Fan, axial flow impeller and design method of axial flow impeller

Abstract

The invention discloses a fan, an axial flow impeller and a design method of the axial flow impeller. The axial flow impeller comprises a hub, a blade assembly and a vortex guide structure. The blade assembly comprises a plurality of blade bodies arranged on the periphery of the hub in the circumferential direction of the hub, and each blade body comprises a blade front edge and a blade top. The vortex guide structure is arranged between the blade front edge and the blade top and fixedly connected with the blade body, and the vortex guide structure is configured to generate a starting vortex when the blade body rotates so as to restrain a blade tip leakage vortex generated on the blade body. The axial-flow impeller solves the problems that an axial-flow impeller in the prior art is poor in control effect on blade tip leakage vortex, complex in structure and high in cost.

Description

Technical Field

[0001] This application relates to the field of impeller technology, and more specifically, to a fan, an axial flow impeller, and a design method for an axial flow impeller. Background Technology

[0002] In related technologies, during operation, the impeller of an axial flow fan inevitably experiences a gap between the blade tips and the stationary duct. This gap allows high-pressure airflow to leak from the pressure side of the blades to the suction side, forming a strong concentrated vortex structure (tip leakage vortex). This vortex increases the impeller's aerodynamic losses and noise. Currently, related technologies mainly try to avoid or reduce the generation of tip leakage vortices by reducing the blade tip clearance, adding blade crowns, or optimizing the duct structure. However, these methods have poor control over tip leakage vortices and result in complex impeller structures and high costs. Summary of the Invention

[0003] The main objective of this application is to provide a fan, an axial impeller, and a design method for an axial impeller, so as to at least solve the problem of poor control of tip leakage vortex in existing axial impellers.

[0004] According to one aspect of this application, an axial flow impeller is provided, comprising: Wheel hub; A blade assembly, the blade assembly comprising a plurality of blade bodies disposed circumferentially around the outer periphery of the hub, the blade body comprising a blade leading edge and a blade tip; A vortex guiding structure is disposed between the leading edge of the blade and the blade tip, and is fixedly connected to the blade body. The vortex guiding structure is configured to generate an initial vortex when the blade body rotates to suppress tip leakage vortices generated on the blade body.

[0005] Furthermore, the vortex guiding structure includes a pointed corner structure protruding from the blade body and extending along the suction side of the blade body and the direction of incoming flow. The pointed corner structure is configured to generate the initial vortex under the action of airflow when the hub drives the blade body to rotate.

[0006] Furthermore, the pointed structure is configured as a biomimetic wing-finger structure, the side of which includes a first arc segment and a second arc segment. The first arc segment is connected to the second arc segment, the first arc segment is smoothly connected to the leading edge of the blade, and the second arc segment is smoothly connected to the tip of the blade.

[0007] Furthermore, the angle θ between the protrusion direction of the biomimetic wing-finger structure and the chord line at the tip position of the blade body satisfies the following relationship: 10°≤θ°≤20°.

[0008] Furthermore, the biomimetic wing-finger structure is fixedly connected to the leading edge of the blade, and the radial distance L1 between the starting point of the biomimetic wing-finger structure at the leading edge of the blade and the apex of the blade tip satisfies the relationship: 0.3C≤L1≤0.4C, where C represents the length of the blade tip.

[0009] Furthermore, along the projection direction of the biomimetic wing-finger structure onto the surface of the blade body, the maximum protrusion height h of the biomimetic wing-finger structure relative to the surface of the blade body satisfies the relationship: 0.014C≤h≤0.018C, where C represents the length of the blade tip.

[0010] Furthermore, the length l of the second arc segment of the biomimetic wing-shaped structure satisfies the following relationship: 24mm≤l≤30mm.

[0011] Furthermore, the pointed structure is configured as at least one of a triangular wedge structure, a semi-elliptical structure, and an airfoil-like structure.

[0012] Furthermore, the vortex guiding structure includes multiple structures, which are sequentially disposed between the leading edge of the blade and the blade tip.

[0013] Furthermore, the vortex guiding structure is either integrally formed with or separate from the blade body.

[0014] According to another aspect of this application, a fan is also provided, including a duct and the aforementioned axial impeller, wherein the axial impeller is disposed inside the duct and can rotate relative to the duct along the circumference of the duct, and a predetermined gap is provided between the axial impeller and the inner wall of the duct.

[0015] According to another aspect of this application, a design method for an axial flow impeller is also provided, applicable to the aforementioned axial flow impeller or fan, comprising: Step S1: Analyze the flow field characteristics of the intersection region between the leading edge and the tip of the blade body of the axial flow impeller based on the design operating parameters of the axial flow impeller, and determine the geometric parameters of the vortex guiding structure according to the flow field characteristics; Step S2: Based on the geometric parameters, set the vortex guiding structure in the intersection area of ​​the leading edge and tip of the blade in the three-dimensional model of the axial flow impeller to obtain the simulation model; Step S3: Configure the boundary conditions of the simulation model according to the design operating parameters of the axial flow impeller; Step S4: Perform unsteady flow field calculations on the simulation model based on transient CFD calculation methods to obtain the flow field data of the simulation model; Step S5: Using the flow field data, calculate the noise spectrum data of the simulation model based on acoustic analogy theory; Step S6: Analyze the suppression effect of the initial vortex generated on the vortex guiding structure on the tip leakage vortex generated on the blade body based on the flow field data and the noise spectrum data, and optimize and adjust the geometric parameters according to the suppression effect.

[0016] Further, step S4 includes: Step S41: Add the simulation model to the CFD analysis software and start transient calculation. Make the axial flow impeller rotate at a preset time step to generate an initial vortex on the vortex guide structure and a blade tip leakage vortex on the blade body. Reduce the size of the blade tip leakage vortex and the gas leakage corresponding to the blade tip leakage vortex through the induced velocity field of the initial vortex. Step S42: Detect the dynamic characteristics of the flow field of the simulation model in real time, and determine the flow field data of the simulation model based on the dynamic characteristics of the flow field.

[0017] Furthermore, the design operating parameters include at least impeller speed and flow rate; and / or, The vortex guiding structure includes a biomimetic wing-finger structure extending along the suction side and the direction of incoming flow of the blade body. The geometric parameters of the vortex guiding structure include at least the angle θ between the protrusion direction of the biomimetic wing-finger structure and the chord line at the tip of the blade body, the radial distance L1 between the starting point of the biomimetic wing-finger structure at the leading edge of the blade and the apex of the blade tip, the maximum protrusion height h of the biomimetic wing-finger structure relative to the surface of the blade body, and the length l of the second arc segment of the biomimetic wing-finger structure.

[0018] In this application, a biomimetic winglet-finger structure is set between the leading edge and the tip of the blade body of the axial flow impeller. When the axial flow impeller rotates, a controlled initiation vortex is actively generated on the biomimetic winglet-finger structure. This initiation vortex can exchange nonlinear energy with the undesirable tip leakage vortex on the blade body, breaking it up and dissipating it into small-scale turbulence. This not only improves the aerodynamic performance of the fan, but also significantly reduces aerodynamic noise and significantly improves the control effect of tip leakage vortex. Moreover, the impeller structure is simple and the manufacturing cost is relatively low. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of the fan disclosed in the embodiments of this application; Figure 2 This is a partial structural schematic diagram of the axial flow impeller disclosed in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the blade body with a biomimetic wing-finger structure disclosed in the embodiments of this application; Figure 4 This is a schematic diagram of the blade body without the biomimetic wing finger structure disclosed in the embodiments of this application; Figure 5 This is a schematic diagram of the biomimetic wing-finger structure disclosed in the embodiments of this application; Figure 6 This is a schematic diagram of the geometric features of the blade body disclosed in the embodiments of this application when viewed from a first perspective. Figure 7 This is a schematic diagram of the geometric features of the blade body disclosed in the embodiments of this application when viewed from a second perspective; Figure 8 This is a schematic diagram of the blade body when the pointed corner structure disclosed in the embodiments of this application is a triangular wedge-shaped structure; Figure 9 This is a schematic diagram of the blade body when the pointed corner structure disclosed in the embodiments of this application is a semi-elliptical structure; Figure 10 This is a schematic diagram of the blade body when the pointed structure disclosed in the embodiments of this application is an airfoil-shaped structure; Figure 11 This is a schematic flowchart of the axial flow impeller design method disclosed in the embodiments of this application; Figure 12 This is a simulation diagram illustrating the flow separation at the blade tip without the biomimetic winglet finger structure disclosed in the embodiments of this application. Figure 13 This is a simulation diagram of the circulating tip vortex at the blade tip when a biomimetic winglet finger structure is disclosed in the embodiments of this application; Figure 14 This is a comparison diagram of the far-field noise spectrum of the biomimetic model and the comparative model disclosed in the embodiments of this application; Figure 15 This is a schematic diagram of the peregrine falcon wing fingers disclosed in an embodiment of this application.

[0020] The above figures include the following reference numerals: 100. Wind tunnel; 10. Hub; 20. Blade body; 201. Tip leakage vortex; 21. Blade leading edge; 22. Blade tip; 30. Vortex guiding structure; 301. Initial vortex; 31. Bionic winglet-shaped structure; 311. First arc segment; 312. Second arc segment; 32. Triangular wedge structure; 33. Semi-elliptical structure; 34. Airfoil-like structure; 40. Flow separation position. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0024] In related technologies, the tip leakage vortex generated by axial flow impellers during operation is mainly avoided or its intensity is reduced by decreasing the tip clearance, increasing the blade crown, or optimizing the duct structure, in order to avoid significant aerodynamic losses and noise. However, these methods are not very effective in controlling tip leakage vortices. Therefore, this application provides a design method for a fan, an axial flow impeller, and an axial flow impeller. By setting a vortex guiding structure fixedly connected to the blade body between the leading edge and the tip of the blade body of the axial flow impeller, when the fan rotates, the vortex guiding structure can generate an initial vortex. The generated initial vortex will interact nonlinearly with the tip leakage vortex generated at the tip of the blade body, which can suppress the intensity and development of the tip leakage vortex, thus avoiding significant aerodynamic losses and noise from the axial flow impeller.

[0025] See Figure 1 As shown, according to a first aspect of an embodiment of this application, a fan is provided, the fan including a duct 100 and an axial impeller, the axial impeller being disposed inside the duct 100 and being rotatable relative to the duct 100 in the circumferential direction of the duct 100, and a predetermined gap being formed between the axial impeller and the inner wall of the duct 100.

[0026] It is understood that there is a predetermined gap between the axial impeller and the air duct 100 in this embodiment. When the axial impeller rotates relative to the air duct 100 along the circumference of the air duct, the axial impeller will not come into contact with the inner wall of the air duct 100, which can avoid sliding friction between the axial impeller and the air duct 100 and ensure that the axial impeller can rotate better inside the air duct 100.

[0027] However, in this embodiment, due to the predetermined gap between the axial impeller and the inner wall of the duct 100, when the axial impeller rotates, the high-pressure airflow leaks from the pressure side (windward side) to the suction side (leeward side) of the axial impeller, forming a strong concentrated vortex structure (tip leakage vortex 201), further generating tip leakage flow. This leads to the following problems with the fan: First, the tip leakage vortex 201 increases the aerodynamic losses of the axial impeller, making the fan more energy-intensive and reducing the isentropic efficiency and pressure ratio of the axial impeller. Second, the narrow stability margin of the tip leakage vortex 201 is a major cause of flow instability phenomena such as axial impeller rotational stall and surge, which endangers the safe operation of the fan. Third, the tip leakage vortex 201 causes strong vortex shedding, generating tip leakage flow with significant noise, increasing the aerodynamic noise of the axial impeller.

[0028] See Figures 1 to 3 , Figures 5 to 10 As shown, according to a second aspect of an embodiment of this application, an axial flow impeller is provided, comprising a hub 10, a blade assembly, and a vortex guide structure 30. The blade assembly includes a plurality of blade bodies 20 disposed circumferentially around the outer periphery of the hub 10, each blade body 20 including a leading edge 21 and a tip 22. The vortex guide structure 30 is disposed between the leading edge 21 and the tip 22 and is fixedly connected to the blade body 20. The vortex guide structure 30 is configured to generate an initial vortex 301 when the blade body 20 rotates to suppress tip leakage vortices 201 generated on the blade body 20.

[0029] In this embodiment, multiple blade bodies 20 arranged circumferentially around the outer periphery of the hub 10 can rotate within the wind tunnel 100 under the drive of the hub 10. When the blade bodies 20 rotate, the airflow first reaches the blade tip position of the blade body 20, that is, between the leading edge 21 and the tip 22 of the blade. Since a vortex guiding structure 30 fixedly connected to the blade body 20 is provided between the leading edge 21 and the tip 22 of the blade body 20, a small-scale initial vortex 301 will be generated on the vortex guiding structure 30 first. The 301 can be controlled by the shape of the vortex guide structure 30 and the rotational speed of the blade body 20. The initial vortex 301 can interact nonlinearly with the tip leakage vortex 201 generated on the blade body 20, which can suppress the intensity and development of the tip leakage vortex 201, achieve the effect of vortex control, avoid a large amount of high-pressure airflow from the pressure surface of the blade body 20 to the suction surface, that is, avoid the generation of a large tip leakage flow, thereby avoiding large aerodynamic losses and aerodynamic noise of the axial impeller, and improving the reliability of the fan operation.

[0030] Furthermore, the vortex guiding structure 30 includes a pointed structure protruding from the blade body 20 and extending along the suction side of the blade body 20 and the direction of the incoming flow. The pointed structure is configured to generate an initial vortex 301 under the action of the airflow when the hub 10 drives the blade body 20 to rotate.

[0031] Understandably, in this embodiment of the application, the vortex guiding structure 30 is configured to protrude from the blade body 20 and extend along the suction side of the blade body 20 and the direction of incoming flow (e.g., Figure 3 , Figure 12 and Figure 13 The pointed structure extending in the direction indicated by the middle arrow x, compared to non-pointed structures such as rounded ridges or chamfered corners, provides a certain degree of convergence to the incoming flow. This results in a stable vortex structure with high shear strength, small range, and precise generation position when the airflow flows around it, thus improving the suppression effect on the tip leakage vortex 201. Secondly, the extension direction of the pointed structure in this embodiment is smoothly transitioned to the surface of the blade body 20. This ensures that when the airflow reaches the blade body 20, it first accurately impacts the pointed structure protruding from the blade body 20, forming a stable shear layer on the suction side of the blade body 20 and causing it to roll up and fall off. This allows a target pre-vortex (initial vortex 301) to be generated on the pointed structure before the tip leakage vortex 201 is generated, ensuring that the initial vortex 301 can effectively suppress the subsequently generated tip leakage vortex 201.

[0032] like Figures 1 to 3 , Figures 5 to 7As shown, the pointed structure in this embodiment includes a biomimetic wing-finger structure 31. The side of the biomimetic wing-finger structure 31 includes a first arc segment 311 and a second arc segment 312. The first arc segment 311 and the second arc segment 312 are connected. The first arc segment 311 is smoothly connected to the leading edge 21 of the blade, and the second arc segment 312 is smoothly connected to the tip 22 of the blade.

[0033] like Figure 15 As shown, the biomimetic wing-finger structure 31 in this embodiment directly imitates the "wing-finger" structure of the leading edge of the wing of the peregrine falcon. Its functional mechanism is to imitate the strategy of the "wing-finger" to actively generate controlled vortices (initial vortex 301) to reattach the flow at high speed and high angle of attack. This structure is a locally sharp structure with a streamlined wing-finger shape in cross-section. The leading edge and the blade body 20 are smoothly transitioned, and the trailing edge is integrated with the surface of the blade body 20 to avoid generating additional flow separation.

[0034] Specifically, such as Figure 2 and Figure 3 As shown, in this embodiment, the leading edge of the biomimetic wing-finger structure 31 adopts an arc-shaped first arc segment 311 and a second arc segment 312. A streamlined, sharp-angled structure with a sharp leading edge is formed between the first arc segment 311 and the second arc segment 312. This sharp leading edge triggers a stable shear layer, generating a directional strong initial vortex 301. The streamlined, sharp-angled structure guides the airflow smoothly around the blade, avoiding airflow separation and secondary vortices, reducing drag and flow losses, and improving the aerodynamic efficiency of the axial impeller. The first arc segment 311 smoothly connects to the blade leading edge 21, and the second arc segment 312 smoothly connects to the blade tip 22. This allows the airflow to flow stably along the first arc segment 311 or the second arc segment 312 towards the blade body 20, avoiding the generation of additional disturbance vortices or additional flow losses between the biomimetic wing-finger structure 31 and the blade body 20, thus enabling the axial impeller to operate stably.

[0035] Specifically, in this embodiment, the biomimetic wing-finger structure 31 acts as an active micro vortex generator. The process of suppressing the tip leakage vortex 201 is divided into three steps: biomimetic vortex generation, vortex interaction, and flow field stabilization. The detailed process is as follows: Step 1, Biomimetic Vortex Generation: When the axial impeller rotates, the high-speed incoming flow impacts the sharp corner structure of the biomimetic airfoil-shaped structure 31. Due to the geometric protrusion of the sharp corner structure and its obstruction of the incoming flow, a local low-pressure zone is generated on its suction side, forcing the airflow to circumvent and generating a shear layer. This shear layer quickly rolls up and falls off, forming a scale-controllable and rotationally stable initial vortex 301.

[0036] Step 2, Vortex Interaction: The initial vortex 301 moves downstream. At this time, the airflow leaking from the pressure surface is about to cross the blade tip 22 and form a large-scale blade tip leakage vortex 201.

[0037] The aerodynamic performance enhancement mechanism includes: a strong interaction between the initial vortex 301 and the tip leakage vortex 201. The induced velocity field generated by the rotation of the initial vortex 301 has a "guiding" and "blocking" effect on the tip leakage flow caused by the tip leakage vortex 201, effectively reducing the leakage flow rate and velocity of the high-pressure fluid to the suction surface. Simultaneously, the interaction between vortices (vortex merging and tearing) consumes the core energy of the tip leakage vortex 201, reducing its ability to entrain and block the main flow. The combined effect is to reduce tip leakage losses, improve the effective work capacity and flow efficiency of the blade body 20, thereby increasing the pressure ratio and isentropic efficiency.

[0038] The noise suppression mechanism includes the following: the large-scale tip leakage vortex 201 is the main source of low-frequency broadband aerodynamic noise. The generation of the initial vortex 301 "breaks up" and "disperses" the originally concentrated, periodically detached strong leakage vortex into multiple small-scale, highly random weak vortex structures. According to aeroacoustic theory, the noise radiation power is proportional to the eighth power of the vortex pulsation in the flow field. Therefore, breaking the large vortex into smaller vortices greatly reduces the intensity of the vortex structure as a noise source, thereby significantly suppressing the generation of broadband noise, especially low-frequency noise.

[0039] Step 3, Flow Field Stabilization: The tip leakage vortex 201 is broken up and dissipated into multiple small-scale, low-energy flows, thereby stabilizing the flow field in the tip region of the blade body 20, compared to... Figure 4 The structure of the blade body 20 without the biomimetic wing-finger structure 31 shown allows the main flow to be more smoothly along the suction surface of the blade body 20, thereby improving aerodynamic performance and suppressing noise.

[0040] Furthermore, in this embodiment, the angle θ between the protrusion direction of the biomimetic wing-finger structure 31 and the chord line at the tip 22 of the blade body 20 satisfies the following relationship: 10°≤θ°≤20° (e.g., Figure 7 (As shown), for example, θ can be set to 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, etc.

[0041] Specifically, the angle θ between the convex direction of the biomimetic wing-finger structure 31 and the chord line at the tip 22 of the blade body 20 can affect the position and intensity of the initial vortex 301. When θ is less than 10°, it indicates that the convex angle of the biomimetic wing-finger structure 31 is too small, and the shear layer formed by the incoming flow on its suction side is insufficient, resulting in a small core vortex of the initial vortex 301, which cannot effectively cover the core energy region of the tip leakage vortex 201, and the suppression effect on the tip leakage vortex 201 is poor, making it difficult to meet the design performance requirements of the biomimetic wing-finger structure 31. When θ is greater than 20°, it indicates that the convex angle of the biomimetic wing-finger structure 31 is too large, forming a large angle of attack with the incoming flow direction, which easily leads to flow separation. The excessively strong shear layer will generate a strong initial vortex 301, which, after interacting with the tip leakage vortex 201, is prone to forming secondary vortex interference, aggravating the flow field turbulence, causing the low-frequency noise sound pressure level to rise, and at the same time, it will cause a significant increase in the stress of the biomimetic wing-finger structure 31, posing a risk of fracture under long-term high-speed rotation.

[0042] Preferably, in this embodiment, the angle θ between the protrusion direction of the biomimetic wing-finger structure 31 and the chord line at the tip 22 of the blade body 20 is set to 15°. This allows for precise matching between the initial vortex 301 generated on the biomimetic wing-finger structure 31 and the tip leakage vortex 201 generated on the blade body 20. This enables the initial vortex 301 to effectively suppress the development of the tip leakage vortex 201, reducing aerodynamic losses. Simultaneously, the incoming flow around the vortex is smooth without separation, resulting in minimal additional losses. The control effect of the tip leakage vortex 201 is stable under all operating conditions, achieving a comprehensive balance between the aerodynamic performance, noise suppression effect, and structural reliability of the axial flow impeller.

[0043] Furthermore, the biomimetic wing-finger structure 31 is fixedly connected to the leading edge 21 of the blade. The radial distance L1 between the starting point of the biomimetic wing-finger structure 31 at the leading edge 21 and the apex of the blade tip 22 satisfies the relationship: 0.3C ≤ L1 ≤ 0.4C (e.g., ...). Figure 5 As shown), for example, L1 can be set to 0.3C, 0.31C, 0.32C, 0.33C, 0.34C, 0.35C, 0.36C, 0.37C, 0.38C, 0.39C, 0.4C, etc., where, for example... Figure 2 The C shown represents the length of the leaf tip 22.

[0044] Specifically, in this embodiment, the biomimetic wing-finger structure 31 is fixedly connected to the leading edge 21 of the blade. This allows the generation of an initial vortex 301 before the formation of the tip leakage vortex 201, without interfering with the airflow on the blade body 20, resulting in minimal additional losses. Furthermore, it is adapted to the aerodynamic profile and rotational force characteristics of the blade, ensuring structural stability and reliability. In this embodiment, L1 can represent the length of the first arc segment 311. When L1 is less than 0.3C, the starting point of the biomimetic wing-finger structure 31 is too close to the apex of the blade tip 22, which may cause a shift in the interaction position between the initial vortex 301 and the tip leakage vortex 201. This reduces the suppression efficiency of the tip leakage vortex 201 and also makes the length of the second arc segment 312 and the surface area of ​​the biomimetic wing-finger structure 31 too small, further resulting in a smaller initial vortex 301 generated on the biomimetic wing-finger structure 31, which cannot effectively interact with the tip leakage vortex 201. When L1 is greater than 0.4C, the starting point of the biomimetic wing-finger structure 31 deviates from the origin core region of the tip leakage vortex 201. The generation position of the initial vortex 301 lags behind the initial development stage of the tip leakage vortex 201. The interaction time between the two is shortened and the intensity is weakened, making it impossible to effectively suppress the tip leakage vortex 201 from the source. At the same time, it will cause the starting point of the biomimetic wing-finger structure 31 to be close to the inner side of the blade leading edge 21, which may interfere with the adhesion and development of normal airflow on the suction surface of the blade body 20, weaken the lift performance of the blade body 20, and lead to a decrease in aerodynamic efficiency.

[0045] Preferably, in this embodiment, the radial distance L1 between the starting point of the biomimetic wing-finger structure 31 at the blade leading edge 21 and the apex of the blade tip 22 is set to 0.35C. This allows the generated initial vortex 301 to be precisely aligned with the core region of the origin of the blade tip leakage vortex 201, enabling the initial vortex 301 to fully interact with the blade tip leakage vortex 201 in its early stages of generation, effectively suppressing the development of the blade tip leakage vortex 201 at its source. Simultaneously, it avoids weakening the suppression and control effect on the blade tip leakage vortex 201 due to being too close to the apex of the blade tip 22 or the inner side of the blade leading edge 21, and does not affect the smooth flow of the main airflow at the blade leading edge 21, resulting in minimal additional losses.

[0046] Furthermore, along the projection direction of the biomimetic wing-finger structure 31 onto the surface of the blade body 20, the maximum protrusion height h of the biomimetic wing-finger structure 31 relative to the surface of the blade body 20 satisfies the relationship: 0.014C≤h≤0.018C (e.g., ...). Figure 6 As shown), for example, h can be set to 0.014C, 0.015C, 0.016C, 0.017C, 0.018C, etc., where, for example... Figure 2 The C shown represents the length of the leaf tip 22.

[0047] Specifically, in this embodiment, since the blade body 20 is an arc-shaped structure, the maximum protrusion height h of the biomimetic wing-finger structure 31 relative to the surface of the blade body 20 is represented as the distance between the sharp apex of the biomimetic wing-finger structure 31 and the lowest point of the surface of the blade body 20 along a direction perpendicular to the blade body 20. When h is less than 0.014C, it indicates that the protrusion height of the biomimetic wing-finger structure 31 is small, making it difficult to form a sufficiently strong airflow shear layer between the surface of the blade body 20 and the surface of the biomimetic wing-finger structure 31. This results in the vortex volume of the initial vortex 301 being too weak, making it difficult to form an effective interaction with the tip leakage vortex 201, and failing to suppress the development of the tip leakage vortex 201 at its source. When h is less than 0.018C, it indicates that the protrusion height of the biomimetic wing finger structure 31 is too high, which will obstruct the incoming flow to a certain extent, generate secondary vortices and additional drag, and also interfere with the adhesion and flow of air on the surface of the blade body 20, weakening the lift performance of the blade body 20. The excessively high protrusion will exacerbate the centrifugal stress concentration when the blade body 20 rotates, reducing the structural reliability.

[0048] Preferably, in this embodiment, the maximum protrusion height h of the biomimetic wing-finger structure 31 relative to the surface of the blade body 20 is set to 0.016C along the projection direction of the biomimetic wing-finger structure 31 onto the surface of the blade body 20. This allows the generation of an initial vortex 301 that matches the intensity of the tip leakage vortex 201, enabling the initial vortex 301 to better suppress the development of the tip leakage vortex 201 at its source, thereby optimizing the aerodynamic performance of the axial impeller and reducing the noise of the tip leakage flow generated by the tip leakage vortex 201. Simultaneously, this height h avoids both insufficient initial vortex 301 strength due to being too low and excessive airflow separation and a surge in additional drag due to being too high, allowing the incoming flow to smoothly circulate along the wing fingers without interfering with the main flow trajectory and with minimal additional losses.

[0049] Furthermore, the length l of the second arc-shaped segment 312 of the biomimetic wing-finger structure 31 satisfies the relationship: 24mm ≤ l ≤ 30mm (e.g., Figure 5 (As shown), for example, l can be set to 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, etc.

[0050] Specifically, in this embodiment, when l is less than 24 mm, it indicates that the second arc segment 312 is too short, resulting in a narrow generation area and a short duration of the initial vortex 301. This makes it impossible to form a stable and sufficiently strong initial vortex 301, resulting in insufficient interaction time and limited coverage between the initial vortex 301 and the tip leakage vortex 201. This makes it difficult to fully dissipate the energy of the tip leakage vortex 201, significantly reducing the suppression effect on the tip leakage vortex 201. Consequently, it is impossible to effectively optimize the aerodynamic performance of the axial flow impeller and suppress noise. At the same time, when the length l of the second arc segment 312 is too short, the smooth transition effect with the blade tip 22 of the blade body 20 deteriorates, making it easy to form local airflow disturbances at the junction and introduce minor additional losses. When l is greater than 30mm, it indicates that the second arc segment 312 is too long. This not only increases the obstruction area to the incoming flow, resulting in a longer airflow path and increased separation risk, but also increases the centrifugal load when the impeller rotates, leading to a more obvious stress concentration phenomenon, reducing structural reliability and service life. At the same time, it may cause additional interference with the surrounding flow field of the blade tip 22, triggering new turbulent noise.

[0051] Preferably, in this embodiment, the length l of the second arc-shaped segment 312 of the biomimetic wing-finger structure 31 is set to 27 mm. This provides a stable and suitable generation area for the initial vortex 301, ensuring sufficient strength and appropriate duration of the initial vortex 301, enabling it to fully interact with the tip leakage vortex 201 to efficiently dissipate the main vortex energy. Simultaneously, setting l to 27 mm avoids both the instability and poor vortex control effect of the initial vortex 301 due to excessive length, and the obstruction of incoming flow, causing airflow separation or flow blockage due to excessive length.

[0052] Optionally, the pointed structure in this embodiment can also be configured as at least one of a triangular wedge structure 32, a semi-elliptical structure 33, and an airfoil-shaped structure 34.

[0053] Among them, such as Figure 8 The diagram shows the structure of the blade body 20 when the sharp corner structure is set as a triangular wedge structure 32. By utilizing the sharp corners and wedge-shaped contour of the triangular wedge structure 32, a strong shear layer is formed on its surface when the incoming flow impacts it, which quickly rolls up to generate a controlled initiation vortex. The triangular wedge structure 32 has a simple structure and can efficiently trigger the initiation vortex 301, and has a more direct initial suppression effect on the tip leakage vortex 201.

[0054] Among them, such as Figure 9 The diagram shows the structure of the blade body 20 when the sharp corner structure is set as a semi-elliptical structure 33. The airflow is guided by the smooth arc contour of the semi-elliptical shape, making the shear layer generation process smoother. The resulting initial vortex 301 has a uniform scale and stable energy distribution, resulting in less disturbance to the flow field, lower flow separation risk, and less additional loss.

[0055] Among them, such as Figure 10 The diagram shows the structure of the blade body 20 when the pointed structure is set as an airfoil-shaped structure 34. The airfoil-shaped structure 34 adopts the aerodynamic shape of a micro airfoil. By utilizing the lift characteristics and streamlined profile of the airfoil, it generates a stronger and more concentrated initial vortex 301, which can quickly dissipate the energy of the tip leakage vortex 201 and significantly improve the aerodynamic performance of the axial force impeller.

[0056] Optionally, the vortex guide structure 30 includes multiple vortex guide structures 30, which are sequentially arranged between the leading edge 21 and the tip 22 of the blade. In this way, multiple small-scale vortex guide structures 30 can be arranged side by side between the leading edge 21 and the tip 22 of the blade body 20 to form an "vortex generator array" to meet different operating conditions or stronger control requirements.

[0057] Optionally, the vortex guiding structure 30 and the blade body 20 can be integrally or separately configured. Preferably, in the integral configuration, if the vortex guiding structure 30 and the blade body 20 are made of metal, they can be formed by additive manufacturing technology followed by precision machining. If the vortex guiding structure 30 and the blade body 20 are made of composite materials (e.g., glass fiber reinforced resin matrix composites), they can be integrally formed by processes such as resin transfer molding. In the separately configured configuration, they can be fixedly connected by a fixed connection structure.

[0058] On the other hand, this application also discloses a design method for an axial flow impeller, which is applicable to the aforementioned axial flow impeller or fan, such as... Figure 11 As shown, the method includes: Step S1: Analyze the flow field characteristics of the intersection region of the leading edge 21 and the tip 22 of the blade body 20 of the axial flow impeller based on the design operating parameters of the axial flow impeller, and determine the geometric parameters of the vortex guiding structure 30 according to the flow field characteristics.

[0059] The vortex guiding structure 30 includes a biomimetic wing-finger structure 31 extending along the suction side and the direction of incoming flow of the blade body 20. The geometric parameters of the vortex guiding structure 30 include at least the angle θ between the protrusion direction of the biomimetic wing-finger structure 31 and the chord line at the blade tip 22 of the blade body 20, the radial distance L1 between the starting point of the biomimetic wing-finger structure 31 at the leading edge 21 of the blade and the apex of the blade tip 22, the maximum protrusion height h of the biomimetic wing-finger structure 31 relative to the surface of the blade body 20, and the length l of the second arc segment 312 of the biomimetic wing-finger structure 31.

[0060] Specifically, before executing step S1, the design operating parameters of the target axial flow impeller are obtained. These parameters include at least the rotational speed and flow rate (flow rate of the fluid passing through the axial flow impeller) at the design point of the impeller. During step S1, based on the rotational speed and flow rate at the design point of the axial flow impeller, the flow field characteristics of the intersection region between the leading edge 21 and the tip 22 of the blade body 20 of the axial flow impeller are analyzed using computational fluid dynamics (CFD) software to obtain key design parameters. These key design parameters include the local boundary layer thickness δ, the incoming flow angle of attack, and the Mach number. Then, based on the obtained key design parameters and design criteria, the geometric parameters of the vortex guiding structure 30 are determined. Among them, the angle θ between the convex direction of the bionic wing finger structure 31 and the chord line at the blade tip 22 of the blade body 20 can represent the installation angle of the bionic wing finger structure 31. The radial distance L1 between the starting point of the bionic wing finger structure 31 at the leading edge 21 of the blade and the vertex of the blade tip 22 can represent the starting position of the bionic wing finger structure 31. The design criteria are industry standardization criteria, such as h≈(0.5~1.5)δ, θ=10~30, etc. According to the design criteria, the height h, length l, installation angle θ, and starting position L1 of the bionic wing finger structure 31 can be obtained.

[0061] Preferably, in this embodiment, the starting position L1 of the biomimetic wing-finger structure 31 is set to 0.35C, the height h is set to 1.6% of the length of the blade tip 22, the length l of the second arc segment 312 is set to 27mm, and the installation angle θ is set to 15°. In this way, the position of the generated starting vortex 301 is accurate and the size is appropriate, which can reliably suppress the tip leakage vortex 201 without affecting the overall operation of the fan and axial impeller.

[0062] Alternatively, computational fluid dynamics (CFD) software may be used, such as Ansys Fluent, Ansys CFX, and STAR-CCM+.

[0063] In some embodiments, by establishing a multivariate nonlinear mapping relationship between geometric parameters (L1,h,l,θ) and key flow field characteristic parameters at the leading edge of the blade tip 22, the optimal values ​​of the geometric parameters can be obtained after system optimization. This ensures that the function of the sharp corner structure of the biomimetic winglet-shaped structure 31 is optimally matched with the flow field, thereby improving the suppression effect on the blade tip leakage vortex 201. The specific relationship is described by a polynomial model of the following form: a) The position coefficient (L1 / C) is determined by both the leading-edge pressure gradient and the boundary layer state: L1 / C=a0+a1*Λ+a2*Λ²+a3*Re_θ+a4*Re_θ²+a5*Λ*Re_θ Where Λ is the pressure gradient parameter at the leading edge of the blade tip 22, Re_θ is the Reynolds number based on the boundary layer momentum thickness, and a0 to a5 are constant coefficients obtained through extensive CFD calculations and regression analysis fitting.

[0064] b) The height coefficient (h / C) is mainly related to the degree of boundary layer development and the incoming flow velocity: h / C=b0+b1*(δ / C)+b2*(δ / C)²+b3*Ma+b4*Ma² Where δ is the local boundary layer thickness, Ma is the incoming Mach number, and b0 to b4 are another set of optimization constant coefficients.

[0065] c) The length-to-height ratio (l / h) is related to vortex shedding characteristics: l / h = c0 + c1*St + c2*St² Where St is the Strouhal number based on the estimated shedding frequency of the tip leakage vortex 201, and c0 to c2 are constant coefficients.

[0066] d) The installation angle (θ) is determined by the actual angle of attack at the local location: θ = d0 + d1*α + d2*α² Where α is the local angle of attack of the blade leading edge, and d0 to d2 are constant coefficients.

[0067] Step S2: Based on the geometric parameters, set the vortex guiding structure 30 in the intersection area of ​​the blade leading edge 21 and blade tip 22 in the three-dimensional model of the axial flow impeller to obtain the simulation model.

[0068] Specifically, before executing step S2, a three-dimensional model of the axial flow impeller needs to be constructed using three-dimensional modeling software. This can be done by inputting the structural feature parameters of the axial flow impeller into the three-dimensional modeling software, such as the inner and outer diameters of the hub 10, the hub width, and the dimensions of the blade body 20. During step S2, based on the previously obtained geometric parameters, the intersection area of ​​the blade leading edge 21 and the blade tip 22 in the three-dimensional model of the axial flow impeller is modeled to generate the vortex guide structure 30. This results in the three-dimensional model including the blade body 20 and the vortex guide structure 30 connected to the blade leading edge 21 of the blade body 20. The generated vortex guide structure 30 and the blade body 20 have a smooth transition connection to avoid stress concentration. Thus, the fluid motion state of the axial flow impeller can be simulated based on the obtained three-dimensional model.

[0069] Step S3: Configure the boundary conditions of the simulation model according to the design operating parameters of the axial flow impeller.

[0070] It is understood that the boundary conditions of the simulation model in this embodiment include the inlet boundary conditions, outlet boundary conditions, and wall boundary conditions of the airflow passing through the axial flow impeller, so as to ensure that the fluid motion state of the airflow passing through the axial flow impeller can be simulated more accurately, thereby improving the accuracy and effectiveness of the design of the axial flow impeller.

[0071] Step S4: Perform unsteady flow field calculations on the simulation model based on transient CFD calculation methods to obtain the flow field data of the simulation model.

[0072] Specifically, step S4 includes: Step S41: Add the simulation model to the CFD analysis software (computational fluid dynamics software) and start the transient calculation. Make the axial flow impeller rotate at a preset time step to generate an initial vortex 301 on the vortex guide structure 30 and a tip leakage vortex 201 on the blade body 20. The induced velocity field of the initial vortex 301 reduces the size of the tip leakage vortex 201 and the gas leakage flow rate corresponding to the tip leakage vortex 201. Step S42: Real-time detection of the dynamic characteristics of the flow field in the simulation model, and determination of the flow field data of the simulation model based on the dynamic characteristics of the flow field.

[0073] Specifically, during execution, the 3D model of the axial flow impeller with the biomimetic airfoil structure 31 generated in step S2 is imported into the CFD analysis software. A computational domain is constructed with the impeller main shaft as the center. The computational domain includes the inlet section, the impeller rotation domain (including the blade body 20, the biomimetic airfoil structure 31, and the hub 10), and the outlet section, while accurately defining the blade tip clearance. Then, the computational domain is meshed, for example, using a tetrahedral unstructured mesh to refine the mesh on the surface of the blade body 20, the surface of the biomimetic airfoil structure 31, and the blade tip clearance area. Then, transient calculation parameters are configured, including starting the transient calculation module of the CFD analysis software, setting the impeller rotation parameters, for example, inputting the design point rotation speed as n=850rpm, flow rate Q=4.813kg / s, and ensuring that the rotation axis coincides with the impeller main shaft. The sliding mesh technique is used to handle the interface coupling between the rotation domain and the stationary domain (inlet section and outlet section), and a reasonable interface interpolation method is selected, such as selecting a conservation interpolation method, to ensure the accuracy of the flow field parameter transfer. Set the time step and total computation time, and configure the numerical solver, such as a coupled solver based on the finite volume method. The turbulence model adopts the SSTk-ω model to balance the accuracy of boundary layer simulation and computational stability. The convection term is discretized using a high-order upwind scheme, and the pressure-velocity coupling uses the SIMPLEC algorithm.

[0074] Furthermore, after initiating transient calculations in the CFD analysis software, the axial flow impeller rotates under the design operating parameters according to a preset time step. The incoming flow smoothly enters the computational domain along the inlet section. When it flows through the leading edge 21 of the blade, the first arc segment 311 and the second arc segment 312 of the biomimetic wing-finger structure 31 (θ=15°, L1=0.35C, h=0.016C, l=27mm) form an adaptive shear layer with the incoming flow, which quickly rolls up on the suction side of the wing-finger to generate a uniformly strong initial vortex 301. At the same time, due to the pressure difference in the blade tip gap, the high-pressure airflow on the pressure surface of the blade body 20 leaks to the suction side to form a blade tip leakage flow, forming a blade tip leakage vortex 201 in the intersection area of ​​the leading edge 21 and the blade tip 22. During the calculation, the CFD analysis software can capture the dynamics of the flow field in real time. The initial vortex 301 continues to develop as the axial impeller rotates, and its induced velocity field is superimposed in opposite directions with the rotation direction of the tip leakage vortex 201. Through momentum exchange, it continuously reduces the core vortex of the tip leakage vortex 201. At the same time, the initial vortex 301 forms a "resistance effect" on the tip leakage flow generated by the tip leakage vortex 201, changing the trajectory of the tip leakage flow and reducing the leakage flow from the high-pressure area to the suction side. After calculation, multi-dimensional flow field data is output, including vortex structure characteristic data, aerodynamic performance data, leakage flow parameters, and flow field visualization data. The vortex structure characteristic data includes the time-varying curves of the core vorticity, vortex core radius, and trajectory coordinates of the tip leakage vortex 201 and the initial vortex 301. The aerodynamic performance data includes the fluctuation data of the inlet and outlet static pressure, total pressure, shaft power, and aerodynamic efficiency of the axial impeller as a function of the time step. The leakage flow parameters include the leakage flow rate and leakage velocity distribution at the tip clearance. The flow field visualization data includes velocity contour maps, pressure contour maps, and vorticity isosurface maps of different cross sections, which can provide complete data support for subsequent analysis of the tip leakage flow control effect.

[0075] Step S5: Calculate the noise spectrum data of the simulation model using flow field data and based on acoustic analogy theory.

[0076] Understandably, acoustic analogy theory mainly transforms aerodynamic disturbances such as vortex pulsation and pressure pulsation in the flow field into equivalent sound sources, substitutes them into the acoustic analogy equation to solve for sound wave propagation, and then uses Fourier transform to convert the time-domain signal into the frequency-domain noise spectrum, quantifying the noise characteristics corresponding to the aerodynamic disturbance, such as frequency and sound pressure level.

[0077] Step S6: Analyze the suppression effect of the initial vortex 301 generated by the vortex guiding structure 30 on the tip leakage vortex 201 generated on the blade body 20 based on the flow field data and noise spectrum data, and optimize and adjust the geometric parameters according to the suppression effect.

[0078] Specifically, in this embodiment, before analyzing the suppression effect of the initial vortex 301 generated by the vortex guiding structure 30 on the tip leakage vortex 201 generated on the blade body 20, the same steps as the above simulation control method are used to perform simulation control analysis on the simulation model of the axial flow impeller without the above-mentioned biomimetic airfoil finger structure 31. As a comparative example of this embodiment, the comparative model is compared with the simulation model of this embodiment with the biomimetic airfoil finger structure 31. All parameters such as blade shape, chord length, span, tip clearance, and rotational speed are completely the same to ensure the reliability of the analysis of the suppression effect of the initial vortex 301 generated by the vortex guiding structure 30 on the tip leakage vortex 201 generated on the blade body 20 in this embodiment.

[0079] like Figure 12 The diagram shown is a simulated gas flow separation diagram at the blade tip 22 of a comparative model without the biomimetic wing finger structure 31. Figure 12 Flow separation occurred at the flow separation location 40, such as... Figure 13 The diagram shows a simulation of gas flow separation at the blade tip 22 of the simulation model with the biomimetic wing-finger structure 31 in this embodiment. For example, according to CFD calculation results, the static pressure of the simulation model in this embodiment is 5 Pa, while the static pressure of the comparative model is 226 Pa, indicating a 4% increase in static pressure. The static pressure efficiency of the simulation model in this embodiment is 48.2%, while the static pressure efficiency of the comparative model is 45.9%, indicating a 2.3% increase in static pressure efficiency. Therefore, this embodiment, by setting the biomimetic wing-finger structure 31 between the leading edge 21 and the blade tip 22 of the blade body 20 of the axial impeller, can effectively manage the blade tip flow field and significantly improve the aerodynamic efficiency and operational stability of the axial impeller.

[0080] like Figure 14 The diagram shows a comparison of the far-field noise spectrum between the comparative model and the simulation model of this embodiment. The solid blue line represents the comparative model without the bionic wing-finger structure 31, while the dashed red line represents the simulation model with the bionic wing-finger structure 31. Analysis reveals that the sound pressure level of the simulation model in this embodiment is consistently lower than that of the comparative model across the entire frequency range (10-10000Hz), indicating that this embodiment achieves a global noise reduction effect by incorporating the bionic wing-finger structure 31. The noise reduction effect is most significant in the low-frequency range (10-1000Hz), with a maximum sound pressure level reduction exceeding 20dB. The noise in this frequency range is mainly caused by the shedding of the tip leakage vortex 201, indicating that the initial vortex 301 generated by the bionic wing-finger structure 31 fundamentally suppresses the primary low-frequency noise source by breaking down and weakening the tip leakage vortex 201. In the high-frequency range (greater than 1000Hz), the sound pressure level also decreased, indicating that the overall flow field tended to be stable, and the mid-to-high frequency noise generated by the interaction between the turbulent boundary layer and the trailing edge was also improved.

[0081] Understandably, in this embodiment, when the simulation model is less effective than the comparative model in suppressing the tip leakage vortex 201 and fails to meet the design requirements, it is necessary to readjust the geometric parameters of the biomimetic wing-fin structure 31 and re-perform simulation control to ensure that the structure can meet the design requirements and effectively suppress the tip leakage vortex 201.

[0082] Preferably, in this example, after completing the design of the axial impeller and obtaining the final geometric parameters, a suitable process is selected to manufacture the axial impeller structure of the fan. When the blade body 20 and the biomimetic wing-finger structure 31 are made of metal materials, the blade body 20 and the biomimetic wing-finger structure 31 are integrally formed by additive manufacturing (3D printing) technology. This technology first generates a three-dimensional model of the blade body 20 containing the biomimetic wing-finger structure 31 using three-dimensional modeling software, and then uses selective laser melting (SLM) technology to melt and coat metal powder layer by layer to manufacture a complete impeller blank. Finally, a small amount of finishing and surface polishing are performed. When the blade body 20 and the biomimetic wing-fin structure 31 are made of composite materials (such as glass fiber reinforced resin matrix composites), the blade body 20 and the biomimetic wing-fin structure 31 are manufactured using an integral composite material molding process. First, a female mold containing the biomimetic wing-fin structure 31 is machined by five-axis milling. Then, resin is injected into the mold cavity filled with fiber reinforcement using resin transfer molding (RTM) process. After heating and curing, the integral impeller with the biomimetic wing-fin structure 31 and the blade body 20 can be obtained by demolding. It is then assembled onto the hub 10 and into the wind duct 100 to finally obtain the overall structure of the fan in this embodiment.

[0083] In summary, compared with the prior art, this application has the following outstanding advantages: 1) Significant performance improvement: Active intervention at the physical source of vortex generation can effectively suppress the intensity and development of tip leakage vortex 201, reduce aerodynamic losses when airflow passes through the blade body 20, and improve efficiency and operating pressure ratio. 2) Wide stability margin: Effectively improves tip flow, significantly widens the stable operating range of axial impeller, delays surge, and improves operational reliability; 3) Excellent acoustic performance: By suppressing the main noise source, tip leakage vortex 201, the low-frequency broadband noise generated by the rotation of the axial impeller can be effectively reduced, achieving dual optimization of aerodynamic and acoustic performance; 4) Simple and reliable structure: It is only an integrated local modification of the blade profile, with no moving parts, no additional weight or system complexity, and high reliability; 5) Low manufacturing cost: It can be integrally formed with the blade through precision casting, machining or additive manufacturing (3D printing), which hardly increases the manufacturing cost and is easy to promote in engineering. 6) Bionic intelligence: It applies advanced flow control strategies that have been verified by millions of years of evolution in nature (achieving "vortex control" through the bionic wing-finger structure 31).

[0084] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0085] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0086] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An axial flow impeller, characterized in that, include: Wheel hub (10); The blade assembly includes a plurality of blade bodies (20) arranged circumferentially around the hub (10) on the outer periphery of the hub (10), the blade body (20) including a blade leading edge (21) and a blade tip (22). A vortex guiding structure (30) is disposed between the leading edge (21) of the blade and the tip (22) of the blade and is fixedly connected to the blade body (20). The vortex guiding structure (30) is configured to generate an initial vortex (301) when the blade body (20) rotates to suppress the tip leakage vortex (201) generated on the blade body (20).

2. The axial flow impeller according to claim 1, characterized in that, The vortex guiding structure (30) includes a pointed structure protruding from the blade body (20) and extending along the suction side and the direction of the incoming flow of the blade body (20). The pointed structure is configured to generate the initial vortex (301) under the action of the airflow when the hub (10) drives the blade body (20) to rotate.

3. The axial flow impeller according to claim 2, characterized in that, The pointed structure is configured as a biomimetic wing-finger structure (31). The side of the biomimetic wing-finger structure (31) includes a first arc segment (311) and a second arc segment (312). The first arc segment (311) is connected to the second arc segment (312). The first arc segment (311) is smoothly connected to the leading edge of the blade (21), and the second arc segment (312) is smoothly connected to the tip of the blade (22).

4. The axial flow impeller according to claim 3, characterized in that, The angle θ between the protrusion direction of the biomimetic wing-finger structure (31) and the chord line at the tip (22) of the blade body (20) satisfies the following relationship: 10°≤θ°≤20°.

5. The axial flow impeller according to claim 3, characterized in that, The biomimetic wing-finger structure (31) is fixedly connected to the leading edge (21) of the blade. The radial distance L1 between the starting point of the biomimetic wing-finger structure (31) at the leading edge (21) of the blade and the vertex of the blade tip (22) satisfies the following relationship: 0.3C≤L1≤0.4C, where C represents the length of the blade tip (22).

6. The axial flow impeller according to claim 3, characterized in that, Along the projection direction of the bionic wing-finger structure (31) on the surface of the blade body (20), the maximum protrusion height h of the bionic wing-finger structure (31) relative to the surface of the blade body (20) satisfies the relationship: 0.014C≤h≤0.018C, where C represents the length of the blade tip (22).

7. The axial flow impeller according to claim 3, characterized in that, The length l of the second arc segment (312) of the biomimetic wing-shaped structure (31) satisfies the following relationship: 24mm≤l≤30mm.

8. The axial flow impeller according to claim 2, characterized in that, The pointed structure is configured as at least one of a triangular wedge structure (32), a semi-elliptical structure (33), and an airfoil-shaped structure (34).

9. The axial flow impeller according to any one of claims 1 to 8, characterized in that, The vortex guiding structure (30) includes multiple structures, and the multiple vortex guiding structures (30) are sequentially disposed between the leading edge (21) of the blade and the tip (22) of the blade.

10. The axial flow impeller according to any one of claims 1 to 8, characterized in that, The vortex guiding structure (30) and the blade body (20) are either integrally arranged or separately arranged.

11. A fan, characterized in that, The device includes a duct (100) and an axial flow impeller according to any one of claims 1 to 10, wherein the axial flow impeller is disposed inside the duct (100) and is rotatable relative to the duct (100) in the circumferential direction of the duct (100), and a predetermined gap is formed between the axial flow impeller and the inner wall of the duct (100).

12. A design method for an axial flow impeller, applicable to the axial flow impeller of any one of claims 1 to 10 or the fan of claim 11, characterized in that, include: Step S1: Analyze the flow field characteristics of the intersection area between the leading edge (21) and the tip (22) of the blade body (20) of the axial flow impeller based on the design operating parameters of the axial flow impeller, and determine the geometric parameters of the vortex guiding structure (30) according to the flow field characteristics; Step S2: Based on the geometric parameters, set the vortex guiding structure (30) in the intersection area of ​​the blade leading edge (21) and blade tip (22) in the three-dimensional model of the axial flow impeller to obtain the simulation model; Step S3: Configure the boundary conditions of the simulation model according to the design operating parameters of the axial flow impeller; Step S4: Perform unsteady flow field calculations on the simulation model based on transient CFD calculation methods to obtain the flow field data of the simulation model; Step S5: Using the flow field data, calculate the noise spectrum data of the simulation model based on acoustic analogy theory; Step S6: Based on the flow field data and the noise spectrum data, analyze the suppression effect of the initial vortex (301) generated on the vortex guide structure (30) on the tip leakage vortex (201) generated on the blade body (20), and optimize and adjust the geometric parameters according to the suppression effect.

13. The design method of the axial flow impeller according to claim 12, characterized in that, Step S4 includes: Step S41: Add the simulation model to the CFD analysis software and start transient calculation. Make the axial flow impeller rotate at a preset time step to generate an initial vortex (301) on the vortex guide structure (30) and a tip leakage vortex (201) on the blade body (20). The induced velocity field of the initial vortex (301) reduces the size of the tip leakage vortex (201) and the gas leakage flow rate corresponding to the tip leakage vortex (201). Step S42: Detect the dynamic characteristics of the flow field of the simulation model in real time, and determine the flow field data of the simulation model based on the dynamic characteristics of the flow field.

14. The design method of the axial flow impeller according to claim 12, characterized in that, The design operating parameters include at least impeller speed and flow rate; and / or, The vortex guiding structure (30) includes a biomimetic wing-finger structure (31) extending along the suction side and the direction of the incoming flow of the blade body (20). The geometric parameters of the vortex guiding structure (30) include at least the angle θ between the protrusion direction of the biomimetic wing-finger structure (31) and the chord of the blade tip (22) of the blade body (20), the radial distance L1 between the starting point of the biomimetic wing-finger structure (31) at the leading edge (21) of the blade and the vertex of the blade tip (22), the maximum protrusion height h of the biomimetic wing-finger structure (31) relative to the surface of the blade body (20), and the length l of the second arc segment (312) of the biomimetic wing-finger structure (31).

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