CN116677653A - Subsonic axial flow fan structure and design method - Google Patents

Subsonic axial flow fan structure and design method Download PDF

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Publication number
CN116677653A
CN116677653A CN202310733710.4A CN202310733710A CN116677653A CN 116677653 A CN116677653 A CN 116677653A CN 202310733710 A CN202310733710 A CN 202310733710A CN 116677653 A CN116677653 A CN 116677653A
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annular
fan
annular plate
liner body
acoustic
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张红亮
欧阳虎平
李劼
廖佳喜
邹忠
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Central South University
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Central South University
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/663—Sound attenuation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/663—Sound attenuation
    • F04D29/665—Sound attenuation by means of resonance chambers or interference
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/10—Noise analysis or noise optimisation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Geometry (AREA)
  • General Physics & Mathematics (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

The application provides a subsonic axial flow fan structure and a design method, the fan structure comprises an acoustic liner body arranged on the periphery of fan blades, the acoustic liner body comprises an annular plate and an annular Helmholtz silencer, an annular cavity is arranged between the annular Helmholtz silencer and the annular plate, the annular cavity and the annular Helmholtz silencer are sequentially connected from inside to outside to form an annular structure. The application adopts the sound liner structure that the microperforated panel is connected in series with a plurality of parallel helmholtz silencers, can convert sound energy into heat energy in the sound propagation process, and realize resonance silencing at the blade passing frequency and the frequency multiplication frequency band of the fan, reduce the sound pressure level of a specific frequency band, improve the problem that the absorption frequency band of the microperforated panel is too narrow, and realize the overall silencing of the fan. The structure has small volume and thin thickness, can not greatly change the original structure of the fan, and has strong adaptability.

Description

Subsonic axial flow fan structure and design method
Technical Field
The application belongs to the field of axial flow fan design, and particularly relates to a subsonic axial flow fan structure and a design method.
Background
With the development of new energy and electronic device industries, heating devices gradually tend to be miniaturized and integrated, and the heating value of the heating devices in the working process is greatly increased. The small axial flow heat radiation fan is a preferred heat radiation device for designers because of the characteristics of large ventilation quantity, small volume, convenient installation, simple operation, low cost and the like. At the same time, noise pollution caused by axial fans is a prominent problem that seriously affects the quality of work and life of people. The generation of fan noise is not only an unenergy dissipation form, but also greatly influences the working performance of the fan and the experience of users on products, and can cause great harm to the working efficiency and the health of people. Therefore, development of fan performance and noise reduction are important issues that must be addressed.
The noise reduction work of the existing subsonic axial flow fan is mainly divided into two aspects: active noise reduction and passive noise reduction. The active noise reduction is realized by optimizing the structure of the fan to reconstruct flow field sound pressure fluctuation of the fan, and mainly comprises the methods of vane airfoil design of the fan, dynamic and static vane design of the fan, front and rear edge design of the fan, bionic vane optimization design and the like; the passive noise reduction is designed mainly from the perspective of cutting off the acoustic wave propagation path of the fan, and mainly comprises the methods of adding an acoustic liner, designing an inlet and outlet short pipeline of the fan and the like.
The active noise reduction modes are various, but the noise reduction effect is not obvious, and the design factors are complex and various, so that the noise reduction effect and the pneumatic performance are difficult to be considered; the passive noise reduction can greatly change the structure of the fan, increase the volume, and is not applicable to the increasingly dense electronic heat dissipation field, and meanwhile, the manufacturing cost of the fan can be increased. Based on the above, all the current main stream noise reduction methods face the problems that the noise reduction potential is limited, the noise reduction frequency band is too narrow, the added additional noise reduction device is too large in volume, and the application scene of the fan is limited.
The application discloses a radiator fan noise reduction device based on acoustic cutoff and a method thereof, and relates to the technical field of fan noise reduction. The application can restrain the axial propagation of the circumferential sound mode of the aerodynamic noise generated by the radiator fan, and can correct the incoming flow deformation of the inlet of the radiator fan when installed at the upstream of the radiator fan, thereby reducing the discrete single-tone noise radiated by the radiator fan. However, the method of cutting off the higher order (the lower order is less likely to be cut off) acoustic modes by short pipes is used in the patent application, the design key is the pipe length, strictly speaking, the noise reduction effect is limited, single and inflexible, i.e. the noise cannot be reduced for a specific frequency, the efficiency in other fans cannot be asserted, and the pipe length still has a restriction on practical installation.
Disclosure of Invention
The application aims to provide a subsonic axial flow fan structure and a design method thereof, which are used for solving the technical problems of poor environmental applicability and frequency pertinence of the existing fan noise reduction equipment.
The subsonic axial flow fan structure comprises a fan shell and fan blades arranged on the fan shell, wherein an acoustic liner body is arranged on the periphery of the fan blades, and the acoustic liner body is fixed on the fan shell;
the acoustic liner body comprises an annular plate and an annular Helmholtz silencer, an annular cavity is arranged between the annular Helmholtz silencer and the annular plate, the annular cavity and the annular Helmholtz silencer are sequentially connected from inside to outside to form an annular structure;
a plurality of through holes which are arranged in a circumferential direction are formed in the annular plate;
the annular Helmholtz silencer comprises a Helmholtz resonance cavity, and the Helmholtz resonance cavity is communicated with the annular cavity through connecting pipes arranged at intervals.
Therefore, the sound liner structure designed by the annular plate and the annular Helmholtz silencer can convert sound energy into heat energy in the sound propagation process according to the mode of micro-perforated plate and Helmholtz resonance silencing, realize resonance silencing at the blade passing frequency and the frequency doubling frequency band of the fan, reduce the sound pressure level of a specific frequency band, improve the problem of over-narrow absorption frequency band of the micro-perforated plate and realize the overall silencing of the fan. The structure has small volume and thin thickness, can not greatly change the original structure of the fan, and has strong adaptability.
Further, the acoustic liner body is integrally thermoformed.
Still further, the cross section of the acoustic liner body parallel to the radial direction is rectangular or trapezoidal.
Still further, the acoustic liner body is made of ABS, POM or PC material.
In addition, the through hole and the connecting pipe are formed by piercing and processing a metal needle.
Based on the same inventive concept, the application also provides a design method of the subsonic axial flow fan structure, wherein the thickness t and the porosity p of the annular plate are obtained by the following formula:
wherein: r is the relative acoustic resistance, m is the relative acoustic mass, f 0 For the resonance frequency of the acoustic liner body, t is the thickness of the annular plate, d 1 P is the porosity of the annular plate;
the thickness D of the annular cavity and the relative acoustic mass m in the equation {1} are determined by the following formula:
wherein: f (f) 2 、f 1 The maximum and minimum frequencies of the sound absorption bandwidth of the sound liner body are represented by r, the relative acoustic resistance and c, the sound velocity in the air;
the arrangement structure of the through holes is obtained by the following formula:
wherein: p is the porosity of the annular plate, d 1 The diameter of the through holes is M, the number of the through holes in each row of the annular plate in the width direction of the annular plate is M, theta is the circle center angle formed by the circle centers of two adjacent through holes in the circumferential direction and the circle center of the fan, R is the radius of the annular plate, and L is the width of the annular plate;
the height H of the Helmholtz resonance cavity is obtained by the following formula:
V＝πL[(R+t+D+l+H) 2 -(R+t+D+l) 2 ] {9}
wherein: s is the cross-sectional area of the connecting pipe, l is the length of the connecting pipe, d 2 Is the diameter of the connecting pipe, c is the sound velocity in the air, f 0 Is resonantThe frequency V is the volume of the Helmholtz resonance cavity, L is the width of the annular plate, R is the radius of the annular plate, t is the thickness of the annular plate, and D is the thickness of the annular cavity.
Therefore, the application provides an accurate design processing method of the acoustic liner structure, so as to ensure that each part of the acoustic liner structure can be well adapted to the subsonic axial flow fan. The sound liner structure obtained by the design method has the advantages that the remarkable noise reduction effect is provided, meanwhile, the adverse effect of the conventional noise reduction structure on the aerodynamic performance of the subsonic axial flow fan is avoided, and the contradiction between the noise reduction design and the performance design is effectively relieved.
Further, the relative acoustic resistance r in the formula {2} is obtained by the following formula:
wherein: alpha 0 Is the sound absorption coefficient.
Still further, said f 2 、f 1 By formula f 0 2 ＝f 2 ×f 1 Obtaining f in 0 For the acoustic liner body resonant frequency, f 2 、f 1 And (3) absorbing the maximum and minimum frequencies of the bandwidth for the acoustic liner body.
The subsonic axial flow fan structure and the design method have the following advantages:
the sound liner structure design method provided by the application has universality for subsonic axial flow fans with different sizes. The application provides an effective noise-reducing acoustic liner structure, which can absorb the high-peak frequency band acoustic energy of a certain fan sound source, convert the acoustic energy into heat energy through resonance noise elimination, reduce discrete single-tone noise of the fan, simultaneously has a wider frequency band acoustic absorption range, does not influence the aerodynamic performance of the axial fan, has a small and exquisite structure and is ultrathin, and the applicability of the axial fan in specific application scenes is considered.
Drawings
FIG. 1 is a schematic view of a subsonic axial fan according to the present application;
FIG. 2 is a schematic view of a partial structure of an acoustic liner body according to the present application;
FIG. 3 is a graph of sound pressure versus frequency for a fan sound source without the acoustic liner structure of the present application;
fig. 4 is a sound pressure-frequency spectrum of a fan sound source with the sound liner structure of the present application.
The figure indicates: 1. an annular plate; 1-1, through holes; 2. an annular cavity; 3. an annular helmholtz muffler; 3-1, connecting the pipes; 3-2, a Helmholtz resonance cavity; 3-3, gaps; 4. fan blades; 5. an acoustic liner body; 6. a fan housing.
Detailed Description
The present application will be described in further detail with reference to the accompanying drawings for a better understanding of the objects, structures and functions of the present application.
As shown in fig. 1 and 2, a subsonic axial flow fan structure of the present embodiment includes a fan housing 6 and fan blades 4 mounted on the fan housing 6, wherein an acoustic liner body 5 is disposed on the periphery of the fan blades 4, and the acoustic liner body 5 is fixed on the fan housing 6. The acoustic liner body 5 comprises an annular plate 1 and an annular Helmholtz silencer 3, an annular cavity 2 is arranged between the annular Helmholtz silencer 3 and the annular plate 1, the annular cavity 2 and the annular Helmholtz silencer 3 are sequentially connected from inside to outside to form an annular structure, and the annular structure is matched with the shape of the fan shell. The acoustic liner body 5 may be integrally thermoformed from ABS, POM or PC material to ensure that the joint is void free. The annular plate 1 is provided with a plurality of through holes 1-1 which are arranged in a circumferential direction. The annular Helmholtz silencer 3 comprises a Helmholtz resonance cavity 3-2, and the Helmholtz resonance cavity 3-2 is communicated with the annular cavity 2 through a plurality of connecting pipes 3-1 arranged at intervals. The number of the connection pipes 3-1 is adjusted according to the actual fan size and the space requirement of the buried wire of the fan. In general, the number of the connecting pipes 3-1 needs to be as large as possible, and the larger the number of the connecting pipes 3-1 is, the larger the noise elimination frequency is, and the wider the noise elimination bandwidth is. Preferably, the acoustic liner body has a rectangular cross section parallel to the radial direction. The through hole 1-1 and the connection pipe 3-1 are formed by piercing with a high temperature metal needle having a small relative target size, wherein the through hole 1-1 is not necessarily strictly required to be a regular cylinder.
Specifically, a fan with a rated rotation speed of 2000rpm, a fan blade radius of 54.745, a fan blade tip clearance of 1mm, a fan width of 20mm, and a number of blades of 9 is taken as an example. The annular plate 1 serves as a fan shield, and a certain gap, generally 0.5-1.5mm, is reserved between the annular plate and the fan blades 4. The annular plate 1 is very thin, a cylindrical through hole 1-1 is formed in the plate, and the axis of the cylinder points to the center of the fan. The annular cavity 2 and the annular Helmholtz silencer 3 are integrally arranged in the buried wire cavity of the fan, and wires are selectively inserted in gaps 3-3 between adjacent connecting pipes 3-1 according to the distribution density and the length of the connecting pipes 3-1 so as to save space.
The design method of the subsonic axial flow fan structure in the embodiment is as follows:
the thickness t and the porosity p of the annular plate 1 are obtained by the following formula:
wherein: r is the relative acoustic resistance, m is the relative acoustic mass, f 0 For the resonance frequency of the acoustic liner body 5, t is the thickness of the annular plate 1, and t is 0.5-2mm. d, d 1 Is the diameter of the through hole (1-1), d 1 Taking 0.1-2mm. p is the porosity of the annular plate 1, and is generally 0.5% -1.5%;
the relative acoustic resistance r in the formula {2} is obtained by the following formula:
wherein: alpha 0 Is the sound absorption coefficient.
The thickness D of the annular cavity 2 and the relative acoustic mass m in the equation {1} are calculated by the following formula:
wherein: f (f) 2 、f 1 The maximum and minimum frequencies of the sound absorption bandwidth of the sound liner body 5 are represented by r, the relative acoustic resistance, c, the sound velocity in the air, and the unit is m/s;
f 2 、f 1 by formula f 0 2 ＝f 2 ×f 1 Obtaining f in 0 For the resonant frequency, f, of the acoustic liner body 5 2 、f 1 The maximum and minimum frequencies of the bandwidth are absorbed for the acoustic liner body 5.
The flow of calculation of the thickness t and the porosity p of the annular plate 1 is as follows:
step one, determining the resonant frequency f 0 And sound absorption coefficient alpha 0 。
Step two, from formula f 0 2 ＝f 2 ×f 1 Determining the maximum and minimum frequency f of sound absorption bandwidth by considering the frequency range distributed by the high peak of sound pressure 2 、f 1 。
Step three, the sound absorption coefficient is determined and then substituted into a formula {2-1}, and two solutions r can be obtained 1 、r 2 The smaller value is discarded and the larger value is taken.
And step four, solving D, m according to the {3}, and {4 }.
Step five, determining the diameter d of the small hole of the annular plate 1 。
Step six, according to the known m, r and f 0 、d 1 Substituting {4}, {5}, and obtaining p and t.
The arrangement structure of the through holes 1-1 is obtained by the following formula:
wherein: p is the porosity of the annular plate 1, d 1 Is the diameter of the through hole 1-1, M is an annular plate1, and the number of each row of through holes 1-1 in the width direction of the fan, wherein theta is the center angle formed by the centers of two adjacent through holes 1-1 in the circumferential direction and the center of the fan. R is the radius of the annular plate 1 and L is the width of the annular plate 1.
The annular plate radius R and the annular plate width L are determined according to the size of the target noise reduction fan. In general, R is the sum of the radius of the blade tip and the top clearance, and L is determined according to the width of the fan, and may be equal to or slightly greater than the thickness of the fan. At the same time, the spacing between the centers of the small holes of the annular plates in the same row in the width direction is 2d 1 -3d 1 。
The number M of the through holes 1-1 in one row of the annular plate 1 in the width direction can be calculated by the width L of the annular plate 1 and the center distance of the through holes 1-1 in the same row. Will R, L, M, d 1 The value substituted into equation {5} can calculate θ.
The height H of the helmholtz resonator 3-2 is found by the following formula:
V＝πL[(R+t+D+l+H) 2 -(R+t+D+l) 2 ] {9}
wherein: s is the cross-sectional area of the connecting tube 3-1, l is the length of the connecting tube 3-1, d 2 For the diameter of the connecting pipe 3-1, c is the sound velocity in the air, f 0 V is the volume of the helmholtz resonator 3-2, L is the width of the annular plate 1, R is the radius of the annular plate 1, t is the thickness of the annular plate 1, and D is the thickness of the annular cavity 2.
Based on the design concept of ultra-thin acoustic liner, the length l of the connecting pipe 3-1 is taken as a smaller value, and d is determined at the same time 2 . The resonance chamber height H can be obtained by substituting the equations {8}, {9} into the equation {7}, and substituting the known R, L, t, D into the equation.
Preferably, the frequency band distributed by the larger sound pressure level of the fan is judged according to the sound pressure-frequency distribution diagram of the fan obtained through theoretical calculation or simulation. Generally, a large sound pressure is distributed in a low frequency band and at a Blade Passing Frequency (BPF) of a fan and a frequency multiplication thereof. The BPF of the fan is calculated by the following formula:
n is the fan speed, rpm; z is the number of fan blades. The relatively high sound pressure of the fan is known to occur approximately at 300HZ, 600HZ, 900HZ, 1200 HZ. As shown in fig. 3, the frequency at the highest peak of sound pressure is selected as the target frequency, i.e., f 0 =210 HZ, expressed by formula f 0 2 ＝f 2 ×f 1 The sound absorption band may be set at 160-280HZ while the sound absorption coefficient is determined to be 0.234, calculated while considering the frequencies at which the high peaks of sound pressure are distributed.
The sound absorption coefficient of the annular plate 1 is not proper to be too high, otherwise, the subsequent plate or through hole 1-1 is too small in size parameter, and the processing and manufacturing are difficult too much, so that the practicability is lost. Even in some cases the equation will not be solved. The sound absorption coefficient is preferably in the range of 0.2 to 0.35.
After the sound absorption coefficient of the annular plate 1 is determined, the sound absorption coefficient is substituted into a formula {2-1}, and two solutions r can be obtained 1 ＝15，r 2 If r is too small, the subsequent equation will not be solved, so r will 2 Discarding, taking r 1 。
Simultaneous {3}, {4} solved for d=0.00576 m, m=0.029. Diameter d of small hole 1 By substituting d, m, r into the formulas {1}, {2}, t=0.6 mm, p=1.56% can be solved.
The arrangement of the through holes 1-1 of the annular plate 1 is calculated by {5} formula, and d 1 1mm, L=20mm, and the center of the small hole near the boundary was 2.5d from the side 1 The distance between the centers of two adjacent small holes in the width direction of the annular plate 1 is 3d 1 The arrangement number M=6 of a row of small holes in the width direction of the annular plate 1 can be calculated, and M, L, p is substituted into {5} to obtain the central angle theta=15.3 degrees formed by the circle centers of the small holes adjacent in the annular direction and the circle center of the annular plate.
The resonance frequency of the annular helmholtz silencer 3 may be identical to that of the annular plate, or may be selected at other high sound pressure values as shown in fig. 3. The sound absorption coefficient of the annular plate is smaller, so f is selected 0 Is the resonant frequency to achieve maximum sound absorption between this frequency band.
The helmholtz resonance cavity 3-2 of the annular helmholtz silencer 3 can be as wide as the annular plate, so that the cross section of the acoustic liner body parallel to the radial direction is rectangular, and can exceed a part of the cross section of the acoustic liner body parallel to the radial direction, so that the cross section of the acoustic liner body parallel to the radial direction is trapezoidal. When the applied scene has strict requirements on the height H of the Helmholtz resonant cavity 3-2, the width can be properly extended equally at both ends so as to make up for the defect of the whole volume. In this embodiment, the helmholtz resonator 3-2 is equal in width to the annular plate 1.
The dimensions of the connecting pipe 3-1 of the annular Helmholtz silencer 3 and the Helmholtz resonance cavity 3-2 are calculated by {3}, {4}, and {5 }. Taking the length l=1mm and the diameter d of the connecting tube 3-1 2 The helmholtz resonator 3-2 height h=6.9 mm is available.
Preferably, the positions of the through holes 1-1 and the connecting pipes 3-1 are in one-to-one correspondence, and in the case of simultaneously having a plurality of connecting pipes 3-1, the resonance frequency of the through holes can be increased, the sound attenuation effect is achieved on the BPF of the fan and the sound pressure of each stage of frequency multiplication stage, and meanwhile, the sound absorption frequency band of +/-20 HZ is widened relative to a small quantity of connecting pipes 3-1.
The annular plate 1 itself may act as a shroud support for the fan and may not account for the increased thickness of the gap between the fan blades 4 and the fan shroud due to the addition of sound absorbing means. The acoustic liner body 5 of this embodiment has a thickness of 13.66mm.
The annular cavity 2 and the annular Helmholtz silencer 3 are integrally arranged in the buried wire cavity of the fan, and wires can be selectively inserted in gaps 3-3 between adjacent connecting pipes 3-1 according to different distribution densities and lengths of the connecting pipes 3-1, so that space is effectively saved.
It can be seen from fig. 4 that the highest sound pressure level in the target noise reduction frequency band is reduced from 27db to 20.5db, and the sound pressure level of each frequency in the target noise reduction frequency band is reduced by about 5db compared with that in fig. 3, and the noise reduction effect is obvious in a high frequency band of about 6000 HZ. This proves that the fan liner has a good noise reduction effect.
It will be understood that the application has been described in terms of several embodiments, and that various changes and equivalents may be made to these features and embodiments by those skilled in the art without departing from the spirit and scope of the application. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the application without departing from the essential scope thereof. Therefore, it is intended that the application not be limited to the particular embodiment disclosed, but that the application will include all embodiments falling within the scope of the appended claims.

Claims (8)

1. The subsonic axial flow fan structure comprises a fan shell (6) and fan blades (4) arranged on the fan shell (6), wherein an acoustic liner body (5) is arranged on the periphery of each fan blade (4), and the acoustic liner body (5) is fixed on the fan shell (6); the method is characterized in that:
the sound liner body (5) comprises an annular plate (1) and an annular Helmholtz silencer (3), an annular cavity (2) is arranged between the annular Helmholtz silencer (3) and the annular plate (1), the annular cavity (2) and the annular Helmholtz silencer (3) are sequentially connected from inside to outside to form an annular structure;
a plurality of through holes (1-1) which are arranged in a circumferential direction are formed in the annular plate (1);
the annular Helmholtz silencer (3) comprises a Helmholtz resonance cavity (3-2), and the Helmholtz resonance cavity (3-2) is communicated with the annular cavity (2) through a plurality of connecting pipes (3-1) which are arranged at intervals.
2. Subsonic axial fan structure as claimed in claim 1, characterized in that the acoustic liner body (5) is integrally thermoplastic.
3. Subsonic axial flow fan structure as in claim 1, characterized in that the acoustic liner body (5) has a rectangular or trapezoidal cross section parallel to the radial direction.
4. Subsonic axial fan structure as claimed in claim 1, characterized in that the acoustic liner body (5) is made of ABS, POM or PC material.
5. Subsonic axial flow fan structure according to claim 1, characterized in that the through hole (1-1) and the connecting tube (3-1) are pierced by a metal needle.
6. A design method of a subsonic axial flow fan structure as set forth in any one of claims 1 to 5, characterized in that the thickness t and the porosity p of the annular plate (1) are obtained by the following formula:
wherein: r is the relative acoustic resistance, m is the relative acoustic mass, f 0 For the resonance frequency of the acoustic liner body (5), t is the thickness of the annular plate (1), d 1 The diameter of the through hole (1-1), p is the porosity of the annular plate (1);
the thickness D of the annular cavity (2) and the relative acoustic mass m in the formula {1} are determined by the following formula:
wherein: f (f) 2 、f 1 Maximum and minimum sound absorption bandwidth for the acoustic liner body (5)The frequency, r, is the relative acoustic resistance, c is the speed of sound in air;
the arrangement structure of the through holes (1-1) is obtained by the following formula:
wherein: p is the porosity of the annular plate (1), d 1 The diameter of the through holes (1-1), M is the number of the through holes (1-1) in each row of the annular plate (1) in the width direction, theta is the center angle formed by the centers of two adjacent through holes (1-1) in the circumferential direction and the center of a fan, R is the radius of the annular plate (1), and L is the width of the annular plate (1);
the height H of the Helmholtz resonance cavity (3-2) is obtained by the following formula:
V＝πL[(R+t+D+l+H) 2 -(R+t+D+l) 2 ] {9}
wherein: s is the cross-sectional area of the connecting pipe (3-1), l is the length of the connecting pipe (3-1), d 2 Is the diameter of the connecting pipe (3-1), c is the sound velocity in the air, f 0 For resonance frequency, V is the volume of the Helmholtz resonance cavity (3-2), L is the width of the annular plate (1), R is the radius of the annular plate (1), t is the thickness of the annular plate (1), and D is the thickness of the annular cavity (2).
7. The design method of subsonic axial flow fan structure as set forth in claim 6, wherein the relative acoustic resistance r in the formula {2} is obtained by the following formula:
wherein: alpha 0 Is the sound absorption coefficient.
8. The method for designing subsonic axial flow fan structure as set forth in claim 6, wherein said f 2 、f 1 By formula f 0 2 ＝f 2 ×f 1 Obtaining f in 0 For the resonant frequency, f, of the acoustic liner body (5) 2 、f 1 -maximum and minimum frequency of sound absorption bandwidth for the acoustic liner body (5).
CN202310733710.4A 2023-06-20 2023-06-20 Subsonic axial flow fan structure and design method Pending CN116677653A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310733710.4A CN116677653A (en) 2023-06-20 2023-06-20 Subsonic axial flow fan structure and design method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310733710.4A CN116677653A (en) 2023-06-20 2023-06-20 Subsonic axial flow fan structure and design method

Publications (1)

Publication Number Publication Date
CN116677653A true CN116677653A (en) 2023-09-01

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Application Number Title Priority Date Filing Date
CN202310733710.4A Pending CN116677653A (en) 2023-06-20 2023-06-20 Subsonic axial flow fan structure and design method

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Country Link
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