KR100798103B1 - Axial Fan and Multi Sectioning Design Method therefor - Google Patents

Abstract

The present invention relates to a multi-zone design method of an axial fan, and the present invention selects a fan diameter using the relationship between the specific speed and the diameter of the Cordier based on the design flow rate and pressure at the operating point. Determining a torque (T *) at an expected operating point from the motor torque characteristic based on the design speed (N *) or the speed from the specific speed of the cordiery in consideration of noise and the like; A second step of determining the number of regions for the multi-region design when the estimated efficiency at the operating point is determined to be low or too large than the estimated torque based on the operating point torque; Determining a voltage distribution function based on a desired torque characteristic to determine an installation angle distribution, a code length distribution, a camber angle distribution, a bending angle distribution, a wing thickness distribution, and the like in each multi-domain so as to satisfy a given performance; A fourth step of assuming velocity triangle determination, flow variable calculation and efficiency; Determining a cutting ratio based on the value of the fourth step, and calculating a detailed camber angle, entrance angle, exit deviation angle, boundary layer thickness, stagger angle, and the like; A sixth step of applying the value calculated in the fifth step to the loss model to determine the efficiency and repeatedly performing the fifth step by adjusting the code length and camber angle again if the desired efficiency is not reached; A seventh step of calculating torque again using the converged efficiency through the sixth step; From the second step to the seventh step until the rotation speed (N) is obtained from the motor torque characteristic curve based on the magnitude of the torque calculated in the seventh step and converges to the design rotation speed (N *) in consideration of noise and the like. Iterating the multi-regional design by repeating the ;; characterized in that it comprises a.

Fan, blower, multi-zone design, impeller, vortex dispersion section, axial flow type, high efficiency, low noise design, rear stage noise

Description

Axial Fan and Multi Sectioning Design Method therefor}

1 is a graph showing the performance characteristics of a conventional DC motor,

2 is a view showing the definition of design variables in the wing cross-sectional design,

3 is a view showing the vortex characteristics occurring on the axial fan produced by a conventional design method,

4 is a view showing the vortex characteristics on the fan by the multiple sweep angle of the axial fan manufactured by a conventional design method,

5 is a view showing the vortex characteristics on the fan by the multi-zone design method of the axial fan according to the present invention,

6 is a flow chart showing a multi-zone design process of the axial fan according to the present invention;

7 is a perspective view showing a propeller-type impeller blade produced by the multi-zone design method of the axial fan according to the present invention;

8 is a graph showing the installation angle distribution of the propeller-type impeller blade shown in FIG.

9 is a schematic view showing the automobile shroud axial fan by the multi-zone design method of the axial fan according to the present invention;

FIG. 10 is a graph showing an installation angle distribution of an automobile shroud axial fan shown in FIG. 9;

11 is a graph showing the movement of the highest efficiency point by the multi-zone design method of the axial fan according to the present invention,

12a is a graph comparing the noise characteristics of the propeller-type impeller blade according to the multi-zone design method and the prior art of the axial fan according to the present invention;

12b is a graph comparing the noise characteristics of the shroud axial fan according to the multi-zone design method of the axial fan and the prior art according to the present invention;

Figure 13 is a table comparing the sound analysis for the fan by the fan design method of the present invention and the prior art measured under the same performance conditions.

* Description of Signs for Main Parts in Drawings *

10: propeller type impeller wing 20: shroud axial flow fan

The present invention relates to a method for designing an axial fan and an axial fan manufactured by the design method. In particular, a multi-zone design method for an axial fan capable of reducing noise and adjusting a load of a fan to obtain the highest efficiency at a desired design point. And an axial fan manufactured by the design method.

In general, research on the aerodynamic design of blowers has been ongoing for decades, and many advances have been made in the design technique. Recently, however, the demand for noise as well as performance has increased and the production cycle of products has been shortened, requiring the development of higher level design means.

In particular, the blower consists of a combination of a motor and a fan, and the motor itself has a torque point with optimum efficiency. Even if the fan is well designed, designing without considering the torque matching between the motor and the fan causes a decrease in the overall efficiency.

Therefore, before designing the fan, it is necessary to understand the performance and characteristics of the motor. A general motor characteristic curve is shown in FIG. 1. The x-axis of FIG. 1 represents a torque value, the left y-axis represents a current value, and the right y-axis represents a rotation speed. In a typical DC motor, the point where the current value and the number of revolutions cross each other is the best motor efficiency. This point is set as the number of revolutions at the design point of the fan when the fan is designed. Using the design rotation speed in the part that is not the optimum efficiency point of the motor caused problems such as the reduction of the overall efficiency of the fan motor coupling and the increase of power consumption. For reference, Figure 2 is a view showing the definition of the design variables in the wing cross-section design, β1 is the wing inlet angle, β2 is the wing exit angle, θ is the wing chamber angle, ξ is the wing installation angle, ι is the inlet angle and δ Represents the flow leaving angle.

After all, torque matching between motor and fan is an important issue in fan design. For example, pressure (ΔP) is 10.2 mmAq (= 99.98 Pa), flow rate (Q) is 2800 CMH (= 2800/3600 CMS), efficiency (η) is 40%, RPM is 2400 (i.e., rotation angle per Ω If there is a fan of) 2π × 2400/60), the torque is calculated by the following Equation 1.

Therefore, the torque of a fan is 7.89 kgfcm from 1N * m = 10.1972kgfcm. However, Δp = 10.2mmAq = 99.98Pa, Q = 2800CMH = 2800/3600 = 0.778 CMS, efficiency (η) = 0.4 (assuming fan efficiency), RPM = 2400 (angle of rotation per second (Ω) = 2π × 2400/60) to be.

By predicting the torque of the fan in the same manner as in Equation 1, a design guideline can be obtained for load and efficiency problems in the initial fan design. In addition, the prediction of the efficiency is performed by a Cordier's equation or a performance prediction method using a loss model.

On the other hand, there are many factors that affect noise. First of all, the length of the cord is required for the required pressure rise and flow rate, but the pressure increases as the length of the cord increases. Increasing the cord length also increases noise level and power, which has a negative effect. The camber angle directly affects the lift coefficient (C _L ) along with the angle of inclination. That is, as the camber angle increases, the lift coefficient increases and the pressure generated also increases. However, excessively large camber angles cause flow separation and increase noise and profile loss due to interaction with the wing tip. In this case, as can be seen from the description of the two variables, there is a method of reducing the code length or camber angle as a strategy for reducing noise, but if both of them are reduced, the desired design result may not be achieved. Calculate the appropriate cord lengths and camber angles to minimize noise in the range. Sweep angle does not affect performance very much, but it is a variable that affects noise, so it can be adjusted by focusing mainly on noise.

The principle of the method using this angle of deflection is that when the wing rotates, it affects the path of the fluid particles in the boundary layer and due to the centrifugal force, the streamline is bent in the radial direction. If the angle is backwards, the flow path moves outwards before reaching the trailing edge, especially when the angle is very large. Conversely, with forward deflection angles, the flow path is shorter than in the original wing. Thus, for very large forward bend angles, the boundary layer thickness is generally thinner than for straight lines, and thicker for backward bend angle wings. However, it is difficult to accurately determine the bending angle in the wings of various shapes, and it is difficult to predict the exact effect of performance because the flow pattern changes according to the shape of the wings and the length of the cord through the flow changes.

Using the characteristics of this bending angle, Korean Laid-Open Patent Publication No. 2002-0094183 devised a waveform of alternating forward and backward shapes as the front and rear ends of the wings move from the hub to the tip of the blade, and flow through the plane of multiple curvatures on the wings. An axial fan is proposed to achieve the effect of dispersion. In addition, U.S. Patent 5,906,179 proposes an axial fan having a minimum value at an arbitrary position with the cord length of the wing varying from the hub to the tip of the blade. The fan is running out.

On the other hand, another effect of the bending angle is the change in lift. In the presence of a bending angle, the lift force is calculated according to the wing code direction, so the bending angle decreases in proportion to the cosine function. This also affects the vortices that are important in determining the noise equation. The factors by which the forward deflection angle reduces noise can be divided as follows. First, noise resonance due to the change of wing shape does not occur very well. Second, the fluid passing through the wing has less influence on the next wing. Reducing vortices. The first and second affect the reduction of interference noise, and the third also affect the reduction of turbulent boundary layer noise. Depending on the shape of the wing, it is known to reduce noise by about 5-10dB _A at 40 ° -50 °.

However, the design method of the existing patent for creating a flow dispersion zone through the bending angle is difficult to design the bending angle distribution corresponding to the characteristics of the motor torque because the change in lift due to the various distribution of the bending angle cannot be reflected in the design. Therefore, due to the various distributions of the bending angles, it is more appropriate to explain the rear noise reduction due to the interaction of the vortex structure at the rear stage than the acoustic cancellation at the leading edge of the blade. In addition, by moving the design point satisfies the performance under various load conditions, and the fan having a vortex dispersion zone has a problem that is impossible by the distribution of the bending angle.

In addition, another method of axial fan low noise is to reduce the noise of the fan by suppressing the vortex of the tip of the blade in the axial fan. At the tip of the wing, the vortex that rotates from the pressure side to the negative pressure side occurs, which not only acts as a loss factor that reduces the blowing efficiency of the axial fan, but also acts as a main factor causing fan noise. At this time, the vortex takes the form of a flow from the blade pressure side to the negative pressure side through the tip of the wing. As described above, in order to improve fan noise due to noise radiation by various noise sources, a reverse design technique for changing the voltage distribution function from the hub to the end of the impeller to find the desired noise distribution function is disclosed. .

On the other hand, when the fluid passes through the blade, the fluid is accelerated at the upper portion (negative pressure surface) of the blade, and the speed is increased, and at the lower portion (pressure surface), it is slowed down. This change in velocity results in a change in pressure and a decrease in pressure on the negative pressure side where the speed increases, and conversely, on the pressure side in which the speed decreases. This pressure difference leads to energy transfer to the fluid by the rotating blades. On the negative pressure side, the pressure is lower than the atmospheric pressure, so the dimensionless pressure value is negative, and on the pressure side, the pressure increases to have a positive value, and the pressure difference between the negative pressure side and the pressure side is at the leading edge of the wing. It is large and known to decrease toward the rear end. In addition, in the case of the negative pressure surface, there exists a reverse pressure gradient and a lot of pressure drops at the leading edge near the wing tip. In general, the pressure at the leading edge of the tip is the highest in terms of pressure. That is, when designing the axial flow fan as a general design technique, as shown in Figure 3, there is a difference between the pressure value and the flow rate between the pressure surface and the negative pressure surface, but the flow flow proceeds in a similar direction and eventually occurs in the rear pressure side The rear end (TE) noise is increased when it collides with the wake accompanied by flow separation from the vortex and negative pressure surface.

In addition, the design technique shown in Figure 4 is to reduce the noise in the form of the angle of bending of each wing forward and backward cross, which is as shown in Figure 4 each wing between at least three sections between the hub and the end The direction of the bending angle in each of the section is divided into the shape from the front to the rear or the rear to the forward direction. In addition, due to the influence of the bending angle, the wing thickness change occurs at the same dimensionless code position (s / C), thereby creating a flow dispersion section. However, due to the combined effects of forward and backward, the boundary layer becomes thinner in one section and thicker in other sections, which reduces the interference of the trailing vortex, but in some cases may be worsened.

In order to solve the above problems, the present invention is to reduce the load loss in the middle region of the wing to create a distribution zone of the load to distribute the pressure by lowering the trailing edge of the blade (Trailing-Edge) noise due to the abnormal load multiple The purpose is to provide a domain design method.

Another object of the present invention is to provide a multi-zone design method for an axial fan that adjusts the load of the fan to increase the efficiency at a desired design point and move the highest efficiency point.

In order to achieve the above object, fan diameter is selected using the relationship between the specific speed and the diameter of Cordier based on the design flow rate and pressure at the operating point, and the design speed (N *) Or a first step of determining the torque T * at the expected operating point from the motor torque characteristic based on the rotational speed from the specific speed of the cordiery; A second step of determining the number of regions for the multi-region design when the estimated efficiency at the operating point is determined to be low or too large than the estimated torque based on the operating point torque; Determining a voltage distribution function based on a desired torque characteristic to determine an installation angle distribution, a code length distribution, a camber angle distribution, a bending angle distribution, a wing thickness distribution, and the like in each multi-domain so as to satisfy a given performance; A fourth step that assumes determination of the velocity triangle, flow variable calculation and efficiency; A fifth step of determining the cutting ratio based on the value of the fourth step, and calculating a detailed camber angle, entrance angle, exit deviation angle, boundary layer thickness and stagger angle; A sixth step of repeatedly applying the value calculated in the fifth step to the loss model to determine the efficiency and repeatedly adjusting the code length and camber angle if the desired efficiency is not reached; A seventh step of calculating torque again using the converged efficiency through the sixth step; From the second step to the seventh step until the rotation speed (N) is obtained from the motor torque characteristic curve based on the magnitude of the torque calculated in the seventh step and converges to the design rotation speed (N *) in consideration of noise and the like. A multi-zone design method for an axial fan comprising a; repeating to proceed to the multi-zone design.

Another feature of the present invention, in the axial flow fan manufactured by the axial flow fan multi-zone design method, satisfies the flow rate and static pressure rise, and installed while going to the end of the blade so that the rotation speed decrease due to insufficient torque of the fan motor It provides an axial fan, characterized in that the combination of two or more wings to increase the installation angle while going to the wing tip and the wing tip is reduced.

In this case, the joining in the wing span direction can achieve a smooth wing surface by matching at least the position function value, the tangent of the connecting line and the first derivative in the normal direction at each connection point.

At least one minimum value of the steepness distribution function in the middle region of the wing is distributed, and the rear end vortices due to the curvature distribution on the wing are dispersed to interact with the vortex on the pressure surface and the wake on the negative pressure surface. This can reduce BPF noise and broadband turbulence noise.

In another aspect of the present invention, in the axial fan manufactured by the axial fan multi-zone design method, in order to create a dispersion zone of the vortex of the trailing edge of the wing, the leading edge is any one of backward to forward, forward to backward, full backward, and total forward. It has a bending angle distribution with one, and the cord length of the wing varies from hub to the tip of the wing and has a minimum value at one or more positions between the hub and the tip of the wing, forming a vortex dispersion zone, and creating a vortex dispersion zone at the middle of the wing. The axial flow fan is characterized by reducing the interaction between the vortex at the rear end of the negative pressure side and the negative pressure side wake by differently flowing the vortex on the negative pressure side and the pressure side.

Hereinafter, a multi-region design method of an axial fan according to the present invention will be described with reference to the accompanying drawings.

5 is a view showing the vortex characteristics on the blade by the multi-zone design method of the axial fan according to the present invention.

Multi-sectioning design method according to the present invention is not a method of making the flow dispersion zone through the bending angle as in the prior art, but as a method of making the vortex dispersion zone through the installation angle, as shown in Fig. By creating vortex dispersion zones in the sections, the flows on the negative pressure side and the pressure side are different, which reduces the interaction between the vortices at the rear end of the negative pressure side and the wake of the negative pressure side, allowing the maximum efficiency point to be shifted.

In the case of the pressure surface, the flow is divided into two sides on the basis of the vortex dispersion zone, and the flow of the part where the flow is divided has the effect of lowering the inlet angle. As a result, the vortex strength generated at the rear end is lower than that of the fan designed by the general design technique, thereby reducing the broadband noise in the vortex dispersion zone.

6 is a flow chart of a multi-section design method according to the present invention.

First, given the design flow rate Q and the pressure ΔP _T at the operating point (S1), the wing type (NACA, ARC, C4, Cottingen, etc.) and the number of wings (NZ) are selected (S2). Based on this, the fan diameter (D) is selected using the relationship between the specific speed (Ns) and the specific diameter (Ds) of Cordier, and also the design rotation speed (N *) or cordierier considering the noise Determines Hub-Tip ratio (d / D) considering the dispersion factor of rotation speed (N *) from the specific velocity of (Cordier) and predicted from motor torque characteristics based on rotation speed (N *) The torque T * at the operating point is determined (S3).
If it is determined that the expected efficiency at the operating point is low or too large than the expected torque based on the motor torque, a multisection such as the number N of regions for the multi-region design is selected (S4). Thus, the voltage distribution coefficients are determined based on the desired torque characteristics from the first section (i = 1) to the last Nth section (i = N), so that in each multi-domain (i = 1 to N) to satisfy the given performance. The installation angle distribution, cord length distribution, camber angle distribution, bending angle distribution, wing thickness distribution, etc. are determined, and the detailed design of these wings is calculated repeatedly until the overall efficiency converges (from S5 to S10). That is, after assuming the determination of the velocity triangle, the calculation of the flow variables (β1, β2, W1, W2, W∞, φ) and the efficiency (ηo) (S6), based on this to determine the ratio (Solidity) (S7) Then, the camber angle, inlet angle, exit angle, boundary layer thickness and stagger angle (β1, β2, W1, W2, W∞, Cθ, φ, ξ) are calculated (S8) and applied to the loss model ( S9), the efficiency is judged (S10), and if the desired efficiency is not reached (i.e., no convergence ((η _{n + 1} -η _n ) / η _{n + 1} ≥ε1), the code length and camber angle again (S11), the process of S7 to S10 is repeated.
In addition, if the desired efficiency comes out in the step S10 ((η _{n + 1} -η _n ) / η _{n + 1} <ε 1), repeating the process of S10 to S10 for the next section while increasing i by one If all sections are completed, the loop of S5 to S10 is exited. In the process of S5 in FIG. 6, steps i in the predetermined loops S5 to S10 starting from 1 (S51) and increasing by one (S53) until determining efficiency when i = N are performed. Repeat (S52) means)
The torque is calculated again according to Equation 1 using the converged efficiency (S12), and the rotation speed (N) is obtained from the motor torque characteristic curve based on the calculated magnitude of the torque (S13). It is determined whether to converge to the design rotation speed (N *) (S14), otherwise ((NN *) / N * ≥ε2), the entire process (S4 to S14) is repeated until the convergence is performed for each multi-region. The design will proceed.
Finally, when it is determined in step S14 that the currently designed motor speed N converges to the first desired speed N * ((NN *) / N * <ε2), drawings and STL The data file of the format form is output and the design data is represented (S15), thereby completing the multi-region design of the axial fan according to the present invention.

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7 and 9 show a propeller type axial fan 10 (see FIG. 7) and a shroud axial fan 20 (see FIG. 9) using the multi-zone design method of the axial fan according to the present invention.

Where Ns is the specific velocity (relative conduction), angular velocity is N (= 2πf) (f is RPM), flow rate or pump discharge rate is Q (m3 / s), pressure is ΔP (Pa), specific gravity is ρ For reference, ΔP / ρ represents the total head (Head).

7 and 9 show a shape designed by applying to a propeller-type axial fan 10 having a specific speed of 3.01 and a shroud axial fan 20 of a vehicle cooling device having a specific speed of 7.52 calculated through Equation 2, respectively. Giving. In this case, the installation angle distribution applied to each is shown in Figs. 8 and 10, respectively.

In addition, as shown in Figure 11, the maximum efficiency point of the conventional fan is located at most intermediate points, not the maximum flow rate point, in the case of the multi-zone design method of the axial flow fan according to the present invention can increase the efficiency toward the maximum flow rate point Will be. In the conventional fan design technique, the distribution of the installation angle is the largest in the hub side and the distribution decreases toward the end, whereas the installation angle distribution of the multi-zone design method according to the present invention is shown in FIG. 8 and FIG. 10. It decreases to the middle region and then increases from the middle region to the end. In order to produce a large flow rate, it is preferable to have a large value of the installation angle at the end of which the rotation speed is large. However, the fan manufactured by the conventional design method increases the installation angle of the end is abnormally increased the installation angle at the hub. Therefore, the overall fan load is increased, resulting in a decrease in flow rate due to an increase in power consumption and a decrease in rotational speed.

On the other hand, Figure 12a is a graph comparing the noise of the propeller-type axial fan 10 produced by the multi-zone design method and the conventional design method according to the present invention, Figure 12b is a multi-domain design method and a conventional design according to the present invention It is a graph which compared the noise of the shroud axial flow fan 20 of the automobile cooling apparatus produced by the method. As shown in Figure 12a and 12b, the BPF frequency and broadband turbulent noise generated in the axial flow fans (10,20) made in accordance with the present invention appears to be about 5dB _A lower as compared to the conventional invention. In other words, the reason why the noise in the high frequency band is reduced is to make the vortex dispersion zone near the middle span to change the vortic flow between the negative pressure side and the pressure side to disperse the vortices at the rear end and to reduce the vorticity due to interaction. Because. In addition, since the operating point or design point of the fan is different for each type of fan, it is possible to design a fan having an optimal use point by adjusting the position of the vortex dispersion zone using the multi-zone design method according to the present invention.

Figure 13 is a table comparing the sound analysis for the fan by the conventional fan design method and the multi-zone design method according to the present invention measured under the same performance conditions.

On the other hand, in psychoacoustics dealing with correlating the subjective evaluation of sound quality with the physical characteristics of the sound signal, the main factors that determine sound quality are loudness, sharpness, roughness, and variation intensity ( Fluctuation Strength).

While sharpness, roughness, and fluctuation intensity are the basic hearings that explain the cause of sound, loudness refers to the loudness of a subjective subjective feeling and is an important factor in determining sound quality in itself. Even if the noise has the same loudness value or noise level, the noise with major noise components in the high frequency band is sharper and more cumbersome than the noise. This measure of hearing is defined as sharpness, which is determined by the frequency distribution of non-loudness. If the fluctuation intensity increases above 20Hz, the fluctuation intensity is hardly felt and a rough feeling is felt. Roughness is a measure of the roughness of the subjective feeling. Noise that is amplitude or frequency modulated below 20 Hz will be more annoying than it would be if exposed to steady-state noise. In other words, the variation intensity refers to the subjective perception of the property of feeling negative change.

Referring to FIG. 13, when Ns = 7.52, the SPL value of the fan by the multi-domain design technique is low, and the values such as loudness, sharpness, roughness, and fluctuation strength are all lowered. . In particular, as a result of applying the same fan with 7.52 specific velocity, the loudness and fluctuation strength of the sound index, as well as the sound index, are remarkably improved.

In the present invention described above, BPF compared with the conventional design method by designing the installation angle, camber angle, and cord length among the main factors for determining the shape of the fan with minimum or minimum values in the middle span of the blade of the fan which is the vortex dispersion section. There is an advantage in reducing the turbulent noise of frequency and broadband.

In addition, the load of the fan can be adjusted to increase the efficiency at the desired design point, and the highest efficiency point can be moved.

 In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments, and the present invention is not limited to the spirit of the present invention. Various changes and modifications will be possible by those who have the same.

Claims (5)

Based on the design flow rate and pressure at the operating point, the fan diameter is selected using the relationship between the specific speed and the diameter of the Cordier, and the design speed (N *) or the specific speed of the Cordier in consideration of noise, etc. Determining a torque (T *) at an expected operating point from the motor torque characteristic based on the rotational speed from; A second step of determining the number of regions for the multi-region design when the estimated efficiency at the operating point is determined to be low or too large than the estimated torque based on the operating point torque; Determining a voltage distribution function based on a desired torque characteristic to determine an installation angle distribution, a code length distribution, a camber angle distribution, a bending angle distribution, a wing thickness distribution, and the like in each multi-domain so as to satisfy a given performance; A fourth step of assuming velocity triangle determination, flow variable calculation and efficiency; A fifth step of determining the cutting ratio based on the value of the fourth step and calculating a detailed camber angle, entrance angle, exit deviation angle, boundary layer thickness, stagger angle, and the like; A sixth step of applying the value calculated in the fifth step to the loss model to determine the efficiency and repeatedly performing the fifth step by adjusting the code length and camber angle again if the desired efficiency is not reached; A seventh step of calculating torque again using the converged efficiency through the sixth step; Based on the magnitude of the torque calculated in the seventh step, the rotation speed (N) is obtained from the motor torque characteristic curve, and the second and the second steps are performed until they converge to the design rotation speed (N *) considering noise and the like. The multi-zone design method of the axial flow fan comprising a; repeating step 7 to proceed to the multi-zone design. An axial flow fan manufactured by the axial flow fan multi-zone design method of claim 1, At least one wing that satisfies the flow rate and the static pressure rise, and that the installation angle decreases toward the tip of the blade and the installation angle increases toward the tip of the blade so as not to reduce the rotational speed due to insufficient torque of the fan motor An axial flow fan, characterized in that at least two wings are joined. The method of claim 2, Bonding in the wing span direction is a axial flow fan characterized in that a smooth wing surface is formed by matching at least the position function value, the tangent of the connecting line and the first derivative in the normal direction at each connection point of the two or more wings. The method of claim 2, At least one minimum value of the Steger angle distribution function in the middle region of the blade is present, and the rear vortices due to the curvature distribution on the blade are dispersed to interact with the vortex on the pressure surface and the wake on the negative pressure surface. Axial flow fan, characterized in that to reduce the BPF noise and broadband turbulent noise. An axial flow fan manufactured by the axial flow fan multi-zone design method of claim 1, The leading edge has a bend angle distribution in any one of backward to forward, forward to backward, full backward, and full forward directions to create a dispersal zone of the wing trailing vortex, and the cord length of the wing varies from the hub to the wing tip and the hub and the wing tip To form a vortex dispersion zone with minimum values at one or more locations in between, By forming the vortex dispersion zone in the middle of the wing to make the flow of the vortex on the negative pressure side and the pressure side different, reducing the interaction between the vortex at the rear side of the negative pressure side and the wake of the negative pressure side to reduce broadband noise. Axial flow fan.

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