Impeller and axial flow fan with noise reduction structure at blade tip region

Abstract

The application discloses an impeller with a noise reduction structure arranged in a blade tip region and an axial flow fan, and the impeller comprises a hub and blades, and the blades are uniformly arranged on the hub; a convex structure is arranged in a blade tip region of a suction surface of the blade, the convex structure of the suction surface is smoothly connected with the suction surface, and the convex structure of the suction surface extends from a leading edge region of the suction surface to a trailing edge region of the suction surface; a convex structure is also arranged in a blade tip region of a pressure surface of the blade, the convex structure of the pressure surface is smoothly connected with the pressure surface, and the convex structure of the pressure surface extends from a leading edge region of the pressure surface to a trailing edge region of the pressure surface. The convex structure arranged in the blade tip region destroys vortex flow in the blade tip gap, and the noise of the blade tip is reduced under the premise of maintaining the performance of the fan.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine technology, specifically relating to an impeller and axial flow fan with a noise reduction structure set in the blade tip area. Background Technology

[0002] Axial flow fans are devices in which gas flows parallel to the fan axis. They are characterized by simple structure and large flow rate, and are widely used in factories, buildings, and other applications. Axial flow fans suffer from noise problems, which mainly originate from three sources: 1. Aerodynamic noise, generated by the interaction between the blades and the air, including phenomena such as airflow turbulence and vortex separation; 2. Mechanical noise, primarily caused by vibration and friction during motor and bearing operation. Loose couplings, worn bearings, or impeller imbalance can exacerbate abnormal noise; 3. Resonance noise, caused by the coupling of the fan's natural frequency and structural vibration, usually due to design flaws or improper installation. Currently, mechanical noise and resonance noise can be reduced or eliminated through regular maintenance and calibration. However, aerodynamic noise is more difficult to solve. During operation under load, the gap between the blades and the collector generates a large number of eddies, leading to increased tip noise. Current solutions mainly include optimizing blade design and collector design. For example, patent CN114458638A discloses a noise reduction structure for an axial flow fan duct, which absorbs noise through a complex noise reduction unit to achieve noise reduction. Patent CN105782090A discloses a noise-reducing and eddy-reducing axial flow fan, which achieves noise reduction by optimizing the blade distribution angle and improving the collector structure. Patent CN116006509A discloses a blade with noise reduction design at the tip gap of the axial flow fan blades, which has a guide groove at the tip of the blade that runs from the suction surface to the pressure surface to achieve noise reduction. Existing solutions for reducing aerodynamic noise still suffer from structural complexity. Improvements to the collector have made the collector structure increasingly complex, while optimization of the blades, although reducing noise, may affect other blade performance aspects, making it difficult to achieve a balance. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention aims to provide an impeller and an axial flow fan with a noise reduction structure in the blade tip region. The convex structure in the blade tip region disrupts the vortex in the blade tip gap, thereby reducing blade tip noise while maintaining fan performance.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect of the invention, the invention proposes an impeller with a noise reduction structure provided in the blade tip region, comprising a hub and blades, wherein a plurality of blades are uniformly disposed on the hub.

[0006] The blade tip area of ​​the suction surface is provided with a convex structure, and the convex structure of the suction surface is smoothly transitioned to the suction surface. The convex structure of the suction surface extends from the front edge area of ​​the suction surface to the rear edge area of ​​the suction surface.

[0007] The tip region of the pressure surface of the blade is also provided with a convex structure. The convex structure of the pressure surface is smoothly transitioned to the pressure surface. The convex structure of the pressure surface extends from the front edge region of the pressure surface to the trailing edge region of the pressure surface.

[0008] Preferably, within the suction / pressure surface, the width / thickness of the convex structure is smallest at both ends and largest in the middle, and the width and thickness of the convex structure gradually increase from the ends to the middle, with the ends of the convex structure being pointed tips.

[0009] More preferably, within the suction surface, there is a gap between one end of the convex structure and the leading edge on the same side, and the other end of the convex structure extends to the trailing edge on the same side.

[0010] More preferably, within the suction surface, there is a gap between the convex structure and the tip edge of the blade, and the gap between the convex structure and the tip edge gradually increases from the leading edge to the trailing edge.

[0011] More preferably, within the pressure surface, the convex structure extends from the leading edge to the trailing edge.

[0012] More preferably, within the pressure surface, there is a gap between the convex structure and the blade tip edge, and the gap between the convex structure and the blade tip edge gradually decreases from the leading edge to the trailing edge.

[0013] Preferably, the blade tip chord length is L, and the maximum protrusion position of the convex structure of the suction / pressure surface is located at 0.5L from the center of the blade tip chord.

[0014] More preferably, the sum of the maximum thicknesses of the convex structures on both sides of the blade accounts for one-third of the maximum thickness at the center of the blade tip chord.

[0015] Preferably, the convex structure is formed based on the following three-dimensional outer contour function:

[0016] Z = -0.00957X 2 -0.34X-0.05475Y 2 -9.88Y-457.59;

[0017] The three-dimensional outer contour function is established in a rectangular coordinate system with the center of the wheel hub as the origin.

[0018] In a second aspect, the present invention provides an axial flow fan, comprising a collector and the aforementioned impeller, wherein the impeller is disposed within the collector.

[0019] Beneficial effects:

[0020] This invention uses a convex structure in the blade tip region to disrupt the eddy current in the blade tip gap, thereby reducing blade tip noise while maintaining fan performance. Compared to fans without a convex structure, this invention can reduce impeller blade tip noise by 1-2 dB. Attached Figure Description

[0021] Figure 1 The diagram shown is a schematic of the axial flow fan of the present invention;

[0022] Figure 2 The diagram shown is a schematic of the impeller of the present invention;

[0023] Figure 3 The diagram shown is a schematic of the blade suction surface of the present invention;

[0024] Figure 4 The diagram shown is a schematic of the blade pressure surface of the present invention;

[0025] Figure 5 The diagram shown is of an existing impeller;

[0026] Figure 6 The diagram shows the tip chord length and center thickness of the blades in an existing impeller.

[0027] Reference numerals: 1-Impeller, 2-Collector, 3-Convex structure, 11-Hub, 12-Blade, 121-Suction surface, 122-Pressure surface, 123-Leading edge, 124-Leading edge. Detailed Implementation

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0029] like Figure 1-4 As shown, the present invention proposes an impeller 1 with a noise reduction structure in the blade tip region, including a hub 11 and blades 12, with multiple blades 12 evenly arranged on the hub 11;

[0030] A convex structure 3 is provided at the tip region of the suction surface 121 of the blade 12. The convex structure 3 of the suction surface 121 is smoothly transitioned to the suction surface 121. The convex structure 3 of the suction surface 121 extends from the leading edge 123 region of the suction surface 121 to the trailing edge 124 region of the suction surface 121.

[0031] The tip region of the pressure surface 122 of the blade 12 is also provided with a convex structure 3. The convex structure 3 of the pressure surface 122 is smoothly transitioned to the pressure surface 122. The convex structure 3 of the pressure surface extends from the leading edge 123 region of the pressure surface 122 to the trailing edge 124 region of the pressure surface 122.

[0032] like Figure 2-5 As shown, in this invention, the convex structure 3 is integrally formed with the blade 12, making it easy to manufacture. The convex structure 3 on the blade 12 gives the overall thickness of the blade 12 a unique variation trend, which is different from the conventional design of thickening the leading edge 123 of the blade 12, and also different from the existing design of opening guide grooves at the blade tip. In this invention, the convex structure 3 located in the suction surface 121 is elongated and located only in the blade tip area, without affecting the rest of the suction surface 121. The maximum air intake of the impeller 1 is not affected, with an error of approximately ±0.4%. Similarly, the convex structure 3 located in the pressure surface 122 is also elongated and has no effect on the air outlet of the impeller 1. The convex structure 3 located in the blade tip area of ​​the suction surface 121 and the pressure surface 122 increases the wind resistance between the blade 12 and the collector 2, which has the effect of disrupting the blade tip vortex, thereby reducing the blade tip noise.

[0033] In this invention, the smooth transition between the convex structure 3 and the suction surface 121 / pressure surface 122 refers to the smooth transition at the connection between the convex structure 3 and the suction surface 121 / pressure surface 122.

[0034] Furthermore, within the suction surface 121 / pressure surface 122, the convex structure 3 has the smallest width / thickness at both ends and the largest width / thickness in the middle. The width and thickness of the convex structure 3 gradually increase from the ends to the middle, with the ends of the convex structure 3 being pointed. That is, the convex structure 3 of the suction surface 121 has a shape with protruding and pointed ends and a large convex middle portion, ensuring a good flow field at the blade tip of the suction surface 121.

[0035] Furthermore, within the suction surface 121, there is a gap between one end of the convex structure 3 and the edge of the leading edge 123 on the same side, and the other end of the convex structure 3 extends to the edge of the trailing edge 124 on the same side. The gap between the convex structure 3 and the leading edge 123 means that air, after being cut by the leading edge 123 region of the suction surface 121 of the blade 12, encounters the convex structure 3 again, thus increasing the wind resistance at the blade tip region on the suction surface 121. The absence of a gap between the convex structure 3 and the trailing edge 124, along with the streamlined design of the convex structure 3, avoids turbulent airflow between the convex structure 3 and the trailing edge 124, which helps reduce the negative impact of the convex structure 3 on the intake air volume and increases the wind resistance at the blade tip region of the suction surface 121.

[0036] Furthermore, within the suction surface 121, there is a gap between the convex structure 3 and the tip edge of the blade 12, and the gap between the convex structure 3 and the tip edge gradually increases from the leading edge 123 to the trailing edge 124. The convex structure 3 of this invention does not completely cover the tip region of the suction surface 121. The placement of the convex structure 3 on the suction surface 121 increases the wind resistance of the suction surface 121 in the tip region while maintaining the maximum air intake volume, thereby reducing noise.

[0037] Furthermore, within the pressure surface 122, the convex structure 3 extends from the edge of the leading edge 123 to the edge of the trailing edge 124, meaning there are no gaps between the convex structure 3 of the pressure surface 122 and the leading and trailing edges 123 and 124. The pressure surface 122 directly bears the kinetic energy of the gas. The absence of gaps between the convex structure 3 and the edge of the leading edge 123, combined with the streamlined design of the convex structure 3, increases wind resistance at the blade tip region of the pressure surface 122 when it comes into contact with air, thus limiting the formation of vortices.

[0038] Furthermore, within the pressure surface 122, there is a gap between the convex structure 3 and the blade tip edge, and the gap between the convex structure 3 and the blade tip edge gradually decreases from the leading edge 123 to the trailing edge 124.

[0039] In this invention, preferably, the tip chord length of blade 12 is L, and the maximum protrusion position of the convex structure 3 of the suction surface 121 / pressure surface 122 is located at the center of the tip chord, i.e., 0.5L. (Reference: Tip chord length of blade 12) Figure 6

[0040] In this invention, preferably, the sum of the maximum thicknesses of the convex structures on both sides of the blade 12 accounts for one-third of the maximum thickness at the center of the blade tip chord. For example... Figure 6 As shown, the thickness at the center of the chord at the tip of the blade without the convex structure 3 is H. After adding the two convex structures 3, the maximum thickness at the center of the chord at the tip of the blade, i.e., the maximum thickness at the center of the chord at the tip of the blade of this invention, is 1.5H.

[0041] The convex structure 3 with the above-mentioned features of the present invention achieves noise reduction without affecting the performance of the fan. Preferably, the convex structure 3 can be formed based on the following three-dimensional outer contour function, Z = -0.00957X. 2 -0.34X-0.05475Y 2 -9.88Y-457.59, this three-dimensional outer contour function is established in a Cartesian coordinate system with the center of hub 11 as the origin. X / Y / Z represent the coordinate points respectively; this convex structure can delay the vortex splitting at the leading edge and weaken the vortex structure morphology at the trailing edge.

[0042] The axial flow fan formed based on the blade 12 structure of the present invention maintains its performance without degrading while disrupting the vortex between the blade 12 and the collector 2, thereby reducing blade tip noise. Compared with existing similar fans, the present invention can reduce noise by 1-2 dB.

[0043] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An impeller with a noise reduction structure in the blade tip region, characterized in that, It includes a hub (11) and blades (12), with multiple blades (12) evenly arranged on the hub (11); A convex structure (3) is provided at the tip region of the suction surface (121) of the blade (12). The convex structure (3) of the suction surface (121) is smoothly transitioned to the suction surface (121). The convex structure (3) of the suction surface (121) extends from the leading edge (123) region of the suction surface (121) to the trailing edge (124) region of the suction surface (121). A convex structure (3) is also provided at the tip region of the pressure surface (122) of the blade (12). The convex structure (3) of the pressure surface (122) is smoothly transitioned to the pressure surface (122). The convex structure (3) of the pressure surface (122) extends from the leading edge (123) region of the pressure surface (122) to the trailing edge (124) region of the pressure surface (122). Among them, within the suction surface (121) or pressure surface (122), the width and thickness of the two ends of the convex structure (3) are the smallest, while the width and thickness in the middle are the largest. The width and thickness of the convex structure (3) gradually increase from the end to the middle, and the end of the convex structure (3) is the tip. Within the suction surface (121), there is a gap between one end of the convex structure (3) and the edge of the front edge (123) on the same side, and the other end of the convex structure (3) extends to the edge of the rear edge (124) on the same side; Within the suction surface (121), there is a gap between the convex structure (3) and the blade tip edge of the blade (12), and the gap between the convex structure (3) and the blade tip edge gradually increases from the leading edge (123) to the trailing edge (124). Within the pressure surface (122), the convex structure (3) extends from the edge of the leading edge (123) to the edge of the trailing edge (124); Within the pressure surface (122), there is a gap between the convex structure (3) and the blade tip edge, and the gap between the convex structure (3) and the blade tip edge gradually decreases from the leading edge (123) to the trailing edge (124).

2. The impeller with a noise reduction structure at the blade tip region as described in claim 1, characterized in that, The blade (12) has a tip chord length of L, and the maximum protrusion position of the convex structure (3) of the suction surface (121) / pressure surface (122) is located at the center of the tip chord 0.5L.

3. The impeller with a noise reduction structure at the blade tip region as described in claim 2, characterized in that, The sum of the maximum thickness of the convex structure (3) on both sides of the blade (12) accounts for one-third of the maximum thickness of the blade tip chord center.

4. The impeller with a noise reduction structure at the blade tip region as described in claim 1, characterized in that, The convex structure (3) is formed based on the following three-dimensional outer contour function: Z=-0.00957X 2 -0.34X-0.05475Y 2 -9.88Y-457 .59; The three-dimensional outer contour function is established in a rectangular coordinate system with the center of the hub (11) as the origin.

5. An axial flow fan, comprising a collector (2), characterized in that, It also includes the impeller (1) as described in any one of claims 1-4, wherein the impeller (1) is disposed within the collector (2).

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