A method for reducing aerodynamic noise of axial flow compressor

Abstract

A method for reducing the aerodynamic noise of an axial flow compressor comprises the following steps: optimizing the casing structure, designing the casing as a double-layer hollow structure, and forming an arc-shaped cavity through the hollow layer between the outer wall plate and the inner wall plate of the casing; optimizing the inner wall plate of the casing, designing the inner wall plate of the casing as a hollow structure, and using the hollow holes on the inner wall plate of the casing as a silencer channel. The present invention utilizes the flow phenomenon at the gap between the rotor blade tip and the casing of the compressor, optimizes the casing structure, adopts a double-layer hollow structure as a whole to form an arc-shaped cavity, and at the same time, adopts a hollow structure to form a silencer channel through the inner wall plate of the casing. The pressure pulsation energy of the noise sound wave generated during the mainstream flow can be converted into heat energy and dissipated through the silencer channel, thereby achieving primary noise reduction, and limiting the noise sound wave to propagate inside the arc-shaped cavity, thereby achieving secondary noise reduction, and finally reducing the aerodynamic noise radiated to the outside by the axial flow compressor.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flow compressors, and in particular relates to a method for reducing aerodynamic noise of an axial flow compressor. Background Art

[0002] The noise pollution issue is one of the key focuses in the aviation field. The noise generated by civil airliners during flight will have adverse effects on the environment around routes and airports. Therefore, the noise requirements for civil airliners during flight are becoming more and more stringent, resulting in higher and higher standards for aircraft noise airworthiness certification.

[0003] Among the noises generated by civil airliners during flight, engine noise is particularly important, and compressor noise is an important component of engine noise, especially for high-load axial flow compressors, which have strong noise and the flow phenomenon at the gap between the compressor's rotor blade tips and the casing is also relatively complex, which is one of the main sources of engine noise. However, there is currently a lack of noise reduction solutions for this area, which limits the further noise reduction of axial flow compressors. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for reducing the aerodynamic noise of an axial flow compressor. The method utilizes the flow phenomenon at the gap between the rotor blade tip and the casing of the compressor, optimizes the design of the casing structure, and adopts a double-layer hollow structure as a whole to form an arc-shaped cavity. At the same time, the inner wall panel of the casing adopts a hollow structure to form a silencer channel. The pressure pulsation energy of the noise sound waves generated during the mainstream flow can be converted into heat energy and dissipated through the silencer channel, thereby achieving primary noise reduction. The noise sound waves are limited to propagate inside the arc-shaped cavity, thereby achieving secondary noise reduction, and finally reducing the aerodynamic noise radiated to the outside by the axial flow compressor.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A method for reducing the aerodynamic noise of an axial flow compressor comprises the following steps:

[0006] Step 1: Optimize the structure of the casing, design the casing as a double-layer hollow structure, and form an arc-shaped cavity in the hollow layer between the outer wall plate and the inner wall plate of the casing;

[0007] Step 2: Optimize the inner wall panels of the receiver and design the inner wall panels of the receiver into a hollow structure. The hollow holes on the inner wall panels of the receiver serve as silencer channels.

[0008] The casing as a whole adopts a spliced ​​structure, and the casing as a whole is formed by splicing a plurality of casing unit bodies along the circumferential direction, and the arc-shaped cavities between adjacent casing unit bodies are connected to each other.

[0009] The axial length of the arc-shaped cavity is 1 to 1.5 times the chord length of the blade, the radial height of the arc-shaped cavity is 3 to 5 mm, and the arc-shaped cavity is located at 0% to 20% of the chord length in front of the leading edge of the blade.

[0010] The shape of the silencer channel is a Tesla valve shape, including a long straight channel section, a circular arc channel section and a short channel section; the extension direction of the long straight channel section is parallel to the chord direction of the blade; the number of the circular arc channel section is at least one, one end of the circular arc channel section is tangentially connected to the long straight channel section, and the other end of the circular arc channel section is tangentially connected to the short channel section.

[0011] The extended length of the long straight channel section is 0.6 to 1 times of the blade chord length.

[0012] When there are two circular arc channel segments, the stretching length from the tangent point of the first circular arc channel segment to the long straight channel segment to the starting point of the long straight channel segment is 0.2 to 0.5 times the blade chord length.

[0013] The center of the circular arc channel section is located at 0% to 20% of the chord length and 60% to 80% of the chord length of the blade.

[0014] The arc outer diameter of the arc channel section is 3 to 5 mm.

[0015] The long straight channel section and the arc channel section are gaps of equal width, and the width of the gap is 1 to 2 mm.

[0016] The short channel section is in a pointed shape, the included angle of the pointed corner of the short channel section is 10° to 30°, and the maximum width of the short channel section is equal to the gap width of the long straight channel section and the arc channel section.

[0017] Beneficial effects of the present invention:

[0018] The method for reducing the aerodynamic noise of an axial flow compressor of the present invention utilizes the flow phenomenon at the gap between the rotor blade tip and the casing of the compressor, optimizes the design of the casing structure, and adopts a double-layer hollow structure as a whole to form an arc-shaped cavity. At the same time, the inner wall panel of the casing adopts a hollow structure to form a silencer channel. The pressure pulsation energy of the noise sound waves generated during the mainstream flow can be converted into heat energy and dissipated through the silencer channel, thereby achieving primary noise reduction. The noise sound waves are restricted from propagating inside the arc-shaped cavity, thereby achieving secondary noise reduction, and finally reducing the aerodynamic noise radiated to the outside by the axial flow compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the position relationship diagram of the optimized casing unit and blades;

[0020] Figure 2 for Figure 1 Enlarged view of middle part I;

[0021] Figure 3 Schematic diagram of the flow field when the mainstream flows through the optimized casing unit silencer channel.

[0022] In the figure, 1 is an outer wall panel, 2 is an inner wall panel, 3 is an arc cavity, 4 is a silencer channel, 4.1 is a long straight channel section, 4.2 is an arc channel section, 4.3 is a short channel section, 5 is a casing unit, 6 is a blade, and 7 is a mainstream. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] A method for reducing aerodynamic noise of an axial flow compressor comprises the following steps:

[0025] Step 1: If Figure 1 , 2 As shown, the casing structure is optimized, and the casing is designed as a double-layer hollow structure as a whole, and the hollow layer between the outer wall plate 1 and the inner wall plate 2 of the casing forms an arc-shaped cavity 3;

[0026] Step 2: Optimize the inner wall panel 2 of the receiver, design the inner wall panel 2 of the receiver into a hollow structure, and use the hollow holes on the inner wall panel 2 of the receiver as the silencer channel 4. The thickness of the inner wall panel 2 of the receiver is 2.5 mm.

[0027] The casing as a whole adopts a spliced ​​structure. The casing as a whole is formed by splicing a plurality of casing unit bodies 5 along the circumferential direction. The arc-shaped cavities 3 between adjacent casing unit bodies 5 are connected to each other.

[0028] The axial length of the arc-shaped cavity 3 is 42.5 mm, the radial height of the arc-shaped cavity 3 is 5 mm, and the arc-shaped cavity 3 is located at 20% of the chord length in front of the leading edge of the blade 6 .

[0029] The shape of the silencer channel 4 is a Tesla valve shape, including a long straight channel section 4.1, an arc channel section 4.2 and a short channel section 4.3; the extension direction of the long straight channel section 4.1 is parallel to the chord direction of the blade 6; there are two arc channel sections 4.2, one end of the arc channel section 4.2 is tangentially connected to the long straight channel section 4.1, and the other end of the arc channel section 4.2 is tangentially connected to the short channel section 4.3.

[0030] The long straight channel section 4.1 has an extended length of 30 mm.

[0031] When there are two circular arc channel segments 4.2, the stretching length from the tangent point of the first circular arc channel segment 4.2 and the long straight channel segment 4.1 to the starting point of the long straight channel segment 4.1 is 8 mm.

[0032] The center of the circular arc channel section 4 . 2 is located at 20% and 60% of the chord length of the blade 6 .

[0033] The arc outer diameter of the arc channel section 4.2 is 5 mm.

[0034] The long straight channel section 4.1 and the arc channel section 4.2 are gaps of equal width, and the width of the gap is 1 mm.

[0035] The short channel section 4.3 is in a pointed shape, the included angle of the pointed corner of the short channel section 4.3 is 20°, and the maximum width of the short channel section 4.3 is 1 mm.

[0036] The working principle of the present invention is described below in conjunction with the accompanying drawings:

[0037] When the mainstream 7 passes through the casing, it will first enter the silencer channel 4 and flow along the long straight channel section 4.1, and then flow to the intersection of the arc channel section 4.2 and the long straight channel section 4.1. A part of the mainstream 7 will flow into the arc channel section 4.2, and the other part of the mainstream 7 will continue to flow along the long straight channel section 4.1 until it flows to the next arc channel section 4.2.

[0038] like Figure 3 As shown, after the mainstream 7 flows into the arc channel section 4.2, the flow direction is changed, and when the mainstream 7 flows into the short channel section 4.3, its flow direction is completely opposite to the flow direction of the mainstream 7 in the long straight channel section 4.1, and the sharp angle shape of the short channel section 4.3 hinders the flow. At the same time, the fluid in the short channel section 4.3 is mixed with the mainstream 7 outside the silencer channel 4, thereby generating a large flow loss, which reduces the tip leakage vortex intensity of the blade 6. The direct effect is to reduce the sound wave energy through the flow loss, convert the pressure pulsation energy into heat energy, and dissipate it in the form of heat energy, thereby achieving the purpose of reducing the aerodynamic noise.

[0039] After the mainstream 7 passes through the silencer channel 4 for primary noise reduction, and then enters the arc-shaped cavity 3 through the silencer channel 4, the sound waves are restricted to propagate in the arc-shaped cavity 3, thereby achieving secondary noise reduction, and ultimately reducing the aerodynamic noise radiated outward by the axial flow compressor.

[0040] The solutions in the embodiments are not intended to limit the patent protection scope of the present invention. All equivalent implementations or changes that do not deviate from the present invention are included in the patent scope of this case.

Claims

1. A method for reducing aerodynamic noise of an axial flow compressor, characterized in that The steps include: Step 1: Optimize the casing structure, design the casing as a double-layer hollow structure, and form an arc-shaped cavity in the hollow layer between the outer wall plate and the inner wall plate of the casing; the casing as a whole adopts a spliced ​​structure, and the casing as a whole is spliced ​​by a plurality of casing unit bodies along the circumferential direction, and the arc-shaped cavities between adjacent casing unit bodies are connected to each other; the axial length of the arc-shaped cavity is 1 to 1.5 times the chord length of the blade, the radial height of the arc-shaped cavity is 3 to 5 mm, and the arc-shaped cavity is located at 0% to 20% of the chord length in front of the leading edge of the blade; Step 2: Optimize the inner wall of the casing, design the inner wall of the casing into a hollow structure, and use the hollow holes on the inner wall of the casing as silencer channels; the silencer channel is in the shape of a Tesla valve, including a long straight channel section, an arc channel section and a short channel section; the extension direction of the long straight channel section is parallel to the chord direction of the blade; the number of the arc channel section is at least one, one end of the arc channel section is tangentially connected to the long straight channel section, and the other end of the arc channel section is tangentially connected to the short channel section; the extension length of the long straight channel section is 0.6 to 1 times the chord length of the blade; when the number of the arc channel sections is two When the length of the first circular arc channel section from the tangent point of the long straight channel section to the starting point of the long straight channel section is 0.2 to 0.5 times the chord length of the blade; the center of the circular arc channel section is located at 0% to 20% of the chord length and 60% to 80% of the chord length of the blade; the outer diameter of the circular arc channel section is 3 to 5 mm; the long straight channel section and the circular arc channel section are equal-width gaps, and the width of the gap is 1 to 2 mm; the short channel section is a pointed shape, and the pointed angle of the short channel section is 10° to 30°, and the maximum width of the short channel section is equal to the gap width of the long straight channel section and the circular arc channel section.

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