Blade and axial flow fan using the same

Abstract

The application discloses a blade, comprising: a pressure surface and a suction surface; a tip, a root, a leading edge and a trailing edge, wherein the leading edge and the trailing edge respectively extend from the tip to the root; wherein the blade comprises a tip region close to the tip and extending from the leading edge to the trailing edge, wherein the tip region comprises a groove recessed from the pressure surface towards the suction surface, and the groove extends from the trailing edge towards the leading edge. The blade of the application can destroy the leakage flow from the pressure surface to the suction surface by setting the groove in the tip region of the blade, and guide the leakage flow back to the middle part of the pressure surface. Thus, the tip leakage of the axial flow fan using the blade can be reduced, the fan efficiency is improved, and the noise is reduced. And since the tip leakage condition is improved, the tip deformation of the blade is also significantly reduced.

Description

Technical Field

[0001] This application relates to the field of rotating machinery such as fans, pumps and compressors, and more specifically to a blade and an axial flow fan using the blade. Background Technology

[0002] Generally, rotating machinery such as fans consists of a number of blades arranged circumferentially at intervals. Each blade is formed by several airfoil sections extending longitudinally along their leading and trailing edges. The blade has a leading edge for inflowing media and a trailing edge for outflowing media, as well as a concave pressure surface and a convex suction surface. The part of the blade near the hub is called the blade root, and the part with the largest diameter is called the blade tip. Existing blades exhibit tip leakage, which affects fan performance. Summary of the Invention

[0003] To address the above problems, at least one objective of this application in a first aspect is to provide a blade comprising: a pressure surface and a suction surface, the pressure surface and the suction surface forming two opposing surfaces of the blade; a blade tip, a blade root, a leading edge, and a trailing edge, the blade tip, the blade root, the leading edge, and the trailing edge defining the outer edges of the pressure surface and the suction surface, wherein the leading edge and the trailing edge extend from the blade tip to the blade root, respectively; wherein the blade includes a blade tip region adjacent to the blade tip and extending from the leading edge to the trailing edge, wherein the blade tip region includes a groove recessed from the pressure surface toward the suction surface, the groove extending from the trailing edge toward the leading edge.

[0004] According to the first aspect above, the blade has a blade radial height, which is the distance between the blade root and the blade tip on the projection of the blade's normal plane; the blade tip region includes an outer edge defined by the blade tip and an inner edge opposite to the blade tip, the inner edge being located at 50% of the blade radial height.

[0005] According to the first aspect above, the groove has a groove length in its extending direction, the groove length being 70%-100% of the circumferential length of the blade tip.

[0006] According to the first aspect above, the groove includes a groove bottom and an outer groove wall and an inner groove wall located on opposite sides of the groove bottom. The outer groove wall and the inner groove wall extend obliquely relative to each other and intersect to form the groove bottom. The outer groove wall is closer to the blade tip side than the inner groove wall. The top edge of the outer groove wall and the top edge of the inner groove wall are located on the pressure surface.

[0007] According to the first aspect above, the blade is capable of rotating about a rotation axis, the rotation axis being perpendicular to the normal plane; wherein, on the projection of the normal plane, the projection line of the top edge of the inner groove wall is an arc-shaped inner groove wall projection line, the projection line of the groove bottom is an arc-shaped groove bottom projection line, and the projection line of the top edge of the outer groove wall is an arc-shaped outer groove wall projection line; wherein, the projection line of the inner groove wall, the projection line of the groove bottom, and the projection line of the outer groove wall are concentric arcs centered on the projection center of the rotation axis.

[0008] According to the first aspect above, on the projection of the normal plane, the distance between the projection line of the inner groove wall and the projection line of the blade root is not less than 75% of the radial height of the blade.

[0009] According to the first aspect above, the top edge of the outer groove wall that forms the groove at the blade tip.

[0010] According to the first aspect above, the groove has a groove depth in the direction from the pressure surface and the suction surface, and in the direction from the tail edge to the leading edge, the groove depth first gradually increases and then gradually decreases.

[0011] According to the first aspect above, in the extending direction of the groove, the maximum depth of the groove is located at a distance of 10% to 40% of the groove length from the tail edge.

[0012] According to the first aspect above, the blade has a blade radius, which is the distance between the blade tip and the axis of rotation; wherein the maximum depth of the groove is 0.02 to 0.2 of the blade radius.

[0013] According to the first aspect above, the shape of the groove mimics the shape of the skin sac on the lower beak of a pelican when it is stretched.

[0014] At least one object of the second aspect of this application is to provide an axial flow impeller comprising: a hub having a rotation axis about which the hub is rotatable; and at least two blades according to any one of the first aspects, the at least two blades being arranged on the outer circumferential surface of the hub. Attached Figure Description

[0015] Figure 1 This is a perspective structural diagram of one embodiment of the axial flow fan of this application;

[0016] Figure 2A for Figure 1 A three-dimensional structural diagram of the hub and one blade in the axial flow fan shown.

[0017] Figure 2B for Figure 2A Right view

[0018] Figure 3 for Figure 2A The projection of the blade onto the normal plane is shown. Detailed Implementation

[0019] Various specific embodiments of this application will now be described with reference to the accompanying drawings, which form part of this specification. It should be understood that although directional terms such as "front," "rear," "upper," "lower," "left," "right," "top," and "bottom" are used in this application to describe various exemplary structural parts and elements, their use is merely for illustrative purposes and is based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this application can be arranged in different orientations, these directional terms are for illustrative purposes only and should not be considered as limiting.

[0020] Figure 1 This is a top-down perspective structural view of one embodiment of the axial flow fan 100 of this application. Figure 1 As shown, the axial flow fan 100 includes an annular guide ring 101, a hub 110, and three blades 102, which are disposed within the annular guide ring 101. The hub 110 has a rotation axis x, and the cross-section of the hub 110 perpendicular to the rotation axis x is circular. The annular guide ring 101 is rotationally symmetrical about the rotation axis x. The three blades 102 are evenly arranged on the outer circumferential surface of the hub 110 and are integrally connected to the hub 110. The hub 110 and the blades 102 can rotate together about the rotation axis x within the cavity 105 of the annular guide ring 101. As an example, the axial flow fan 100 of this application rotates counterclockwise (i.e.,...). Figure 1 The hub 110 rotates about the rotation axis x (in the direction indicated by the middle arrow). Those skilled in the art will understand that the hub 110 can also be other shapes, and the number of blades 102 can be at least two. The shape of the hub 110 can be configured to match the number of blades 102. For example, when the number of blades 102 is four, the cross-section of the hub 110 perpendicular to the rotation axis x can also be quadrilateral.

[0021] To enable the blade 102 to rotate, a radial gap exists between the tip of the blade 102 and the inner wall of the annular guide ring 101. When the axial fan 100 is running, air can flow from one side of the axial fan 100 to the other along the direction of the rotation axis x, for example, from below to above in the figure. The convergence of the airflow creates a pressure difference between the upper and lower sides of the blade 102, forming a pressure surface 111 with higher pressure on the upper surface of the blade and a suction surface 112 with lower pressure on the lower surface of the blade. Due to the radial gap between the blade tip (see blade tip 215 in Figure 2) and the annular guide ring 101, when a pressure difference exists between the pressure surface 111 and the suction surface 112 of the blade 102, airflow will flow from the pressure surface 111 to the suction surface 112 at this radial gap, causing blade tip leakage. Blade tip leakage of the axial fan 100 reduces the performance of the axial fan 100 and also causes noise. To mitigate tip leakage, the blade 102 of this application has a groove 120 recessed from the pressure surface 111 toward the suction surface 112 near the tip.

[0022] Figure 2A for Figure 1 A three-dimensional structural diagram of the hub 110 and one of the blades 102, viewed from the front. Figure 2B for Figure 2A The right view is used to show the specific shape and structure of blade 102. (See right view for example.) Figure 2A and Figure 2B As shown, the blade 102 has a tip 215, a root 216, a leading edge 213, and a trailing edge 214. The root 216 is located at the edge of the blade 102 for connection with the outer circumferential surface of the hub 110. The tip 215 is located on the opposite side edge to the root 216. The leading edge 213 extends from the leading edge of the tip 215 to the leading edge of the root 216, and the trailing edge 214 extends from the trailing edge of the tip 215 to the trailing edge of the root 216. Thus, the tip 215, root 216, leading edge 213, and trailing edge 214 define the outer edges of the pressure surface 111 and suction surface 112 of the blade 102.

[0023] The blade 102 has a radial height and a radius. The radial height is the distance between the blade tip 215 and the blade root 216 of the blade 102. The radius is the distance between the blade tip 215 and the axis of rotation x.

[0024] The blade 102 also includes a tip region 218, within which a groove 120 is disposed. The tip region 218 is adjacent to the tip 215 and extends from the leading edge 213 to the trailing edge 214. "Adjacent" here refers to the region located on the side adjacent to the tip 215 between the tip 215 and the root 216 of the blade 102. Specifically, the tip region 218 includes an outer edge defined by the tip 215 and an opposing inner edge 219, the inner edge 219 being located at 50% of the blade height. That is, the tip region 218 generally comprises half of the blade 102 along the blade height direction from the tip 215 to the root 216. The groove 120, disposed within the tip region 218, disrupts leakage flow from the pressure surface 111 to the suction surface 112 and guides the leakage flow back to the center of the pressure surface 111, thereby reducing tip leakage of the axial fan 100, improving the efficiency of the axial fan 100, and reducing noise. Furthermore, due to the improved leakage at the leaf tip, the deformation of the leaf tip of blade 102 will also be significantly reduced.

[0025] Still as Figure 2A and Figure 2B As shown, the groove 120 is formed within the blade tip region 218, extending between the trailing edge 214 and the leading edge 213. In the direction of extension, the groove 120 has a groove length L, which is 70%-100% of the circumferential length of the blade tip 215. Here, the groove length L refers to the circumferential length of the groove 120. That is, the groove 120 begins to form at the trailing edge 214 and may extend to the leading edge 213.

[0026] In the embodiments of this application, the groove 120 has a biomimetic shape, mimicking the shape of the skin sac of a pelican's lower beak when extended. Specifically, in the direction from the pressure surface 111 to the suction surface 112, the groove 120 also has a groove depth H. In the extension direction of the groove 120 from the leading edge to the trailing edge, the groove depth H first gradually increases to a maximum value, and then gradually decreases. The maximum value of the groove depth H is 0.02 to 0.2 of the blade radius. In this embodiment, in the extension direction of the groove 120, the groove 120 reaches its maximum depth after extending 10% to 40% of the groove length L from the trailing edge 214. That is, the maximum depth of the groove depth H of the groove 120 is located at a distance of 10% to 40% of the groove length L from the trailing edge 214.

[0027] The groove 120 includes a groove bottom 223, an outer groove wall 221, and an inner groove wall 222. The outer groove wall 221 and the inner groove wall 222 are located on opposite sides of the groove bottom 223, with the outer groove wall 221 being closer to the blade tip 215 than the inner groove wall 222. The top edge 228 of the outer groove wall 221 and the top edge 227 of the inner groove wall 222 are located on the pressure surface 111. As an example, the outer groove wall 221 and the inner groove wall 222 extend obliquely from their respective top edges toward the suction surface 112 and intersect to form the groove bottom 223. In this embodiment, the blade tip 215 forms the top edge 228 of the outer groove wall 221. That is, the outer groove wall 221 extends obliquely from the blade tip 215 toward the suction surface 112. As a more specific example, the groove 120 is approximately a "V" shaped groove. The groove length L is approximately the circumferential length of the groove bottom 223.

[0028] Figure 3 The projection of the normal plane of blade 102 in Figure 2 is shown; this normal plane is perpendicular to the axis of rotation x. Figure 3 As shown, on the projection of the blade 102 onto the normal plane, the rotation axis x forms a point-like projection center O. The blade root 216 forms an arc-shaped blade root projection line (344), i.e., arc line IJ, and the blade tip 215 forms an arc-shaped blade tip projection line (345), i.e., arc line AD. The top edge 228 of the outer groove wall 221 forms an arc-shaped outer groove wall projection line (i.e., arc line AK) 343, which is a part of the blade tip projection line 345. The top edge 227 of the inner groove wall 222 forms an arc-shaped inner groove wall projection line 341, i.e., arc line CN, and the groove bottom 223 forms an arc-shaped groove bottom projection line (i.e., arc line BM) 342. These arc-shaped projection lines are concentric arcs centered at the projection center O.

[0029] In such Figure 3 On the projection of the normal plane shown, at the radial height of the blade 102, the distance between the projection line 341 of the inner groove wall and the projection line 344 of the blade root is not less than 75% of the radial height of the blade. That is to say, on the projection of the normal plane of the blade 102, the groove 120 is approximately located within the range of 75% to 100% of the radial height of the blade from the blade root 216.

[0030] The axial flow fan 100 of this application and a conventional axial flow fan (e.g., an axial flow fan with the same diameter of 510 mm) were compared in a test according to the ANSI / AMCA Standard 210-16. The results are shown in Table 1.

[0031] Conventional axial flow fan This embodiment features an axial flow fan. Fan efficiency (%) 42.4 51.5 Noise equivalent parameter value 0.22 0.179 Blade tip deformation value (mm) 29mm 17mm

[0032] Table 1 Comparison results between conventional axial flow fans and axial flow fan 100

[0033] As can be seen from Table 1, the fan efficiency of the axial flow fan 100 of this application is more than 20% higher than that of conventional axial flow fans, and the noise and blade tip deformation are also improved.

[0034] The blade of this application, by providing grooves in the blade tip region, can disrupt the leakage flow from the pressure surface to the suction surface and guide the leakage flow back to the center of the pressure surface. This reduces tip leakage in axial flow fans using this blade, improving fan efficiency and reducing noise. Furthermore, due to the improved tip leakage, blade tip deformation is significantly reduced.

[0035] Although this application will be described with reference to the specific embodiments shown in the accompanying drawings, it should be understood that the blades and axial flow fans of this application can have many variations without departing from the spirit, scope, and context of the teachings of this application. Those skilled in the art will also recognize that there are different ways to modify the structural details of the embodiments disclosed in this application, all of which fall within the spirit and scope of this application and the claims.

Claims

1. A blade, characterized in that: The blade (102) comprises: A pressure surface (111) and a suction surface (112) form two opposing surfaces of the blade (102), wherein the blade (102) is configured to drive gas to flow from one side of the suction surface (112) to one side of the pressure surface (111) by rotation of the blade (102); The leaf tip (215), leaf root (216), leading edge (213), and trailing edge (214) define the outer edges of the pressure surface (111) and the suction surface (112), wherein the leading edge (213) and the trailing edge (214) extend from the leaf tip (215) to the leaf root (216), respectively. The blade (102) includes a tip region (218) that is close to the tip (215) and extends from the leading edge (213) to the trailing edge (214). The tip region (218) includes a groove (120) recessed from the pressure surface (111) toward the suction surface (112). The groove (120) extends from the trailing edge (214) toward the leading edge (213), and the groove (120) includes a slot. The groove (120) is a bottom (223) and an outer groove wall (221) and an inner groove wall (222) located on opposite sides of the bottom (223), wherein the groove (120) recessed from the pressure surface (111) toward the suction surface (112) has a groove depth (H) in the direction from the pressure surface (111) to the suction surface (112), and the groove depth (H) of the groove (120) first gradually increases and then gradually decreases in the direction from the tail edge (214) to the leading edge (213).

2. The blade according to claim 1, characterized in that: The blade (102) has a blade radial height, which is the distance between the blade root (216) and the blade tip (215) on the projection of the blade (102) onto the normal plane. The blade tip region (218) includes an outer edge defined by the blade tip (215) and an inner edge (219) opposite to the blade tip (215), the inner edge (219) being located at 50% of the radial height of the blade.

3. The blade according to claim 2, characterized in that: The groove (120) has a groove length (L) in its extending direction, the groove length (L) being 70%-100% of the circumferential length of the blade tip (215).

4. The blade according to claim 3, characterized in that: The outer groove wall (221) and the inner groove wall (222) extend obliquely relative to each other and intersect to form the groove bottom (223), wherein the outer groove wall (221) is closer to the blade tip (215) than the inner groove wall (222), wherein the top edge (228) of the outer groove wall (221) and the top edge (227) of the inner groove wall (222) are located on the pressure surface (111).

5. The blade according to claim 4, characterized in that: The blade (102) is capable of rotating about a rotation axis (x), which is perpendicular to the normal plane; In the projection onto the normal plane, the projection line of the top edge (227) of the inner groove wall (222) is an arc-shaped inner groove wall projection line (341), the projection line of the groove bottom (223) is an arc-shaped groove bottom projection line (342), and the projection line of the top edge (228) of the outer groove wall (221) is an arc-shaped outer groove wall projection line (343). The inner wall projection line (341), the bottom projection line (342), and the outer wall projection line (343) are concentric arcs centered on the projection center (O) of the rotation axis (x).

6. The blade according to claim 5, characterized in that: On the projection of the normal plane, the distance between the projection line (341) of the inner groove wall and the projection line (344) of the blade root (216) is not less than 75% of the radial height of the blade.

7. The blade according to claim 6, characterized in that: The blade tip (215) forms the top edge (228) of the outer groove wall (221) of the groove (120).

8. The blade according to claim 5, characterized in that: In the extending direction of the groove (120), the maximum depth of the groove (120) is located at 10% to 40% of the groove length (L) from the tail edge (214).

9. The blade according to claim 5, characterized in that: The blade (102) has a blade radius, which is the distance between the blade tip (215) and the axis of rotation (x); The maximum depth of the groove (H) of the groove (120) is 0.02 to 0.2 times the radius of the blade.

10. The blade according to claim 2, characterized in that: The groove (120) is shaped to mimic the shape of the skin sac on the lower beak of a pelican when it is stretched.

11. An axial flow impeller (100), characterized in that... include: A hub (110) having a rotation axis (x) and being rotatable about the rotation axis (x); and At least two blades (102) according to any one of claims 1-10 are arranged on the outer circumferential surface of the hub (110).

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