A noise reduction structure of a tip trailing edge of an axial flow fan blade

Abstract

The application discloses a kind of tail edge noise reduction structure of axial flow fan blade, including fan main body, fan blade and tail edge noise reduction structure.The tail edge noise reduction structure is located at the tail edge of the blade tip of fan blade, and bottom is flush with the leeward surface of fan blade tail edge, and extend along the edge of blade tip direction.Where tail edge noise reduction structure front end portion main body and fan blade are an entirety, rear end portion main body is suspended outside fan blade trailing edge, airflow can flow through the inner cavity of tail edge noise reduction structure from front to back;The fan rotates, and the fan blade rotates extrusion cutting airflow, produces a certain rotating noise, in the process of fan blade rotation, tail edge noise reduction structure can guide fan blade blade tip wake, suppress blade tip separation vortex flow, reduce the aerodynamic loss of axial flow fan blade tip, while reducing blade tip vortex gap noise.

Description

Technical Field

[0001] This invention patent belongs to the field of turbomachinery design technology, specifically relating to a noise reduction structure for the tip and trailing edge of an axial flow fan blade. Technical Background

[0002] Axial flow fans propel gas along the axial direction through a rotating impeller and are widely used in industry, mining, chemical, construction, shipbuilding, and high-speed rail equipment for ventilation and cooling. A portion of the noise from axial flow fans comes from the fan's own rotation, primarily the rotational noise generated by the fan cutting through the airflow. Additionally, large axial flow fans typically have a shroud added to the outside of the fan to minimize airflow losses during operation, resulting in additional gap aerodynamic noise from the interaction between the fan blade tip vortices and the shroud's inner wall. Most axial flow fan blade modification noise reduction measures focus more on the rotational noise generated by the fan's own rotation cutting through the airflow, paying less attention to the gap noise generated by the airflow impacting the shroud, such as the commonly used serrated blade trailing edge structure. This invention patent adds a trailing edge noise reduction structure to the tip of the fan blades, reducing aerodynamic losses at the blade tip and weakening the tip vortex intensity, achieving noise reduction without reducing the fan's static pressure efficiency. This invention patent's trailing edge noise reduction structure provides a new modification technique for improving the efficiency and reducing noise of impeller blade mechanical devices. Summary of the Invention

[0003] The purpose of this invention is to provide a noise reduction structure for the tip trailing edge of an axial fan blade, which achieves the noise reduction target of the axial fan by suppressing the tip vortex and reducing the gap noise under the action of the shroud.

[0004] To achieve the above objectives, the following solution is provided: a blade tip trailing edge noise reduction structure for an axial fan blade, comprising a fan body 1, a fan blade 2, and a trailing edge noise reduction structure 3, characterized in that: the trailing edge noise reduction structure 3 is located on the windward side of the blade tip trailing edge of the fan blade 2, and is integral with the fan blade 2.

[0005] The trailing edge noise reduction structure 3 is funnel-shaped, and the front end 4 part is an integral part of the fan blade 2, while the rear end 5 part is suspended outside the trailing edge of the fan blade 2. In addition, the inner guide line 10 and the outer guide line 11 extend along the edge of the blade tip.

[0006] The trailing edge noise reduction structure 3 has semi-circular arc-shaped front and rear ends, and the arc surfaces of the front and rear ends gradually decrease from front to back, with the inner arc surface portion extending beyond the trailing edge of the airfoil being removed.

[0007] The trailing edge noise reduction structure 3 has a front end width w = 1%–3%d, where d is the diameter of the fan blade 2; an overall length s = 7%–14%c; an inner structure width L = 3%–6%c, where c is the tip chord length of the fan blade 2; the thicknesses of the inner wall 7 and outer wall 6 of the trailing edge noise reduction structure 3 are t = 15%–20%h, where h is the thickness of the airfoil at the tip of the fan blade 2; the front end 4 has a cross-sectional radius r1 = 6–10mm, the rear end 5 has a cross-sectional radius r2 = 4–8mm, and the corner radius r at the leading and trailing edges of the structure surface is... 3 =1mm. The bottom of the trailing edge noise reduction structure 3 is flush with the leeward side, and the bottom thickness t is consistent with the trailing edge thickness t of the fan blade.

[0008] Compared with existing technologies, the beneficial effects of this invention patent are:

[0009] (1) The trailing edge noise reduction structure in this invention patent can reduce the overall noise of the fan without reducing or even improving the aerodynamic performance of the fan. The trailing edge noise reduction structure is mainly located at the trailing edge of the blade tip, which can effectively guide the blade tip wake, suppress separation vortex, reduce aerodynamic losses due to blade tip leakage, and thus improve aerodynamic efficiency; at the same time, by weakening the impact disturbance between the blade tip vortex and the inner wall of the wind shield and the downstream blades, the goal of reducing blade tip clearance noise is achieved.

[0010] (2) The present invention has a simple structure, simple preparation process, simple installation method, and great application potential. Attached Figure Description

[0011] Figure 1 This is an isometric view of the fan body.

[0012] Figure 2 This is an isometric view of a single fan blade.

[0013] Figure 3 This is an isometric view of the trailing edge noise reduction structure.

[0014] Figure 4 This is a magnified view of a portion of the trailing edge noise reduction structure.

[0015] Figure 5 This is a schematic diagram of the airfoil section at the blade tip.

[0016] Figure 6 This is a schematic diagram of the main structure of the trailing edge noise reduction structure.

[0017] Figure 7 This is a top view schematic diagram of the trailing edge noise reduction structure.

[0018] Figure 8 This is a schematic diagram of the trailing edge noise reduction structure viewed from below.

[0019] Figure 9 This is a schematic diagram of the left-side structure of the trailing edge noise reduction structure.

[0020] Figure 10 This is a schematic diagram of the trailing edge noise reduction structure from the right side.

[0021] Figure label:

[0022] 1. Fan body; 2. Fan blades; 3. Trailing edge noise reduction structure; 4. Front end; 5. Rear end; 6. Outer wall surface; 7. Inner wall surface; 8. Bottom surface; 9. Through hole; 10. Inner guide line; 11. Outer guide line; s, length; t, thickness; w, width; d, fan blade diameter; c, blade tip chord length; h, blade tip thickness; r1, front end radius; r2, rear end radius; r 3 1. Fillet radius; L. Width of the inner structure. Detailed Implementation

[0023] The technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0024] Please see Figure 1-9 This invention patent provides a technical solution: a noise reduction structure for the tip and trailing edge of an axial fan blade, comprising a fan body 1, a fan blade 2, a trailing edge noise reduction structure 3, a front end 4, a rear end 5, an outer wall surface 6, an inner wall surface 7, a bottom surface 8, a through hole 9, an inner guide line 10, an outer guide line 11, a length s, a thickness t, a width w, a fan blade diameter d, a tip chord length c, a tip thickness h, a front end radius r1, a rear end radius r2, and a rounded corner radius r. 3 The width L of the inner structure. For example... Figure 2 As shown, the trailing edge noise reduction structure 3 is located on the windward side of the tip of the fan blade 2 and is an integral part of the fan blade 2.

[0025] like Figure 2 As shown, the trailing edge noise reduction structure 3 is funnel-shaped, and the main body of the front end 4 is integrated with the fan blade 2, while the main body of the rear end 5 is suspended outside the trailing edge of the fan blade 2. In addition, the inner guide line 10 and the outer guide line 11 extend along the edge of the blade tip.

[0026] like Figure 3 As shown, the trailing edge noise reduction structure 3 has a semi-circular arc shape at the front and rear ends, and the arc surface of the front and rear ends gradually decreases from front to back. The inner arc surface part of the part that exceeds the trailing edge of the airfoil is removed.

[0027] The trailing edge noise reduction structure 3 has a front end width w = 1%–3%d, where d is the diameter of the fan blade 2; an overall length s = 7%–14%c; an inner structure width L = 3%–6%c, where c is the tip chord length of the fan blade 2; the thicknesses of the inner wall 7 and outer wall 6 of the trailing edge noise reduction structure 3 are t = 15%–20%h, where h is the thickness of the airfoil at the tip of the fan blade 2; the front end 4 has a section radius r1 = 6–10mm, the rear end 5 has a section radius r2 = 4–8mm, and the corner radius r at the leading and trailing edges of the structure is... 3 =1mm. The bottom of the trailing edge noise reduction structure 3 is flush with the leeward side, and the bottom thickness t is the same as the trailing edge thickness t of the fan blade.

[0028] Specific Implementation Case 1

[0029] The noise reduction structure at the tip and trailing edge of this invention is specifically implemented on the blades of an axial flow fan. Aerodynamic performance tests conducted on a dedicated fan test bench show that, under mass flow rates of 10.35 kg / s, 8.76 kg / s, and 7.45 kg / s, the static pressure efficiency of the axial flow fan is increased by 0.95% to 1.21%, and the noise is reduced by 1.62 to 1.83 dB. According to the national standard GB / T2888-2008, "Methods for Noise Measurement of Fans and Roots Blowers", acoustic testing equipment shows that the total sound pressure level can be reduced by up to 1.95 dB.

[0030] Specific Implementation Case 2

[0031] The noise reduction structure at the blade tip and trailing edge of this invention is specifically implemented on the blades of an air conditioner fan. Aerodynamic performance tests conducted on a dedicated fan test bench show that, under speeds of 600 r / min, 720 r / min, and 840 r / min, the static pressure efficiency of the air conditioner fan is increased by 1.01% to 1.32%, and the noise is reduced by 1.63 to 2.32 dB. According to the national standard GB / T2888-2008, "Methods for Noise Measurement of Fans and Roots Blowers", acoustic testing equipment shows that the total sound pressure level can be reduced by up to 2.43 dB.

[0032] Specific Implementation Case 2

[0033] The noise reduction structure at the blade tip and trailing edge of this invention is specifically implemented on the blades of a ventilation fan. Aerodynamic performance tests conducted on a dedicated fan test bench show that, under speeds of 2400 r / min, 3000 r / min, and 3600 r / min, the static pressure efficiency of the ventilation fan is increased by 1.15% to 1.32%, and the noise is reduced by 2.35 to 3.02 dB. According to the national standard GB / T2888-2008, "Methods for Noise Measurement of Fans and Roots Blowers", acoustic testing equipment shows that the total sound pressure level can be reduced by up to 3.53 dB.

Claims

1. A tip shroud noise reduction structure of an axial fan blade, comprising a fan body (1), a fan blade (2), and a shroud noise reduction structure (3), characterized in that: The trailing edge noise reduction structure (3) is located on the windward side of the tip of the fan blade (2), and is funnel-shaped, forming a whole with the fan blade (2); its front end (4) is connected to the fan blade (2), and its rear end (5) is suspended outside the trailing edge of the fan blade (2), and the inner guide line (10) and the outer guide line (11) extend along the edge of the tip; the front and rear ends of the trailing edge noise reduction structure (3) are semi-circular arcs, and the arc surfaces of the front and rear ends gradually decrease from front to back, and the inner arc surface portion exceeding the trailing edge of the airfoil is removed; the width of the front end (4) of the trailing edge noise reduction structure (3) is w=1%~3%d, where d is the diameter of the fan blade (2); The overall length s = 7%~14%c, the inner structural width L = 3%~6%c, where c is the tip chord length of the fan blade (2); the thickness t of the inner wall (7) and outer wall (6) of the trailing edge noise reduction structure (3) is 15%~20%h, where h is the thickness of the airfoil at the tip of the fan blade (2); the front end (4) cross-sectional radius r1 = 6~10mm, the rear end (5) cross-sectional radius r2 = 4~8mm, and the radius of the rounded corners at the front and rear edges of the structural surface r3 = 1mm; the bottom of the trailing edge noise reduction structure (3) is flush with the leeward side, and the bottom thickness t is consistent with the trailing edge thickness t of the fan blade.

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