Axial flow fan blade and fan comprising same

Abstract

The invention provides an axial flow fan blade and a fan comprising the same. The axial flow fan blade comprises a hub and blades. Each blade sequentially comprises a plurality of base circle sections in the direction from the blade inner edge to the blade outer edge. The contour line SP of each base circle section is generated by a first multinomial function; the starting points of the contour lines SP are connected together to form a blade front edge, the blade front edge is a large-radian curved surface, and the blade front edge is generated by a second multinomial function; the chord length L of each contour line SP is generated by a third multinomial function; the suction surface and the pressure surface of the blade in the direction from the inner edge of the blade to the outer edge of the blade are both of a curved surface structure, and the curved surface is generated by boundary mixing of a fourth multi-term function; the end points of the contour lines SP are connected together to form a blade tail edge, and the blade tail edge is of a wavy curved surface structure and is generated by a fifth multi-term function. The blades and the trailing edge of the axial flow fan blade are both based on multi-frequency harmonic superposition collaborative optimization design, the operation power consumption of the fan blade is remarkably reduced while the requirement for the air volume is met, and noise is greatly restrained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fan, in particular to an axial fan blade and a fan comprising the same. BACKGROUND

[0002] With the continuous improvement of global energy efficiency and environmental protection requirements, air conditioning equipment, as one of the important household appliances, is facing the urgent needs of improving energy efficiency ratio and reducing energy consumption. Axial fan is widely used in air conditioners, ventilation systems and other fields due to its simple structure, large air volume, high efficiency and other characteristics. However, ordinary axial fan is prone to produce significant aerodynamic noise during operation, mainly due to the interaction of blade and airflow and the shedding of trailing edge vortex, which not only affects the user experience, but also may cause noise pollution to the environment.

[0003] In addition, the axial fan blade as an important energy-consuming component of air conditioner outdoor unit, its performance optimization is of great significance to improve the overall energy efficiency of the system. By optimizing the fan blade design, the motor power consumption and operating noise can be reduced while maintaining sufficient air volume, thereby realizing the dual optimization of energy efficiency and noise. The existing axial fan blade for air conditioner outdoor unit usually needs to meet the following performance requirements: 1. sufficient air flow to ensure heat dissipation requirements; 2. low operating energy consumption to reduce power consumption and motor load; 3. meet the noise control standards and comply with environmental regulations.

[0004] However, there is a mutual restrictive relationship among air volume, energy consumption and noise: increasing air volume usually requires increasing impeller power consumption, and will cause aerodynamic noise to increase. Therefore, it is urgent to develop an axial fan blade design scheme that can meet the air volume while considering low energy consumption and low noise at the same speed, to realize the optimization balance among the three. SUMMARY

[0005] The purpose of the present application is to provide an axial fan blade and a fan comprising the same, to solve the technical problems of unreasonable axial fan blade profile design in the prior art, which cannot simultaneously meet the requirements of large air volume, low power consumption and low noise.

[0006] To achieve the above purpose, the present application provides the following technical solutions: The axial flow fan blade provided by the application comprises a hub and a plurality of blades, all the blades are arranged circumferentially along the hub, the blade comprises a plurality of base circle sections from the inner edge of the blade to the outer edge of the blade, the profile line SP of each base circle section is generated by a first multinomial function, the starting points of each profile line SP are connected together to form a blade leading edge, the blade leading edge is a large-radian curved surface, and the blade leading edge is generated by a second multinomial function, the chord length L of each profile line SP is generated by a third multinomial function, the suction surface and the pressure surface of the blade from the inner edge of the blade to the outer edge of the blade are both curved surface structures, the curved surface is generated by a fourth multinomial function through boundary mixing, and the ending points of each profile line SP are connected together to form a blade trailing edge, the blade trailing edge is a wavy curved surface structure, and the blade trailing edge is generated by a fifth multinomial function.

[0007] The axial flow fan blade provided by the application is designed by a multi-target optimization method, five multinomial functions are used to accurately control the blade section profile, the leading edge curvature, the chord length distribution, the surface curved surface and the trailing edge wavy shape, the generation and development of separation vortexes are effectively improved, the wavy trailing edge structure can scatter vortexes and reduce turbulent noise, the large-radian leading edge can enhance the guiding ability of the inlet airflow, the air volume is improved, and the flow loss is reduced. The design realizes 25% power consumption reduction and 0.5-1db (A) noise value reduction of the fan blade under the same speed, is significantly better than the traditional straight trailing edge blade, and achieves the synergistic optimization of air volume, energy efficiency and quiet performance.

[0008] As a further improvement of the application, the base circle section comprises six base circle sections, namely the first to sixth base circle sections, the relationship between the radius of each base circle section and the radius R of the blade is as follows: the first base circle section radius R1=0.364R, the second base circle section radius R2=0.553R, the third base circle section radius R3=0.692R, the fourth base circle section radius R4=0.808R, the fifth base circle section radius R5=0.909R, and the sixth base circle section radius R6=R.

[0009] The axial flow fan blade provided by the application sets the radial distribution of the six key sections, constructs the non-uniform blade chord length and torsion angle gradient, optimizes the aerodynamic load distribution along the span, and avoids local stall.

[0010] As a further improvement of the application, the first multinomial function comprises a pressure surface profile cylindrical coordinate function f z (θ) and a suction surface profile cylindrical coordinate function g z (θ); wherein: f z (θ)=aθ 5 +bθ 4 +cθ3 +dθ 2 +eθ+f; g z (θ)=Aθ 5 +Bθ 4 +Cθ 3 +Dθ 2 +Eθ+F; where θ is the central angle, and a, b, c, d, e, f, A, B, C, D, E, and F are all coefficients.

[0011] This invention achieves precise control over the aerodynamic shape of the blade cross-section by accurately fitting the cylindrical coordinate distribution of the pressure and suction surfaces using a fifth-order polynomial, effectively improving the lift-to-drag ratio. The coefficients a to f and A to F are optimized using a multi-objective genetic algorithm, balancing the requirements of high airflow, low noise, and a wide operating range. This maintains good airflow adhesion characteristics at different angles of attack, significantly enhancing the overall aerodynamic efficiency and stability of the blade.

[0012] As a further improvement of the present invention, the second polynomial function is the relative bending angle function β(R). x ), β(R) x )=-2E-06(R x ) 3 +0.001(R x ) 2 -3.458; where R x Let β(R) be the radius of each base circle section. x () represents the relative bend angle at different base circle sections.

[0013] This invention constructs a third-order polynomial relative bend angle distribution function to achieve a smooth transition and optimal load distribution of the blade spanwise bend angle, effectively suppressing radial flow deviation. Aerodynamic simulation and experimental verification show that β(Rx) forms a reasonable pressure gradient within the range of 0.364R to R, avoiding airflow separation and improving the blade's work capacity. This function ensures stable aerodynamic performance under different speed conditions, enhancing the overall impeller efficiency and anti-stall capability.

[0014] As a further improvement of the present invention, the relative bend angle includes an initial relative bend angle βs corresponding to the first base circle section and a final relative bend angle βe corresponding to the sixth base circle section; wherein: βs∈[3°, 6°], βe∈[35°, 37°].

[0015] This invention ensures good air intake conditions at the blade root and sufficient work capacity at the blade tip by setting the range of initial relative bend angle βs and final relative bend angle βe. The bend angle distribution gradient has been verified through multi-condition simulations, achieving optimal aerodynamic load distribution at rated speed and effectively reducing secondary flow losses. Combining fifth-order polynomial profile control with third-order bend angle function adjustment enables the blade to maintain efficient and stable operation over a wide flow range, significantly improving the overall performance of the axial flow fan blade.

[0016] As a further improvement of the present invention, the third polynomial function is the chord length function L(Rx) of each base circle section, L(R x )=-7E-08(R x ) 5 +7E-05(R x ) 4 -0.0269(R x ) 3 +4.9019(R x ) 2 -431.5(R x ) +14777; where: R x Let be the radius of each base circle cross section.

[0017] As a further improvement of the present invention, the fourth polynomial function is the height function H(x) of each base circle section. ; Where x is the axial distance from the center of the circle. For leaf height, A k For amplitude, w k For frequency, φ k For phase.

[0018] As a further improvement of the present invention, the amplitude A k >0, the frequency w k >0.

[0019] As a further improvement of the present invention, the fifth polynomial function is the trailing edge curve axial height function F(x). in, For amplitude, For frequency, For phase.

[0020] The present invention provides a fan, including the axial flow fan blades.

[0021] The fan of the application, the axial fan blade is designed by multi-parameter coordination optimization, which significantly improves the aerodynamic efficiency while ensuring the structural strength. The blade spanwise bending angle and chord length, height function are coupled to control and realize the uniform distribution of flow field, effectively suppress the boundary layer separation and vortex generation. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 is a structural schematic diagram of the axial fan blade of the present application; Figure 2 is a structural schematic diagram of the pressure surface and the suction surface of the axial fan blade of the present application; Figure 3 is a schematic diagram of the radius of each base circle of the axial fan blade of the present application; Figure 4 is a schematic diagram of the profile line of each base circle of the axial fan blade of the present application; Figure 5 is a schematic diagram of the relative bending angle of the profile line of the leading edge of the axial fan blade of the present application; Figure 6 is a schematic diagram of the chord length of the base circle profile line of the blade profile of the axial fan blade of the present application; Figure 7 is a schematic diagram of the blade profile structure of the axial fan blade of the present application; Figure 8 is a schematic diagram of the multi-frequency harmonic superposition optimization design profile structure of the axial fan blade of the present application; Figure 9 is a schematic diagram of the curve fitting of the multi-frequency harmonic superposition optimization design of the axial fan blade of the present application; Figure 10 is a schematic diagram of the trailing edge based on the multi-frequency harmonic superposition optimization design structure of the axial fan blade of the present application; Figure 11 is a power comparison curve of the axial fan blade of the present application under the same rotational speed; Figure 12 is a noise comparison curve of the axial fan blade of the present application under the same rotational speed; Figure 13 is a schematic diagram of the local three-dimensional structure of the axial fan blade of the present application.

[0024] In the figure: 1, hub; 2, blade; 3, blade leading edge; 4, blade outer edge; 5, blade inner edge; 6. Blade tip; 7. The outer edge of the blade is bent; 8. Pressure surface; 9. Suction surface. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] like Figures 1-13 As shown, this invention provides an axial flow fan blade based on multi-frequency harmonic superposition optimization design, including a hub 1 and multiple blades 2; all blades 2 are arranged circumferentially along the hub 1; the blades 2 include several base circle sections in sequence from the inner edge 5 to the outer edge 4; the contour line SP of each base circle section is generated by a first polynomial function; the starting points of each contour line SP are connected together to form the blade leading edge, which is a large-radius curved surface and is generated by a second polynomial function; the chord length L of each contour line SP is generated by a third polynomial function; the suction surface and pressure surface of the blade from the inner edge to the outer edge are both curved surface structures, which are generated by a fourth polynomial function through boundary mixing; the ending points of each contour line SP are connected together to form the blade trailing edge, which is a wavy curved surface structure and is generated by a fifth polynomial function.

[0027] Specifically, blade 2 includes a leading edge 3, an outer edge 4, an inner edge 5, a trailing edge 6, a pressure surface 8, and a suction surface 9; the outer edge 4 has an outer edge bend 7. The leading edge 3 is a large-angle arc structure, and the trailing edge 6 is a wavy airfoil trailing edge structure. The windward surface of the blade in this invention does not have a windward groove, and the trailing edge is locally concave to form a wavy shape. By controlling the chord length and relative bending angle parameters of different basic blade profiles of the axial flow fan, the trailing edge of the blade and the gradually changing corrugated structure of the blade surface are better matched, avoiding excessively large local velocity gradients. This allows the airflow to better converge at the blade outlet, improving the wind gathering effect and dispersing the noise spectrum.

[0028] The axial flow fan blade of the application effectively improves the airflow field distribution, and suppresses the generation and development of separation vortex by using five multinomial functions to accurately control the blade cross section profile, leading edge curvature, chord length distribution, surface curvature and trailing edge wave form through multi-objective optimization design method. The wave-shaped trailing edge structure can scatter the vortex shed, and reduce the turbulent noise; the large-radius leading edge enhances the inlet airflow guiding ability, and improves the air volume while reducing the flow loss. The design realizes 25% power consumption reduction and 0.5-1db(A) noise value reduction of the fan blade under the same speed, which is significantly better than the traditional straight trailing edge blade, and achieves the synergistic optimization of air volume, energy efficiency and quiet performance.

[0029] As a further improvement of the application, the base circle cross section includes six base circle cross sections, which are first to sixth base circle cross sections; the relationship between the radius of each base circle cross section and the radius R of the blade is: the first base circle cross section radius R1=0.364R, the second base circle cross section radius R2=0.553R, the third base circle cross section radius R3=0.692R, the fourth base circle cross section radius R4=0.808R, the fifth base circle cross section radius R5=0.909R, and the sixth base circle cross section radius R6=R.

[0030] The axial flow fan blade of the application sets the radial distribution of six key cross sections, constructs the non-uniform blade chord length and torsion angle gradient, optimizes the aerodynamic load distribution along the spanwise direction, and avoids local stall. The parameters of each base circle cross section are iterated through fluid dynamics simulation to ensure high efficient flow characteristics under different working conditions.

[0031] As a further improvement of the application, the first multinomial function includes a pressure surface profile cylindrical coordinate function f z (θ) and a suction surface profile cylindrical coordinate function g z (θ); wherein: f z (θ)=aθ 5 +bθ 4 +cθ 3 +dθ 2 +eθ+f; g z (θ)=Aθ 5 +Bθ 4 +Cθ 3 +Dθ 2 +Eθ+F; wherein, θ is the central angle, a, b, c, d, e, f, A, B, C, D, E, F are all coefficients.

[0032] This invention achieves precise control over the aerodynamic shape of the blade cross-section by accurately fitting the cylindrical coordinate distribution of the pressure and suction surfaces using a fifth-order polynomial, effectively improving the lift-to-drag ratio. The coefficients a to f and A to F are optimized using a multi-objective genetic algorithm, balancing the requirements of high airflow, low noise, and a wide operating range. This maintains good airflow adhesion characteristics at different angles of attack, significantly enhancing the overall aerodynamic efficiency and stability of the blade.

[0033] As a further improvement of the present invention, the second polynomial function is the relative bending angle function β(R). x ), β(R) x )=-2E-06(R x ) 3 +0.001(R x ) 2 -3.458; where R x Let β(R) be the radius of each base circle section. x () represents the relative bend angle at different base circle sections.

[0034] This invention constructs a third-order polynomial relative bend angle distribution function to achieve a smooth transition and optimal load distribution of the blade spanwise bend angle, effectively suppressing radial flow deviation. Aerodynamic simulation and experimental verification show that β(Rx) forms a reasonable pressure gradient within the range of 0.364R to R, avoiding airflow separation and improving the blade's work capacity. This function ensures stable aerodynamic performance under different speed conditions, enhancing the overall impeller efficiency and anti-stall capability.

[0035] As a further improvement of the present invention, the relative bend angle includes an initial relative bend angle βs corresponding to the first base circle section and a final relative bend angle βe corresponding to the sixth base circle section; wherein: βs∈[3°, 6°], βe∈[35°, 37°].

[0036] This invention ensures good air intake conditions at the blade root and sufficient work capacity at the blade tip by setting the range of initial relative bend angle βs and final relative bend angle βe. The bend angle distribution gradient has been verified through multi-condition simulations, achieving optimal aerodynamic load distribution at rated speed and effectively reducing secondary flow losses. Combining fifth-order polynomial profile control with third-order bend angle function adjustment enables the blade to maintain efficient and stable operation over a wide flow range, significantly improving the overall performance of the axial flow fan blade.

[0037] As a further improvement to the present invention, the third polynomial function is the chord length function L(Rx) of each base circle section, L(R x )=-7E-08(R x ) 5 +7E-05(R x ) 4 -0.0269(R x ) 3+ 4.9019 (R x ) 2 - 431.5 (R x ) + 14777; wherein: R x is the radius of each base circle cross section.

[0038] As a further improvement of the application, the fourth polynomial function is a function of the height of each base circle cross section H(x), ; wherein x is the axial distance from the center of the circle, is the height of the blade, A k is the amplitude, w k is the frequency, and k is the phase.

[0039] As a further improvement of the application, the amplitude A k > 0, and the frequency w k > 0.

[0040] The blade 2 in the axial flow fan blade is designed based on the multi-frequency harmonic superposition optimization structure, can realize smooth transition of airflow, effectively suppresses the generation of turbulence and vortex, improves the flow stability and reduces the local pressure fluctuation, thereby significantly delays the airflow separation. The design introduces controllable micro-disturbance stable boundary layer, enhances the flow control ability, and significantly improves the wind blade wind gathering effect and reduces the generation of wind blade noise source.

[0041] As a further improvement of the application, the fifth polynomial function is a function of the axial height of the trailing edge curve F(x), wherein, is the amplitude, is the frequency, is the phase.

[0042] The application is partially wavy in the longitudinal direction, and is also gradually wavy in the axial direction. The blade suction surface and the pressure surface adopt a gradually wavy structure design, so that the airflow is more smoothly transitioned, thereby reducing the generation of turbulence and vortex, reducing the fluctuation of high pressure area and low pressure area, and further reducing the possibility of airflow separation.

[0043] By controlling the chord length and the relative bending angle parameter of different basic element blade profiles of the axial flow fan blade, the trailing edge, the pressure surface and the suction surface of the blade are all designed by multi-frequency superposition optimization. Through the matching of fluid mechanics characteristics, the local excessively large velocity gradient can be avoided, so that the airflow is better gathered to the outlet of the blade, the wind gathering effect is improved, the noise spectrum is dispersed, the airflow is more smoothly, the power fluctuation and the aerodynamic noise are significantly reduced, and the synergistic optimization of high efficiency and low noise is realized.

[0044] The axial flow fan blade provided by the application has three blades, and the above design can reduce noise and power under the premise of meeting the air volume level, can significantly improve the aerodynamic performance of the fan blade, reduce noise, and improve efficiency; through optimization of airflow distribution, generation of turbulence and vortex is significantly reduced, wind gathering effect is improved, and noise is reduced.

[0045] As shown in Figures 1-13 , the application provides a fan, which comprises an axial flow fan blade.

[0046] Specifically, the axial flow fan blade comprises a hub 1 and a blade 2, and the blade 2 is three in number and is uniformly distributed along the circumference of the hub 1 and fixedly connected to the outer circumferential surface of the hub 1.

[0047] The blade 2 has a blade leading edge 3, an airfoil blade trailing edge 6, a blade outer edge 4, a blade inner edge 5, a blade outer edge bending 7, a pressure surface 8 and a suction surface 9, respectively, the blade leading edge 3 is located on the windward side of the blade, the curvature thereof is designed by fitting multiple circular arcs to reduce inlet impact loss, the airfoil blade trailing edge 6 adopts an asymmetric thin-walled structure and combines with an axial height function F(x) to control the geometric shape thereof, and the tail vortex intensity is effectively reduced.

[0048] Specifically, the radius of the axial flow fan blade is R, and in the embodiment, R=275mm; the radii corresponding to the six base circle sections are R1=0.364R, R2=0.553R, R3=0.0.692R, R4=0.808R, R5=0.909R and R6=R; the blade shape is generated by controlling the base circle half pitch, as shown in Figure 3 .

[0049] The pressure surface 8 and the suction surface 9 of the blade 2 are generated by boundary mixing of the profile lines SP1, SP2, SP3, SP4, SP5 and SP6 (circular arc segments) on the six base circle sections, as shown in Figure 4 , the profile lines SP1, SP2, SP3, SP4, SP5 and SP6 are composed of the pressure surface 8 and the suction surface 9 of the blade 2, wherein the pressure surface 8 and the suction surface 9 of the profile lines SP1, SP2, SP3, SP4, SP5 and SP6 are respectively determined by polynomials fz(θ) and gz(θ).

[0050] The polynomial equation of the pressure surface 8 is (cylindrical coordinates) fz(θ)=aθ 5 +bθ 4 +cθ 3 +dθ 2 +eθ+f, wherein θ is the central angle, and the preferred values of the coefficients in the equation are shown in Table 1: Table 1 Preferred values of applicable coefficients of the pressure surface airfoil equation Contour line a b c d e f SP1 -0.123 0.519 0.113 7.414 -34.923 22.774 SP2 -0.469 0.436 0.980 7.367 -45.576 3.614 SP3 0.101 -0.159 -0.693 10.520 -50.016 -11.237 SP4 0.892 1.102 -1.719 11.749 -51.858 -32.265 SP5 -0.517 -0.320 -1.413 16.226 -69.399 -14.557 SP6 -0.297 0.486 0.306 16.9373 -75.411 -23.063 The blade suction surface 9 is fitted by the coordinate points of the profile lines on the six base circle sections SP1-SP6, and the polynomial equation of the profile line suction surface 9 is (cylindrical coordinates) g z (θ)=Aθ 5 +Bθ 4 +Cθ 3 +Dθ 2 +Eθ+F, wherein θ is the central angle, and the preferred values of the coefficients in the equation are shown in Table 2: Table 2 Preferred values of applicable coefficients of the suction surface blade profile equation Section radius A B C D E F SP1 -0.1304 -0.7820 0.1666 8.3017 -35.0783 24.25 SP2 -0.364 -1.685 0.265 11.630 -44.518 -3.259 SP3 0.0552 -1.246 -0.667 12.542 -50.933 -7.323 SP4 0.456 -1.122 -0.772 12.066 -53.406 -10.695 SP5 -0.517 -0.320 -1.413 16.226 -69.399 -14.557 SP6 -0.368 -0.602 0.390 19.454 -73.939 -27.011 The initial relative camber angle of the blade leading edge 3 is β s , and the terminal relative camber angle is β e , as shown in the following formula: Figure 5 wherein each relative camber angle β (Rx) of the blade leading edge 3 and each base circle radius Rx are determined by the polynomial β (Rx) =-2E-06 (Rx) 3 +0.001 (Rx) 2 -3.458, wherein the initial relative camber angle β s (βs∈[3°, 6°], preferably β s =4.35°; the terminal relative camber angle β e (βe∈[35°, 37°], preferably β s =36.36°, and each base circle radius Rx∈[100mm, 275mm].

[0051] The chord length L (Rx) of each base circle section of the blade and each base circle radius Rx are determined by the polynomial L (Rx) =-7E-08 (Rx) 5 +7E-05 (Rx) 4 -0.0269 (Rx) 3 +4.9019 (Rx) 2 -431.5 (Rx) +14777, wherein L (Rx) ∈[190mm, 495mm], preferably L (R1) =192.97mm, L (R2) =252mm, L (R3) =308.76mm, L (R4) =337.72mm, L (R5) =427.88mm, and L (R6) =490.26mm. It should be noted that the blade chord length herein is the chord length commonly used in the art, which is the distance between the two ends of the blade arc segment when flattened in space.

[0052] In the present application, the pressure surface and the suction surface are smoothly transitioned into a gradually changing corrugated shape by controlling the arc length of the base circle profile line, and are concave-convex shaped, so that the airflow is more smoothly transitioned, thereby reducing the generation of blade turbulence and vortex, and helping to improve the stability of the airflow.

[0053] The blade curve of the present application extends radially from the inner edge of the blade to the outside, the blade thickness d=4mm, as shown in Figure 7 . As shown in the two-dimensional plane Figure 8 , the blade radius is R, R=275mm in the present embodiment, x is the axial distance from the center, the center , is the height of the blade, the radial coordinate R=275mm, x is the axial distance from the center, the center , is the height of the blade, the radial coordinate , is the outer edge of the blade, is the inner edge of the blade, x is a negative value indicating the radial position extending outward from the blade root (axle), and H(x) satisfies the mathematical expression: ; Among them, the optimization parameters are verified by aerodynamic performance, and the optimal value is: Hx and the height of the horizontal plane; In the expression, the amplitude , the frequency , ensures that the curve is smooth and has no physically unachievable oscillation, and the phase makes the cross-sectional curvature continuous and derivable, avoiding airflow separation. As shown in Figure 9 , it is a schematic diagram of the fitting curve of the blade based on the multi-frequency harmonic superposition optimization design structure.

[0054] The blade optimization design based on multi-frequency harmonic superposition of the blade can realize smooth transition of airflow, effectively suppress the generation of turbulence and vortex, improve the flow stability and reduce the local pressure fluctuation, thereby significantly delaying the airflow separation. The design introduces controllable perturbation to stabilize the boundary layer, enhances the flow control ability, and significantly improves the wind blade wind gathering effect and reduces the generation of wind blade noise source.

[0055] As shown in Figure 10 , in the two-dimensional section, O is the center, the axial X of the trailing edge presents a multi-frequency harmonic superposition design structure, in the present embodiment, the blade radius is R=275mm, F(x) is the axial height of the trailing edge curve, the axial distance to the center x∈(-0.9R, -0.19R)mm, and the multi-frequency harmonic superposition optimization design curve F(x) satisfies the mathematical expression: in the expression, is an amplitude, is a frequency, is a phase, the optimal parameter is verified by aerodynamic performance, and the optimal value is: Table 3 Coefficient optimization value of tail edge based on multi-frequency harmonic superposition optimization design equation Coefficient Preferred value Lower limit Upper limit S1 156.42 -1.97E+04 2.00E+04 ω1 0.73 -4.75E+01 4.90E+01 Φ1 1.65 -6.24E+00 9.54E+00 S2 71.10 -1.88E+04 1.90E+04 ω2 1.43 -1.11E+02 1.14E+02 Φ2 -1.47 -1.04E+01 7.42E+00 S3 18.73 -8.32E+02 8.70E+02 ω3 2.96 -1.99E+01 2.58E+01 Φ3 0.93 -2.62E+01 2.81E+01 S4 3.05 -5.69E+01 6.30E+01 ω4 4.97 -2.28E+01 3.28E+01 Φ4 -4.27 -1.78E+01 9.25E+00 S5 -2.56E+03 -1.63E+12 1.63E+12 ω5 9.17 -1.19E+05 1.19E+05 Φ5 -3.09 -5.86E+04 5.86E+04 S6 1.81 -2.87E+02 2.91E+02 ω6 8.05 -7.16E+01 8.78E+01 Φ6 -2.53 -4.26E+01 3.75E+01 S7 2.56E+03 -1.63E+12 1.63E+12 ω7 9.17 -1.19E+05 1.19E+05 Φ7 3.19 -5.86E+04 5.86E+04 The blade tail edge, the pressure surface and the suction surface of the application are all designed by multi-frequency superposition optimization, and the following effects can be achieved through fluid mechanics characteristics matching: (1) significantly improving airflow wind gathering effect and enhancing wind energy conversion efficiency; (2) effectively suppressing tail edge turbulence and boundary layer separation and reducing flow resistance; (3) simultaneously reducing power fluctuation and aerodynamic noise, and realizing the synergistic optimization of high efficiency and low noise. From Figure 11 , Figure 12 It can be seen from the experimental data that the axial flow fan blade of the application can reduce the power by 25% on average under the same speed when meeting the air volume; the input power value of the new fan motor is reduced by about 50W under the same speed, and the noise value of the new fan blade is reduced by 0.5~1dB(A) under the same speed. The experiment proves that the application realizes the simultaneous reduction of input energy consumption by 25% and noise suppression by 1.5 dB(A) under the premise of maintaining the air volume, effectively solving the technical bottleneck of high power consumption and high noise of the original fan system.

[0056] The fan of the application is designed by multi-parameter synergistic optimization, the chord length and relative bending angle parameters of different basic element blade types of the axial flow fan blade are controlled, the blade tail edge, the pressure surface and the suction surface are all designed by multi-frequency superposition optimization, the aerodynamic efficiency is significantly improved while the structural strength is ensured. The spanwise bending angle, chord length and height function are coupled and controlled to realize uniform distribution of the flow field and effectively suppress boundary layer separation and vortex generation.

[0057] First of all, it should be noted that "inward" is the direction towards the center of the accommodation space, and "outward" is the direction away from the center of the accommodation space.

[0058] In the description of the application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the accompanying drawings. Figure 1The illustrated position or positional relationship is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements indicated must have a particular position, be constructed and operated in a particular position, and therefore cannot be understood as a limitation of the present application.

[0059] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0060] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0061] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0062] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0063] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An axial flow fan blade comprising a hub, a plurality of blades; all of said blades are arranged circumferentially along said hub; characterized in that, The blade comprises a plurality of base circle sections from the blade inner edge to the blade outer edge; the outline of each base circle section is generated by a first multinomial function; the starting points of each outline are connected to form a blade leading edge, which is a large-radian curved surface and is generated by a second multinomial function; the chord length L of each outline is generated by a third multinomial function; the suction surface and the pressure surface of the blade from the blade inner edge to the blade outer edge are both curved surface structures, which are generated by a fourth multinomial function through boundary blending; the ending points of each outline are connected to form a blade trailing edge, which is a wavy curved surface structure and is generated by a fifth multinomial function.

2. The axial fan blade of claim 1, wherein, The base circle sections comprise six base circle sections, namely the first to sixth base circle sections; the relationship between the radius of each base circle section and the radius R of the blade is as follows: the first base circle section radius R1=0.364R, the second base circle section radius R2=0.553R, the third base circle section radius R3=0.692R, the fourth base circle section radius R4=0.808R, the fifth base circle section radius R5=0.909R, and the sixth base circle section radius R6=R.

3. The axial fan blade of claim 1, wherein, The first multinomial function includes a pressure surface profile cylindrical coordinate function f z (θ) and a suction surface profile cylindrical coordinate function g z (θ); wherein: f z (θ) = aθ 5 +bθ 4 +cθ 3 +dθ 2 +eθ+f; g z (θ) = Aθ 5 +Bθ 4 +Cθ 3 +Dθ 2 +Eθ+F; wherein θ is the central angle, a, b, c, d, e, f, A, B, C, D, E, F are all coefficients.

4. The axial fan blade of claim 2, wherein, The second polynomial function is a relative bend angle function β(R x ), β(R x ) = -2E-06(R x ) 3 + 0.001(R x ) 2 - 3.458; where R x is the radius of each base circle section, and β(R x ) is the relative bend angle at different base circle sections.

5. The axial fan blade of claim 4, wherein, The relative bending angle comprises an initial relative bending angle βs corresponding to the first base circle section and a terminal relative bending angle βe corresponding to the sixth base circle section; wherein: βs∈[3°, 6°], and βe∈[35°, 37°].

6. The axial fan blade of claim 2, wherein, the third polynomial function is a function of the chord length of each base circle cross section L(Rx), L(R x ) x ) 5 x ) 4 x ) 3 x ) 2 x ) +14777; wherein: R x is the radius of each base circle cross section.​​​​ 7. The axial fan blade of claim 1, wherein, The fourth multinomial function is a base circle section height function H(x), ； where x is the axial distance from the center of the circle, is the leaf height, A k is the amplitude, w k is the frequency, φ k is the phase.

8. The axial fan blade of claim 7, wherein, the amplitude A k > 0, the frequency w k > 0.

9. The axial fan blade of claim 1, wherein, The fifth polynomial function is a trailing edge curve axial height function F(x), wherein, is an amplitude, is a frequency, is a phase.

10. A fan, characterized by The axial flow fan blade comprises the axial flow fan blade according to any one of claims 1-9.

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