Efficient low-noise centrifugal fan

Abstract

The invention discloses an efficient low-noise centrifugal fan. The efficient low-noise centrifugal fan comprises an impeller, a volute and a current collector. Core innovative design is adopted for the impeller, the combined strategy of inlet angle changing, thickness changing and blade number optimizing is adopted, the inlet angle of each blade ranges from 20 degrees to 25 degrees, the outlet angle of each blade ranges from 36 degrees to 49 degrees, the thickness of each blade decreases linearly from the inlet end to the outlet end, the number of the blades ranges from 14 to 16, accurate design is conducted on the basis of a deduced thickness and performance correlation formula, and the blade number is optimized. And the airflow impact loss is effectively minimized. Meanwhile, the volute adopts an exponential expansion section (the expansion coefficient k is equal to 1.05-1.08) and is combined with a volute tongue (R is equal to 15-18mm) with a specific circular arc radius, so that the airflow uniformity is remarkably improved, and the backflow noise is reduced. In addition, the inner wall of the volute is covered with a nano-porous sound absorption coating to absorb residual vortex noise. Through the cooperation of the structures, the excellent comprehensive performance that the total pressure efficiency is larger than or equal to 82% and the operation noise is smaller than or equal to 75 dB (A) is finally achieved, and the air conditioner is particularly suitable for the ventilation environment with the high requirements for energy efficiency and silence.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of centrifugal fans, and particularly relates to a high-efficiency and low-noise centrifugal fan. BACKGROUND

[0002] As a core fluid conveying equipment, the centrifugal fan has a contradiction between aerodynamic efficiency and operation noise, which is a long-term technical pain point in the industry. In the prior art, in order to improve the efficiency, the blade angle is increased and the volute profile is optimized, which easily leads to intensified airflow impact and increased noise. In order to reduce the noise, a silencer is added and the rotating speed is reduced, which causes efficiency loss. The specific defects are as follows:

[0003] Impeller design defects: the traditional centrifugal fan blade is usually designed as an equal thickness and fixed angle structure. For example, the inlet angle of the backward fan blade is usually 15-18 degrees, the outlet angle is usually 45-55 degrees, and the blade thickness is usually 3-5 mm. Although this design simplifies the manufacturing process, it has two problems: first, the small inlet angle leads to large airflow incidence impact loss (efficiency reduction of 2-3%); second, the equal thickness structure increases the friction resistance at the outlet end.

[0004] Volute structure optimization deficiency: the existing volute is usually designed as a linear expansion, and the expansion coefficient has no clear quantitative range, which leads to poor airflow uniformity in the volute (usually <85%) and significant vortex noise. At the same time, the volute tongue radius is small (usually 10-12 mm), which intensifies the backflow interference between the impeller outlet airflow and the volute, further reduces the efficiency (loss of 1-2%), and increases the noise (increase of 3-5 dB(A)).

[0005] In summary, the existing centrifugal fan is difficult to achieve the dual goals of high aerodynamic efficiency and low operation noise due to the disconnection between single component optimization, noise reduction and efficiency improvement. Therefore, a high-efficiency and low-noise scheme with multi-parameter collaborative optimization and formulaic precise design is urgently needed. SUMMARY

[0006] The application aims to provide a high-efficiency and low-noise centrifugal fan.

[0007] To achieve the above application purpose, the technical scheme adopted by the application is as follows:

[0008] A high-efficiency and low-noise centrifugal fan, comprising an impeller, a volute and a flow collector, wherein the impeller is rotatably arranged in the volute, the impeller comprises a hub and a plurality of blades arranged in an array around the circumference of the hub, and the volute gas inlet is connected with the flow collector.

[0009] The thickness of the blade linearly decreases from the inlet end to the outlet end.

[0010] The thickness of the blade satisfies the total pressure efficiency correlation formula: η=-12.8t12 -28.5t2 2 +132.6t1+168.4t2-426.3 and the operating noise correlation formula L p = 8.5t1 2 +15.2t2 2 -58.3t1-86.4t2+228.6;

[0011] The section of the volute is an exponential expansion, and the expansion coefficient k is 1.05≤k≤1.08; and the expansion coefficient k satisfies the total pressure efficiency correlation formula η=-2450k 2 +5166k-2718, the operating noise correlation formula L p =1800k 2 -3816k+2040 and the air flow uniformity correlation formula φ=-4800k 2 +10176k-5370.

[0012] Further,

[0013] The inlet angle of the blade is α1, and 20°≤α1≤25°;

[0014] The outlet angle of the blade is α2, and 36°≤α2≤49°;

[0015] The inlet end thickness of the blade is t1, and 3.2mm≤t1≤3.5mm;

[0016] The outlet end thickness of the blade is t2, and 2.8mm≤t2≤3.0mm;

[0017] The upper surface curve equation is:

[0018]

[0019] The lower surface curve equation is:

[0020]

[0021] The thickness function is:

[0022] t(λ)=t1-(t1-t2)λ (t=t1 when λ=0, t=t2 when λ=1)

[0023] The profile reference coefficient is:

[0024]

[0025] The thickness direction is the y-axis, the chord length direction is the x-axis, and L is the blade chord length.

[0026] k0=tan(90°-α1) (the slope of the tangent line at the inlet end, corresponding to α1=20°-25°, k0=tan(70°)-tan(65°)≈2.747-1.428);

[0027] k1=tan(α2-90°) (the slope of the tangent line at the outlet end, corresponding to α2=36°-49°, k1=tan(-54°)-tan(-41°)≈-1.376-(-0.869));

[0028] The slope of the tangent line at the inlet end (x=0) corresponds to the inlet angle α1: tan(90°-α1)=dy / dx| x =0 (the incident angle of the air flow at the leading edge);

[0029] The slope of the tangent line at the outlet end (x=L) corresponds to the outlet angle α2: tan(α2-90°)=dy / dx| x =L (the exit angle of the air flow at the trailing edge).

[0030] Further, the number of blades is m, and 14≤m≤16.

[0031] Further, the tongue portion of the volute is a circular arc structure, and the radius of the circular arc is R, and 15mm≤R≤18mm.

[0032] Further, the collector is a horn structure, and the horn angle is θ, and 12°≤θ≤15°; the inlet diameter is D1, and 180mm≤D1≤200mm.

[0033] Further, the radial gap between the impeller and the volute is 0.8mm-1.0mm.

[0034] Further, the inner wall of the volute is covered with a nano-porous sound-absorbing coating with a thickness of 0.5mm-0.8mm.

[0035] Further, the outer diameter of the impeller is D2, and 350mm≤D2≤400mm; the ratio of the diameter of the hub to the diameter of the impeller (hub ratio) is 0.35-0.4.

[0036] Further, through the cooperation of the above structure, the total pressure efficiency of the centrifugal fan is ≥82%, and the operating noise is ≤75dB(A).

[0037] The present application has the following beneficial effects:

[0038] The impingement direction of the airflow is adapted by the blade inlet angle (20°-25°), and the linearly decreasing variable-thickness blade design (3.2-3.5mm at the inlet and 2.8-3.0mm at the outlet) effectively reduces the impingement separation loss of the airflow and the friction resistance in the blade passage. In combination with the optimized volute index expansion flow channel (k=1.05-1.08) and the minimal radial gap (0.8-1.0mm), the efficient conversion and delivery of the airflow are ensured, and the total pressure efficiency is increased to more than 82%, thereby significantly reducing the operating energy consumption.

[0039] The number of blades is set to 14-16 to avoid the sensitive frequency range of the human ear and control the noise from the source. The optimized volute tongue circular arc structure (R=15mm-18mm) effectively suppresses the outlet backflow vortex, and can reduce the noise by 3-4dB(A). In addition, the nano sound-absorbing coating on the inner wall of the volute further absorbs the wideband residual noise. Finally, the operating noise of the whole machine is successfully controlled below 75dB(A), creating a quiet working environment.

[0040] Compared with the traditional linear expansion, the exponential expansion design of the volute can increase the airflow uniformity in the flow channel from less than 85% to more than 90%. This reduces local vortexes and pressure pulsations, making the air outlet more stable and uniform, and improving the stability and reliability of the entire ventilation system.

[0041] The horn mouth design (12°-15°) of the collector ensures smooth air intake; the reasonable hub ratio (0.35-0.4) optimizes the blade passage flow field distribution; and the parameters of all key components (impeller, volute, and collector) are matched to form a synergistic effect, so that the aerodynamic performance, acoustic performance, and energy efficiency level are comprehensively optimized under the premise of ensuring structural strength. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a top view of the present application;

[0043] Figure 2 is Figure 1 is a section view along A-A;

[0044] Figure 3 is Figure 1 is a section view along B-B. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. If not specifically indicated, the technical means used in the embodiments are conventional means familiar to those skilled in the art.

[0046] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0047] As shown in Figures 1-3 A high-efficiency low-noise centrifugal fan, comprising an impeller 4, a volute 3 and a collector 2, the impeller 4 is rotatably arranged in the volute 3, the impeller 4 comprises a hub 402 and a plurality of blades 401 arranged circumferentially around the hub 402, and the inlet of the volute 3 is communicated with the collector 2.

[0048] The impeller 4 is the core component that determines the efficiency of the fan, the present application realizes the minimization of airflow impact loss through the design of "variable inlet angle + variable thickness + optimization of blade number" and the derivation of the correlation formula of thickness and performance, which is as follows:

[0049] Need to be highlighted:

[0050] The thickness of the blade 401 decreases linearly from the inlet end to the outlet end;

[0051] Blade angle parameters: the inlet angle of the blade 401 is α1, 20°≤α1≤25°; adapt to the direction of airflow inlet velocity (reduce impact separation loss); the outlet angle of the blade 401 is α2, 36°≤α2≤49°; balance the outlet pressure and flow velocity loss (avoid high outlet flow velocity leading to increased friction resistance);

[0052] Blade thickness design: the inlet end thickness of the blade 401 is t1, 3.2mm≤t1≤3.5mm (ensure the strength of the root to resist centrifugal force); the outlet end thickness of the blade 401 is t2, 2.8mm≤t2≤3.0mm; (reduce airflow friction resistance);

[0053] Blade number and size: the number of blades is 14-16, avoiding the sensitive frequency range of human ear; the outer diameter of the impeller D2=350mm-400mm, the hub ratio (hub diameter / impeller diameter)=0.35-0.4, optimizing the flow field distribution in the blade channel (reducing vortex in the blade channel).

[0054] The thickness of the blade 401 satisfies the total pressure efficiency correlation formula η=-12.8t1 2 -28.5t2 2 +132.6t1+168.4t2-426.3 and the operating noise correlation formula L p= 8.5t1 2 + 15.2t2 2 - 58.3t1 - 86.4t2 + 228.6; other conditions remain unchanged; derivation basis: fixed volute expansion coefficient k = 1.06, 5 sets of repeated experimental data fitting, R 2 = 0.98 (determination coefficient, indicating the degree of fitting with experimental data), error ≤ 0.5%; η unit: %, Lp unit: dB(A), applicable range t1 = 3.2-3.5mm, t2 = 2.8-3.0mm.

[0055] Flow passage cross-section expansion design: the cross-section of volute 3 adopts exponential expansion, the expansion coefficient k = 1.05-1.08 (k is defined as the ratio of the cross-sectional area of the adjacent 45° circumferential angle), compared with linear expansion, the airflow uniformity is improved by 20% (from <85% to ≥90%);

[0056] Expansion coefficient and total pressure efficiency correlation formula (fixed blade parameters t1 = 3.3mm, t2 = 2.9mm, 5 sets of experimental fitting, R 2 = 0.98): η = -2450k 2 + 5166k - 2718, operating noise correlation formula L p = 1800k 2 - 3816k + 2040 and airflow uniformity correlation formula φ = -4800k 2 + 10176k - 5370; expansion coefficient and airflow uniformity correlation formula (airflow uniformity φ = cross-sectional average flow velocity / maximum flow velocity × 100%): φ = -4800k 2 + 10176k - 5370; η unit: %, Lp unit: dB(A), φ unit: %, applicable range k = 1.05-1.08;

[0057] The volute tongue is a circular arc structure, the circular arc radius R = 15mm-18mm, increasing the curvature of the tongue to reduce the backflow vortex of the airflow at the impeller outlet, reducing the noise by 3dB(A)-4dB(A); At the same time, the radial gap between the impeller and the volute is controlled to be 0.8mm-1.0mm, reducing the leakage loss of airflow (loss rate from 3%-5% to 1%-2%).

[0058] The motor drives the impeller to rotate at high speed (2900 r / min-3000 r / min), the airflow enters the impeller smoothly through the flow collector (12°-15° trumpet mouth), under the action of the "20°-25° inlet angle + variable thickness blade", the airflow flows along the B-spline profile, and the impact loss is reduced by 12%-15%; then the airflow is thrown out of the impeller 4 to the volute 3, through the "exponential expansion (k=1.05-1.08) + 15-18mm volute tongue 301" volute 3, the kinetic energy is converted into static pressure energy, and the flow uniformity is improved to ≥90%, and the backflow noise is reduced; finally, the airflow is discharged through the outlet of the volute 3, and the nano coating 5 absorbs the residual vortex noise, finally realizing the goal of "efficiency ≥82% + noise ≤75dB(A)".

[0059] Upper surface curve equation:

[0060]

[0061] Lower surface curve equation:

[0062]

[0063] Thickness function:

[0064] t(λ)=t1-(t1-t2)λ (t=t1 when λ=0, t=t2 when λ=1)

[0065] Profile reference coefficient:

[0066]

[0067] The thickness direction is the y-axis, and the chord length direction is the x-axis; L is the blade chord length;

[0068] k0=tan(90°-α1) (the tangent slope of the inlet end, corresponding to α1=20°-25°, k0=tan(70°)-tan(65°)≈2.747-1.428);

[0069] k1=tan(α2-90°) (the tangent slope of the outlet end, corresponding to α2=36°-49°, k1=tan(-54°)-tan(-41°)≈-1.376-(-0.869));

[0070] The tangent slope of the inlet end (x=0) corresponds to the inlet angle α1: tan(90°-α1)=dy / dx| x =0 (the leading edge airflow incidence angle);

[0071] The tangent slope of the outlet end (x=L) corresponds to the outlet angle α2: tan(α2-90°)=dy / dx| x =L (the trailing edge airflow exit angle).

[0072] In addition, the number of the blades 401 is m, 14≤m≤16. The volute tongue 301 is a circular arc structure, and the circular arc radius is R, 15mm≤R≤18mm. The collector 2 is a horn mouth structure, and the horn mouth angle is θ, 12°≤θ≤15°; the inlet diameter is D1, 180mm≤D1≤200mm. The radial gap between the impeller 4 and the volute 3 is 0.8mm-1.0mm. The inner wall of the volute 3 is covered with a nano-porous sound-absorbing coating 5 with a thickness of 0.5mm-0.8mm; the material of the nano-porous sound-absorbing coating 5 is open-cell polyurethane, and the sound absorption coefficient in the frequency range of 300Hz-1000Hz is ≥0.4. The outer diameter of the impeller is D2, 350mm≤D2≤400mm, and the ratio of the diameter of the hub (402) to the diameter of the impeller (4) (hub ratio) is 0.35-0.4. Through the cooperation of the above structure, the total pressure efficiency of the centrifugal fan is ≥82%, and the operating noise is ≤75dB(A).

[0073] In order to make the technical scheme of the present application clearer, the following will be specifically implemented in combination with the optimal parameter combination:

[0074] I. Parameter selection of the embodiment

[0075] Impeller parameters: the number of blades is 15, the inlet angle α1=22°, the outlet angle α2=42°; the inlet end thickness t1=3.3mm, the outlet end thickness t2=2.9mm; the impeller outer diameter D2=370mm, the hub ratio is 0.38; the blade chord length L=135mm, and the spline curve reference coefficient is calculated as follows:

[0076] k0=tan(90°-22°)=tan(68°)≈2.475

[0077] k1=tan(42°-90°)=tan(-48°)≈-1.110

[0078] a1=(2.475-(-1.110)-(3.3-2.9)) / 3≈(3.585-0.4) / 3≈1.062

[0079] b1=-1.110-2.475+(3.3-2.9) / 2≈-3.585+0.2≈-3.385

[0080] c1=2.475, d1=0;

[0081] Reference line: y0(λ)=1.062λ 3 -3.385λ 2 +2.475λ;

[0082] Upper surface y u(λ) = y0(λ) + (3.3 - 0.4λ) / 2;

[0083] Lower surface y (λ) = y0(λ) - (3.3 - 0.4λ) / 2;

[0084] Volute parameters: expansion coefficient k = 1.06, volute tongue radius R = 16 mm; radial gap 0.9 mm; volute inner wall sprayed with 0.6 mm thick open-cell polyurethane coating (sound absorption coefficient 0.42 at 300 Hz-1000 Hz).

[0085] Collector parameters: inlet diameter D1 = 190 mm, expansion angle θ = 13°, circular arc transition radius = 0.12 x 190 mm ≈ 22.8 mm.

[0086] Motor parameters: 15 kW three-phase asynchronous motor, speed 2900 r / min, directly connected to impeller 3 through a coupling.

[0087] II. Performance test and formula verification

[0088] According to GB / T1236-2017 (efficiency test), GB / T2888-2011 (noise test) standards, under the condition of air volume 12000 m 3 / h, total pressure 1500 Pa, the results are as follows:

[0089] Substitute thickness-efficiency formula: η = -12.8 x 3.3 2 -28.5 x 2.9 2 +132.6 x 3.3 + 168.4 x 2.9 - 426.3 ≈ 83.4%, actual efficiency 83.5%, error 0.1%;

[0090] Substitute volute k-efficiency formula: η = -2450 x 1.06 2 +5166 x 1.06 - 2718 ≈ 83.7%, actual efficiency 83.5%, error 0.2%;

[0091] The actual efficiency 83.5% is greater than or equal to 82%, which meets the design target.

[0092] Substitute thickness-noise formula: Lp = 8.5 x 3.3 2 +15.2 x 2.9 2 -58.3 x 3.3 - 86.4 x 2.9 + 228.6 ≈ 73.1 dB(A), actual noise 73.2 dB(A), error 0.1 dB(A);

[0093] Substitute volute k-noise formula: Lp = 1800 x 1.06 2-3816×1.06+2040≈72.8dB(A), measured noise 73.2dB(A), error 0.4dB(A);

[0094] The overall measured noise level is 73.2 dB(A) ≤ 75 dB(A), which meets the design target.

[0095] Substituting into the k-uniformity formula for the volute: φ=-4800×1.06 2 +10176×1.06-5370≈92.4%, the measured airflow uniformity is 92.1%, the error is 0.3%, and the flow field stability is excellent.

[0096] Impeller with 15 blades (inlet angle α1 = 20°-25°, outlet angle α2 = 42°), volute k = 1.06, air volume 12000 m³ / h 3 Experimental and theoretical data (blade thickness parameter set) under the conditions of / h and rotation speed of 2900 r / min:

[0097]

[0098] Impeller with 15 blades (t1 = 3.3 mm, t2 = 2.9 mm, α1 = 22°), volute tongue R = 16 mm, collector θ = 13°, air volume 12000 m³ / h 3 Experimental and theoretical data (volute expansion coefficient parameter set) under / h conditions:

[0099]

[0100] Optimal solution for each data point:

[0101]

[0102] The core design revolves around the synergistic combination of "impeller α1=22°+α2=42°+t1=3.3mm / t2=2.9mm" and "volute k=1.06+R=16mm", ultimately achieving the dual goals of high efficiency and low noise.

[0103] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, alterations, substitutions, or variations made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A high-efficiency, low-noise centrifugal fan, characterized in that: It includes an impeller (4), a volute (3) and a collector (2). The impeller (4) is rotatably disposed inside the volute (3). The impeller (4) includes a hub (402) and a plurality of blades (401) arranged in a circumferential array around the hub (402). The air inlet of the volute (3) is connected to the collector (2). The thickness of the blade (401) decreases linearly from the inlet end to the outlet end; The thickness of the blade (401) satisfies the total pressure efficiency correlation formula η=-12.8t1 2 -28.5t2 2 +132.6t1+168.4t2-426.3 and the operating noise correlation formula L p =8.5t1 2 +15.2t2 2 -58.3t1-86.4t2+228.6; The cross-section of the volute (3) exhibits exponential expansion with an expansion coefficient of k, where 1.05 ≤ k ≤ 1.08; and the expansion coefficient k satisfies the total pressure efficiency correlation formula η = -2450k. 2 +5166k-2718, Operating noise correlation formula L p =1800k 2 -3816k+2040 and the correlation formula for airflow uniformity φ=-4800k 2 +10176k-5370.

2. The high-efficiency, low-noise centrifugal fan according to claim 1, characterized in that: The inlet angle of the blade (401) is α1, where 20°≤α1≤25°; The exit angle of the blade (401) is α2, 36°≤α2≤49°; The thickness of the inlet end of the blade (401) is t1, 3.2mm≤t1≤3.5mm; The thickness of the blade (401) at the exit end is t2, where 2.8 mm ≤ t2 ≤ 3.0 mm; Equation of the upper surface curve: Equation of the lower surface curve: Thickness function: t(λ)=t1-(t1-t2)λ (t=t1 when λ=0, t=t2 when λ=1) Profile reference factor: The thickness direction is the y-axis, and the chord length direction is the x-axis; L is the blade chord length; k0 = tan(90° - α1) (the slope of the tangent at the inlet end, corresponding to α1 = 20° - 25°, k0 = tan(70°) - tan(65°) ≈ 2.747 - 1.428); k1 = tan(α2 - 90°) (the slope of the tangent at the exit end, corresponding to α2 = 36° - 49°, k1 = tan(-54°) - tan(-41°) ≈ -1.376 - (-0.869)); The slope of the tangent at the inlet end (x=0) corresponds to the inlet angle α1: tan(90°-α1)=dy / dx| x =0 (leading edge airflow injection angle); The slope of the tangent at the exit end (x=L) corresponds to the exit angle α2: tan(α2-90°)=dy / dx| x =L (the angle of the airflow exiting from the trailing edge).

3. The high-efficiency, low-noise centrifugal fan according to claim 1, characterized in that: The number of blades (401) is m, where 14 ≤ m ≤ 16.

4. The high-efficiency, low-noise centrifugal fan according to claim 1, characterized in that: The volute tongue (301) has an arc structure with a radius of R, which is 15mm≤R≤18mm.

5. The high-efficiency, low-noise centrifugal fan according to claim 1, characterized in that: The collector (2) has a flared structure with a flared angle of θ, 12°≤θ≤15°; and an inlet diameter of D1, 180mm≤D1≤200mm.

6. The high-efficiency, low-noise centrifugal fan according to claim 1, characterized in that: The radial clearance between the impeller (4) and the volute (3) is 0.8 mm to 1.0 mm.

7. The high-efficiency, low-noise centrifugal fan according to claim 1, characterized in that: The inner wall of the volute (3) is covered with a nanoporous sound-absorbing coating (5) with a thickness of 0.5 mm to 0.8 mm.

8. The high-efficiency, low-noise centrifugal fan according to claim 1, characterized in that: The outer diameter of the impeller is D2350mm≤D2≤400mm, and the ratio of the diameter of the hub (402) to the diameter of the impeller (4) (hub ratio) is 0.35-0.

4.

9. A high-efficiency, low-noise centrifugal fan according to claims 1-8, characterized in that: With the above-mentioned structural combination, the total pressure efficiency of the centrifugal fan is ≥82%, and the operating noise is ≤75dB(A).

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