. Without conflict, the technical features in the embodiments of the present invention and the embodiments can be combined with each other.

[0031] The following further details an impeller with low noise applied to a multi-wing centrifugal fan provided by an embodiment of the present invention with reference to the accompanying drawings of the specification. The specific implementation manner may include: a hub 1 with a through hole for fixedly installing the impeller at the center; a front disc 2 arranged coaxially with the hub; a plurality of blades 3 evenly distributed circumferentially between the hub and the front disc; the plurality of blades are divided into a plurality of identical distributed periodic arc segments along the circumferential direction of the hub, and one blade at the connection is shared by adjacent periodic arc segments. The radial lengths of the blades within each periodic arc segment are first distributed from large to small and then from small to large.

[0032] The arc length of the outlet section of the blades within each periodic arc segment is first distributed from large to small and then from small to large.

[0033] Within a periodic radian, the arc lengths of the outlet sections of the blades at both ends are the same.

[0034] The inlet angles and shapes of all the blades of the impeller are the same. Mainly by changing the size of the profile line at the blade outlet, the outlet angles and shapes of the blades are changed, thereby realizing the asymmetry of the blades within a single period; the shape and size of the blades within each period decrease from the initial maximum value to the minimum value and then increase to the maximum value, thereby realizing the gradual change of the blades within a single period, and further achieving the asymmetry in the circumferential direction; the shapes and sizes of the adjacent blades 3 in adjacent periods are the same, avoiding the aerodynamic and vibration problems caused by too large a difference in the shapes of adjacent blades; for the blades within a period, the maximum difference in the arc lengths of different blades is between 0 and 0.3L, where L is the maximum blade arc length. The difference in the arc lengths of adjacent blades and the maximum difference present a sine or cosine relationship.

[0035] In the solution provided by the embodiments of the present invention, by changing the size of the blade outlet arc line evenly distributed circumferentially on the fan impeller, the purpose of changing the outlet angle and shape of the blade is achieved, thereby realizing the symmetry of the circumferential distribution of the air flow at the outlet of the blade passage, changing the periodicity of the impact of the blade outlet air flow on the volute tongue 6 of the fan, and thus reducing the rotational noise of the centrifugal fan. The low-noise impeller 4 is characterized by blades 3 evenly distributed circumferentially along the hub 1, which are divided into multiple periods according to different blade shapes, realizing the asymmetry of the blade shape along the circumferential direction of the hub 1 within a single period, as well as the asymmetry of the entire circumferential direction of the hub 1; the size of the blade shape within each period decreases from the initial maximum value to the minimum value, and then increases to the maximum value, thereby realizing the gradual change of the blade within a single period, and further achieving the circumferential asymmetry of the blade shape within a single period; the shapes and sizes of adjacent blades 3 in adjacent periods are the same, avoiding the aerodynamic and vibration problems caused by too large a difference in the shapes of adjacent blades; within a period of blades, the maximum difference in the arc lengths of different blades is between 0 and 0.3L, where L is the maximum blade arc length. The difference in the arc lengths of adjacent blades and the maximum difference show a sine or cosine relationship.

[0036] The working principle is as follows:

[0037] A low-noise impeller applied to a multi-wing centrifugal fan of the present invention mainly includes a hub 1, a front disc 2, and blades 3; through the circumferential distribution design of the asymmetric blades 3, without much impact on the fan performance, the aerodynamic noise of the multi-wing centrifugal fan is reduced, and it has the characteristics of simple processing, good material universality, and convenient assembly, as Figures 1 to 3 shown;

[0038] By changing the size of the blade outlet arc line evenly distributed circumferentially on the fan impeller, the purpose of changing the outlet angle and shape of the blade is achieved, as Figure 4 shown.

[0039] In order to realize the circumferential distribution design of the asymmetric blades 3, the blades are equally divided into m periodic arc segments along the circumferential direction of the hub 1 according to different blade shapes. The length of the outlet arc line of the blade profile within each periodic arc segment is different, and the circumferential angle corresponding to each periodic arc segment is θ, as Figure 4 shown.

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

[0041] The shape and size of the blades within each period are different, showing a decrease from the maximum value on both sides to the minimum value in the middle, and then increasing to the maximum value, thereby realizing the gradual change of the blade within a single period,

[0042] The gradual change of the blade within a single cycle achieves the circumferential asymmetry of the blade shape within a single cycle and the circumferential asymmetry throughout the entire hub 1;

[0043] The shapes and sizes of adjacent blades 3 in adjacent cycles are the same, avoiding the aerodynamic and vibration problems caused by too large a difference in the shapes of adjacent blades;

[0044] For the blades within one cycle, the maximum difference in the arc lengths of different blades ranges from 0 to 0.3L, where L is the maximum blade arc length. The difference in the arc lengths of adjacent blades and the maximum difference exhibit a sine or cosine relationship.

[0045] In the present invention, the blades have no influence on the blade inlet flow passage and the circumferential installation angle, so the circumferential installation angle of the blades is evenly distributed circumferentially. The hub and the front disc of the impeller have good versatility and are characterized by simple processing and low cost;

[0046] For the processing of the blades in the present invention, the materials of the blades can include metals or other non-metallic materials, which is characterized by the universality of materials.

[0047] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

[0048] The content not detailedly described in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A low-noise impeller for a multi-blade centrifugal fan, characterized in that: include: A hub, the center of which is provided with a through hole for fixing and installing the impeller; a front disc, arranged coaxially with the wheel hub; A plurality of blades are evenly distributed between the hub and the front disk along the circumferential direction; the plurality of blades are divided into a plurality of equally distributed periodic arc segments along the circumferential direction of the hub, adjacent periodic arc segments share a blade at a connection point, and the radial length of the blades in each periodic arc segment is distributed first from large to small and then from small to large.

2. A low-noise impeller for a multi-blade centrifugal fan according to claim 1, characterized in that: The arc lengths of the outlet sections of the blades in each periodic arc section are distributed first from large to small and then from small to large.

3. A low-noise impeller for a multi-blade centrifugal fan according to claim 2, characterized in that: In one arc cycle, the arc lengths of the outlet sections of the blades at both ends are the same.

4. The low-noise impeller for a multi-blade centrifugal fan according to claim 2, characterized in that: In one cycle segment, the maximum difference of the blade arc length is between 0 and 0.3L, where L is the longest arc length of the blade.

5. The low-noise impeller for a multi-blade centrifugal fan according to claim 2, characterized in that: L=2*Pi*R*θ1 / 360, wherein Pi is the pi constant, R is the radius of the arc, and θ1 is the arc angle of the arc.

6. The low-noise impeller for a multi-blade centrifugal fan according to claim 2, characterized in that: The circumferential asymmetry of the blade shape is achieved by changing the arc length of the blade outlet section, thereby achieving the difference in outlet flow field parameters between each blade flow channel outlet within a single cycle.

7. The low-noise impeller for a multi-blade centrifugal fan according to claim 1, characterized in that: Within one arc cycle, the radial lengths of the blades at both ends are the same.

8. The low-noise impeller for a multi-blade centrifugal fan according to claim 1, characterized in that: The number of blades in each cycle arc segment is an odd number greater than 4.

9. The low-noise impeller for a multi-blade centrifugal fan according to claim 1, characterized in that: The number of periodic arc segments is not less than 3 and not more than 8.

Images