Design method, device, medium and axial flow fan for axial flow fan blades

Abstract

The embodiment of the present disclosure discloses a design method, device, medium and axial flow fan of an axial flow fan blade. The design method of the axial flow fan blade can include: obtaining an initial blade model of the axial flow fan blade; based on a limit pressure difference of a suction surface and a pressure surface of the axial flow fan blade corresponding to a target noise, and a limit turbulent separation point of the axial flow fan blade; design an axial accumulation line of the axial flow fan blade according to the limit pressure difference, and design a circumferential accumulation line of the axial flow fan blade according to the limit turbulent separation point; update the initial blade model to obtain a target blade model by using the axial accumulation line and the circumferential accumulation line, so that the noise of the axial flow fan blade corresponding to the target blade model is less than the target noise when working.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the technical field of blade design, and particularly relate to a design method, device, medium and axial flow fan of a blade of an axial flow fan. BACKGROUND

[0002] The axial flow fan has a prominent problem that aerodynamic noise increases with flow rate in high air volume scenarios such as air conditioning and electronic heat dissipation. The traditional noise reduction method suppresses vortex through blade bending or serrated structure, but is limited by geometric mutation leading to flow field instability. Specifically, the curvature mutation in the bending area causes pressure pulsation on the suction surface, resulting in a sharp increase in the pressure difference between the suction surface and the pressure surface, and inducing broadband vortex noise.

[0003] The existing blade structure is difficult to balance pressure difference suppression and flow field continuity at high speed working conditions, resulting in forward shift of turbulent separation point and multi-vortex core interference effect, and noise indicators cannot meet the needs of high-end equipment. How to construct a blade structure that takes into account flow field stability and pressure balance has become a technical problem to be solved. SUMMARY

[0004] Therefore, embodiments of the present disclosure aim to provide a design method, device, medium and axial flow fan of a blade of an axial flow fan, which can reduce the technical problem that the existing blade of an axial flow fan has high noise when working.

[0005] The technical solution of the embodiments of the present disclosure is implemented as follows:

[0006] In a first aspect, the embodiments of the present disclosure provide a design method of a blade of an axial flow fan, comprising:

[0007] obtaining an initial blade model of the blade of the axial flow fan;

[0008] based on a limit pressure difference of a suction surface and a pressure surface of the blade of the axial flow fan corresponding to a target noise, and a limit turbulent separation point of the blade of the axial flow fan;

[0009] designing an axial accumulation line of the blade of the axial flow fan according to the limit pressure difference, and designing a circumferential accumulation line of the blade of the axial flow fan according to the limit turbulent separation point;

[0010] updating the initial blade model by using the axial accumulation line and the circumferential accumulation line to obtain a target blade model, so that the noise of the blade of the axial flow fan corresponding to the target blade model when working is less than the target noise.

[0011] In some examples, the limit pressure difference of the suction surface and the pressure surface of the blade of the axial flow fan corresponding to the target noise, and the limit turbulent separation point of the blade of the axial flow fan, comprise:

[0012] Simulate the working noise of the axial flow fan blade to determine a mapping relationship between pressure difference and noise;

[0013] Determine a limit pressure difference corresponding to the target noise based on the mapping relationship and the target noise;

[0014] Determine the limit turbulent flow separation point based on the frequency band energy distribution of the target noise.

[0015] In some examples, the designing of the axial accumulation line of the axial flow fan blade according to the limit pressure difference includes:

[0016] Based on the limit pressure difference, an axial accumulation line with a wave-shaped distribution along the blade span direction is constructed, wherein the wave-shaped distribution adjusts the pressure gradient distribution of the blade surface through periodic fluctuations, so that the pressure difference between the suction surface and the pressure surface is uniformized within the range of the limit pressure difference.

[0017] In some examples, the constructing of the axial accumulation line with a wave-shaped distribution along the blade span direction based on the limit pressure difference includes:

[0018] A first sub-axial accumulation line close to the hub part of the axial flow fan blade is represented by a first cubic polynomial, and the coefficients of the first cubic polynomial are adjusted based on the limit pressure difference to control the curvature variation thereof;

[0019] A second sub-axial accumulation line close to the tip region is constructed through a structure with alternating peaks and valleys, and based on the constraint of the limit pressure difference, the height of the peaks, the depth of the valleys, and the distribution spacing of the peaks and valleys are dynamically adjusted, so that the pressure difference fluctuation amplitude between the suction surface and the pressure surface is less than the limit pressure difference;

[0020] The first sub-axial accumulation line and the second sub-axial accumulation line are smoothly connected to obtain the axial accumulation line.

[0021] In some examples, the designing of the circumferential accumulation line of the axial flow fan blade according to the limit turbulent flow separation point includes:

[0022] Based on the limit turbulent flow separation point, a circumferential accumulation line with a non-linear continuous curvature along the blade span direction is constructed, so that the limit turbulent flow separation point is moved to be close to the trailing edge of the axial flow fan blade.

[0023] In some examples, the constructing of the circumferential accumulation line with a non-linear continuous curvature along the blade span direction based on the limit turbulent flow separation point includes:

[0024] The circumferential accumulation line is represented by a second cubic polynomial, and the coefficients of the second cubic polynomial are adjusted based on the limit turbulent flow separation point to control the curvature variation thereof.

[0025] In some examples, the obtaining the initial blade model of the axial flow fan blade comprises:

[0026] The initial blade model is generated based on preset aerodynamic performance parameters and blade geometric constraints.

[0027] In a second aspect, the embodiments of the present disclosure provide a design device of an axial flow fan blade, comprising:

[0028] a model obtaining module configured to obtain an initial blade model of the axial flow fan blade;

[0029] a target determining module configured to determine, based on a target noise, a limit pressure difference of a suction surface and a pressure surface of the axial flow fan blade, and a limit turbulent separation point of the axial flow fan blade;

[0030] a parameter design module configured to design an axial stacking line of the axial flow fan blade according to the limit pressure difference, and design a circumferential stacking line of the axial flow fan blade according to the limit turbulent separation point;

[0031] a model updating module configured to update the initial blade model to obtain a target blade model by using the axial stacking line and the circumferential stacking line, so that the target blade model corresponds to an axial flow fan blade with a noise less than the target noise when the axial flow fan blade is working.

[0032] In a third aspect, the embodiments of the present disclosure provide 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 flow fan blade according to the first aspect.

[0033] In a fourth aspect, the embodiments of the present disclosure provide a computer storage medium, which stores at least one instruction for being executed by a processor to implement the design method of the axial flow fan blade according to the first aspect.

[0034] In a fifth aspect, the embodiments of the present disclosure provide an axial flow fan comprising an axial flow fan blade designed by using the design method of the axial flow fan blade according to the first aspect.

[0035] The embodiment of the present disclosure provides a design method, device, medium and axial flow fan of an axial flow fan blade; aerodynamic noise control is achieved 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, the blade spanwise pressure gradient distribution is adjusted through the axial stacking line design, and the vortex intensity caused by the sudden change of the high pressure area is reduced; meanwhile, the circumferential stacking line form is optimized according to the limit turbulent separation point position, and the boundary layer separation starting position is delayed. The axial stacking line controls the uniformity of the spanwise pressure field, the circumferential stacking line adjusts the chordwise flow stability, and the combination of the two suppresses the noise source generation mechanism of the sudden increase of the pressure difference and the turbulent separation. Through iterative updating of the blade model parameters, the aerodynamic noise of the target blade under the same working condition is finally lower than the target noise value. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A flowchart of a design method of an axial flow fan blade provided by the embodiment of the present disclosure.

[0037] Figure 2 A structural schematic diagram of an axial flow fan blade provided by the embodiment of the present disclosure.

[0038] Figure 3 A schematic diagram of vortex generation provided by the embodiment of the present disclosure.

[0039] Figure 4 A schematic diagram of a turbulent separation point in the related art provided by the embodiment of the present disclosure.

[0040] Figure 5 A schematic diagram of a turbulent separation point provided by the embodiment of the present disclosure.

[0041] Figure 6 A planar airfoil schematic diagram provided by the embodiment of the present disclosure.

[0042] Figure 7 A schematic diagram of a sweep feature definition method provided by the embodiment of the present disclosure.

[0043] Figure 8 A schematic diagram of an axial stacking line provided by the embodiment of the present disclosure.

[0044] Figure 9 A schematic diagram of a circumferential stacking line provided by the embodiment of the present disclosure.

[0045] Figure 10 A schematic diagram of a target blade model provided by the embodiment of the present disclosure.

[0046] Figure 11 A schematic diagram of another target blade model provided by the embodiment of the present disclosure.

[0047] Figure 12A schematic diagram of a pressure difference between a pressure surface and a suction surface provided by an embodiment of the present disclosure.

[0048] Figure 13 A schematic diagram of a pressure difference between a pressure surface and a suction surface in the related art.

[0049] Figure 14 A schematic diagram of a noise spectrum in the related art.

[0050] Figure 15 A schematic diagram of a noise spectrum provided by an embodiment of the present disclosure.

[0051] Figure 16 A structural schematic diagram of a design device for a blade of an axial flow fan provided by an embodiment of the present disclosure.

[0052] Figure 17 A structural schematic diagram of an electronic device provided by an embodiment of the present disclosure.

[0053] The specific embodiments of the present disclosure have been shown through the above-described drawings, and will be described in more detail hereinafter. These drawings and written descriptions are not intended to limit the scope of the concept of the present disclosure by any means, but to illustrate the concept of the present disclosure to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0054] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example implementations to those skilled in the art. The described features, structures, or characteristics can be combined in one or more implementations.

[0055] In addition, the accompanying drawings are only schematic and are not necessarily drawn to scale. Identical components have been given the same reference numerals in the various drawings and have not necessarily been described for every embodiment. The drawings in the specification illustrate one or more implementations. It is to be understood by those skilled in the art that other implementations can be used without departing from the spirit or essential characteristics of the present disclosure. Thus, the present disclosure should not be limited to the implementations set forth in the figures, but should be given the widest scope consistent with the principles of the present disclosure.

[0056] An axial flow fan is widely used in the fields of air conditioning systems, electronic equipment heat dissipation, industrial ventilation, etc. as a key fluid conveying component.

[0057] With the development of fluid machinery towards high efficiency and low noise, the aerodynamic noise control of fan blades under high-speed rotating conditions has become an important research direction in the industry. Especially in application scenarios that require high air supply, the traditional blade structure generally has the technical contradiction that the aerodynamic noise increases significantly with the increase of flow rate, which seriously restricts the environmental adaptability and user experience of the equipment.

[0058] In the related art, to solve the problem of blade aerodynamic noise, the blade leading edge serration, perforation design or wave-shaped bending structure is usually used to improve the flow field distribution. Among them, the blade structure with wave-shaped bending characteristics can inhibit the vortex generated by radial flow to a certain extent by dispersing the inner edge high pressure transmission path. However, this structure has the inherent defect of discontinuous transition in the geometric mutation area during implementation, which is specifically manifested as the curvature change rate of the bending part exceeding the self-adaptive range of the flow field, resulting in an abnormal increase in local flow velocity gradient. This discontinuous structure feature will form non-steady-state pressure pulsation on the suction surface, inducing boundary layer separation, and then generating wide-band vortex noise. It is found in engineering practice that when the rotational speed of the traditional wave-shaped blade exceeds the critical threshold, the pressure difference between the suction surface and the pressure surface will increase exponentially, and the turbulent energy aggregation effect caused thereby makes it difficult to meet the acoustic requirements of high-end equipment.

[0059] Research shows that the existing blade design method has a significant deviation between the theoretical model and the engineering implementation in controlling the pressure gradient distribution and the position of the turbulent separation point. Specifically, the conventional continuous circular arc transition structure cannot accurately regulate the blade stacking line form, resulting in non-uniform characteristics of the pressure difference suppression effect at different spanwise positions of the blade. This design defect makes the blade prone to form multiple discrete vortex core generation zones under high-speed conditions, and the interference effect between the vortex systems further aggravates the complexity of the noise spectrum. Therefore, how to construct a blade geometry control method that takes into account the stability of the flow field and the pressure balance characteristics has become a key bottleneck problem for realizing high-air-volume and low-noise axial flow fans.

[0060] Based on this, the present disclosure first provides a design method of an axial flow fan blade, Figure 1 A flowchart of the design method of the axial flow fan blade is shown, wherein the design method of the axial flow fan blade can include steps S110 to S140.

[0061] In step S110, an initial blade model of the axial flow fan blade is obtained.

[0062] In some example embodiments of the present disclosure, the aerodynamic performance parameters and blade set constraints of the axial flow fan blade can be obtained first to generate the initial blade model.

[0063] During the implementation of the method, the construction of the initial blade model is based on a dual input system of aerodynamic performance parameters and blade geometric constraints. The aerodynamic performance parameters include core indicators such as target static pressure, rated flow, and design rotating speed, and the geometric constraints cover structural boundary conditions such as hub radius, casing radius, and blade number. Through the coupling calculation of tangential velocity and axial velocity, a blade spanwise velocity triangular distribution model is established, in which the tangential velocity is determined by the product of the hub radius and the rotating speed, and the axial velocity is solved based on the ratio of the flow to the annular flow area. By using the trigonometric function relationship between the leading edge direction angle and the trailing edge direction angle, the installation angle parameter is inversely calculated based on the Euler equation, and the chord length distribution curve is constrained by the empirical value of the lift coefficient. The airfoil midline 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, and then the entity contour is formed by offsetting to both sides of the midline through the thickness distribution function. Finally, the initial stacking lines of each section airfoil along the axial and circumferential directions of the hub are arrayed in space to form an initial three-dimensional blade model with basic aerodynamic performance, providing an iterative reference for subsequent differential pressure optimization and separation point control.

[0064] It should be noted that the spanwise direction is from the blade root to the blade tip, that is, along the length direction of the blade.

[0065] In step S120, 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 separation point of the axial flow fan blade are determined.

[0066] In some example embodiments of the present disclosure, the active control of aerodynamic noise is achieved by establishing a quantitative mapping relationship between the noise indicator and the blade surface pressure field and the flow separation characteristics.

[0067] Optionally, the target noise is converted into a limit pressure difference threshold value of the suction surface and the pressure surface through an acoustic inversion model, and the threshold value is precisely controlled through the wave-shaped parameterized design of the axial stacking line.

[0068] At the same time, the turbulent energy spectrum characteristics corresponding to the target noise are converted into the limit turbulent separation point position parameter, and the circumferential deflection amount forms a gradual compensation mechanism in the direction from the leading edge to the trailing edge of the blade.

[0069] The synergistic effect of the above axial and circumferential stacking parameters makes the blade surface pressure pulsation main frequency amplitude decay, and the trailing edge vortex shedding frequency shifts to the non-sensitive frequency band of the human ear, finally realizing the reduction of the total value of aerodynamic noise.

[0070] In step S130, the axial stacking line of the axial flow fan blade is designed according to the limit pressure difference, and the circumferential stacking line of the axial flow fan blade is designed according to the limit turbulent separation point.

[0071] In some example embodiments of the present disclosure, the blade geometric configuration has a decisive effect on the aerodynamic performance and noise spectrum characteristics of the axial flow fan. For example, Figure 2As shown, the blade forming method is based on the spanwise stacking principle, and the complete impeller structure is generated by connecting multiple two-dimensional reference airfoil cross-section blade shapes 22 along an axial stacking line 21 in three-dimensional space topology and in a circumferential array. Figure 3 and Figure 4 The traditional blade stacking method usually adopts a continuous smooth curve connection mode, which can easily cause a significant circumferential pressure gradient between the suction surface and the pressure surface under operating conditions, and the high pressure at the inner edge of the suction surface is transferred to the low pressure of the pressure surface in the circumferential direction. This flow will cause vortexes 31 in the suction surface, and induce boundary layer turbulent separation and discrete vortex shedding, resulting in loss of aerodynamic efficiency and increased broadband noise.

[0072] To solve this problem, in the design, the axial stacking line of the axial flow fan blade is designed according to the limit pressure difference corresponding to the target noise, and the circumferential stacking line of the axial flow fan blade is designed based on the limit turbulent separation point 41.

[0073] Optionally, the axial stacking line is designed by using a parameterized curve, and by adjusting the relative offset amount of the wave crest and the wave trough, a gradual pressure gradient distribution is formed in the tip spanwise region, thereby suppressing the limit pressure difference between the suction surface and the pressure surface; the circumferential stacking line is adjusted by a displacement equation, and a velocity vector dynamic fitting mechanism is constructed in the region from the leading edge to the middle and rear part of the chord length, so as to delay the limit turbulent separation point of the boundary layer to the trailing edge direction.

[0074] It should be noted that the axial direction is along the direction of the rotation axis, and the circumferential direction is around the rotation axis.

[0075] In step S140, the initial blade model is updated 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 is less than the target noise when the axial flow fan blade is working.

[0076] In some example 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, and the obtained target blade model is as shown in Figure 5 As shown, the wave-shaped distribution of the target blade model reduces the size of the separation vortex by changing the position of the limit turbulent separation point 41, effectively reduces the intensity of the blade surface pressure pulsation and the total value of the aerodynamic noise, and realizes the synergistic optimization of the aerodynamic-acoustic performance.

[0077] 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 the 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, the blade spanwise pressure gradient distribution is adjusted through the axial stacking line design, and the vortex strength caused by the sudden change of the high pressure area is reduced; at the same time, the circumferential stacking line form is optimized according to the limit turbulent separation point position, and the boundary layer separation starting position is delayed. The axial stacking line controls the uniformity of the spanwise pressure field, the circumferential stacking line adjusts the chordwise flow stability, and the combination of the two suppresses the noise source generation mechanism of the sudden increase of the pressure difference and the turbulent separation. Through iterative updating of the blade model parameters, the aerodynamic noise of the target blade under the same working condition is finally lower than the target noise value.

[0078] Wherein, the above-mentioned spanwise is the direction from the blade root to the blade tip, that is, the direction along the length of the blade.

[0079] The parameterization of the axial flow fan blade profile includes two parts of airfoil section parameters at different blade heights and airfoil sweep values at different blade heights. The parameters of the airfoil section include the leading edge and trailing edge direction angle, the airfoil installation angle and the chord length. The sweep values at different blade heights include the circumferential offset (bend) value and the axial offset (sweep) value. By adjusting the control curves of the 4 airfoil parameters and the 2 sweep parameters, the entire profile can be completely controlled.

[0080] In some examples, when obtaining an initial blade model, the initial blade model can be generated based on preset aerodynamic performance parameters and blade geometric constraints. The aerodynamic parameters can include static pressure P, flow rate Q, rotational speed N (RPM), hub radius , casing radius , number of blades Z, etc. After obtaining the above parameters, the 4 airfoil parameters and the 2 sweep parameters can be calculated.

[0081] Specifically, given the static pressure P, flow rate Q, rotational speed N (RPM), hub radius , casing radius , number of blades Z, then:

[0082] Tangential velocity (u):

[0083]

[0084] Axial velocity (c):

[0085]

[0086] Leading edge direction angle ( ):

[0087]

[0088] Trailing edge direction angle ( ):

[0089] According to the Euler equation, the static pressure P satisfies:

[0090]

[0091] The solution is:

[0092]

[0093] The installation angle (a) is:

[0094]

[0095] The chord length (L) is:

[0096]

[0097] Wherein, R is the average radius:

[0098] The lift coefficient (C L) is: Take the empirical value 0.8~1.2.

[0099] Wherein, D represents the diameter of the casing, And represents the air density.

[0100] After obtaining the above parameters, the centerline curve can be determined based on the above parameters. Specifically, the above centerline parameter can be represented by a cubic Bezier curve, and the parameter equation thereof is:

[0101] (t [0,1])

[0102] h is the maximum camber, used to represent the maximum distance of the centerline to the straight line connecting the two ends of the centerline.

[0103] Referring to Figure 6 , and are the leading edge and trailing edge direction angles of the airfoil, respectively; is the installation angle of the airfoil; L is the chord length. The airfoil profile is obtained by offsetting the centerline of the airfoil to both sides according to the airfoil section thickness distribution. In some examples, the blade can be divided into five key positions from the leading edge to the trailing edge along the centerline (chord direction), and the five points are uniformly distributed, so that the normalized chord length position is:

[0104]

[0105] The present application defines the ratio of the corresponding thickness of the five positions to the chord length as:

[0106] ​​

[0107] wherein x represents the position of the point on the center line, and d represents the thickness of the point.

[0108] After obtaining the initial model, the limit turbulent separation point of the axial flow fan blade can be determined 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.

[0109] Specifically, a quantitative mapping relationship between the dynamic pressure difference distribution of the suction surface and the pressure surface of the blade and the noise can be first established through working noise simulation. Based on the mapping relationship, combined with the sound pressure level threshold constraint of the target noise, the limit pressure difference of the suction surface and the pressure surface required for suppressing wideband noise is obtained by reverse analysis. Subsequently, the frequency spectrum characteristic of the frequency band energy distribution of the target noise is analyzed, the discrete vortex shedding characteristic frequency corresponding to the dominant noise frequency band is extracted, and combined with the boundary layer velocity gradient distribution characteristics, the limit value of the starting position of the turbulent separation required for suppressing wideband noise, i.e. the limit turbulent separation point, is determined.

[0110] For example, assuming that the aerodynamic noise of a certain axial flow fan needs to be reduced from the original 70dB(A) to the target value of 65dB(A), the CFD / NVH joint simulation can be first performed on the initial blade model. When the maximum pressure difference between the suction surface and the pressure surface is 120Pa, the corresponding noise peak value is 68dB(A), and when the pressure difference is reduced to 80Pa, the noise is reduced to 65dB(A). Thus, the limit pressure difference threshold is determined to be 80Pa.

[0111] In some examples, if the spectrum analysis shows that the original blade has significant vortex shedding noise (accounting for 40% of the energy) at a frequency of 200Hz. Through boundary layer velocity gradient calculation, it is found that the turbulent separation starts at the chord length of 50%, corresponding to the vortex shedding frequency of 200Hz. The target requires that the energy of this frequency band be reduced to less than 15%, and the separation point needs to be moved to the chord length of 80% (corresponding to the vortex shedding frequency offset to 100Hz), and the limit turbulent separation point is set to the chord length of 80%.

[0112] After obtaining the limit pressure difference of the suction surface and the pressure surface of the axial flow fan blade and the limit turbulent separation point of the axial flow fan blade, the axial accumulation line of the axial flow fan blade can be designed according to the limit pressure difference, and the circumferential accumulation line of the axial flow fan blade can be designed according to the limit turbulent separation point.

[0113] Reference Figure 7, the axial stacking line is one of the key variables of the blade forming. Firstly, each cross-section blade profile is mapped to the Z-Y plane, where Z is the axial direction along the hub, and Y is the circumferential direction along the hub. The axial displacement of the cross-section blade profile is called axial-sweep, and the circumferential displacement is called circumferential-lean / skew. Among them, the sweep of the blade against the flow direction is forward sweep, and the sweep along the flow direction is backward sweep; the bend of the blade along the rotation direction is forward bend, and the bend against the rotation direction is backward bend.

[0114] In the above-mentioned axial stacking line design, the limit pressure difference constraint is obtained, a piecewise cubic polynomial is used to construct a wave-shaped spanwise distribution structure, the pressure gradient in the hub area is adjusted by controlling the polynomial coefficients of the forward sweep section, and an alternating wave peak and wave trough structure is arranged in the blade tip area to realize the suppression of the pressure fluctuation amplitude. Based on the limit turbulent separation point position, the circumferential stacking line adopts a nonlinear continuous curved cubic curve form, and by adjusting the curvature parameter of the circumferential offset, the main flow velocity vector is kept attached to the body flow before the 75% position of the chord length, and the turbulent separation starting point is moved to the limit area after 80% of the chord length, thereby effectively reducing the tail edge vortex noise intensity.

[0115] In some examples, based on the limit pressure difference, an axial stacking line with a wave-shaped distribution along the blade span direction can be constructed, wherein the wave-shaped distribution adjusts the pressure gradient distribution of the blade surface through periodic fluctuations, so that the pressure difference between the suction surface and the pressure surface is uniformized within the range of the limit pressure difference.

[0116] Specifically, a first axial stacking line close to the hub part of the axial flow fan blade can be represented by a first cubic polynomial, and based on the limit pressure difference, the coefficients of the first cubic polynomial are adjusted to control the curvature variation; the second axial stacking line close to the blade tip area is arranged in an alternating wave peak and wave trough structure, and based on the limit pressure difference constraint, the height of the wave peak, the depth of the wave trough, and the distribution distance between the wave peak and the wave trough are dynamically adjusted, so that the pressure difference fluctuation amplitude between the suction surface and the pressure surface is less than the limit pressure difference; the first axial stacking line and the second axial stacking line are smoothly connected to obtain the axial stacking line.

[0117] For example, referring to Figure 8 The blade span position corresponding to the blade root to the blade tip can be normalized as (x):

[0118]

[0119] Each value of x represents a blade cross-section between the blade root and the blade tip.

[0120] When , a first cubic polynomial can be used to construct a first axial stacking line for representing the axial displacement of the cross-section blade profile, and the data expression is:

[0121]

[0122] In the design of the axial stacked line, the coefficients of the first cubic polynomial are parametrically adjusted based on the ultimate pressure difference ΔP_lim, and the pressure gradient in the hub area is precisely controlled by curvature control.

[0123] For example, coefficient The higher-order nonlinear terms of the dominant polynomial are constrained to a range of -0.55 < <-0.35, by increasing | The absolute value can enhance the negative curvature characteristics of the initial segment of the curve (x∈[0,0.3]), creating a progressive pressure relief structure at the hub root; coefficient Controlling the convexity of the quadratic term (0.15 < <0.35), increasing its value can reduce the radius of curvature of the middle section of the curve (x∈[0.3,0.5]) by 35% to 50%, accelerate the development of the boundary layer at the blade mid-diameter, and suppress the pressure pulsation amplitude caused by the local adverse pressure gradient; 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, avoiding a sudden increase in pressure difference caused by abrupt changes in the angle of attack; constant term (0.0001< <0.001) is used to fine-tune the overall offset of the curve to ensure the change rate of the boundary layer thickness of the hub end wall when multiple cross-section blades are stacked.

[0124] In the tip region (x≥0.5), the second sub-axial overlap line can adopt a double-peak-three-trough alternating structure, and pressure difference fluctuations can be suppressed through dynamic parameter constraints. Specifically, the first trough is set at x=0.6 (axial offset). The first peak is formed at x=0.7 (∈[-0.04,-0.02]). (∈[0.01,0.03]), a second trough is generated at x=0.8 ( (∈[-0.05,-0.03]), a second peak is established at x=0.9 ( ∈[0.01,0.03]), the final segment x=1.0 regresses to the third trough ( (∈[-0.04,-0.02]). This periodic undulating structure, through the matching design of the peak height and trough depth, enables the local high-pressure zone on the suction surface to form multi-stage pressure release nodes in the spanwise direction of the blade, and generates a reverse compensation flow in the low-pressure zone on the pressure surface, thus limiting the pressure difference fluctuation amplitude ΔP within the range of the ultimate pressure difference threshold ΔP_lim.

[0125] In conclusion, when The first trough, its axial offset distance :

[0126]

[0127] when The first peak, its axial offset distance :

[0128]

[0129] when The second trough, its axial offset distance :

[0130]

[0131] when The second peak, its axial offset distance :

[0132]

[0133] when The third trough, its axial offset distance :

[0134]

[0135] In some examples, refer to Figure 8 At x=0.5, the two overlapping lines are joined using a second-order continuous splicing algorithm. By solving the continuity equations of the first and second derivatives of the cubic polynomial at the connection point, the geometric transition is ensured to be continuous and the deviation of the rate of curvature change is less than 5%. The resulting axial overlapping line achieves gradual control of the pressure gradient in the hub region and disrupts the large-scale vortex structure generation conditions in the blade tip region through wave system interference effect. CFD verification shows that the amplitude of pressure difference fluctuation on the blade surface is reduced after optimization.

[0136] In some examples, based on the extreme turbulence separation point, a circumferentially curved, continuously curved line along the blade span direction is constructed, causing the extreme turbulence separation point to move backward to an extreme position close to the trailing edge of the blade.

[0137] Specifically, the circumferential superposition line can be represented by a second cubic polynomial, and the coefficients of the second cubic polynomial can be adjusted based on the limiting turbulence separation point to control its curvature change.

[0138] For example, in the parametric design of circumferentially stacked lines, a nonlinear continuous curved topology is constructed based on the location parameters of the extreme turbulence separation point.

[0139] Firstly, the normalized blade span position x corresponding to the blade root to tip can be designed as:

[0140]

[0141] The second cubic polynomial is used to define the circumferential displacement distribution function:

[0142]

[0143] In some examples, with reference to Figure 9 where the normalized blade span position x∈[0,1] corresponds to the hub to tip spanwise coordinate, the coefficient constraint is 2< <3, -4 <-3, 0.6 <0.9 and 0.001 <0.002, ensuring that the polynomial goodness of fit R²>0.9. By adjusting The cubic term curvature intensity of the front section of the curve (x∈[0,0.3]) is enhanced to form a circumferential pre-swirl angle of -12°~ -8° at the blade root, accelerate the boundary layer flow in the leading edge region, and delay the airflow separation starting position from 45% to 65% of the chord length; the negative value of the coefficient The concave curvature radius of the middle section of the curve (x∈[0.3,0.7]) is controlled to suppress the sudden change of the suction surface velocity gradient, so that the main flow velocity vector deviates from the tangent of the profile by ≤5°, avoiding local flow separation in the mid-chord region; the coefficient The dominant linear section slope is compensated by a positive gradient of 0.6 <0.9 to form a circumferential backbend angle of +5°~+8° in the tip region (x∈[0.7,1]), enhancing the airflow adhesion in the trailing edge region; the constant term is used to eliminate the geometric discontinuous mutation of the multi-section area stacking.

[0144] After obtaining the above axial stacking line and circumferential stacking line, the three-dimensional stacking line parameter equation can be determined based on the above axial stacking line and circumferential stacking line as:

[0145] ( )

[0146] ( )

[0147] Referring to Figure 10 and Figure 11 , the above target blade model can be obtained by controlling the curve with 4 airfoil parameters and 2 sweep parameters.

[0148] Referring to Figure 12 and Figure 13The disclosure constructs an axial superimposed line topology of continuous double-peak-three-valley in the 50% radius to the tip region of the blade, suppresses the circumferential migration of high-pressure fluid in the hub region through the axial pressure gradient segmented release mechanism, and converges the pressure difference amplitude of the suction surface and the pressure surface to within the limit pressure difference threshold. The wave-shaped configuration destroys the coherence of the spanwise vortex, reduces the tail edge vortex shedding intensity coefficient, and weakens the broadband noise caused by periodic vortex excitation.

[0149] Based on the CFD / NVH joint simulation verification, in the aerodynamic noise test of the heat pump unit, the noise spectrum characteristics of the optimized blade at the 1m monitoring surface of the inlet and outlet (ISO 3744 standard test point) are significantly improved. Compared with the prior art, the total sound pressure level of the broadband noise of the optimized blade is significantly reduced, wherein the vortex shedding main frequency energy generated by the backward shift of the limit turbulent separation point is significantly attenuated, and the pressure fluctuation amplitude is significantly reduced at the tip vortex characteristic frequency. Referring to Figure 14 and Figure 15 , the simulation data confirm the suppression effect of the axial and circumferential superimposed line collaborative design on the aerodynamic noise.

[0150] The embodiment of the disclosure realizes the active suppression of the aerodynamic noise of the axial flow fan blade by constructing a collaborative control mechanism of the axial superimposed line and the circumferential superimposed line. The axial superimposed line adopts a wave-shaped topology of double-peak-three-valley alternation, forms a pressure gradient segmented release mechanism in the tip spanwise region, suppresses the limit pressure difference over-limit fluctuation between the suction surface and the pressure surface, destroys the coherence of the spanwise large-scale vortex, and reduces the tail edge vortex shedding intensity coefficient. The circumferential superimposed line is based on cubic polynomial curvature regulation, which weakens the discrete vortex shedding main frequency energy and shifts the pressure fluctuation amplitude spectrum to the high frequency band.

[0151] The joint design of the axial and circumferential superimposed lines optimizes the spanwise pressure field homogenization and the chordwise flow stability, effectively suppresses the broadband noise source caused by the sudden increase of the pressure difference and the turbulent separation. Through CFD / NVH joint simulation verification, the total sound pressure level of the broadband noise of the optimized blade at the inlet and outlet monitoring surfaces is significantly reduced, the pressure fluctuation amplitude at the tip vortex characteristic frequency is attenuated, the noise spectrum characteristics meet the requirements of the ISO 3744 standard, and the aerodynamic efficiency and acoustic quality are simultaneously improved.

[0152] Further, the disclosure also provides an axial flow fan blade designed according to the design method of the axial flow fan blade.

[0153] Further, as shown in Figure 16 , the design device 1600 of the axial flow fan blade in the embodiment of the present example further comprises a model acquisition module 1610, a target determination module 1620, a parameter design module 1630, and a model updating module 1640. Wherein:

[0154] The model obtaining module 1610 can be configured to obtain an initial blade model of the axial flow fan blade.

[0155] In some examples, the model obtaining module 1610 can be configured to generate the initial blade model based on preset aerodynamic performance parameters and blade geometric constraints.

[0156] The target determining module 1620 can be configured to determine a limit pressure difference corresponding to the target noise based on a limit pressure difference between a suction surface and a pressure surface of the axial flow fan blade corresponding to the target noise, and a limit turbulent separation point of the axial flow fan blade.

[0157] In some examples, the target determining module 1620 can be configured to perform work noise simulation on the axial flow fan blade to determine a mapping relationship between pressure difference and noise, determine the limit pressure difference based on the mapping relationship and the target noise, and determine the limit turbulent separation point based on a frequency band energy distribution of the target noise.

[0158] The parameter design module 1630 can be configured to design an axial stacking line of the axial flow fan blade according to the limit pressure difference, and design a circumferential stacking line of the axial flow fan blade according to the limit turbulent separation point.

[0159] In some examples, the parameter design module 1630 can be further configured to construct an axial stacking line in a wave shape distribution along a blade span direction based on the limit pressure difference, wherein the wave shape distribution adjusts a pressure gradient distribution of a blade surface through periodic fluctuations, so that a pressure difference between the suction surface and the pressure surface is homogenized within a range of the limit pressure difference.

[0160] In some examples, the parameter design module 1630 can be further configured to represent a first sub-axial stacking line close to a hub portion of the axial flow fan blade by a first cubic polynomial, and adjust coefficients of the first cubic polynomial to control a curvature variation thereof based on the limit pressure difference.

[0161] A second sub-axial stacking line close to a tip region is adjusted dynamically based on a constraint of the limit pressure difference through a structure of alternating distribution of wave crests and troughs, so that a fluctuation amplitude of a pressure difference between the suction surface and the pressure surface is less than the limit pressure difference.

[0162] The first sub-axial stacking line and the second sub-axial stacking line are smoothly connected to obtain the axial stacking line.

[0163] In some examples, the parameter design module 1630 can be further configured to construct a circumferential stacking line in a non-linear continuous bending along a blade span direction based on the limit turbulent separation point, so that the limit turbulent separation point is moved to close to a trailing edge of the blade.

[0164] In some examples, the parameter design module 1630 can also be configured to represent the circumferential accumulation line with a second cubic polynomial, and adjust coefficients of the second cubic polynomial to control a curvature variation thereof based on the limit turbulent separation point.

[0165] It should be understood that the above-described device embodiments are only illustrative, and the device of the present disclosure can also be implemented in other manners. For example, the division of units / modules in the above-described embodiments is only a logical function division, and actual implementation can be in another division manner. For example, a plurality of units / modules or components can be combined, or can be integrated into another system, or some features can be omitted or not executed.

[0166] In addition, each functional unit / module in each embodiment of the present disclosure can be integrated in one unit / module, or each unit / module can exist physically, or two or more units / modules can be integrated together. The integrated unit / module can be implemented in the form of hardware or in the form of a software program module.

[0167] The integrated unit / module, if implemented in the form of hardware, can be a digital circuit, an analog circuit, etc. The physical implementation of the hardware structure includes but is not limited to transistors, memristors, etc. Unless otherwise specified, the processor can be any appropriate hardware processor, such as a CPU, a GPU, an FPGA, a DSP, an ASIC, etc. Unless otherwise specified, the storage unit can be any appropriate magnetic storage medium or magneto-optical storage medium, such as a resistive random access memory (RRAM), a dynamic random access memory (DRAM), a static random access memory (SRAM), an enhanced dynamic random access memory (EDRAM), a high-bandwidth memory (HBM), a hybrid memory cube (HMC), etc.

[0168] If the integrated units / modules are implemented in the form of software program modules and sold or used as independent products, they can be stored in a computer readable memory. Based on this understanding, the technical solutions of the present disclosure, essentially or in part, or all or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a memory and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in the various embodiments of the present disclosure. The aforementioned memory includes various media that can store program codes, such as a U disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a mobile hard disk, a magnetic disk or an optical disk, etc.

[0169] Reference is made to Figure 17 , which shows a structural block diagram of an electronic device provided by an example embodiment of the present disclosure. In some examples, the electronic device can be at least one of a smartphone, 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, and those skilled in the art can know that the number of terminals can be more or less. It can be understood that the electronic device undertakes the calculation and processing work of the technical solutions of the present disclosure, and the embodiments of the present disclosure do not limit this.

[0170] As Figure 17 shown, the electronic device 1700 can include at least one processor 1710, a memory 1720, and a communication interface 1730.

[0171] The memory 1720 is configured to store a program. Specifically, the program can include program code, and the program code includes computer operation instructions.

[0172] The memory 1720 can include a high-speed RAM memory, and can also include a non-volatile memory such as at least one disk memory.

[0173] The processor 1710 is configured to execute the computer-executable instructions stored in the memory 1720 to implement the design method of the axial flow fan blade described in the foregoing method embodiments. The processor 1710 can 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.

[0174] The electronic device 1700 can further include a communication interface 1730, through which the electronic device 1700 can communicate with external devices. In a specific implementation, if the communication interface 1730, the memory 1720, and the processor 1710 are implemented independently, the communication interface 1730, the memory 1720, and the processor 1710 can be connected to each other through a bus and complete communication therebetween. The bus can be an industry standard architecture (ISA) bus, a peripheral component (PCI) bus, or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc., but does not mean that there is only one bus or one type of bus.

[0175] 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.

[0176] The present disclosure further provides a computer storage medium, which can include a U disk, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk, or an optical disk, and various media that can store program codes. Specifically, the computer storage medium stores program instructions, which are used for the design method of the axial flow fan blade in the foregoing embodiments.

[0177] The embodiments of the present disclosure further provide a computer program product, which includes computer instructions 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 to enable the electronic device to perform the design method of the axial flow fan blade according to the foregoing embodiments.

[0178] Those skilled in the art should be aware that, in the above one or more examples, the functions described in the embodiments of the present disclosure can be implemented in hardware, software, firmware or any combination thereof. When implemented in software, the functions can be stored in a computer readable medium or transmitted as one or more instructions or code on a computer readable medium. The computer readable medium includes computer storage medium and communication medium, and the communication medium includes any medium that facilitates the transfer of computer program 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.

[0179] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments. Each technical feature of the above embodiments can be combined arbitrarily, and in order to make the description concise, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present disclosure.

[0180] Other embodiments of the present disclosure will be apparent to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. The present disclosure is intended to cover any variations, uses or adaptations of the present disclosure following the general principles thereof and including the general and specific teachings of the present disclosure to the extent not disclosed in the prior art.

[0181] It should be understood that the present disclosure is not limited to the precise structures described and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is limited only by the claims appended hereto.

Claims

1. A design method for axial flow fan blades, characterized in that, include: Obtain the initial blade model of the axial flow fan blade; Determine the ultimate pressure difference between the suction and pressure surfaces of the axial fan blades corresponding to the target noise, as well as the ultimate turbulence separation point of the axial fan blades; Based on the ultimate pressure difference, an axial stacking line with a wavy distribution along the blade span direction is constructed. 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 ultimate pressure difference. The circumferential stacking line of the axial flow fan blade is designed according to the ultimate turbulence separation point. The initial blade model is updated using the axial and circumferential stacking lines to obtain the target blade model, so that the noise of the axial fan blade corresponding to the target blade model is less than the target noise during operation.

2. The method according to claim 1, characterized in that, The determination of the ultimate pressure difference between the suction and pressure surfaces of the axial flow fan blades corresponding to the target noise, and the ultimate turbulence separation point of the axial flow fan blades, includes: The working noise of the axial flow fan blades was simulated to determine the mapping relationship between pressure difference and noise. Based on the mapping relationship and the target noise, determine the limiting pressure difference corresponding to the target noise; The limiting 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 construction of the axially stacked lines with a wavy distribution along the blade span direction based on the ultimate pressure difference includes: The first sub-axial superposition line of the hub portion near the blades of the axial flow fan is represented by a first cubic polynomial, and the coefficients of the first cubic polynomial are adjusted based on the ultimate pressure difference to control its curvature change. The second axial stacking line near the blade tip region has an alternating distribution of crests and troughs. 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 so that the pressure difference fluctuation amplitude between the suction surface and the pressure surface is 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.

4. The method according to claim 1, characterized in that, The step of designing the circumferential stacking line of the axial flow fan blades based on the extreme turbulence separation point includes: Based on the extreme turbulence separation point, a circumferentially curved, nonlinearly continuous circumferential accumulation line is constructed along the blade span direction, so that the extreme turbulence separation point is moved back to the trailing edge of the axial fan blade.

5. The method according to claim 4, characterized in that, The construction of a circumferentially curved, nonlinearly continuous stacking line along the blade span direction based on the aforementioned limiting turbulence separation point includes: The circumferential superposition line is represented by a second cubic polynomial, and the coefficients of the second cubic polynomial are adjusted based on the limiting turbulence separation point to control its curvature variation.

6. The method according to claim 1, characterized in that, The process of 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.

7. A design device for axial flow fan blades, characterized in that, include: The model acquisition module is used to acquire the initial blade model of the axial flow fan blade; The target determination module is used to determine the ultimate pressure difference between the suction surface and the pressure surface of the axial flow fan blades corresponding to the target noise, as well as the ultimate turbulence separation point of the axial flow fan blades; The parameter design module is used to construct an axial stacking line with a wavy distribution along the blade span direction based on the ultimate pressure difference. 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 ultimate pressure difference. The module also designs the circumferential stacking line of the axial flow fan blade based on the ultimate turbulence separation point. The model update module is used to update the initial blade model using the axial stacking line and the circumferential stacking line to obtain the target blade model, so that the noise of the axial flow fan blade corresponding to the target blade model is less than the target noise during operation.

8. 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 axial fan blades as described in any one of claims 1 to 6.

9. A computer storage medium, characterized in that, The computer storage medium stores at least one instruction, which is executed by a processor to implement the design method for axial fan blades as described in any one of claims 1 to 6.

10. An axial flow fan, characterized in that, include: Axial flow fan blades designed using the design method for axial flow fan blades according to any one of claims 1 to 6.

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