Axial impeller and axial flow fan

Abstract

The application discloses an axial impeller and an axial flow fan, which comprise a hub rotating around an axis and a plurality of blades distributed in the circumferential direction of the hub. The diameter of the hub gradually decreases from the air outlet side to the air inlet side. The leading edge of the blade is close to the air inlet side, the trailing edge of the blade is close to the air outlet side, and the contact surface between the root of the blade and the outer circumferential surface of the hub is arc-shaped. The axial impeller can control the secondary flow and flow separation on the suction surface and the pressure surface, reduce flow loss, and improve aerodynamic performance. Meanwhile, the leading edge and the trailing edge of the blade can exhibit good airflow guiding effect, fluid impact and energy loss at the inlet side of the axial impeller are reduced, and the performance of the impeller is improved.

Description

Technical Field

[0001] This application relates to the field of axial flow impeller technology, and in particular to an axial flow impeller and an axial flow fan. Background Technology

[0002] The three-dimensional geometry of an axial flow impeller determines its aerodynamic performance. It consists of a hub, blades, and additional structures on the blade crown side. A good geometry can improve the uniformity of airflow through the impeller, thereby reducing aerodynamic losses when the airflow enters, passes through, and exits the impeller.

[0003] Most existing axial flow impellers use single-plate blades or curved blades of uniform thickness. This restricts the fluid movement along a single path on the pressure and suction surfaces of the blades, resulting in separation or large vortices, leading to energy loss and decreased efficiency. In reality, the fluid's path through the impeller is more complex than a neat, linear one. This necessitates that the pressure and suction surfaces of the blades exhibit different characteristics to adapt to the fluid flow path, suppress secondary flow within the flow channel, reduce flow losses, and improve aerodynamic performance. Summary of the Invention

[0004] The purpose of this application is to provide an axial flow impeller and an axial flow fan that can control secondary flow and flow separation on the suction and pressure surfaces, reduce flow losses, and improve aerodynamic performance.

[0005] To achieve the above objectives, this application provides an axial flow impeller, including a hub that rotates around an axis and a plurality of blades distributed around the circumference of the hub. The diameter of the hub gradually decreases along the axial direction from the air outlet side to the air inlet side. The leading edge of the blades is close to the air inlet side, the trailing edge of the blades is close to the air outlet side, and the contact surface between the root of the blades and the outer circumferential surface of the hub is arc-shaped.

[0006] Preferably, in the projection of the blade onto the plane containing the axis along the rotation direction of the hub, the projected profile of the blade includes the crown profile line, the leading edge profile line, the trailing edge profile line, and the hub surface profile line.

[0007] The leading edge profile line intersects the blade crown profile line and the hub surface profile line at points A and B, respectively. The trailing edge profile line intersects the blade crown profile line and the hub surface profile line at points C and D, respectively. The angle between the tangent line of the leading edge profile line at point A and the tangent line at point B is greater than 120° and less than 180°. The angle between the tangent line of the trailing edge profile line at point C and the tangent line at point D is greater than 120° and less than 180°.

[0008] The hub surface profile is a parabola, and the angle between the tangent to the hub surface profile at point B and the axis is greater than 15° and less than 30°.

[0009] Preferably, the axis of symmetry of the parabola is perpendicular to the axis, the leaf crown profile is parallel to the axis, and the trailing edge profile is closer to the vertex of the parabola than the leading edge profile.

[0010] Preferably, the leading edge contour line and the trailing edge contour line are spline curves or circular arcs, and the leading edge contour line and the trailing edge contour line bulge towards one side of the vertex in the axial direction.

[0011] Preferably, the formula for the parabola is defined as:

[0012] ;

[0013] Where the absolute value of a is greater than less than b and c are constants, and x and y are the curve coordinates of the parabola.

[0014] Preferably, the trailing edge intersects the outer peripheral surface of the hub at a preset point, and the trailing edge extends in a direction away from the hub. In the projection of any blade along the axial direction of the hub, the preset point after projection is defined as point E, the trailing edge after projection is defined as the trailing edge projection line, the line connecting point E and the hub axis is defined as the first line, and any point F other than point E is selected on the trailing edge projection line. The line connecting point F and the hub axis is defined as the second line.

[0015] The second line is located on the first side of the first line, and the angle between the first line and the second line is the stacking angle θ. As point F gradually moves away from point E on the path of the trailing edge projection line, the stacking angle θ gradually increases.

[0016] Preferably, between point E and the middle of the trailing edge projection line, as point F gradually moves away from point E along the path of the trailing edge projection line, the rate of increase of the stacking angle θ gradually decreases.

[0017] Between the middle of the trailing edge projection line and the top of the trailing edge projection line, as point F gradually moves away from point E along the path of the trailing edge projection line, the rate of increase of the stacking angle θ gradually increases.

[0018] Preferably, the leading edge fitting curve of the blade falls within the surface equation:

[0019] ;

[0020] in, , , , ; , x and y are the curve coordinates of the leading edge fitting curve.

[0021] Preferably, the contact surface, along the rotation direction of the hub, projects onto the plane containing the axis in the form of a parabola;

[0022] In the projection of the trailing edge along the axial direction of the hub, the angle between the line connecting the root of the trailing edge and the hub axis and the line connecting a point on the trailing edge and the hub axis gradually increases in the extension direction of the trailing edge.

[0023] The leading edge fitting curve of the blade falls into the preset curve equation.

[0024] An axial flow fan includes the axial flow impeller described above.

[0025] Compared to existing technologies, this application improves aerodynamic performance by optimizing the hub structure, resulting in better diffusion in the axial flow impeller. Furthermore, by optimizing the blade structure, it controls secondary flow and flow separation on the suction and pressure surfaces, reducing flow losses and further enhancing aerodynamic performance. Simultaneously, the leading and trailing edges of the blades exhibit better airflow guidance, reducing fluid impact and energy loss at the impeller inlet and improving impeller performance. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the meridional region structure provided in an embodiment of this application;

[0028] Figure 2 This is a schematic diagram of the shape of the meridional region provided in an embodiment of this application;

[0029] Figure 3 This is a simulation diagram of the effect of angles β and φ on airflow efficiency provided in the embodiments of this application;

[0030] Figure 4 This is a three-dimensional structural diagram of an axial flow impeller provided in an embodiment of this application;

[0031] Figure 5This is a schematic diagram of the axial projection of an axial flow impeller provided in an embodiment of this application;

[0032] Figure 6 This is a schematic diagram illustrating the simulation change of the stacking angle θ provided in an embodiment of this application;

[0033] Figure 7 This is a side view of an axial flow impeller provided in an embodiment of this application;

[0034] Figure 8 This is a schematic diagram of blade edge curve fitting provided in an embodiment of this application;

[0035] Figure 9 This is a schematic diagram of leading edge curve fitting provided in an embodiment of this application.

[0036] In the diagram: 1-hub; 2-blade; 3-plane; 4-meridian region;

[0037] 21-Leading edge; 22-Cover; 23-Piercing edge; 24-Pressure surface; 25-Suction surface;

[0038] 41-Leading edge profile line; 42-Cover profile line; 43-Leading edge profile line; 44-Hub surface profile line;

[0039] 51 - Leading edge projection line; 52 - Leaf crown projection line; 53 - Trailing edge projection line;

[0040] 61 - Leading edge fitting curve; 62 - Leaf crown fitting curve; 63 - Trailing edge fitting curve. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] It should be noted that in this embodiment, the orientation or positional relationship indicated by terms such as "upper," "lower," "front," and "rear" is based on the orientation or positional relationship shown in the accompanying drawings. It is used only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] like Figure 1 As shown, this embodiment provides an axial flow impeller, which includes a hub 1 rotating around an axis and a plurality of blades 2 distributed around the circumference of the hub 1. The blades 2 are integrally connected to the hub 1, and the blades 2 and the hub 1 can rotate together around the aforementioned axis. The blades 2 are typically evenly distributed on the outer circumferential surface of the hub 1, exhibiting high dynamic balance and flow field stability. Of course, the blades 2 can also be unevenly distributed on the outer circumferential surface of the hub 1 to adapt to complex operating conditions and reduce resonance; these variations are not detailed here but fall within the scope of this application.

[0045] Along the axial direction from the air outlet side to the air inlet side, the diameter of the hub 1 gradually decreases. The root of the blade 2 contacts the outer peripheral surface of the hub 1. The leading edge 21 of the blade 2 is close to the air inlet side, and the trailing edge 23 of the blade 2 is close to the air outlet side. The length of the leading edge 21 is greater than the length of the trailing edge 23. The contact surface between the root of the blade 2 and the outer peripheral surface of the hub 1 is arc-shaped. Furthermore, the above contact surface, along the rotation direction of the hub 1, is projected onto the plane 3 where the axis of the hub 1 is located in the form of a parabola.

[0046] Furthermore, in the projection of blade 2 onto plane 3 containing the axis along the rotational direction of hub 1, please refer to... Figure 1 The blade 2 will form a projection area on the plane 3, which is defined as the meridional region 4. The boundaries of this region include the crown profile 42 as the upper boundary, the leading edge profile 41 as the front boundary, the trailing edge profile 43 as the rear boundary, and the hub surface profile 44 as the lower boundary. The intermediate flow area surrounded by the four profiles is the meridional region 4 through which the fluid flows.

[0047] Among them, the blade crown contour line 42 is the contour line formed by the projection of the blade crown 22 of blade 2, the leading edge contour line 41 is the contour line formed by the projection of the leading edge 21 of blade 2, the trailing edge contour line 43 is the contour line formed by the projection of the trailing edge 23 of blade 2, and the hub surface contour line 44 is the contour line formed by the projection of the outer surface of hub 1. The contour line refers to the boundary line of the projected shape, that is, the projections of the blade crown 22, the leading edge 21, the trailing edge 23, and the outer surface of hub 1 respectively serve as the boundary lines of the meridional region 4.

[0048] Please refer to Figure 2 , Figure 2The diagram illustrates the shape of meridional region 4. It shows that the leading edge contour line 41 intersects the blade crown contour line 42 and the hub surface contour line 44 at points A and B, respectively. The angle β formed by the tangents to the leading edge contour line 41 at point A and point B is 120° < β < 180°. The trailing edge contour line 43 intersects the blade crown contour line 42 and the hub surface contour line 44 at points C and D, respectively. The angle φ formed by the tangents to the trailing edge contour line 43 at point C and point D is 120° < φ < 180°. Within the aforementioned angle range, please refer to [reference needed]. Figure 3 The airflow efficiency is significantly improved. Therefore, within this angle range, the arrangement of the leading edge 21 and the trailing edge 23 can exhibit a good airflow guiding effect. Furthermore, the efficiency is highest when β=150 and φ=150°.

[0049] Furthermore, in this embodiment, the hub surface profile 44 is the aforementioned parabola, which allows the axial flow impeller to exhibit a better diffusion effect, thereby improving aerodynamic performance. The hub 1 is an axisymmetric component about the axis, meaning its outer surface has the same parabolic characteristics. The angle α between the tangent to the hub surface profile 44 at point B and the axis is 15° < α < 30°. This angle range reduces fluid impact and energy loss at the inlet side of the axial flow impeller, improving its performance. Through the above design of the meridional region 4, secondary flow and flow separation on the suction surface 25 and pressure surface 24 can be controlled, reducing flow losses and improving aerodynamic performance.

[0050] In some embodiments, the blade crown profile 42 is arranged parallel to the axis, and the leading edge profile 41 and trailing edge profile 43 are located outside the parabola. Specifically, the leading edge profile 41 and trailing edge profile 43 of the parabola are located between the blade crown profile 42 and the hub surface profile 44, while the trailing edge profile 43 is located closer to the vertex of the parabola than the leading edge profile 41. It can be seen that the leading edge profile 41 is closer to the inlet side of the axial flow impeller, and is longer than the trailing edge profile 43. Therefore, the leading edge 21 can generate greater thrust, making the airflow between the impellers smoother and more efficient. The shorter trailing edge profile 43 allows the airflow to flow out more smoothly, ensuring aerodynamic performance.

[0051] It should be noted that the wheel hub profile line 44 is not a complete parabola, but rather a segment selected from a complete parabola. The axis of symmetry of the parabola is perpendicular to the axis of rotation. Please refer to [reference needed]. Figure 2 The hub 1 has different diameters at its two axial ends, with the smaller diameter end facing the air intake side. This arrangement reduces the impact of the hub 1 on the airflow and improves efficiency. Furthermore, the hub 1 is axially symmetric about its axis, allowing it to rotate stably around the axis. This ensures smooth rotation of the hub 1 and the corresponding blades 2 mounted on it, preventing separation or large vortices.

[0052] Please refer to Figure 2 The leading edge contour line 41 and the trailing edge contour line 43 are spline curves or circular arcs. The leading edge contour line 41 and the trailing edge contour line 43 bulge towards one side of the vertex in the axial direction. In other words, compared with the leading edge contour line 41, the line connecting points A and B is closer to the air inlet side, and the vertex of the parabola is closer to the air outlet side. The leading edge 21 can cut the air more easily and reduce the impact of the air on the leading edge 21. Similarly, compared with the trailing edge contour line 43, the line connecting points C and D is closer to the air inlet side.

[0053] The parabola constructed by the above hub surface profile line 44 is defined as follows:

[0054] ;

[0055] Where the absolute value of a is greater than less than b and c are constants, and x and y are the curvilinear coordinates of the parabola; it should be noted that the range of a includes The sign of 'a' only determines the opening direction of the parabola; no excessive restrictions are imposed here, as long as the shape of the parabola falls within the range defined by the above formula. Based on the equation of the parabola and the range of values ​​for angle α, the axial flow impeller can exhibit optimal diffusion effect, thereby improving the overall aerodynamic performance.

[0056] Please refer to Figure 4 and Figure 5 In the projection of the trailing edge 23 along the axial direction of the hub 1, the angle between the line connecting the root of the trailing edge 23 and the axis of the hub 1, and the line connecting a point on the trailing edge 23 and the axis of the hub 1, gradually increases in the extension direction of the trailing edge 23. Specifically, in the projection of the blade 2 along the axial direction of the hub 1, the area formed by the projection includes the blade crown projection line 52 as the upper boundary, the leading edge projection line 51 as the front boundary, the trailing edge projection line 53 as the rear boundary, and the hub projection line as the lower boundary. That is, the above projection lines are also contour lines. It should be noted that in three-dimensional space, the root of the trailing edge 23 is not located at the boundary of the outer circumference of the hub 1, but at a predetermined point relative to the outer circumference. Therefore, in the axial projection, due to the influence of the parabolic structure of the hub 1, the projection of the hub 1 will block the predetermined point and part of the projection line of the trailing edge 23. Similarly, the projection of the hub 1 will also block part of the projection line of the leading edge 21 and part of the root area of ​​the blade 2.

[0057] For a more accurate explanation, the aforementioned preset point is defined as point E in the axial projection. Please refer to [reference needed]. Figure 5The trailing edge 23 extends away from the hub 1. In projection, the trailing edge 23 is defined as the trailing edge projection line 53, which is the actual projection line of the trailing edge 23, including the portion of the projection line obscured by the projection of the hub 1. In axial projection, the axis center of the hub 1 is projected as a point. The line connecting point E and the axis center projection is defined as the first line. Any point F outside point E on the trailing edge projection line 53 is selected, and the line connecting point F and the axis center projection is defined as the second line.

[0058] The second line is located on the first side of the first line. More precisely, the second line is located on the side closer to the leading edge projection line 51. That is, regardless of the position of point F, the second line is always located on the side of the first line closer to the leading edge projection line 51. The angle between the first and second lines is the stacking angle θ. As point F gradually moves away from point E along the path of the trailing edge projection line 53, the stacking angle θ gradually increases, and the change in the stacking angle θ is non-linear. Specifically, the path of the trailing edge projection line 53 is dimensionless, and the trailing edge projection line 53 from point E to the top is defined as ranging from zero to one. Please refer to [reference needed]. Figure 6 The horizontal axis represents the dimensionless width and length, i.e., 0-1, and the vertical axis represents the stacking angle θ.

[0059] It can be seen that along the path from point E to the middle of the trailing edge projection line 53, as point F moves further away from point E, the rate of increase of the stacking angle θ gradually decreases. Specifically, the stacking angle θ shows a continuously increasing trend in the range of 0-0.5, while the rate of increase continuously decreases, i.e., the slope continuously decreases. Along the path from the middle of the trailing edge projection line 53 to the top of the trailing edge projection line 53, as point F moves further away from point E, the rate of increase of the stacking angle θ gradually increases. Specifically, in the range of 0.5-1, the stacking angle θ continues to increase, but the rate of increase accelerates, i.e., the slope continuously increases, until it reaches a certain specific value. The stacking angle variation achieved in this way allows the trailing edge 23 of blade 2 to exhibit a special twisted shape when viewed from the outlet side, which can reduce airflow separation at the trailing edge 23 and improve aerodynamic noise. Please refer to the schematic diagrams for the inlet and outlet sides. Figure 7 .

[0060] Figure 8 This is a schematic diagram of the three-dimensional fitting curves for the edge of leaf 2. The leading edge 21 corresponds to the leading edge fitting curve 61, the crown 22 corresponds to the crown fitting curve 62, and the trailing edge 23 corresponds to the trailing edge fitting curve 63. The leading edge fitting curve 61 is shown below. Figure 9 The leading edge fitting curve 61 falls on a preset surface equation, which is as follows:

[0061]

[0062] in, , , , ; , x and y are the curve coordinates of the leading edge fitting curve 61; this makes the inlet angle of the leading edge fitting curve 61 present a reasonable distribution, which can reduce the impact of the leading edge 21 on the inlet side fluid, avoid energy loss, and improve the performance of the fan. Further, A=0.0339; B=0.02433; C=-0.05745; D=-97.59.

[0063] When the axial flow impeller of this application rotates, the airflow enters from the inlet side. Due to the angular arrangement of the key positions of the blades 2 and the special profiles of the leading edge 21, trailing edge 23, and hub 1, the fluid medium generates kinetic energy and static pressure when passing through the blades 2 (including the leading edge 21, trailing edge 23, pressure surface 24, and suction surface 25). Under the action of a certain amount of kinetic and static pressure energy, the fluid medium flows out from the outlet side along the hub 1 and blades 2. Through the special meridional region 4, the secondary flow and flow separation on the suction surface 25 and pressure surface 24 are controlled, reducing flow losses and improving aerodynamic performance. The design of the stacking angle θ reduces flow separation at the tail of the blades 2, reducing aerodynamic noise. The curve design of the leading edge 21 reduces the impact loss when the fluid enters the blades 2, improving efficiency.

[0064] This application also provides an axial flow fan, which includes the aforementioned axial flow impeller.

[0065] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0066] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An axial impeller, characterized by The hub (1) rotates around the axis, and a plurality of blades (2) are distributed circumferentially on the hub (1), the diameter of the hub (1) gradually decreases from the air outlet side to the air inlet side, the leading edge (21) of the blade (2) is close to the air inlet side, the trailing edge (23) of the blade (2) is close to the air outlet side, and the contact surface between the root of the blade (2) and the outer circumferential surface of the hub (1) is arc-shaped. In the projection of the blade (2) onto the plane (3) along the rotation direction of the hub (1), the projection profile of the blade (2) includes a blade crown profile line (42), a leading edge profile line (41), a trailing edge profile line (43), and a hub surface profile line (44). The leading edge profile line (41) intersects with the blade crown profile line (42) and the hub surface profile line (44) at points A and B, respectively, and the trailing edge profile line (43) intersects with the blade crown profile line (42) and the hub surface profile line (44) at points C and D, respectively, the included angle between the tangent line of the leading edge profile line (41) at the point A and the tangent line at the point B is greater than 120° and less than 180°, and the included angle between the tangent line of the trailing edge profile line (43) at the point C and the tangent line at the point D is greater than 120° and less than 180°. The hub surface profile line (44) is a parabola, and the included angle between the tangent line of the hub surface profile line (44) at the point B and the axis is greater than 15° and less than 30°.

2. The axial impeller of claim 1, wherein The symmetry axis of the parabola is perpendicular to the axis, the blade crown profile line (42) is parallel to the axis, and the trailing edge profile line (43) is closer to the vertex of the parabola than the leading edge profile line (41).

3. The axial impeller of claim 2, wherein, The leading edge profile line (41) and the trailing edge profile line (43) are spline curves or circular arc lines, and the leading edge profile line (41) and the trailing edge profile line (43) are convex to one side of the vertex in the direction of the axis.

4. The axial impeller according to any one of claims 1-3, characterized in that The formula of the parabola is defined as: ； Wherein, the absolute value of a is greater than Less than ; b, c are constants, x, y are the curve coordinates of the parabola.

5. The axial impeller of claim 1, wherein The trailing edge (23) intersects with the outer circumferential surface of the hub (1) at a preset point, the trailing edge (23) extends away from the hub (1), in the projection of any blade (2) along the axis of the hub (1), the projected preset point is defined as point E, the projected trailing edge (23) is defined as trailing edge projection line (53), the line connecting the point E and the hub (1) center is defined as the first connecting line, and the line connecting any point F on the trailing edge projection line (53) and the hub (1) center is defined as the second connecting line. The second connecting line is located on the first side of the first connecting line, the included angle between the first connecting line and the second connecting line is the stacking angle θ, and the stacking angle θ gradually increases as the point F gradually moves away from the point E on the path of the trailing edge projection line (53).

6. The axial impeller of claim 5, wherein Between the point E and the middle of the trailing edge projection line (53), as the point F gradually moves away from the point E along the path of the trailing edge projection line (53), the increasing rate of the stacking angle θ gradually decreases; Between the middle of the trailing edge projection line (53) and the top end of the trailing edge projection line (53), as the point F gradually moves away from the point E along the path of the trailing edge projection line (53), the increasing rate of the stacking angle θ gradually increases.

7. The axial impeller of claim 1, wherein The leading edge fitting curve (61) of the blade (2) falls into a curve equation: ； wherein , , , ; , x, y are the curve coordinates of the leading edge fitting curve (61).

8. The axial impeller of claim 1, wherein The contact surface is a parabola projected onto the plane (3) along the rotation direction of the hub (1); In the projection of the trailing edge (23) along the axial direction of the hub (1), the included angle between the line connecting the root of the trailing edge (23) and the hub (1) center and the line connecting a point on the trailing edge (23) and the hub (1) center gradually increases in the extension direction of the trailing edge (23); The leading edge fitting curve (61) of the blade (2) falls into a preset curve equation.

9. An axial flow fan characterised in that, The axial flow impeller comprises the hub (1) and the blade (2). The axial flow impeller comprises the hub (1) and the blade (2).

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