A double-wall force-added anti-vibration screen with bidirectional oscillation suppression

Abstract

The present application belongs to the field of aircraft engine design, and is a double-wall afterburner anti-vibration screen for bidirectional oscillation suppression, comprising a coaxially arranged afterburner combustion chamber casing, an outer anti-vibration screen and an inner anti-vibration screen; when the afterburner combustion chamber is working, circumferential propagation pulsation and radial propagation pulsation are simultaneously generated in the afterburner combustion chamber, and the circumferential propagation pulsation can enter the wave-shaped vibration absorption cavity through the vibration absorption holes on the inner anti-vibration screen, and the pulsation energy will gradually be consumed and absorbed, thereby weakening the influence of the circumferential propagation pulsation, suppressing mechanical resonance at the same frequency, and effectively avoiding the occurrence of afterburner oscillation combustion; the radially propagating pulsation also enters the wave-shaped vibration absorption cavity through the vibration absorption holes on the inner anti-vibration screen, and the pulsation energy enters the wave-shaped vibration absorption cavity and is consumed and absorbed, thereby weakening the influence of the radial propagation pulsation, and effectively avoiding the occurrence of afterburner oscillation combustion; in this way, the afterburner anti-vibration screen can simultaneously suppress vibrations in both circumferential and radial directions, and the vibration absorption quality is effectively improved.

Description

Technical Field

[0001] The present application belongs to the field of aero-engine design, and in particular relates to a double-wall afterburner anti-vibration screen for bidirectional oscillation suppression. Background Art

[0002] The afterburner is an important component of military aircraft engines. It can increase engine thrust in a short period of time and improve the acceleration and maneuverability of the aircraft. As a low-pressure component for ignition and combustion organization of aircraft engines, the afterburner is prone to combustion pulsation during the combustion process. In severe cases, it will develop into oscillating combustion, which will endanger the hardware structure. Its generation is related to the coupling of the inherent sound field mode of the afterburner itself and the heat release of the afterburner, and its mechanism is relatively complex. In order to reduce the impact of afterburner pulsation, an anti-vibration screen is usually set in the afterburner. Through its porous thin-walled structure, it forms a combination structure similar to the Helmholtz vibration absorption cavity with the casing to absorb the pulsation.

[0003] With the development of afterburner combustion chambers of aircraft engines, their structural changes have brought about changes including inherent acoustic field modes, fuel atomization, oil droplet evaporation, ignition combustion, turbulent mixing, flame stabilizer vortex shedding, etc., which will cause afterburner combustion to produce combustion pulsations of different modes, increasing the risk of use. At the same time, with the continuous increase in the heat load of the afterburner combustion chamber, the requirements for the amount of cooling air flowing through the anti-vibration screen are becoming more and more stringent.

[0004] Traditional aircraft engine afterburner anti-vibration screens are mostly single-layer porous thin-walled structures with corrugations. Their structural characteristics determine that they have a good suppression effect on pulsation in a specific propagation direction, but the pulsation suppression effect in other propagation directions is not obvious, and they can no longer meet the needs of advanced aircraft engine afterburner pulsation absorption. In addition, the single-wall heat insulation screen must increase the opening rate to absorb high-frequency pulsation energy. Therefore, even under low external-to-internal pressure ratio conditions, the external cooling air will flow in through the anti-vibration screen holes in large quantities, while the amount of cooling air flowing to the rear heat insulation screen will be reduced accordingly, resulting in an increased risk of ablation of the afterburner and nozzle. Summary of the invention

[0005] The purpose of the present application is to provide a double-wall force-added anti-vibration screen with bidirectional oscillation suppression to solve the problem that the prior art can only suppress pulsation in a certain characteristic propagation direction.

[0006] The technical solution of the present application is: a double-wall afterburner vibration-proof screen with bidirectional oscillation suppression, comprising a coaxially arranged afterburner combustion chamber casing, an outer vibration-proof screen and an inner vibration-proof screen; the outer vibration-proof screen is arranged between the inner vibration-proof screen and the combustion chamber casing, an outer cooling channel is formed between the outer vibration-proof screen and the afterburner combustion chamber casing, and the inner side of the inner vibration-proof screen is a high-temperature inner channel; vibration-absorbing holes are provided on the outer vibration-proof screen and the inner vibration-proof screen, and the outer vibration-proof screen and the inner vibration-proof screen are both arranged as wavy circular ring structures along the circumferential direction, there is a gap between the outer vibration-proof screen and the inner vibration-proof screen and a wavy vibration-absorbing cavity is formed between the two; an vibration-proof screen bracket is connected between the outer vibration-proof screen and the afterburner combustion chamber casing, and an vibration-proof screen support ring is connected between the outer vibration-proof screen and the inner vibration-proof screen.

[0007] Preferably, the outer layer anti-vibration screen and the inner layer anti-vibration screen both comprise arc-shaped concave sections and arc-shaped convex sections, and there are multiple groups of the arc-shaped concave sections and arc-shaped convex sections, and the multiple groups of arc-shaped concave sections and arc-shaped convex sections are staggered, and there are smooth arc transitions between the arc-shaped concave sections and adjacent arc-shaped convex sections.

[0008] Preferably, the anti-vibration screen bracket is arranged at the front end and the rear end of the outer anti-vibration screen, and the anti-vibration screen bracket is arranged in multiple groups along the circumferential interval of the outer anti-vibration screen; the anti-vibration screen bracket includes a trapezoidal portion and a connecting portion, the trapezoidal portion is connected between the arc-shaped outer convex section and the afterburner casing, one inner end of the trapezoidal portion is against the arc-shaped outer convex section, there are two groups of connecting portions and the two groups of connecting portions are respectively connected to the two sides of the arc-shaped outer convex section, and the connecting portion is arranged tangent to the side wall surface of the arc-shaped outer convex section.

[0009] Preferably, the vibration absorbing holes on the outer vibration-proof screen are small vibration-absorbing holes, and the vibration absorbing holes on the inner vibration-proof screen are large vibration-absorbing holes, and each of the small vibration-absorbing holes is coaxially arranged corresponding to a large vibration-absorbing hole.

[0010] Preferably, the axial length of the outer vibration-proof screen is greater than the axial length of the inner vibration-proof screen, the vibration-proof screen support ring is arranged at the front end and the rear end of the inner vibration-proof screen, the vibration-proof screen support ring is arranged as a wavy circular ring structure along the circumferential direction, and the vibration-proof screen support ring forms a stepped structure along the axial direction.

[0011] The present application discloses a double-wall afterburner anti-vibration screen for bidirectional oscillation suppression, comprising a coaxially arranged afterburner combustion chamber casing, an outer anti-vibration screen and an inner anti-vibration screen; when the afterburner combustion chamber is working, circumferential propagation pulsation and radial propagation pulsation are simultaneously generated in the afterburner combustion chamber, and the circumferential propagation pulsation can enter the wave-shaped vibration absorption cavity through the vibration absorption holes on the inner anti-vibration screen, and the pulsation energy will gradually be consumed and absorbed, thereby weakening the influence of the circumferential propagation pulsation, suppressing mechanical same-frequency resonance, and effectively avoiding the occurrence of afterburner oscillation combustion; the radially propagating pulsation also enters the wave-shaped vibration absorption cavity through the vibration absorption holes on the inner anti-vibration screen, and the pulsation energy enters the wave-shaped vibration absorption cavity and is consumed and absorbed, thereby weakening the influence of the radial propagation pulsation, effectively avoiding the occurrence of afterburner oscillation combustion; in this way, the afterburner anti-vibration screen can simultaneously suppress vibrations in both circumferential and radial directions, and the vibration absorption quality is effectively improved, and at the same time, there is no need to increase the opening rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0013] Figure 1 This is a schematic diagram of the overall structure of this application;

[0014] Figure 2 This is a schematic diagram of the circumferential pulsation structure of the afterburner chamber of this application;

[0015] Figure 3 This is a schematic diagram of the radial pulsation structure of the afterburner in this application;

[0016] Figure 4 This is a schematic diagram of the cold air flow structure when the engine of this application is working at a state point with a relatively large bypass;

[0017] Figure 5 This is a schematic diagram of the cross-sectional structure of the anti-vibration screen of this application;

[0018] Figure 6 This is a schematic diagram of the cold air flow structure when the engine of this application operates at a state point where the bypass is relatively small.

[0019] 1. Afterburner casing; 2. Outer anti-vibration screen; 3. Inner anti-vibration screen; 4. Anti-vibration screen support ring; 5. Anti-vibration screen bracket; 6. Wave-shaped vibration absorption cavity; 7. Arc-shaped concave section; 8. Arc-shaped convex section; 9. Trapezoidal part; 10. Connecting part; 11. Small vibration absorption hole; 12. Large vibration absorption hole. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0021] A double-walled force-added anti-vibration screen with bidirectional oscillation suppression, such as Figure 1-2 As shown, it includes a coaxially arranged afterburner casing 1, an outer anti-vibration screen 2 and an inner anti-vibration screen 3. The outer anti-vibration screen 2 is arranged between the inner anti-vibration screen 3 and the combustion chamber casing, and an outer culvert cooling channel is formed between the outer anti-vibration screen 2 and the afterburner casing 1 for circulating the outer culvert cooling air, and the inner side of the inner anti-vibration screen 3 is a high-temperature inner channel for circulating the high-temperature combustion gas. At the same time, the outer side of the outer anti-vibration screen 2 is the cold air side, and the inner side of the inner anti-vibration screen 3 is the combustion gas side.

[0022] Vibration absorbing holes are provided on the outer anti-vibration screen 2 and the inner anti-vibration screen 3 for absorbing vibration and transmitting vibration. The outer anti-vibration screen 2 and the inner anti-vibration screen 3 are both arranged as wavy circular ring structures along the circumferential direction. There is a gap between the outer anti-vibration screen 2 and the inner anti-vibration screen 3 and a wavy vibration absorbing cavity 6 is formed therebetween. An anti-vibration screen bracket 5 is connected between the outer anti-vibration screen 2 and the afterburner casing 1, and an anti-vibration screen support ring 4 is connected between the outer anti-vibration screen 2 and the inner anti-vibration screen 3.

[0023] When the afterburner is working, circumferential propagation pulsation and radial propagation pulsation are simultaneously generated in the afterburner. The circumferential propagation pulsation can enter the wavy vibration absorption cavity 6 through the vibration absorption holes on the inner anti-vibration screen 3. According to the Helmholtz vibration absorption principle, since the interior of the wavy vibration absorption cavity 6 is an arc surface with repeatedly changing diameter, the pulsation energy will continuously reflect up and down and collide left and right on the inner wall surface of the wavy vibration absorption cavity 6. In this process, the pulsation energy will gradually be consumed and absorbed, and part of the pulsation energy will enter the outer culvert cooling channel through the vibration absorption holes on the outer anti-vibration screen 2, thereby weakening the influence of the circumferential propagation pulsation, suppressing mechanical same-frequency resonance, and effectively avoiding the occurrence of afterburner oscillation combustion.

[0024] Combination Figure 3 The radially propagating pulsation also enters the wave-shaped vibration absorption cavity 6 through the vibration absorption holes on the inner anti-vibration screen 3. Part of the pulsation energy enters the wave-shaped vibration absorption cavity 6 and is consumed and absorbed, and part of the pulsation energy enters the outer culvert cooling channel through the vibration absorption holes on the outer anti-vibration screen 2, thereby weakening the influence of the radially propagating pulsation and effectively avoiding the occurrence of afterburner shock combustion.

[0025] In this way, the force-added anti-vibration screen can suppress vibrations in both the circumferential and radial directions at the same time, effectively improving the vibration absorption quality without increasing the opening rate.

[0026] Combination Figure 4 For heating the combustion chamber, the vibration-proof screen can be used as part of the cooling system and act as a heat shield. When the engine is working at a state point with a relatively large duct, the pressure on the cold air side is significantly higher than that on the gas side. Due to the pressure difference, sufficient cold air can pass through the vibration-absorbing holes to form a cooling air film on the surface of the vibration-proof screen, thereby reducing the temperature of the vibration-proof screen.

[0027] Preferably, the outer anti-vibration screen 2 and the inner anti-vibration screen 3 both include arc-shaped inward concave sections 7 and arc-shaped outward convex sections 8, and the arc-shaped inward concave sections 7 and arc-shaped outward convex sections 8 both have multiple groups, and the multiple groups of arc-shaped inward concave sections 7 and arc-shaped outward convex sections 8 are arranged alternately, and the arc-shaped inward concave sections 7 and the adjacent arc-shaped outward convex sections 8 are all smoothly transitioned in the form of circular arcs. By arranging the arc-shaped inward concave sections 7 and arc-shaped outward convex sections 8 with smooth transitions, while ensuring the bidirectional oscillation suppression of pulsation, the obstruction to the high-temperature gas is minimized to ensure the smooth flow of the high-temperature gas.

[0028] Preferably, the anti-vibration screen bracket 5 is arranged at the front and rear ends of the outer anti-vibration screen 2, and multiple groups of anti-vibration screen brackets 5 are arranged at circumferential intervals along the outer anti-vibration screen 2; the anti-vibration screen bracket 5 includes a trapezoidal portion 9 and a connecting portion 10, the trapezoidal portion 9 is connected between the arc-shaped outer convex section 8 and the afterburner casing 1, and one inner end of the trapezoidal portion 9 is against the arc-shaped outer convex section 8. There are two groups of connecting portions 10 and the two groups of connecting portions 10 are respectively connected to the two sides of the arc-shaped outer convex section 8, and the connecting portions 10 are arranged tangent to the side wall surface of the arc-shaped outer convex section 8, and the flow of external cooling air is used between adjacent anti-vibration screen brackets 5.

[0029] When the afterburner is working, both the outer anti-vibration screen 2 and the inner anti-vibration screen 3 are heated and thermally deformed. The combined design of the trapezoidal portion 9 and the connecting portion 10 can effectively absorb the thermal deformation and reduce the amount of cold air used when absorbing vibration.

[0030] like Figure 5 As shown, preferably, the vibration absorbing holes on the outer anti-vibration screen 2 are small vibration absorbing holes 11, and the vibration absorbing holes on the inner anti-vibration screen 3 are large vibration absorbing holes 12, and each small vibration absorbing hole 11 is coaxially arranged with a large vibration absorbing hole 12. In this way, the space between the small vibration absorbing holes 11 and the large vibration absorbing holes 12 and the afterburner casing 1 forms a two-layer combined structure similar to the Helmholtz vibration absorbing cavity, thereby performing efficient vibration absorption.

[0031] At the same time, by setting the outer side as small vibration absorption holes 11 and the inner side as large vibration absorption holes 12, the pulsation inside the afterburner will be more likely to stay in the wave-shaped vibration absorption cavity 6 instead of being discharged, so that more pulsation can be consumed and absorbed in the wave-shaped vibration absorption cavity 6.

[0032] Combination Figure 6 When the engine operates at a state point where the duct is relatively small, the outer duct cooling air flow is small, which makes the pressure difference between the cold air side and the gas side of the vibration shield small. According to the flow formula, the smaller aperture of the vibration absorption hole of the outer layer vibration shield 2 ensures a smaller flow coefficient here, which allows more cooling air to flow to the rear hot end components, achieving a better cooling effect and improving the overall cooling efficiency of the afterburner.

[0033] Preferably, the axial length of the outer anti-vibration screen 2 is greater than the axial length of the inner anti-vibration screen 3, the anti-vibration screen support ring 4 is arranged at the front end and the rear end of the inner anti-vibration screen 3, and the anti-vibration screen support ring 4 is arranged as a wavy circular ring structure along the circumferential direction so as to be able to efficiently cooperate with the inner and outer heat insulation screens; the anti-vibration screen support ring 4 forms a stepped structure along the axial direction, which ensures stable support while allowing high-temperature fuel gas to flow in more conveniently.

[0034] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A double-wall force-added anti-vibration screen with bidirectional oscillation suppression, characterized in that: The invention comprises a coaxially arranged afterburner casing (1), an outer anti-vibration screen (2) and an inner anti-vibration screen (3); the outer anti-vibration screen (2) is arranged between the inner anti-vibration screen (3) and the combustion chamber casing, an outer cooling channel is formed between the outer anti-vibration screen (2) and the afterburner casing (1), and the inner side of the inner anti-vibration screen (3) is a high-temperature inner channel; The outer anti-vibration screen (2) and the inner anti-vibration screen (3) are both provided with vibration absorbing holes, the outer anti-vibration screen (2) and the inner anti-vibration screen (3) are both arranged in a wavy circular ring structure along the circumferential direction, there is a gap between the outer anti-vibration screen (2) and the inner anti-vibration screen (3), and a wavy vibration absorbing cavity (6) is formed between the two; An anti-vibration screen bracket (5) is connected between the outer anti-vibration screen (2) and the afterburner casing (1), and an anti-vibration screen support ring (4) is connected between the outer anti-vibration screen (2) and the inner anti-vibration screen (3).

2. The double-wall force-added anti-vibration screen for bidirectional oscillation suppression as claimed in claim 1 is characterized by: The outer anti-vibration screen (2) and the inner anti-vibration screen (3) both comprise arc-shaped inwardly concave sections (7) and arc-shaped outwardly convex sections (8), and the arc-shaped inwardly concave sections (7) and arc-shaped outwardly convex sections (8) both comprise multiple groups, and the multiple groups of arc-shaped inwardly concave sections (7) and arc-shaped outwardly convex sections (8) are arranged in an alternating manner, and the arc-shaped inwardly concave sections (7) and the adjacent arc-shaped outwardly convex sections (8) are both smoothly transitioned in the form of circular arcs.

3. The double-wall force-added anti-vibration screen for bidirectional oscillation suppression as claimed in claim 2 is characterized by: The anti-vibration screen bracket (5) is arranged at the front end and the rear end of the outer anti-vibration screen (2), and a plurality of anti-vibration screen brackets (5) are arranged at intervals along the circumference of the outer anti-vibration screen (2); the anti-vibration screen bracket (5) comprises a trapezoidal portion (9) and a connecting portion (10), the trapezoidal portion (9) is connected between the arc-shaped outer convex section (8) and the afterburner casing (1), one inner end of the trapezoidal portion (9) is abutted against the arc-shaped outer convex section (8), there are two groups of connecting portions (10) and the two groups of connecting portions (10) are respectively connected to the two sides of the arc-shaped outer convex section (8), and the connecting portion (10) is arranged tangent to the side wall surface of the arc-shaped outer convex section (8).

4. The double-wall force-added anti-vibration screen for bidirectional oscillation suppression as claimed in claim 1 is characterized by: The vibration absorbing holes on the outer vibration-proof screen (2) are small vibration-absorbing holes (11), and the vibration absorbing holes on the inner vibration-proof screen (3) are large vibration-absorbing holes (12). Each of the small vibration-absorbing holes (11) is coaxially arranged corresponding to a large vibration-absorbing hole (12).

5. The double-wall force-added anti-vibration screen for bidirectional oscillation suppression as claimed in claim 1, characterized in that: The axial length of the outer anti-vibration screen (2) is greater than the axial length of the inner anti-vibration screen (3); the anti-vibration screen support ring (4) is arranged at the front end and the rear end of the inner anti-vibration screen (3); the anti-vibration screen support ring (4) is arranged as a wavy circular ring structure along the circumferential direction; and the anti-vibration screen support ring (4) forms a stepped structure along the axial direction.

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