Design method and equipment of axial flow fan blade, medium and axial flow fan

Abstract

The embodiment of the invention discloses a design method and device of an axial flow fan blade, a medium and an axial flow fan. The design method of the axial flow fan blade can comprise the steps that an initial blade model of the axial flow fan blade is obtained; based on the limit pressure difference of the suction surface and the pressure surface of the axial flow fan blade corresponding to the target noise and the limit turbulent flow separation point of the axial flow fan blade; designing an axial stacking line of the axial flow fan blade according to the limit pressure difference, and designing a circumferential stacking line of the axial flow fan blade according to the limit turbulence separation point; and updating the initial blade model by using the axial stacking line and the circumferential stacking line to obtain a target blade model, so that the noise of the axial flow fan blade corresponding to the target blade model during working is smaller than the target noise.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of blade design, and in particular to a design method, equipment, medium, and axial flow fan for axial flow fan blades. Background Art

[0002] Axial fans, used in high-air-volume applications such as air conditioning and electronic cooling, commonly experience a prominent problem: aerodynamic noise increases with flow rate. Traditional noise reduction methods employ blade bending or serration to suppress vortices, but these methods are limited by geometric abrupt changes that can lead to flow field instability. Specifically, sudden changes in curvature in the bend area trigger pressure pulsations on the suction side, causing a sudden increase in the pressure differential between the suction and pressure sides and inducing broadband vortex noise.

[0003] Existing blade structures struggle to balance pressure differential suppression and flow field continuity at high speeds, leading to a shifted turbulent separation point and the interference of multiple vortex cores. This results in noise levels that fail to meet the requirements of high-end equipment. Developing a blade structure that balances flow field stability and pressure balance has become a pressing technical challenge. Summary of the Invention

[0004] In view of this, the embodiments of the present disclosure hope to provide a design method, equipment, medium and axial flow fan for axial flow fan blades, which can reduce the technical problem of high noise in existing axial flow fan blades during operation.

[0005] The technical solution of the embodiment of the present disclosure is implemented as follows: In a first aspect, an embodiment of the present disclosure provides a method for designing an axial flow fan blade, comprising: Obtaining an initial blade model of the axial flow fan blade; The limit pressure difference between the suction side and the pressure side of the axial flow fan blade corresponding to the target noise, and the limit turbulence separation point of the axial flow fan blade; Designing an axial stacking line of the axial flow fan blades according to the limit pressure difference, and designing a circumferential stacking line of the axial flow fan blades according to the limit turbulent separation point; The initial blade model is updated using the axial stacking line and the circumferential stacking line to obtain a target blade model, so that the noise of the axial flow fan blade corresponding to the target blade model during operation is less than the target noise.

[0006] In some examples, the target noise-based limit pressure difference between the suction side and the pressure side of the axial flow fan blade, and the limit turbulent separation point of the axial flow fan blade, include: Performing a working noise simulation on the axial flow fan blades to determine a mapping relationship between pressure difference and noise; determining a limit pressure difference corresponding to the target noise based on the mapping relationship and the target noise; The critical turbulence separation point is determined based on the frequency band energy distribution of the target noise.

[0007] In some examples, designing the axial stacking line of the axial flow fan blades according to the limit pressure difference includes: Based on the limit pressure difference, an axial stacking line is constructed with a wave-shaped distribution along the blade span direction, wherein the wave-shaped distribution adjusts the pressure gradient distribution on the blade surface through periodic fluctuations, so that the pressure difference between the suction surface and the pressure surface is uniform within the range of the limit pressure difference.

[0008] In some examples, constructing the axial stacking lines distributed in a wave shape along the blade span direction based on the extreme pressure difference includes: Using a first cubic polynomial to represent a first sub-axial stacking line near the hub portion of the axial flow fan blade, and adjusting coefficients of the first cubic polynomial based on the limit pressure difference to control a change in its curvature; The second sub-axial stacking line near the blade tip region passes through a structure in which crests and troughs are alternately distributed. Based on the constraint of the ultimate pressure difference, the height of the crests, the depth of the troughs, and the distribution spacing between the crests and troughs are dynamically adjusted to make the pressure difference fluctuation amplitude between the suction side and the pressure side less than the ultimate pressure difference. The first sub-axial stacking line and the second sub-axial stacking line are smoothly connected to obtain the axial stacking line.

[0009] In some examples, designing the circumferential stacking line of the axial flow fan blade according to the extreme turbulent separation point includes: Based on the extreme turbulence separation point, a circumferential stacking line with nonlinear continuous curvature along the blade span direction is constructed, so that the extreme turbulence separation point is moved back to be close to the trailing edge of the axial flow fan blade.

[0010] In some examples, constructing a circumferential stacking line that is nonlinearly and continuously curved along the blade span direction based on the extreme turbulent separation point includes: The circumferential stacking line is represented by a second cubic polynomial, and based on the extreme turbulent separation point, the coefficient of the second cubic polynomial is adjusted to control the curvature change thereof.

[0011] In some examples, obtaining the initial blade model of the axial flow fan blade includes: The initial blade model is generated based on preset aerodynamic performance parameters and blade geometric constraints.

[0012] In a second aspect, an embodiment of the present disclosure provides a design device for an axial flow fan blade, comprising: A model acquisition module, configured to acquire an initial blade model of the axial flow fan blade; a target determination module for determining the limit pressure difference between the suction side and the pressure side of the axial flow fan blade corresponding to the target noise, and the limit turbulence separation point of the axial flow fan blade; a parameter design module, configured to design an axial stacking line of the axial flow fan blades according to the limit pressure difference, and to design a circumferential stacking line of the axial flow fan blades according to the limit turbulent separation point; The model updating module is used to update the initial blade model using the axial stacking line and the circumferential stacking line to obtain a target blade model, so that the noise of the axial flow fan blade corresponding to the target blade model during operation is less than the target noise.

[0013] In a third aspect, an embodiment of the present disclosure provides an electronic device comprising: a processor and a memory; the processor is configured to execute instructions stored in the memory to implement the design method of the axial fan blades described in the first aspect.

[0014] In a fourth aspect, an embodiment of the present disclosure provides a computer storage medium storing at least one instruction, wherein the at least one instruction is used to be executed by a processor to implement the design method of the axial flow fan blade as described in the first aspect.

[0015] In a fifth aspect, an embodiment of the present disclosure provides an axial flow fan, comprising axial flow fan blades designed using the design method for axial flow fan blades described in the first aspect.

[0016] The disclosed embodiments provide a design method, equipment, medium and axial flow fan for axial flow fan blades; aerodynamic noise control is achieved through the collaborative design of axial and circumferential stacking lines. First, the ultimate pressure difference threshold between the suction surface and the pressure surface is determined based on the target noise, and the spanwise pressure gradient distribution of the blade is adjusted through the design of the axial stacking line to reduce the vortex intensity caused by the sudden change in the high-pressure area; at the same time, the circumferential stacking line shape is optimized according to the position of the ultimate turbulent separation point to delay the starting position of boundary layer separation. The axial stacking line controls the uniformity of the spanwise pressure field, and the circumferential stacking line adjusts the chordwise flow stability. The combination of the two suppresses the noise source generation mechanism of sudden pressure difference increase and turbulence separation. By iteratively updating the blade model parameters, the aerodynamic noise of the target blade under the same working conditions is eventually made lower than the target noise value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a method for designing axial flow fan blades provided in an embodiment of the present disclosure.

[0018] Figure 2 A schematic structural diagram of an axial flow fan blade provided in an embodiment of the present disclosure.

[0019] Figure 3A schematic diagram of generating a vortex provided in an embodiment of the present disclosure.

[0020] Figure 4 A schematic diagram of a turbulent separation point in a related technology provided in an embodiment of the present disclosure.

[0021] Figure 5 A schematic diagram of a turbulent separation point provided in an embodiment of the present disclosure.

[0022] Figure 6 A schematic diagram of a plane airfoil provided in an embodiment of the present disclosure.

[0023] Figure 7 A schematic diagram of a method for defining a bend and sweep feature provided in an embodiment of the present disclosure.

[0024] Figure 8 A schematic diagram of an axial stacking line provided in an embodiment of the present disclosure.

[0025] Figure 9 A schematic diagram of a circumferential stacking line provided in an embodiment of the present disclosure.

[0026] Figure 10 A schematic diagram of a target blade model provided in an embodiment of the present disclosure.

[0027] Figure 11 A schematic diagram of another target blade model provided in an embodiment of the present disclosure.

[0028] Figure 12 A schematic diagram of the pressure difference between the pressure side and the suction side provided in an embodiment of the present disclosure.

[0029] Figure 13 Schematic diagram of the pressure difference between the pressure side and the suction side in the related art.

[0030] Figure 14 Schematic diagram of noise spectrum in related technology.

[0031] Figure 15 A schematic diagram of a noise spectrum provided by an embodiment of the present disclosure.

[0032] Figure 16 A schematic structural diagram of a device for designing axial flow fan blades provided in an embodiment of the present disclosure.

[0033] Figure 17 A schematic structural diagram of an electronic device provided in an embodiment of the present disclosure.

[0034] The above drawings illustrate specific embodiments of the present disclosure, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the present disclosure in any way, but rather to illustrate the concepts of the present disclosure to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0035] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0036] In addition, the accompanying drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. Identical reference numerals in the figures denote identical or similar parts, and thus repetitive descriptions thereof will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities that do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0037] As a key fluid conveying component, axial flow fans are widely used in air-conditioning systems, electronic equipment heat dissipation, industrial ventilation and other fields.

[0038] As fluid machinery evolves toward higher efficiency and lower noise levels, controlling aerodynamic noise from high-speed fan blades has become a key research area in the industry. In particular, in applications requiring high airflow rates, traditional blade structures often suffer from a technical disadvantage: aerodynamic noise increases significantly with increasing airflow, severely restricting the equipment's environmental adaptability and user experience.

[0039] In related technologies, in order to solve the problem of blade aerodynamic noise, blade leading edge serration, perforation design or wave-shaped bending structure are usually adopted to improve the flow field distribution. Among them, the blade structure with wavy bending characteristics can suppress the vortex generated by radial flow to a certain extent by dispersing the high-pressure transmission path on the inner edge. However, this structure has an inherent defect of discontinuous transition in the geometric mutation area during implementation. Specifically, the curvature change rate of the bending part exceeds the adaptive range of the flow field, resulting in an abnormal increase in the local flow velocity gradient. This discontinuous structural feature will form non-steady-state pressure pulsations on the suction surface, induce premature separation of the boundary layer, and then generate wide-band vortex noise. In engineering practice, it is found that when the speed of a traditional wavy blade exceeds the critical threshold, the pressure difference between the suction surface and the pressure surface will show an exponential growth. The turbulent kinetic energy accumulation effect caused by this makes it difficult for the aerodynamic noise index to meet the acoustic requirements of high-end equipment.

[0040] Research has shown that existing blade design methods have significant deviations between theoretical models and engineering implementations in controlling pressure gradient distribution and the location of turbulent separation points. Specifically, the conventional continuous arc transition structure cannot accurately control the shape of the blade stacking line, resulting in non-uniform pressure difference suppression effects at different spanwise positions of the blade. This design flaw makes it easy for the blade to form multiple discrete vortex core generation areas under high-speed conditions, and the interference effect between the vortex systems further exacerbates the complexity of the noise spectrum. Therefore, how to construct a blade geometry control method that takes into account both flow field stability and pressure balance characteristics has become a key bottleneck in achieving high-volume, low-noise axial flow fans.

[0041] Based on this, the present disclosure first provides a design method for axial flow fan blades. Figure 1 A flow chart of a method for designing an axial flow fan blade is shown, wherein the method for designing an axial flow fan blade may include steps S110 to S140.

[0042] In step S110 , an initial blade model of the axial flow fan blade is obtained.

[0043] In some exemplary embodiments of the present disclosure, aerodynamic performance parameters and blade set constraints of an axial flow fan blade may be first obtained to generate an initial blade model.

[0044] In this method, the initial blade model is constructed based on a dual input system of aerodynamic performance parameters and blade geometric constraints. Aerodynamic performance parameters include core indicators such as target static pressure, rated flow rate, and design speed. Geometric constraints encompass structural boundary conditions such as hub radius, casing radius, and number of blades. A triangular distribution model for the spanwise velocity is established by coupling the tangential and axial velocities. The tangential velocity is determined by the product of the hub radius and the speed, while the axial velocity is calculated based on the ratio of the flow rate to the annular flow area. The trigonometric relationship between the leading and trailing edge orientation angles is used in conjunction with the Euler equation to infer the mounting angle parameters, and the chord length distribution curve is constrained by empirical values ​​of the lift coefficient. The airfoil centerline parameters of each spanwise section are substituted into the cubic Bezier curve equation to generate a continuous profile from the leading edge to the trailing edge. This is then offset to either side of the centerline using a thickness distribution function to form a solid contour. Finally, the profiles of each section are spatially arrayed along the initial stacking lines in the hub axial and circumferential directions, forming an initial three-dimensional blade model with basic aerodynamic performance. This provides an iterative benchmark for subsequent pressure differential optimization and separation point control.

[0045] It should be noted that the span direction is the direction from the blade root to the blade tip, that is, the direction along the length of the blade.

[0046] In step S120, based on the limit pressure difference between the suction surface and the pressure surface of the axial flow fan blade corresponding to the target noise, and the limit turbulence separation point of the axial flow fan blade.

[0047] In some exemplary embodiments of the present disclosure, active control of aerodynamic noise is achieved by establishing a quantitative mapping relationship between noise indicators and blade surface pressure fields and flow separation characteristics.

[0048] Optionally, the target noise is converted into an ultimate pressure difference threshold between the suction surface and the pressure surface through an acoustic inversion model, and this threshold is precisely controlled through the wave-shaped parameterized design of the axial stacking line.

[0049] At the same time, the turbulence energy spectrum characteristics corresponding to the target noise are converted into the position parameters of the extreme turbulence separation point, and the circumferential deflection forms a progressive compensation mechanism from the leading edge to the trailing edge of the blade.

[0050] The synergistic effect of the above-mentioned axial and circumferential stacking parameters attenuates the amplitude of the main frequency of the pressure pulsation on the blade surface, and shifts the frequency of the trailing edge vortex shedding to a frequency band insensitive to the human ear, ultimately reducing the total value of the aerodynamic noise.

[0051] In step S130, the axial stacking line of the axial flow fan blades is designed according to the extreme pressure difference, and the circumferential stacking line of the axial flow fan blades is designed according to the extreme turbulent separation point.

[0052] In some exemplary embodiments of the present disclosure, the blade geometry plays a decisive role in the aerodynamic performance and noise spectrum characteristics of the axial flow fan. Figure 2As shown, the blade forming method is based on the spanwise stacking principle, by topologically connecting multiple two-dimensional reference airfoil section blade shapes 22 along the axial stacking line 21 in three-dimensional space, and generating a complete impeller structure in a circumferential array. Figure 3 and Figure 4 The traditional stacking method of blades usually adopts a continuous smooth curve connection mode. This structure easily leads to the formation of a significant circumferential pressure gradient between the suction surface and the pressure surface under operating conditions. The high pressure at the inner edge of the suction surface is transferred circumferentially to the low pressure on the pressure surface. This flow will generate disturbances on the suction surface, causing vortices 31, and induce boundary layer turbulent separation and discrete vortex shedding, resulting in a loss of aerodynamic efficiency and enhanced broadband noise.

[0053] To address this issue, during the design of the embodiment of the present disclosure, the axial stacking line of the axial flow fan blades is designed according to the extreme pressure difference corresponding to the target noise, and the circumferential stacking line of the axial flow fan blades is designed based on the extreme turbulent separation point 41.

[0054] Optionally, the axial stacking line is designed with a parameterized curve, and by regulating the relative offset of the crest and the trough, a progressive pressure gradient distribution is formed in the spanwise area of ​​the blade tip, thereby suppressing the ultimate pressure difference between the suction surface and the pressure surface; the circumferential stacking line is adjusted by a displacement equation, and a dynamic fitting mechanism of the velocity vector is constructed in the area from the leading edge to the middle and rear section of the chord length, so that the boundary layer extreme turbulence separation point is delayed toward the trailing edge.

[0055] It should be noted that the axial direction is the direction along the rotation axis, and the circumferential direction is the direction around the rotation axis.

[0056] In step S140, the initial blade model is updated using the axial stacking lines and the circumferential stacking lines to obtain a target blade model, so that the noise of the axial flow fan blade corresponding to the target blade model during operation is less than the target noise.

[0057] In some exemplary embodiments of the present disclosure, after obtaining the above-mentioned axial stacking line and circumferential stacking line, the above-mentioned initial blade model can be updated based on the axial stacking line and the circumferential stacking line to obtain a target blade model. The obtained target blade model is as follows: Figure 5 As shown in FIG, the wavy distribution of the target blade model reduces the separation vortex size by changing the position of the extreme turbulence separation point 41, effectively reduces the pressure pulsation intensity on the blade surface and the total aerodynamic noise, and realizes the coordinated optimization of aerodynamic and acoustic performance.

[0058] The design method of the axial flow fan blade in the embodiment of the present disclosure realizes aerodynamic noise control through the coordinated design of axial and circumferential stacking lines. First, the limit pressure difference threshold of the suction surface and the pressure surface is determined based on the target noise, and the spanwise pressure gradient distribution of the blade is adjusted through the design of the axial stacking line to reduce the vortex intensity caused by the sudden transfer of the high-pressure area; at the same time, the circumferential stacking line shape is optimized according to the position of the limit turbulent separation point to delay the starting position of the boundary layer separation. The axial stacking line controls the uniformity of the spanwise pressure field, and the circumferential stacking line adjusts the chordwise flow stability. The combination of the two suppresses the noise source generation mechanism of the sudden increase in pressure difference and turbulence separation. By iteratively updating the blade model parameters, the aerodynamic noise of the target blade under the same working conditions is eventually made lower than the target noise value.

[0059] The span direction is the direction from the blade root to the blade tip, that is, the direction along the length of the blade.

[0060] The parameterization of axial fan blade shape involves two components: the airfoil cross-sectional parameters at different blade heights and the airfoil sweep and camber values ​​at different blade heights. The airfoil cross-sectional parameters include the leading and trailing edge orientation angles, the airfoil mounting angle, and the chord length. The sweep and camber values ​​at different blade heights include the circumferential offset (camber) and the axial offset (sweep). By adjusting these four airfoil parameters and the two sweep and camber control curves, the entire blade shape can be fully controlled. In some examples, when obtaining the initial blade model, the initial blade model may be generated based on preset aerodynamic performance parameters and blade geometric constraints, wherein the aerodynamic parameters may include static pressure P, flow rate Q, speed N (RPM), hub radius, , Receiver radius , blade number Z, etc. After obtaining the above parameters, the four airfoil parameters and two sweep parameters can be calculated.

[0061] Specifically, given the static pressure P, flow rate Q, speed N (RPM), hub radius , Receiver radius , the number of blades Z, then: Tangential velocity (u):

[0062] Axial speed (c):

[0063] Leading edge direction angle ( ) :

[0064] Trailing edge direction angle ( ): According to Euler's equation, the static pressure P satisfies:

[0065] The solution is:

[0066] Installation angle ( ):

[0067] Chord length (L):

[0068] in is the mean radius:

[0069] lift coefficient Take the experience value of 0.8~1.2.

[0070] Where D represents the diameter of the casing. Indicates the air density.

[0071] After obtaining the above parameters, the midline curve can be determined based on the above parameters. Specifically, the above midline parameters can be represented by a cubic Bezier curve, and its parametric equation is: (t [0,1]) , h is the maximum curvature, which is used to characterize the maximum distance from the center line to the straight line connecting the two ends of the center line.

[0072] Reference Figure 6 , and are the leading and trailing edge direction angles of the airfoil, respectively; is the airfoil's installation angle; L is the chord length. The airfoil profile is obtained by offsetting the airfoil centerline to the sides according to the airfoil cross-sectional thickness distribution. In some examples, the blade can be divided into five key locations along the centerline (chord direction) from the leading edge to the trailing edge. These five points are evenly distributed, and the normalized chord length position is:

[0073] The present invention defines the ratio of the corresponding thickness to the chord length at these five positions as:

[0074] Where x represents the position of the point on the midline and d represents the thickness of the point.

[0075] After the initial model is obtained, the limit turbulence separation point of the axial flow fan blade can be determined based on the limit pressure difference between the suction side and the pressure side of the axial flow fan blade corresponding to the target noise.

[0076] Specifically, a quantitative mapping relationship between the dynamic pressure difference distribution between the suction and pressure surfaces of the blade and the noise can be first established through operational noise simulation. Based on this mapping relationship, combined with the sound pressure level threshold constraint of the target noise, an inverse analysis is performed to obtain the ultimate pressure difference between the suction and pressure surfaces required to suppress broadband noise. Subsequently, the frequency band energy distribution of the target noise is analyzed for its spectral characteristics, and the characteristic frequencies of discrete vortex shedding corresponding to the dominant noise frequency band are extracted. Combined with the boundary layer velocity gradient distribution characteristics, the ultimate value of the turbulence separation starting position shift required to suppress broadband noise is determined, i.e., the ultimate turbulence separation point.

[0077] For example, assuming that an axial fan needs to reduce its aerodynamic noise from the original 70dB(A) to the target value of 65dB(A), the initial blade model can be simulated with CFD / NVH. The measured noise peak value is 68dB(A) when the maximum pressure difference between the suction side and the pressure side is 120Pa. When the pressure difference drops to 80Pa, the noise drops to 65dB(A). The ultimate pressure difference threshold is determined to be 80Pa.

[0078] In some cases, if spectrum analysis reveals significant vortex shedding noise in the 200Hz frequency band (accounting for 40% of the energy), boundary layer velocity gradient calculations reveal that turbulent separation begins at 50% of the chord length, corresponding to a vortex shedding frequency of 200Hz. The goal is to reduce the energy in this frequency band to below 15%, shifting the separation point to 80% of the chord length (corresponding to a vortex shedding frequency shift of 100Hz), setting the critical turbulent separation point at 80% of the chord length.

[0079] After obtaining the above-mentioned extreme pressure difference between the suction side and the pressure side of the axial fan blade, as well as the extreme turbulent separation point of the axial fan blade, the axial stacking line of the axial fan blade can be designed according to the extreme pressure difference, and the circumferential stacking line of the axial fan blade can be designed according to the extreme turbulent separation point.

[0080] Reference Figure 7 The stacking line is one of the key variables in blade shaping. First, each cross-section of the blade is mapped onto the ZY plane, where Z is along the hub axial direction and Y is along the hub circumference. The axial displacement of the cross-section of the blade is called axial sweep 72, and the circumferential displacement is called circumferential lean / skew 71. The sweep of the blade against the incoming flow is called forward sweep, while the sweep with the incoming flow is called backward sweep. The blade bends in the direction of rotation, which is called forward bend, and bends against the direction of rotation, which is called backward bend.

[0081] The axial stacking line design, based on the ultimate pressure differential constraint, employs a piecewise cubic polynomial to construct a wavy spanwise distribution structure. The pressure gradient in the hub region is adjusted by controlling the swept-forward polynomial coefficient, and an alternating peak-trough structure is implemented in the blade tip region to suppress pressure pulsation amplitude. The circumferential stacking line, based on the ultimate turbulent separation point, employs a nonlinear, continuously curved cubic curve. By adjusting the circumferential offset curvature parameter, the mainstream velocity vector maintains attached flow before the 75% chord length position, shifting the turbulent separation starting point to the extreme region after 80% of the chord length, effectively reducing the trailing edge vortex noise intensity.

[0082] In some examples, based on the extreme pressure difference, an axial stacking line with a wavy distribution along the blade span direction can be constructed, wherein the wavy distribution adjusts the pressure gradient distribution on the blade surface through periodic fluctuations, so that the pressure difference between the suction surface and the pressure surface is uniform within the range of the extreme pressure difference.

[0083] Specifically, the first cubic polynomial can be used to represent the first sub-axial stacking line near the hub portion of the axial flow fan blade, and based on the ultimate pressure difference, the coefficient of the first cubic polynomial is adjusted to control its curvature change; the second sub-axial stacking line near the tip area is dynamically adjusted based on the ultimate pressure difference constraint through a structure in which crests and troughs are alternately distributed, and the height of the crests, the depth of the troughs, and the distribution spacing between the crests and troughs are adjusted to make the pressure difference fluctuation amplitude between the suction surface and the pressure surface less than the ultimate pressure difference; the first sub-axial stacking line and the second sub-axial stacking line are smoothly connected to obtain the axial stacking line.

[0084] For example, refer to Figure 8 , can be normalized to the blade span position from the root to the tip (x):

[0085] Here, each value of x represents a blade section from the root to the tip.

[0086] when When , the first cubic polynomial can be used to construct the first sub-axial product line to represent the displacement of the cross-section blade along the axial direction. Its data expression is:

[0087] In the axial stacking line design, the first cubic polynomial coefficients are parametrically adjusted based on the limiting pressure difference ΔP_lim, and precise control of the pressure gradient in the hub area is achieved through curvature control.

[0088] For example, the coefficient The higher-order nonlinear terms of the dominant polynomial are constrained to have a value range of -0.55< <-0.35, by increasing | |The absolute value can enhance the negative curvature characteristics of the front section of the curve (x∈[0,0.3]), so that the hub root forms a progressive pressure release structure; the coefficient Control the convexity change of the quadratic term (0.15< <0.35), increasing its value can reduce the curvature radius of the middle section of the curve (x∈[0.3,0.5]) by 35% to 50%, accelerate the development of the boundary layer of the airflow at the mid-diameter position of the blade, and suppress the pressure pulsation amplitude caused by the local adverse pressure gradient; the coefficient (-0.035< <-0.01) By adjusting the slope of the linear term, the angle of attack deviation from the leading edge to the mid-diameter section of the blade is compensated to avoid the sudden increase in pressure difference caused by the sudden change in the angle of attack; the constant term (0.0001< <0.001) is used to fine-tune the overall offset of the curve to ensure the change rate of the hub end wall boundary layer thickness when multiple cross-section blades are stacked.

[0089] In the blade tip area (x≥0.5), the second sub-axial stacking line can adopt a double peak-three trough alternating structure to achieve pressure difference fluctuation suppression through dynamic parameter constraints. Specifically, the first trough is set at x=0.6 (axial offset ∈[-0.04,-0.02]), the first peak is formed at x=0.7 ( ∈[0.01,0.03]), the second trough is generated at x=0.8 ( ∈[-0.05,-0.03]), the second peak is established at x=0.9 ( ∈[0.01,0.03]), the final segment x=1.0 returns to the third trough ( ∈[-0.04,-0.02]). This periodic undulating structure is designed by matching the peak height with the trough depth, so that the local high-pressure area on the suction surface forms multi-stage pressure release nodes in the span direction of the blade, and the low-pressure area on the pressure surface generates reverse compensation flow, limiting the pressure difference fluctuation amplitude ΔP to the maximum pressure difference threshold ΔP_lim.

[0090] In summary, when It is the first trough, and its axial offset distance :

[0091] when It is the first wave peak, and its axial offset distance :

[0092] when It is the second trough, and its axial offset distance :

[0093] when It is the second wave peak, and its axial offset distance :

[0094] when It is the third trough, and its axial offset distance :

[0095] In some examples, reference Figure 8 The two stacked lines are joined using a second-order continuous splicing algorithm at x=0.5. By solving the continuity equations for the first and second derivatives of the cubic polynomial at the connection point, the geometric transition is ensured to be continuous and the curvature rate of change deviation is less than 5%. The resulting axial stacked line achieves progressive pressure gradient control in the hub region. The wave interference effect in the blade tip region disrupts the formation of large-scale vortex structures. CFD verification shows that the optimized pressure differential fluctuation amplitude on the blade surface is reduced.

[0096] In some examples, based on the extreme turbulence separation point, a circumferential stacking line that is nonlinearly and continuously curved along the blade span direction is constructed to move the extreme turbulence separation point backward to an extreme position close to the trailing edge of the blade.

[0097] Specifically, the circumferential stacking line may be represented by a second cubic polynomial, and based on the extreme turbulent separation point, the coefficient of the second cubic polynomial may be adjusted to control the curvature change thereof.

[0098] For example, in the parametric design of circumferential stacking lines, a nonlinear continuous curved topology structure is constructed based on the position parameters of the extreme turbulent separation point.

[0099] First, the blade span position from the blade root to the blade tip can be normalized to (x):

[0100] The circumferential displacement distribution function is defined using the second and third degree polynomials:

[0101] In some examples, reference Figure 9 , where the normalized blade span position x∈[0,1] corresponds to the spanwise coordinate from hub to blade tip, and the coefficient constraint is 2< <3, -4< <-3, 0.6< <0.9 and 0.001< <0.002, ensuring the polynomial goodness of fit R²>0.9. The cubic curvature strength of the front section of the curve (x∈[0,0.3]) is enhanced to form a circumferential pre-rotation angle of -12°~-8° at the blade root, accelerate the boundary layer flow in the leading edge area, and delay the start position of the airflow separation from 45% of the chord length to 65%; the coefficient The negative value characteristic of controls the concave curvature radius of the middle section of the curve (x∈[0.3,0.7]), suppresses the sudden change of the velocity gradient on the suction surface, makes the tangential deviation of the mainstream velocity vector and the profile ≤5°, and avoids local flow separation in the mid-diameter area; the coefficient The slope of the dominant linear segment is 0.6< The positive gradient compensation of <0.9 makes the blade tip area (x∈[0.7,1]) form a circumferential backward bend angle of +5°~+8°, enhancing the airflow fit in the trailing edge area; the constant term Used to eliminate geometric discontinuities when multiple cross-sections overlap.

[0102] After obtaining the above-mentioned axial stacking line and circumferential stacking line, the three-dimensional stacking line parameter equation can be determined based on the above-mentioned axial stacking line and circumferential stacking line as follows: ( ) ( ) Reference Figure 10 and Figure 11 As shown in FIG, the target blade model can be obtained through the control curves of four airfoil parameters and two sweep parameters.

[0103] Reference Figure 12 and Figure 13 The present invention constructs a continuous double-peak and triple-trough axial stacked line topology from the 50% radius of the blade to the tip. This structure suppresses the circumferential migration of high-pressure fluid in the hub region through a segmented release mechanism of the axial pressure gradient, confining the pressure differential amplitude between the suction and pressure surfaces within the critical pressure differential threshold. This wavy configuration disrupts spanwise vortex coherence, reduces the trailing edge vortex shedding intensity coefficient, and attenuates the broadband noise caused by periodic vortex excitation forces.

[0104] Based on CFD / NVH joint simulation verification, in the aerodynamic noise test of the heat pump unit, the noise spectrum characteristics of the optimized blades disclosed in this disclosure at 1m from the inlet and outlet monitoring surfaces (ISO 3744 standard measurement point) are significantly improved. Compared with the existing technology, the total sound pressure level of the broadband noise of the optimized blades is significantly reduced, among which the main frequency energy of the vortex shedding caused by the backward shift of the extreme turbulent separation point is significantly attenuated, and the pressure pulsation amplitude is significantly reduced at the characteristic frequency of the tip vortex. Figure 14 and Figure 15,The simulation data confirms the suppressive effect of the coordinated design of axial and circumferential stacking lines on aerodynamic noise.

[0105] The disclosed embodiments achieve active suppression of aerodynamic noise from axial fan blades by constructing a coordinated control mechanism for axial and circumferential stacking lines. The axial stacking line utilizes a wavy topology with alternating double peaks and three troughs, creating a segmented pressure gradient release mechanism in the spanwise region of the blade tip. This suppresses excessive fluctuations in the ultimate pressure difference between the suction and pressure surfaces, destroys the coherence of large-scale spanwise vortices, and reduces the trailing edge vortex shedding intensity coefficient. The circumferential stacking line is controlled by cubic polynomial curvature, weakening the primary frequency energy of discrete vortex shedding and shifting the pressure pulsation amplitude spectrum toward the high frequency band.

[0106] The combined design of axial and circumferential stacking lines effectively suppresses broadband noise sources caused by sudden pressure differential surges and turbulent separation by synergistically optimizing spanwise pressure field homogenization and chordwise flow stability. CFD / NVH co-simulations have demonstrated a significant reduction in the overall sound pressure level of broadband noise at the inlet and outlet monitoring surfaces of the optimized blades, attenuated the amplitude of pressure pulsations at the characteristic frequencies of the tip vortex, and achieved noise spectrum characteristics that meet ISO 3744 standards, achieving simultaneous improvements in aerodynamic efficiency and acoustic quality.

[0107] Furthermore, the present disclosure also provides an axial flow fan blade, which is designed according to the above-mentioned design method of the axial flow fan blade.

[0108] For further reference, Figure 16 As shown, in the embodiment of this example, a design device 1600 for an axial flow fan blade is also provided, comprising a model acquisition module 1610, a target determination module 1620, a parameter design module 1630, and a model update module 1640. Among them: The model acquisition module 1610 may be used to acquire an initial blade model of the axial flow fan blade.

[0109] In some examples, the model acquisition module 1610 may be configured to generate the initial blade model based on preset aerodynamic performance parameters and blade geometric constraints.

[0110] The target determination module 1620 may be configured to determine the limit pressure difference between the suction side and the pressure side of the axial flow fan blade corresponding to the target noise, and the limit turbulence separation point of the axial flow fan blade.

[0111] In some examples, the operating noise of the axial fan blades is simulated to determine a mapping relationship between pressure difference and noise; based on the mapping relationship and the target noise, the limit pressure difference corresponding to the target noise is determined; and based on the frequency band energy distribution of the target noise, the limit turbulence separation point is determined.

[0112] The parameter design module 1630 may be configured to design the axial stacking line of the axial flow fan blades according to the extreme pressure difference, and to design the circumferential stacking line of the axial flow fan blades according to the extreme turbulent separation point.

[0113] In some examples, the parameter design module 1630 can also be used to construct an axial stacking line with a wavy distribution along the span direction of the blade based on the extreme pressure difference, wherein the wavy distribution adjusts the pressure gradient distribution on the blade surface through periodic fluctuations, so that the pressure difference between the suction surface and the pressure surface is uniform within the range of the extreme pressure difference.

[0114] In some examples, the parameter design module 1630 may further be configured to represent a first sub-axial stacking line near the hub portion of the axial flow fan blade using a first cubic polynomial, and adjust coefficients of the first cubic polynomial based on the limit pressure difference to control a change in its curvature; The second sub-axial stacking line near the blade tip region passes through a structure in which crests and troughs are alternately distributed. Based on the constraint of the ultimate pressure difference, the height of the crests, the depth of the troughs, and the distribution spacing between the crests and troughs are dynamically adjusted to make the pressure difference fluctuation amplitude between the suction side and the pressure side less than the ultimate pressure difference. The first sub-axial stacking line and the second sub-axial stacking line are smoothly connected to obtain the axial stacking line.

[0115] In some examples, the parameter design module 1630 may also be used to construct a nonlinear and continuously curved circumferential stacking line along the blade span direction based on the extreme turbulence separation point, so as to move the extreme turbulence separation point back to be close to the blade trailing edge.

[0116] In some examples, the parameter design module 1630 may be further configured to express the circumferential stacking line using a second cubic polynomial, and adjust coefficients of the second cubic polynomial based on the extreme turbulent separation point to control the curvature change thereof.

[0117] It should be understood that the above-described device embodiments are merely illustrative, and the devices of the present disclosure may also be implemented in other ways. For example, the division of units / modules in the above-described embodiments is merely a logical functional division, and actual implementations may employ other division methods. For example, multiple units, modules, or components may be combined or integrated into another system, or some features may be omitted or not implemented.

[0118] In addition, unless otherwise specified, the functional units / modules in the various embodiments of the present disclosure may be integrated into a single unit / module, each unit / module may exist physically separately, or two or more units / modules may be integrated together. The aforementioned integrated units / modules may be implemented in the form of hardware or software program modules.

[0119] If an integrated unit / module is implemented in hardware, the hardware may be digital circuits, analog circuits, etc. The physical implementation of the hardware structure includes, but is not limited to, transistors, memristors, etc. Unless otherwise specified, the processor may be any appropriate hardware processor, such as a CPU, GPU, FPGA, DSP, and ASIC. Unless otherwise specified, the storage unit may be any appropriate magnetic storage medium or magneto-optical storage medium, such as resistive random access memory (RRAM), dynamic random access memory (DRAM), static random access memory (SRAM), enhanced dynamic random access memory (EDRAM), high-bandwidth memory (HBM), hybrid memory cube (HMC), etc.

[0120] If the integrated unit / module is implemented in the form of a software program module and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present disclosure, or the part that contributes to the existing technology, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a memory and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the present disclosure. The aforementioned memory includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc. Various media that can store program code.

[0121] Please refer to Figure 17 , which shows a structural block diagram of an electronic device provided by an exemplary embodiment of the present disclosure. In some examples, the electronic device can be at least one of a smart phone, a smart watch, a desktop computer, a laptop computer, a virtual reality terminal, an augmented reality terminal, a wireless terminal and a laptop computer. The electronic device has a communication function and can access a wired network or a wireless network. The electronic device can generally refer to one of a plurality of terminals. Those skilled in the art will appreciate that the number of the above terminals can be more or less. It is understandable that the electronic device undertakes the calculation and processing work of the technical solution of the present disclosure, and the embodiments of the present disclosure are not limited to this.

[0122] like Figure 17 As shown, the electronic device 1700 may include: at least one processor 1710 , a memory 1720 , and a communication interface 1730 .

[0123] The memory 1720 is used to store programs. Specifically, the programs may include program codes, and the program codes include computer operation instructions.

[0124] The memory 1720 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0125] Processor 1710 is configured to execute computer-executable instructions stored in memory 1720 to implement the axial fan blade design method described in the aforementioned method embodiment. Processor 1710 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present disclosure.

[0126] The electronic device 1700 may also include a communication interface 1730, which can communicate with external devices through the communication interface 1730. In a specific implementation, if the communication interface 1730, memory 1720, and processor 1710 are implemented independently, the communication interface 1730, memory 1720, and processor 1710 may be interconnected via a bus to enable communication between them. The bus may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. Buses can be categorized as address buses, data buses, control buses, etc., but this does not mean that there is only one bus or only one type of bus.

[0127] Optionally, in a specific implementation, if the communication interface 1730, the memory 1720 and the processor 1710 are integrated on a chip, the communication interface 1730, the memory 1720 and the processor 1710 can complete communication through an internal interface.

[0128] The present disclosure also provides a computer storage medium, which may include: a U disk, a mobile hard disk, a read-only memory, a random access memory, a disk or an optical disk, and other media that can store program codes. Specifically, the computer storage medium stores program instructions, and the program instructions are used for the design method of the axial flow fan blades in the above embodiment.

[0129] An embodiment of the present disclosure also provides a computer program product, which includes computer instructions, which are stored in a computer storage medium; a processor of an electronic device reads the computer instructions from the computer storage medium, and the processor executes the computer instructions, so that the electronic device executes to implement the design method of the axial fan blades of the above-mentioned embodiments.

[0130] Those skilled in the art will appreciate that in one or more of the above examples, the functions described in the embodiments of the present disclosure can be implemented using hardware, software, firmware, or any combination thereof. When implemented using software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any media that facilitates the transmission of computer programs from one place to another. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0131] In the above embodiments, the description of each embodiment has its own emphasis. For parts not described in detail in a particular embodiment, please refer to the relevant description of other embodiments. The technical features of the above embodiments can be combined in any way. To keep the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the invention claimed herein. This disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not claimed in this disclosure.

[0133] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for designing an axial flow fan blade, characterized in that: include: Obtaining an initial blade model of the axial flow fan blade; The limit pressure difference between the suction side and the pressure side of the axial flow fan blade corresponding to the target noise, and the limit turbulence separation point of the axial flow fan blade; Designing an axial stacking line of the axial flow fan blades according to the limit pressure difference, and designing a circumferential stacking line of the axial flow fan blades according to the limit turbulent separation point; The initial blade model is updated using the axial stacking line and the circumferential stacking line to obtain a target blade model, so that the noise of the axial flow fan blade corresponding to the target blade model during operation is less than the target noise.

2. The method according to claim 1, characterized in that The limit pressure difference between the suction side and the pressure side of the axial flow fan blade corresponding to the target noise, and the limit turbulence separation point of the axial flow fan blade, include: Performing a working noise simulation on the axial flow fan blades to determine a mapping relationship between pressure difference and noise; determining a limit pressure difference corresponding to the target noise based on the mapping relationship and the target noise; The critical turbulence separation point is determined based on the frequency band energy distribution of the target noise.

3. The method according to claim 1, characterized in that The step of designing the axial stacking line of the axial flow fan blades according to the limit pressure difference comprises: Based on the limit pressure difference, an axial stacking line is constructed with a wave-shaped distribution along the blade span direction, wherein the wave-shaped distribution adjusts the pressure gradient distribution on the blade surface through periodic fluctuations, so that the pressure difference between the suction surface and the pressure surface is uniform within the range of the limit pressure difference.

4. The method according to claim 3, characterized in that The step of constructing an axial stacking line distributed in a wave shape along the blade span direction based on the extreme pressure difference comprises: Using a first cubic polynomial to represent a first sub-axial stacking line near a hub portion of the axial flow fan blade, and adjusting coefficients of the first cubic polynomial based on the limit pressure difference to control a change in its curvature; The second sub-axial stacking line near the blade tip region passes through a structure in which crests and troughs are alternately distributed. Based on the constraint of the ultimate pressure difference, the height of the crests, the depth of the troughs, and the distribution spacing between the crests and troughs are dynamically adjusted to make the pressure difference fluctuation amplitude between the suction side and the pressure side less than the ultimate pressure difference. The first sub-axial stacking line and the second sub-axial stacking line are smoothly connected to obtain the axial stacking line.

5. The method according to claim 1, wherein The designing of the circumferential stacking line of the axial flow fan blade according to the extreme turbulence separation point comprises: Based on the extreme turbulence separation point, a circumferential stacking line with nonlinear continuous curvature along the blade span direction is constructed, so that the extreme turbulence separation point is moved back to be close to the trailing edge of the axial flow fan blade.

6. The method according to claim 5, characterized in that The step of constructing a circumferential stacking line that is nonlinearly and continuously curved along the blade span direction based on the extreme turbulent separation point comprises: The circumferential stacking line is represented by a second cubic polynomial, and based on the extreme turbulent separation point, the coefficient of the second cubic polynomial is adjusted to control the curvature change thereof.

7. The method according to claim 1, characterized in that The obtaining of the initial blade model of the axial flow fan blade includes: The initial blade model is generated based on preset aerodynamic performance parameters and blade geometric constraints.

8. A design device for axial flow fan blades, characterized in that: include: A model acquisition module, configured to acquire an initial blade model of the axial flow fan blade; a target determination module for determining the limit pressure difference between the suction side and the pressure side of the axial flow fan blade corresponding to the target noise, and the limit turbulence separation point of the axial flow fan blade; a parameter design module, configured to design an axial stacking line of the axial flow fan blades according to the limit pressure difference, and to design a circumferential stacking line of the axial flow fan blades according to the limit turbulent separation point; The model updating module is used to update the initial blade model using the axial stacking line and the circumferential stacking line to obtain a target blade model, so that the noise of the axial flow fan blade corresponding to the target blade model during operation is less than the target noise.

9. An electronic device, characterized in that: The electronic device includes: a processor and a memory; the processor is used to execute instructions stored in the memory to implement the design method of the axial fan blade according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that The computer storage medium stores at least one instruction, and the at least one instruction is used to be executed by a processor to implement the design method of an axial flow fan blade according to any one of claims 1 to 7.

11. An axial flow fan, characterized in that: include: An axial flow fan blade designed using the design method for an axial flow fan blade according to any one of claims 1 to 7.

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