A fan blade optimization design method based on blade profile curve and a high-efficiency fan

Abstract

The present invention provides a blade optimization design method based on a blade profile curve and a high-efficiency fan, which obtains an intersecting curve by using a concentric section coaxial with the direction of the rotating shaft to cross-section the blade with a curved surface, and then unfolds the plane to obtain a blade profile curve, wherein the blade profile curve is the trajectory surface of the air hit by the fan pressure surface (i.e., the surface facing the axial outflow wind direction) in its movement direction; the curvature, radian or inclination angle elements of the blade profile curve are adjusted according to performance goals and size goals, thereby achieving optimized adjustment of the fan blade surface that directly hits the air, hitting the air with the optimal curved surface, the fan has high efficiency, few back vortices, and large vortices are broken up into small vortices, thereby directly reducing the vibration of the blades and the wind noise during operation, and solving the problems of large fan vibration and high operating noise.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioning equipment, and specifically relates to a fan blade optimization design method based on a blade profile curve and a high-efficiency fan. Background Art

[0002] Noise and vibration in air conditioners have always been an important criterion for the quality of air conditioners. The fan blades of the air conditioner outdoor unit are not only required to effectively reduce vibration, but also to reduce noise to provide a comfortable environment for users.

[0003] Fan vibration and aerodynamic noise are mainly caused by the blades hitting the surrounding air, generating pressure pulsations, which also cause rotational noise, and the surrounding air pressure distribution characteristics causing local eddies and eddy current noise. Summary of the invention

[0004] The present invention aims to provide a fan blade optimization design method based on a blade profile curve to solve the problems of large fan vibration and high operating noise.

[0005] The specific scheme is as follows: A fan blade optimization design method based on blade profile curve, comprising:

[0006] S1, with the fan rotation axis as the central axis, multiple groups of cylindrical concentric sections are set; the concentric sections intersect with the pressure surface of the fan blade to obtain an intersection curve;

[0007] S2, unfold the intersecting curve plane to obtain the blade curve;

[0008] S3, adjusting the curvature, radian or inclination angle of the blade profile according to the performance target or size target;

[0009] S4, according to the corresponding concentric cross-sections, each blade curve is wound and arranged in sequence, and adjacent blade curves are connected with a smooth surface to obtain an optimized fan blade pressure surface.

[0010] Furthermore, it also includes:

[0011] S5, establishing an optimized fan model, and obtaining air volume, pressure, flow field distribution or pressure distribution parameters through CFD numerical simulation analysis.

[0012] Furthermore, in step S1, adjacent concentric cross sections are arranged at equal intervals.

[0013] Furthermore, the spacing between adjacent concentric sections is 1 / 10 of the blade diameter.

[0014] Further, in step S3, the blade profile curve is an arc line convex toward the airflow direction of the fan.

[0015] The present invention also provides a high-efficiency fan, comprising a central rotor and fan blades fixed on the central rotor, wherein the side of the fan blade facing the air outlet direction is a pressure surface; the fan is characterized in that there are multiple cylindrical concentric sections coaxial with the central rotor axis, and the plane unfolding line of the intersection of the concentric section and the pressure surface is a circular arc line.

[0016] A further technical solution of the high-efficiency fan of the present invention is that along the radial direction of the fan blades, the intersection lines of the circular arc lines are evenly distributed at equal intervals.

[0017] Beneficial effect: The blade optimization design method based on blade profile curve and the high-efficiency fan of the present invention obtain an intersecting curve by cross-cutting the blade with a curved surface through a concentric section coaxial with the direction of the rotating shaft, and then unfolding the plane to obtain a blade profile curve. The blade profile curve is the trajectory surface of the air hit by the fan pressure surface (that is, the surface facing the axial outflow wind direction) in its movement direction; it adjusts the curvature, radian or inclination elements of the blade profile curve through performance goals and size goals, thereby realizing the optimization adjustment of the fan blade surface that directly hits the air, hitting the air with the optimal curved surface, the fan efficiency is high, the back vortex is small, and the large vortex is broken up into small vortices, which directly reduces the vibration of the blade and the wind noise during operation, and solves the problems of large fan vibration and high operating noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A side view of the fan is shown;

[0019] Figure 2 A front view of a plurality of concentric sections across the fan is shown;

[0020] Figure 3 A front view of the intersecting curves on the fan blade is shown;

[0021] Figure 4 A front view showing the process of developing the intersection curve;

[0022] Figure 5 The blade profile curve after expansion is shown;

[0023] Figure 6 The shaft power curves of the comparative example and the embodiment of the present invention are shown;

[0024] Figure 7 The performance curves of the comparative example and the embodiment of the present invention are shown. DETAILED DESCRIPTION

[0025] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0026] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0027] Combination Figures 1 to 5 As shown, this embodiment provides a blade optimization design method based on blade profile curve, which is used to optimize a low-pressure axial flow fan. The fan has a central rotor 1, and three blades 2 are evenly distributed on the circumference of the central rotor 1. Each blade has a pressure surface 20 protruding toward the air outlet direction of the axis. The pressure surface 20 directly hits the air at the front end through the rotation of the central rotor 1 to force the airflow to flow out axially.

[0028] The fan blade optimization design method comprises the following steps:

[0029] S1, with the rotation axis of the fan central rotor 1 as the central axis, multiple groups of cylindrical concentric sections 3 are set. In this embodiment, preferably 6 groups of concentric sections are set; the concentric sections intersect with the pressure surface 20 of the fan blade 2 to obtain an intersection curve 30;

[0030] In this step, each adjacent concentric section 3 is arranged at equal intervals, and the interval between adjacent concentric sections is 1 / 10 of the rotation diameter of the blade 2. The section of the blade 2 close to the central rotor 1 has a low linear speed and a small effective area, and the optimization design can be omitted; the section close to the outer edge of the blade 2 needs to be set with a smooth outer edge transition, which is not suitable for the optimization design of the concentric section 3.

[0031] S2, unfolding the intersecting curve 30 in a plane to obtain a blade profile curve 31, wherein the specific unfolding method is to unfold the intersecting curve 30 in a plane perpendicular to the radial direction of the blade 2, thereby realizing the opening of the intersecting curve 30 in a two-dimensional plane;

[0032] S3, adjusting the curvature, radian or inclination angle of the blade profile according to the performance target or size target;

[0033] In this step, the blade profile curve 31 is an arc line convex toward the airflow direction of the fan, and has a chord length A and an inclination angle B.

[0034] S4, according to the corresponding concentric cross-sections, each blade curve is wound and arranged in sequence, and adjacent blade curves are connected with a smooth surface to obtain an optimized fan blade pressure surface.

[0035] S5, establishing an optimized fan model, and obtaining air volume, pressure, flow field distribution or pressure distribution parameters through CFD numerical simulation analysis.

[0036] The embodiment also provides a high-efficiency fan using the blade optimization design method based on the blade profile curve, comprising a central rotor 1 and blades 2 fixed on the central rotor 1, wherein the side of the blade 2 facing the air outlet direction is a pressure surface 20; there are multiple cylindrical concentric sections coaxial with the central rotor axis, and the plane unfolding lines of the intersection lines of the concentric sections and the pressure surface are circular arc lines; and along the radial direction of the blade 2, the intersection lines unfolded into circular arc lines are evenly spaced and arranged.

[0037] After optimization, the blade curve elements of the fan are shown in Table 1:

[0038] Table 1: Blade curve elements

[0039] diameter inclination Chord Length First blade curve 330 31.3 281 Second leaf curve 396 30.14 330 The third leaf curve 462 29.16 374 Fourth leaf curve 528 28.06 407 Fifth leaf curve 594 26.78 449 Sixth leaf curve 660 24.79 503

[0040] Among them, compared with the existing fans on the market, that is, the fans before optimization, their diameter, number of blades, pressure surface projection and blade axial projection are the same as those of the optimized fans. The main difference is that the pressure surface of the existing fans is a regular curved surface, and the intersection line intercepted by its concentric sections is an irregular curve.

[0041] The existing fans on the market and the optimized fans are modeled as model "old" and model "new" respectively, and CFD numerical simulation analysis is performed. The fan speed is fixed at 920rpm, and the performance data of the two fan models are obtained in Tables 2 and 3:

[0042] Table 2: Fan model "old" performance data table

[0043]

[0044] Table 3: Fan model "new" performance data table

[0045]

[0046] According to Table 2 and Table 3, draw Figure 6 The shaft power curve is shown:

[0047] From the shaft power curve, we can see that the shaft power of the newly designed fan, i.e. the model "new", is significantly lower than that of the original fan, i.e. the model "old". That is, under the same air volume output, it consumes less power, has less eddy current during fan operation, has less friction resistance between the blades and airflow, and has low fan noise.

[0048] At the same time, combined with the shaft power curve, it can be seen that the shaft power of the newly designed fan has an obvious "inflection point" effect: that is, the shaft power curve of the model "new" is obviously different from the traditional inverted "U"-shaped shaft power curve of the model "old". 3 / h), there is a local minimum point of shaft power, which can be used as a point for selecting a limited flow rate high-efficiency gear. That is, in step S5 of this embodiment, the optimized shaft power curve can be obtained through CFD numerical simulation analysis, and the optimized fan high-efficiency flow parameters can be obtained.

[0049] This optimization design method is particularly suitable for fan equipment with multi-speed adjustment of air output. It can optimize shaft power by adjusting flow parameters and further effectively reduce power consumption.

[0050] At the same time, according to Table 2 and Table 3, draw Figure 7 The performance curves shown are:

[0051] 1. At 920rpm, the PQ curve of the model "new" is better than that of the original fan as a whole, mainly reflected in the "inflection point" area of ​​the fan being significantly better than the original fan;

[0052] 2. The efficiency of the new fan is significantly better than that of the original fan, which is about 2 to 4 percentage points higher at the same air volume. At the same time, the optimal efficiency air volume point is moved backward, and the highest efficiency of the fan is 12500m 3 / h area, reaching about 80%, achieving a simultaneous increase in air volume and efficiency.

[0053] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A blade optimization design method based on blade profile curve, characterized in that: include: S1. With the fan rotation axis as the central axis, multiple groups of cylindrical concentric sections are set; The concentric section intersects with the pressure surface of the fan blade to obtain an intersection curve; S2, unfold the intersecting curve plane to obtain the blade curve; S3. Adjust the curvature, radian or inclination angle of the blade profile according to the performance target or size target; S4. Wind and arrange the blade profile curves in sequence according to the corresponding concentric cross sections, connect the adjacent blade profile curves with a smooth curved surface, and obtain an optimized blade pressure surface; S5. Establish an optimized fan model, and obtain air volume, pressure, flow field distribution or pressure distribution parameters through CFD numerical simulation analysis; The fan includes a central rotor and fan blades fixed on the central rotor, and the side of the fan blade facing the air outlet direction is a pressure surface; there are multiple cylindrical concentric sections coaxial with the central rotor axis, and the plane unfolding line of the intersection of the concentric section and the pressure surface is a circular arc line.

2. The fan blade optimization design method based on blade profile curve according to claim 1, characterized in that: In step S1, adjacent concentric cross sections are arranged at equal intervals.

3. The fan blade optimization design method based on blade profile curve according to claim 2, characterized in that: The distance between adjacent concentric sections is 1 / 10 of the blade diameter.

4. The fan blade optimization design method based on blade profile curve according to claim 1, characterized in that: In step S3, the blade profile curve is an arc line convex toward the airflow direction of the fan.

5. The fan blade optimization design method based on blade profile curve according to claim 1, characterized in that: Along the radial direction of the fan blade, the intersection lines of the expanded circular arc lines are evenly distributed at equal intervals.

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