Multi-wing centrifugal impeller and multi-wing centrifugal fan

Abstract

The invention belongs to the technical field of centrifugal fans, and discloses a multi-wing centrifugal impeller and a multi-wing centrifugal fan. The multi-wing centrifugal impeller comprises an impeller disc, a plurality of blades and an impeller ring, the impeller disc and the impeller ring are connected to the two ends of the blades, and each blade extends towards the circle center of the impeller disc; each blade is provided with a front end and a rear end which are arranged at intervals in the radial direction of the impeller disc and a pressure face and a suction face which are arranged at intervals in the circumferential direction of the impeller disc, the front ends are arranged close to the circle center of the impeller disc, and sand dune type protrusions protruding towards the suction face are formed on the portions, close to the front ends, of the blades. The flow field uniformity and stability of the multi-wing centrifugal impeller are high, the flow channel shrinkage coefficient of the impeller is increased, and therefore the problem that the aerodynamic performance is poor when inlet impact loss and blade tail edge separation loss of airflow of an existing multi-wing centrifugal fan are large is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fans, and particularly to a multi-wing centrifugal impeller and a multi-wing centrifugal fan. Background Art

[0002] Multi-wing forward centrifugal fans are widely used in the fields of heating, ventilation and air conditioning, electronic equipment heat dissipation, and industrial ventilation systems due to their advantages such as high pressure coefficient, large flow coefficient, low noise characteristics, and compact structure. However, there are still significant technical bottlenecks in their aerodynamic performance. There is an obvious asymmetric flow phenomenon in the impeller flow passage. The fluid on the pressure surface side flows stably along the profile line, while on the suction surface side, due to the excessive inlet attack angle, flow separation occurs. Approximately 70% of the flow passage area forms large-scale separation vortices at the leading edge of the blade, resulting in significant flow losses.

[0003] Aerodynamic noise research shows that the shedding of the suction surface separation vortex in the impeller rear disk area is the main broadband noise source, and its sound pressure level is positively correlated with the flow field pulsation intensity. Numerical simulations show that when the separation vortex intensity is reduced by 30%, the 500 Hz - 2000 Hz frequency band in the noise spectrum can be attenuated by 5 dB - 8 dB. This indicates that optimizing the flow field stability has dual benefits in aerodynamics and acoustics.

[0004] The current designs generally adopt the process of equal-thickness circular arc blades. Although it has advantages such as low processing cost and flexible profile parameters, it has significant aerodynamic defects: large inlet impact losses, serious blade trailing edge separation losses, etc., making it difficult to obtain good aerodynamic performance. While using an airfoil blade structure can reduce the inlet impact loss and blade trailing edge separation loss of the airflow, when the airfoil structure meets the inlet and outlet angles, its bend angle is too large and the airfoil structure changes significantly, making it difficult to meet the optimal aerodynamic performance. Summary of the Invention

[0005] The first object of the present invention is to provide a multi-wing centrifugal impeller with high flow field uniformity and stability, which improves the flow passage contraction coefficient of the impeller, thereby improving the problem of poor aerodynamic performance caused by large inlet impact losses and blade trailing edge separation losses of the airflow in the existing multi-wing centrifugal fans.

[0006] The second object of the present invention is to propose a multi-wing centrifugal fan with relatively small inlet impact losses and blade trailing edge separation losses of the airflow, high flow field uniformity and stability, and superior aerodynamic performance.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] The present invention discloses a multi-wing centrifugal impeller, which includes an impeller disc, a plurality of blades and an impeller ring. The impeller disc and the impeller ring are connected to both ends of the plurality of blades. Each blade extends towards the center of the impeller disc. Each blade has a front end and a rear end that are spaced apart radially along the impeller disc, and a pressure surface and a suction surface that are spaced apart circumferentially along the impeller disc. The front end is arranged close to the center of the impeller disc. A dune-shaped protrusion protruding towards the suction surface is formed on a part of the blade close to the front end. The dune-shaped protrusion is used to reduce the vortex formed by the airflow at the front end.

[0009] In some embodiments, in the direction from the front end towards the rear end, the dune-shaped protrusion includes a gradually expanding section with a gradually increasing width and a gradually contracting section with a gradually decreasing width. The large end of the gradually expanding section is arranged towards the large end of the gradually contracting section.

[0010] In some embodiments, a conical structure with a gradually decreasing width is formed at the front end of the blade.

[0011] In some embodiments, the maximum width of the dune-shaped protrusion is greater than the maximum width of the rear end, and the maximum width of the rear end is greater than the maximum width of the front end.

[0012] In some embodiments, a strengthening structure extending axially along the impeller disc is provided on the outer peripheral wall of the impeller ring.

[0013] In some embodiments, the vertex of the front end is a, the highest point of the dune-shaped protrusion is b, the vertex of the rear end is c. The line connecting the vertex a of the front end and the vertex c of the rear end is the blade chord of the blade. The length of the blade chord is L1. Along the length direction of the blade chord, the distance between the highest point b of the dune-shaped protrusion and the vertex a of the front end is L2. L1 and L2 satisfy the relationship: 1 / 8 ≤ L2 / L1 ≤ 1 / 2.

[0014] In some embodiments, the vertex of the front end is a, the highest point of the dune-shaped protrusion is b, the vertex of the rear end is c. The line connecting the vertex a of the front end and the vertex c of the rear end is the blade chord of the blade. The length of the blade chord is L1. In the direction perpendicular to the length direction of the blade chord, the distance between the highest point b of the dune-shaped protrusion and the vertex a of the front end is H1. L1 and H1 satisfy the relationship: 1 / 6 ≤ H1 / L1 ≤ 3 / 4.

[0015] In some embodiments, the vertex of the front end is a, the highest point of the pressure surface is d, the vertex of the rear end is c, the line connecting the vertex a of the front end and the vertex c of the rear end is the blade chord of the blade, the length of the blade chord is L1, along the length direction of the blade chord, the distance between the highest point d of the pressure surface and the vertex a of the front end is L3, and L1 and L3 satisfy the relational expression: 1 / 5 ≤ L3 / L1 ≤ 1 / 2.

[0016] In some embodiments, the vertex of the front end is a, the highest point of the pressure surface is d, the vertex of the rear end is c, the line connecting the vertex a of the front end and the vertex c of the rear end is the blade chord of the blade, the length of the blade chord is L1, along the direction perpendicular to the length direction of the blade chord, the distance between the highest point d of the pressure surface and the vertex a of the front end is H2, and L1 and H2 satisfy the relational expression: 1 / 10 ≤ H2 / L1 ≤ 3 / 4.

[0017] The present invention discloses a multi-wing centrifugal fan, including the multi-wing centrifugal impeller and the volute described above, and the multi-wing centrifugal impeller is installed in the volute.

[0018] The beneficial effects of the multi-wing centrifugal impeller of the present invention: Since a dune-shaped protrusion protruding toward the suction surface is provided at a position near the front end of the blade, the structure of the dune-shaped protrusion has a good air flow guiding effect, and the position of the dune-shaped protrusion occupies the position where a separation vortex is most likely to appear at the inlet. After the air flow flows into the blade from the inlet, under the guiding action of the dune-shaped protrusion, the flow field uniformity and flow field stability can be improved, and at the same time, the flow passage contraction coefficient of the impeller is also improved, thereby improving the problem of poor aerodynamic performance caused by large impact losses at the inlet and separation losses at the blade trailing edge of the existing multi-wing centrifugal fan.

[0019] The beneficial effects of the multi-wing centrifugal fan of the present invention: Since it has the multi-wing centrifugal impeller described above, after the air flow flows into the blade from the inlet, under the guiding action of the dune-shaped protrusion, the flow field uniformity and flow field stability can be improved, and at the same time, the flow passage contraction coefficient of the impeller is also improved, thereby improving the problem of poor aerodynamic performance caused by large impact losses at the inlet and separation losses at the blade trailing edge of the existing multi-wing centrifugal fan.

[0020] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of the multi-wing centrifugal impeller according to an embodiment of the present invention;

[0022] Figure 2 is a partial structural diagram of the multi-wing centrifugal impeller according to an embodiment of the present invention;

[0023] Figure 3 It is a schematic structural diagram of the blade of the multi-wing centrifugal impeller according to an embodiment of the present invention;

[0024] Figure 4 It is a schematic structural diagram of the multi-wing centrifugal impeller in another direction according to an embodiment of the present invention;

[0025] Figure 5 It is a schematic structural diagram of another type of blade of the multi-wing centrifugal impeller according to an embodiment of the present invention.

[0026] Reference numerals:

[0027] 100, impeller disc; 110, rotating shaft;

[0028] 200, blade; 210, front end; 220, rear end; 230, pressure surface; 240, suction surface; 250, dune-shaped protrusion; 260, blade chord;

[0029] 300, impeller ring; 310, strengthening structure. Detailed implementation manners

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the sake of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0031] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0032] In the description of this embodiment, the orientation or positional relationship such as "upper", "lower", "left", "right", "front", and "rear" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for distinction in description and do not have special meanings.

[0033] The present invention discloses a multi-wing centrifugal impeller. Refer to Figure 1 、 Figure 2 andFigure 4 As shown, it includes an impeller disk 100, a plurality of blades 200, and an impeller ring 300. The impeller disk 100 and the impeller ring 300 are connected to both ends of the plurality of blades 200. Each blade 200 extends towards the center of the impeller disk 100. Each blade 200 has a front end 210 and a rear end 220 that are spaced apart radially along the impeller disk 100, and a pressure surface 230 and a suction surface 240 that are spaced apart circumferentially along the impeller disk 100. The front end 210 is arranged close to the center of the impeller disk 100. Refer to Figure 3 As shown, a dune-shaped protrusion 250 that protrudes towards the suction surface 240 is formed on the part of the blade 200 close to the front end 210. The dune-shaped protrusion 250 can cover a part of the separation zone formed by the airflow at the front end 210. It can be understood that the simulation and experimental verification of the optimized model show that the blade structure in the prior art is very likely to form a separation vortex at the inlet, thereby reducing the aerodynamic performance of the entire impeller. For the multi-wing centrifugal impeller of this embodiment, since a dune-shaped protrusion 250 that protrudes towards the suction surface 240 is provided at the position of the blade 200 close to the front end 210, the dune-shaped protrusion 250 structure has a good air flow guiding effect, and the position of the dune-shaped protrusion 250 occupies the position where the separation vortex is most likely to appear at the inlet. After the airflow flows in from the inlet of the blade 200, under the guiding action of the dune-shaped protrusion 250, the flow field uniformity and flow field stability can be improved, and at the same time, the flow channel contraction coefficient of the impeller is also improved, thereby improving the problem of poor aerodynamic performance caused by the large impact loss of the airflow at the inlet and the separation loss at the trailing edge of the blade 200 in the existing multi-wing centrifugal fan.

[0034] In addition, it should be supplemented that one end of the blade 200 is connected to the impeller disk 100, and the other end is fixed by the impeller ring 300. The fixing method at both ends can improve the installation stability of the blade 200, reduce the probability of deformation of the blade 200 during operation, and thus extend the service life of the multi-wing centrifugal impeller.

[0035] Optionally, refer to Figure 3 、 Figure 5As shown, in the direction from the front end 210 towards the rear end 220, the dune-shaped protrusion 250 includes a gradually expanding section with a gradually increasing width and a gradually shrinking section with a gradually decreasing width. The large end of the gradually expanding section is arranged towards the large end of the gradually shrinking section. It can be understood that according to the simulation and experimental verification of the optimization model, the larger the width of the dune-shaped protrusion 250, the better the effect of reducing the impact loss and separation loss. However, when the dune-shaped protrusion 250 is relatively large, it will cause the size of the blade 200 near the front section to be relatively large, which increases the manufacturing difficulty of the blade 200 during the manufacturing process, and is prone to delamination during the manufacturing process, reducing the manufacturing yield of the blade 200. In this embodiment, the dune-shaped protrusion 250 is split into two parts, one part is a gradually expanding section with a gradually increasing width, and the other end is a gradually shrinking section with a gradually decreasing width. This structure can, on the one hand, ensure the effect of the dune-shaped protrusion 250 in reducing the impact loss and separation loss, and on the other hand, facilitate the manufacturing of the blade 200, avoid delamination of the blade 200 during the manufacturing process, and is conducive to improving the manufacturing yield of the blade 200.

[0036] Optionally, referring to Figure 3 , Figure 5 As shown, the front end 210 of the blade 200 is formed with a tapered structure with a gradually decreasing width. It can be understood that when the front end 210 of the blade 200 is formed into a tapered structure, when the airflow enters the flow channel from the front end 210 of the blade 200, the tapered structure can, on the one hand, play a good role in guiding the airflow, and on the other hand, it can reduce the impact loss of the airflow at the inlet. Further optionally, the end of the tapered structure is an arc surface. Compared with the sharp corner structure, the end surface of the tapered structure designed as an arc surface can, on the one hand, simplify the manufacturing process and facilitate the manufacturing of the blade 200, and on the other hand, reduce the probability of damage to the blade 200, thus being conducive to extending the service life of the blade 200. It should be additionally noted that in other embodiments of the present invention, the shape of the front end 210 of the blade 200 can also be selected as other shapes according to the simulation and experimental verification of the optimization model, and is not limited to the tapered structure of this embodiment.

[0037] Optionally, the maximum width of the dune-shaped protrusion 250 is greater than the maximum width of the rear end 220, and the maximum width of the rear end 220 is greater than the maximum width of the front end 210. Thus, it can further improve the flow field uniformity and flow field stability, and at the same time improve the flow channel contraction coefficient of the impeller, thereby improving the problem of poor aerodynamic performance caused by large impact loss at the inlet of the airflow and large separation loss at the trailing edge of the blade 200 in the existing multi-wing centrifugal fan.

[0038] Further optionally, referring to Figure 1 and Figure 2As shown, a strengthening structure 310 extending along the axial direction of the impeller disc 100 is provided on the outer peripheral wall of the impeller ring 300. It can be understood that the added strengthening structure 310 can enhance the strength of the entire multi-wing centrifugal impeller, further reduce the deformation probability of the blades 200 during operation, and thus extend the service life of the multi-wing centrifugal impeller.

[0039] Optionally, the blade 200, the impeller ring 300, the impeller disc 100, and the strengthening structure 310 are integrally formed parts. It can be understood that the blade 200, the impeller ring 300, the impeller disc 100, and the strengthening structure 310 being integrally formed parts can, on the one hand, enhance the strength of the entire multi-wing centrifugal impeller, further reduce the deformation probability of the blades 200 during operation, and thus extend the service life of the multi-wing centrifugal impeller. On the other hand, it simplifies the manufacturing process of the multi-wing centrifugal impeller and is beneficial to reducing the manufacturing cost of the multi-wing centrifugal impeller.

[0040] Optionally, referring to Figure 1 As shown, a rotating shaft 110 extending along the circumferential direction of the impeller disc 100 is provided at the center position of the impeller disc 100. It can be understood that the added rotating shaft 110 can conveniently connect the multi-wing centrifugal impeller to the driving motor, thus facilitating the use of the multi-wing centrifugal impeller. Further optionally, the rotating shaft 110 and the impeller disc 100 are integrally formed parts, which can simplify the manufacturing process of the multi-wing centrifugal impeller and is beneficial to reducing the manufacturing cost of the multi-wing centrifugal impeller.

[0041] Referring to Figure 3 As shown, the vertex of the front end 210 is a, the highest point of the dune-shaped protrusion 250 is b, the vertex of the rear end 220 is c, and the highest point of the pressure surface 230 is d. The parameter range of the blade 200 in this embodiment is as follows:

[0042] Along the length direction of the blade chord 260, the distance between the highest point b of the dune-shaped protrusion 250 and the vertex a of the front end 210 is L2, and L1 and L2 satisfy the relationship: 1 / 8 ≤ L2 / L1 ≤ 1 / 2. Specifically, the ratio of L2 / L1 can be 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2, or other values within the range from 1 / 8 to 1 / 2.

[0043] Along the direction perpendicular to the length direction of the blade chord 260, the distance between the highest point b of the dune-shaped protrusion 250 and the vertex a of the front end 210 is H1, and L1 and H1 satisfy the relationship: 1 / 6 ≤ H1 / L1 ≤ 3 / 4. Specifically, the ratio of H1 / L1 can be 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2, 3 / 4, or other values within the range from 1 / 6 to 3 / 4.

[0044] In the length direction of the blade chord 260, the distance between the highest point d of the pressure surface 230 and the vertex a of the front end 210 is L3, and L1 and L3 satisfy the relationship: 1 / 5 ≤ L3 / L1 ≤ 1 / 2. Specifically, the ratio of L6 / L1 can be 1 / 5, 1 / 4, 1 / 3, 1 / 2, or other values within the range from 1 / 5 to 1 / 2.

[0045] In the direction perpendicular to the length direction of the blade chord 260, the distance between the highest point d of the pressure surface 230 and the vertex a of the front end 210 is H2, and L1 and H2 satisfy the relationship: 1 / 10 ≤ H2 / L1 ≤ 3 / 4. Specifically, the ratio of H5 / L1 can be 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2, 3 / 4, or other values within the range from 1 / 10 to 3 / 4.

[0046] The simulation and experimental verification based on the optimization model show that the multi-wing centrifugal impeller of this embodiment has the following advantages:

[0047] First, compared with the prior art, the separation area of the suction surface 240 of the blade 200 is significantly reduced;

[0048] Second, the contraction coefficient of the gas flow channel increases, and the flow field uniformity of the multi-wing centrifugal impeller is greatly improved;

[0049] Third, the static pressure efficiency is significantly improved, the static pressure under the rated condition increases significantly, and the flow rate-pressure curve is broadened;

[0050] Fourth: Under the condition of maintaining the same air volume, the rotational speed of the multi-wing centrifugal impeller is greatly reduced, and the working noise of the multi-wing centrifugal fan can be greatly reduced.

[0051] The present invention discloses a multi-wing centrifugal fan, including the multi-wing centrifugal impeller and the volute described above, and the multi-wing centrifugal impeller is installed in the volute. Due to the multi-wing centrifugal impeller described above in this embodiment, after the air flow flows in from the inlet of the blade 200, under the guiding action of the dune-shaped protrusion 250, the flow field uniformity and flow field stability can be improved, and at the same time, the flow channel contraction coefficient of the impeller is also improved, thereby improving the problem of poor aerodynamic performance caused by large inlet impact loss and blade 200 trailing edge separation loss of the air flow of the existing multi-wing centrifugal fan.

[0052] It should be added that the structure of the volute of the multi-wing centrifugal fan can be selected according to actual needs, and the connection method between the multi-wing centrifugal impeller and the volute is the prior art, and the connection method between the multi-wing centrifugal impeller and the volute is not specifically limited herein.

[0053] In the description of this specification, the descriptions referring to the terms "some embodiments", "other embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0054] Obviously, the above embodiments of the present invention are merely examples given for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A multi-blade centrifugal impeller, characterized in that: The invention comprises an impeller disk (100), a plurality of blades (200) and an impeller ring (300), wherein the impeller disk (100) and the impeller ring (300) are connected to two ends of the plurality of blades (200), each blade (200) is extended toward the center of the impeller disk (100), and each blade (200) has a front end (210) and a rear end (220) which are arranged at intervals along the radial direction of the impeller disk (100). , and a pressure surface (230) and a suction surface (240) arranged at intervals along the circumference of the impeller disk (100), the front end (210) is arranged close to the center of the impeller disk (100), and a portion of the blade (200) close to the front end (210) is formed with a dune-shaped protrusion (250) protruding toward the suction surface (240), and the dune-shaped protrusion (250) is used to reduce the vortex formed by the airflow at the front end (210).

2. The multi-blade centrifugal impeller according to claim 1, characterized in that: In the direction from the front end (210) toward the rear end (220), the dune-shaped protrusion (250) comprises a gradually expanding section with a gradually increasing width and a gradually contracting section with a gradually decreasing width, and the large end of the gradually expanding section is arranged toward the large end of the gradually contracting section.

3. The multi-blade centrifugal impeller according to claim 1, characterized in that: The front end (210) of the blade (200) is formed into a tapered structure with a gradually decreasing width.

4. The multi-blade centrifugal impeller according to claim 1, characterized in that: The maximum width of the dune-shaped protrusion (250) is greater than the maximum width of the rear end (220), and the maximum width of the rear end (220) is greater than the maximum width of the front end (210).

5. The multi-blade centrifugal impeller according to claim 1, characterized in that: The outer peripheral wall of the impeller ring (300) is provided with a reinforcement structure (310) extending along the axial direction of the impeller disc (100).

6. The multi-blade centrifugal impeller according to claim 1, characterized in that: The apex of the front end (210) is a, the highest point of the dune-shaped protrusion (250) is b, and the apex of the rear end (220) is c. The line between the apex a of the front end (210) and the apex c of the rear end (220) is the blade chord (260) of the blade (200). The length of the blade chord (260) is L1. Along the length direction of the blade chord (260), the distance between the highest point b of the dune-shaped protrusion (250) and the apex a of the front end (210) is L2. L1 and L2 satisfy the relationship: 1 / 8≤L2 / L1≤1 / 2.

7. The multi-blade centrifugal impeller according to claim 1, characterized in that: The apex of the front end (210) is a, the highest point of the dune-shaped protrusion (250) is b, and the apex of the rear end (220) is c. The line between the apex a of the front end (210) and the apex c of the rear end (220) is the blade chord (260) of the blade (200). The length of the blade chord (260) is L1. In a direction perpendicular to the length direction of the blade chord (260), the distance between the highest point b of the dune-shaped protrusion (250) and the apex a of the front end (210) is H1. L1 and H1 satisfy the relationship: 1 / 6≤H1 / L1≤3 / 4.

8. The multi-blade centrifugal impeller according to claim 1, characterized in that: The vertex of the front end (210) is a, the highest point of the pressure surface (230) is d, and the vertex of the rear end (220) is c. The line between the vertex a of the front end (210) and the vertex c of the rear end (220) is the blade chord (260) of the blade (200). The length of the blade chord (260) is L1. Along the length direction of the blade chord (260), the distance between the highest point d of the pressure surface (230) and the vertex a of the front end (210) is L3. L1 and L3 satisfy the relationship: 1 / 5≤L3 / L1≤1 / 2.

9. The multi-blade centrifugal impeller according to claim 1, characterized in that: The vertex of the front end (210) is a, the highest point of the pressure surface (230) is d, and the vertex of the rear end (220) is c. The line between the vertex a of the front end (210) and the vertex c of the rear end (220) is the blade chord (260) of the blade (200). The length of the blade chord (260) is L1. In a direction perpendicular to the length direction of the blade chord (260), the distance between the highest point d of the pressure surface (230) and the vertex a of the front end (210) is H2. L1 and H2 satisfy the relationship: 1 / 10≤H2 / L1≤3 / 4.

10. A multi-blade centrifugal fan, characterized in that: It comprises a multi-blade centrifugal impeller and a volute as described in any one of claims 1 to 9, wherein the multi-blade centrifugal impeller is installed in the volute.

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