A vibration-proof screen for a reheat combustor with an insertion tube

Abstract

This invention discloses a vibration damper for an afterburner with an insertion tube, belonging to the design field of afterburners. It includes a vibration damper, a flame stabilizer, and a central cone. The vibration damper is located at the downstream end of the outer bypass channel, closely attached to the inner wall of the afterburner shell, forming a double-wall structure. Cold air from the outer bypass flows through it, cooling the wall surface and absorbing oscillation energy, thus suppressing high-frequency vibrations in the combustion chamber. The flame stabilizer is located in the inner bypass channel, its inner end connected to the central cone. The inner bypass and part of the outer bypass airflow meet here, forming a low-speed recirculation zone, achieving fuel-air mixing and stable ignition. The vibration damper has openings, employing a deep-hole structure with an insertion tube. The insertion tube is placed within a hole in the vibration damper's base, significantly increasing the equivalent neck length of the vibration damper while maintaining the same main plate thickness. This shifts the peak sound absorption frequency towards lower frequencies, improving the vibration damper's absorption capacity for low-frequency oscillation modes in the afterburner.

Description

Technical Field

[0001] This invention belongs to the design field of afterburners, specifically an anti-vibration screen for afterburners with an insertion tube. Background Technology

[0002] Under afterburning conditions, aero-engine afterburners are prone to thermoacoustic coupling-induced oscillating combustion / combustion instability (including longitudinal / tangential modes). To suppress oscillating combustion and reduce pressure pulsation amplitude, acoustic bushings are often installed near the flame stabilizer, with vibration dampers being a typical component. Vibration dampers typically isolate the internal and external airflow and are structurally sound-absorbing structures formed by a combination of perforated plates and external cavities. Their acoustic mechanism can be equivalent to a Helmholtz resonator or its array. By matching the design of parameters such as orifice diameter, orifice depth (neck length), back cavity height, and orifice ratio, the vibration damper can absorb oscillating pressure within the target frequency band, thereby improving the stability margin of the afterburner.

[0003] Existing vibration damping screens mostly use thin plate straight holes or simple chamfered hole structures. Due to the requirements for engine weight reduction, the wall thickness of vibration damping screens is often relatively thin (for example, a common wall thickness of about 0.8mm). This kind of traditional structure has the following typical shortcomings in the real afterburner environment:

[0004] 1) The peak frequency of sound absorption is too high and it is difficult to cover the target frequency band. The effective length of the hole neck of the thin plate structure is limited, which makes the tuning master frequency of the Helmholtz type sound absorption structure often too high, making it difficult to effectively cover the mid-to-low frequency large amplitude oscillation combustion frequency band commonly found in afterburners (e.g., 300–500Hz of some tangential modes).

[0005] 2) Sound absorption degrades significantly under strong biased flow and grazing flow conditions. The main flow velocity in the afterburner is relatively high, resulting in a significant grazing flow for the vibration damper. The vibration damper requires cooling, and there is a cooling bias flow within the holes. The sharp boundary of the straight holes in the thin plate makes the grazing flow prone to instability of the shear layer near the hole, vortex shedding and separation, which increases the flow loss at the hole and causes the acoustic impedance to deviate from the design value, resulting in a decrease in sound absorption capacity.

[0006] 3) At high sound pressure levels, the nonlinear acoustic impedance increases significantly, resulting in unstable vibration suppression. The pressure pulsation amplitude in the afterburner is generally greater than 10 kPa; under strong oscillation, the oscillation velocity amplitude of the airflow inside the orifice is very large, and complex phenomena such as vortex separation easily occur in the oscillating flow inside and outside the orifice, thus introducing and significantly amplifying the nonlinear acoustic impedance of the vibration damping screen; when the grazing flow and the offset flow are superimposed, the nonlinear acoustic impedance increases further, leading to a decrease in the sound absorption coefficient and insufficient vibration suppression robustness. Summary of the Invention

[0007] In view of the above-mentioned technical defects, the technical problems to be solved by the present invention are: (1) how to increase the equivalent neck length of the opening without significantly increasing the overall thickness and weight of the anti-vibration screen and without significantly increasing the structural complexity, so as to realize the sound absorption main frequency shift and make it closer to the low-frequency target unstable frequency band of the afterburner; (2) how to weaken the interference of the swirling flow and the bias flow on the orifice oscillating jet, reduce the additional losses caused by orifice separation and vortex shedding, thereby reducing the additional nonlinear acoustic impedance induced by the swirling flow and the bias flow, and making the impedance closer to the matching range; (3) how to suppress the rapid increase of nonlinear acoustic impedance with the increase of oscillation intensity under the condition of high sound pressure level and flow, improve the sound absorption coefficient and effective bandwidth of the anti-vibration screen, thereby enhancing the oscillation combustion suppression effect and working condition robustness.

[0008] To address this, the present invention provides a novel vibration damping screen structure for a combustion chamber with an insertion tube, irregularly shaped holes, and rolled edges. The insertion holes achieve a local deep hole / local thick plate effect, thereby reducing the main sound absorption frequency and increasing the sound absorption coefficient. At the same time, the insertion tube, irregularly shaped holes, and rolled edges protect the oscillating jet at the orifice, enhancing the oscillating jet's ability to resist swirling bends and vortex shedding, thus improving nonlinear acoustic impedance characteristics, increasing the sound absorption coefficient, and enhancing the vibration damping effect.

[0009] This invention is implemented as follows:

[0010] A vibration damper for an afterburner with an insertion tube, characterized in that it comprises a vibration damper, a flame stabilizer, and a center cone; wherein, the vibration damper is located at the downstream end of the outer bypass channel, closely attached to the inner wall of the afterburner shell, forming a double-wall structure, through which the outer bypass cold air flows, both cooling the wall surface and absorbing oscillation energy, thus suppressing high-frequency vibrations of the combustion chamber; the flame stabilizer is located in the inner channel, its inner end connected to the center cone, where the inner and part of the outer bypass airflow meet, forming a low-speed recirculation zone, achieving fuel-air mixing and stable ignition; the center cone is entirely located on the central axis of the afterburner, extending rearward from the turbine rear frame, with a tail-expansion section forming a sudden expansion section, which... The flame stabilizer provides the return core and guides the main flow; the vibration damper is set in the afterburner chamber to isolate the internal airflow from the external airflow, and together with the external cavity, forms a sound-absorbing back cavity structure to absorb and suppress the oscillation pressure generated in the afterburner chamber; the vibration damper has openings, which adopt a deep hole structure with an insertion tube. The insertion tube is set in the hole of the vibration damper base, so that the vibration damper obtains a significantly increased equivalent neck length without changing the thickness of the main plate, thereby shifting the peak sound absorption frequency to the low-frequency direction and improving the absorption capacity of the vibration damper for low-frequency oscillation modes in the afterburner chamber.

[0011] Furthermore, the vibration damping screen includes a vibration damping screen substrate and vibration damping screen insertion holes distributed on the vibration damping screen substrate; the vibration damping screen substrate is in the form of a plate or a screen body; the vibration damping screen insertion holes include a plurality of through-hole structures and an insertion tube; the insertion tube of the vibration damping screen insertion hole is in the form of a short tube, which is inserted into the opening of the vibration damping screen substrate, and each vibration damping screen insertion hole is located on the side close to the main flow of the afterburner.

[0012] The structure of the anti-vibration screen substrate opening and the anti-vibration screen insertion hole can be divided into different hole types and different hole boundary forms; the anti-vibration screen insertion hole can increase the effective hole depth by locally thickening or locally protruding, or the anti-vibration screen insertion hole can be used in conjunction with rolled edges or alone.

[0013] Furthermore, the vibration damping screen is a circular straight-edge insertion tube type vibration damping screen, that is, the opening of the vibration damping screen substrate is a circular straight-edge substrate hole of the vibration damping screen, and the insertion hole structure of the vibration damping screen is a circular straight-edge insertion tube; the circular straight-edge insertion tube cooperates with the circular straight-edge substrate hole of the vibration damping screen, and the circular straight-edge insertion tube is placed on one side of the afterburner chamber.

[0014] Furthermore, the vibration damping screen is a circular rolled-edge insert tube type vibration damping screen, that is, the opening of the vibration damping screen base is a circular rolled-edge base hole; the vibration damping screen insertion hole structure is a circular rolled-edge insert tube; the circular rolled-edge insert tube cooperates with the circular rolled-edge base hole of the vibration damping screen, and the circular rolled edge 303 is set at the outlet of the circular insert tube. The circular rolled-edge insert tube and the circular rolled edge are placed on the main flow side of the afterburner; the circular rolled edge includes: single-sided rolled edge structure, double-sided rolled edge, inward rolled edge, outward rolled edge, rounded corner rolled edge, and flared mouth rolled edge.

[0015] Furthermore, the vibration damping screen is an elliptical straight-edge insertion tube type vibration damping screen; that is, the opening of the vibration damping screen base 101 is an elliptical straight-edge base hole of the vibration damping screen; the insertion hole structure of the vibration damping screen is an elliptical straight-edge insertion tube, the elliptical straight-edge insertion tube cooperates with the elliptical straight-edge base hole of the vibration damping screen, and the elliptical straight-edge insertion tube is placed on one side of the afterburner chamber.

[0016] Furthermore, the vibration damping screen is an elliptical rolled-edge insert tube type vibration damping screen; that is, the opening of the vibration damping screen base is an elliptical rolled-edge base hole, and the insertion hole structure of the vibration damping screen is an elliptical rolled-edge insert tube. The elliptical rolled-edge insert tube cooperates with the elliptical rolled-edge base hole of the vibration damping screen. The elliptical rolled edge is set at the outlet of the elliptical rolled-edge insert tube. The elliptical rolled-edge insert tube and the elliptical rolled edge are placed on one side of the afterburner, and the major axis of the ellipse is consistent with the direction of the central axis of the afterburner. The elliptical rolled edge includes: single-sided rolled edge structure, double-sided rolled edge, inward rolled edge, outward rolled edge, rounded corner rolled edge, and flared mouth rolled edge.

[0017] Furthermore, the vibration damping screen is a triangular straight-edge / rolled-edge insert tube type vibration damping screen; when the vibration damping screen is a triangular straight-edge insert tube type vibration damping screen, that is, the opening of the vibration damping screen base is a triangular base hole of the vibration damping screen; the insertion hole structure of the vibration damping screen is a triangular insert tube, the triangular insert tube cooperates with the triangular base hole of the vibration damping screen, the triangular insert tube is placed on one side inside the afterburner, and the apex of the triangle is aligned with the upstream direction of the central axis of the afterburner.

[0018] Furthermore, the vibration damper insertion hole is used to increase the equivalent thickness of the vibration damper substrate, causing the peak sound absorption frequency of the vibration damper to shift towards lower frequencies, and improving the vibration damper's absorption capacity for low-frequency oscillation modes in the afterburner. The height parameter range of the vibration damper insertion hole is 4–8 mm. When the vibration damper substrate uses a vibration damper main plate, the thickness t of the vibration damper main plate is 0.8 mm. The opening ratio φ can be designed according to the target mode and sound absorption requirements (reference value approximately 3%). The rolled edge orientation can preferably face the swirling flow direction, and the back cavity depth H is determined based on the actual engine outer bypass cavity structure and spatial boundary. The vibration damper substrate also includes other irregularly shaped holes to resist swirling flow mixing, including elongated holes, star-shaped holes, and square holes. The hole diameter or equivalent hydraulic diameter d of the vibration damper substrate is 4–12 mm.

[0019] Furthermore, the manufacturing process of the afterburner vibration damper includes: stamping and flanging, roll forming, laser cutting followed by secondary flanging, additive manufacturing integral forming, and brazing or welding of the sleeve. The insertion tube and rolled edge structure of this invention can be achieved through various manufacturing processes such as stamping and flanging, roll forming, laser cutting followed by secondary flanging, additive manufacturing integral forming, and brazing or welding of the sleeve. This is suitable for the modification and upgrading of existing vibration damper structures and has good engineering application and promotion value.

[0020] The working mode of the afterburner vibration damping screen described in this invention is as follows:

[0021] The vibration damping shield base is installed circumferentially downstream of the afterburner flame stabilizer and coaxial with the central cone, used to isolate the high-temperature combustion gas inside the casing from the cooling airflow outside the casing;

[0022] The vibration damping screen substrate is provided with several vibration damping screen insertion holes, and combined with the outer cavity to form a sound-absorbing back cavity, so as to absorb and suppress the oscillation pressure generated in the afterburner.

[0023] A short tube is inserted into the insertion hole of the vibration damper. The insertion tube is arranged on the side close to the mainstream of the afterburner, so that the vibration damper can obtain a local deep hole / local thick plate effect, increase the equivalent thickness of the vibration damper substrate, shift the peak frequency of sound absorption to a lower frequency, and enhance the vibration damper's ability to absorb low-frequency oscillation modes in the afterburner.

[0024] The outlet end of the insertion tube may be provided with a rolled edge, and the insertion hole of the vibration damping screen is an irregularly shaped hole, which is used to protect the oscillating jet at the orifice, suppress the swirling bend and vortex shedding, and improve the nonlinear acoustic impedance characteristics. By adjusting the type of the rolled edge, the shape of the irregularly shaped hole and the height of the insertion tube, the sound absorption coefficient can be increased in the target frequency band and the vibration suppression effect can be further improved, thereby improving the stability margin of the afterburner.

[0025] The acoustic impedance and sound absorption coefficient of a vibration damper are two key parameters characterizing its sound absorption properties. When the acoustic impedance of the vibration damper is equal to the characteristic acoustic impedance of the combustion chamber gas (the product of density and sound velocity), sound waves do not reflect when they reach the damper, thus achieving the goal of absorbing oscillating pressure. Compared to the characteristic acoustic impedance, an excessively large or small acoustic impedance of the vibration damper is detrimental to sound absorption and vibration suppression. In actual use environments, the pressure pulsation amplitude generated by the combustion chamber is generally greater than 10 kPa. Under such intense oscillation conditions, the airflow oscillation velocity amplitude within the damper's openings is extremely large, and complex flow conditions such as vortex separation exist in the oscillating airflow on both the inner and outer sides of the damper. This greatly increases the vibration damper's acoustic impedance (referred to as nonlinear acoustic impedance).

[0026] This invention utilizes different forms of vibration damping shield substrates, vibration damping shield insertion holes, and corresponding rolled edges to achieve the effect of localized thick plates and resistance to interference from grazing and biased flow on the sound wave absorption path—a feature not previously mentioned. The vibration damping shield uses a deep-hole structure with an insertion tube, which is positioned within the hole in the vibration damping shield substrate. This significantly increases the equivalent neck length of the vibration damping shield while maintaining the same main plate thickness, thereby shifting the peak sound absorption frequency towards lower frequencies and improving the vibration damping shield's absorption capacity for low-frequency oscillation modes in the afterburner.

[0027] The present invention provides a rolled edge structure at the outlet of the insertion tube near the main flow side of the afterburner chamber. The rolled edge provides local protection and shaping of the orifice oscillating jet, weakens the direct scouring of the orifice flow by the swirling and offset flow, suppresses flow separation and vortex shedding, and reduces the additional nonlinear acoustic impedance induced by the swirling flow. This allows the vibration damping screen to maintain a better impedance matching state and a higher sound absorption coefficient even under high sound pressure level conditions.

[0028] This invention achieves the acoustic effect of an equivalent thick plate without overall thick plate design by coordinating the insertion tube and the rolled edge structure. This significantly improves sound absorption performance and vibration suppression effect while greatly reducing the weight, heat load, and structural and cooling risks of the vibration damping screen caused by overall thickening.

[0029] The insertion tube and rolled edge structure of the present invention can be adapted to various hole shapes, including circular, elliptical, polygonal, star-shaped and other irregularly shaped holes. The adaptability of the orifice to the swirling impact can be enhanced by adjusting the hole shape direction (such as the direction of the major axis of the ellipse, the apex of the triangle facing upstream, etc.), thereby improving the stability and versatility of the vibration damping screen in complex flow environments.

[0030] This invention limits the range of key parameters such as insertion tube height, aperture or equivalent hydraulic diameter, opening ratio, rolled edge form and its orientation, and back cavity depth to adapt to different afterburner structures and operating conditions, ensuring sound absorption performance while taking into account engineering feasibility.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] Compared to existing afterburner vibration damping screens that use thin plates with straight holes or simple chamfered holes, this invention significantly increases the equivalent neck length of the opening by incorporating an insertion tube within the holes of the damping screen substrate and introducing a rolled edge structure at the tube outlet. This is achieved without increasing the wall thickness or overall weight of the damping screen, thus shifting the peak sound absorption frequency of the damping screen towards lower frequencies, which is more conducive to covering the mid-to-low frequency oscillation modes commonly found in afterburners. Simultaneously, the insertion tube, rolled edge, and various irregularly shaped hole structures provide local protection and shaping for the oscillating jet at the orifice on the swirling flow side, effectively weakening the impact of swirling and offset flows on the orifice flow, suppressing flow separation and vortex shedding, and significantly reducing nonlinear acoustic impedance. This allows the damping screen to maintain a superior impedance matching state and a high sound absorption coefficient even under high sound pressure levels and strong swirling flow conditions. Compared to overall thicker plate solutions, this invention significantly improves vibration suppression performance while greatly reducing structural weight, thermal load, and engineering risks. Furthermore, its flexible structural form and mature manufacturing process make it highly feasible for engineering implementation and widespread application. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the afterburner vibration damping screen;

[0034] Figure 2 This is a schematic diagram of the vibration damping screen structure of the afterburner combustion chamber with rolled edge and deep hole opening structure of the present invention;

[0035] Figure 3 This is a schematic diagram of the circular insertion hole in this invention;

[0036] Figure 4 This is a schematic diagram of the circular insertion hole with rolled edges in this invention;

[0037] Figure 5 This is a schematic diagram of the elliptical insertion hole in this invention;

[0038] Figure 6This is a schematic diagram of the elliptical insertion hole with rolled edges in this invention;

[0039] Figure 7 This is a schematic diagram of the triangular insertion hole in this invention;

[0040] Figure 8 The results of acoustic impedance tests on traditional vibration damping screens under no-flow conditions are based on the principles of this invention.

[0041] Figure 9 This is the result of a nonlinear acoustic impedance test on a thin plate under flowing conditions, based on the principle of this invention.

[0042] Figure 10 The results are from a nonlinear acoustic impedance test of a thick plate under flowing conditions, based on the principles of this invention.

[0043] Among them, 1-vibration damper, 2-flame stabilizer, 3-center cone; 101-vibration damper substrate, 102-vibration damper insertion hole; 201-vibration damper circular straight-edge substrate hole, 202-circular straight-edge insertion tube; 301-vibration damper circular rolled-edge substrate hole, 302-circular rolled-edge insertion tube, 303-circular rolled edge, 401-vibration damper elliptical straight-edge substrate hole, 402-elliptical straight-edge insertion tube, 501-vibration damper elliptical rolled-edge substrate hole, 502-elliptical rolled-edge insertion tube, 503-elliptical rolled edge, 601-vibration damper triangular substrate hole, 602-triangular insertion tube. Detailed Implementation

[0044] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following examples provide a more detailed description of the invention. It should be noted that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0045] like Figures 1-7As shown, the afterburner vibration damping screen of the present invention includes a vibration damping screen 1, a flame stabilizer 2, and a central cone 3. The vibration damping screen 1 is located at the downstream end of the outer bypass channel, closely attached to the inner wall of the afterburner shell, forming a double-wall structure. The outer bypass cold air flows over it, both cooling the wall surface and absorbing oscillation energy, thus suppressing high-frequency vibrations in the combustion chamber. The flame stabilizer 2 is located in the inner bypass channel, its inner end connected to the central cone 3. The inner bypass and part of the outer bypass airflow meet here, forming a low-speed recirculation zone, achieving fuel-air mixing and stable ignition. The central cone 3 is entirely located on the central axis of the afterburner, extending rearward from the turbine rear frame, with its tail section expanding to form a sudden expansion section, which is the flame... The flame stabilizer provides the return core and guides the main flow; the vibration damper 1 is set in the afterburner chamber to isolate the internal airflow from the external airflow, and together with the external cavity, forms a sound-absorbing back cavity structure to absorb and suppress the oscillation pressure generated in the afterburner chamber; the vibration damper 1 has openings, which adopt a deep hole structure with an insertion tube. The insertion tube is set in the hole of the vibration damper base, so that the vibration damper obtains a significantly increased equivalent neck length without changing the thickness of the main plate, thereby shifting the peak frequency of sound absorption to the low-frequency direction and improving the absorption capacity of the vibration damper for the low-frequency oscillation mode in the afterburner chamber. The vibration damping screen 1 includes a vibration damping screen base 101 and vibration damping screen insertion holes 102 distributed on the vibration damping screen base 101; the vibration damping screen base 101 is in the form of a plate or a screen body; the vibration damping screen insertion holes 102 include several through-hole structures and an insertion tube; the insertion tube of the vibration damping screen insertion hole 102 is a short tube that is inserted into the opening of the vibration damping screen base 101, and each vibration damping screen insertion hole 102 is located on the side near the main flow of the afterburner; the opening of the vibration damping screen base 101 and the structure of the vibration damping screen insertion hole 102 can be divided into different hole types and different hole boundary forms; the effective hole depth of the vibration damping screen insertion hole 102 can be increased by local thickening or local protrusion, or the vibration damping screen insertion hole 102 can be used in conjunction with rolled edges or alone.

[0046] The solutions shown in Figures 1-7 of this invention employ circular straight-edge insertion hole, circular rolled-edge insertion hole, elliptical straight-edge insertion hole, elliptical rolled-edge insertion hole, and triangular straight / rolled-edge insertion hole.

[0047] Figure 8 The test results of the acoustic impedance of a typical traditional vibration damper under stagnant conditions are presented (acoustic impedance of traditional vibration damper under stagnant conditions (wall thickness t=0.8mm, opening ratio σ=0.041)). Under the oscillating combustion environment of the afterburner, the amplitude of the oscillation velocity in the holes of the vibration damper generally exceeds 20m / s. Therefore, the actual acoustic impedance of the vibration damper in the afterburner is generally greater than the characteristic acoustic impedance, that is, the dimensionless acoustic impedance is greater than 1. This results in a small sound absorption coefficient of the vibration damper, which is very unfavorable for suppressing oscillating combustion.

[0048] Figure 9 The experimental results of biased flow (vb) and swept flow (vg) on ​​the nonlinear acoustic impedance of a traditional vibration damper are presented (nonlinear acoustic impedance of thin plate under flow conditions (aperture d=2mm, wall thickness t=0.8mm, opening ratio σ=0.041)). The mainstream velocity in the afterburner is relatively high, which interferes with the oscillating jet within the vibration damper, causing problems such as bending and vortex shedding. In addition, there is also an average flow from the outer duct to the inner duct within the vibration damper (referred to as biased flow), and these two flows increase the nonlinear acoustic impedance.

[0049] Figure 10 Experimental results were presented on the impact of biased flow and grazing flow on the nonlinear acoustic impedance of traditional vibration damping screens for thick plates (nonlinear acoustic impedance of thick plates under flow conditions (pore diameter d=2mm, wall thickness t=4mm, open area ratio σ=0.041)). Under conditions with both significant biased flow and grazing flow, the dimensionless acoustic impedance of thin-plate vibration damping screens was generally above 2.2, while that of thick-plate vibration damping screens was generally below 1.5. Even under conditions with only grazing flow and no biased flow, increasing the wall thickness of the vibration damping screen can still significantly reduce the nonlinear acoustic impedance. Therefore, increasing the wall thickness is beneficial for increasing the sound absorption coefficient and achieving better vibration combustion suppression.

[0050] Based on the aforementioned fundamental principles, the wall thickness of vibration damping screens should be designed as a thick plate. However, overall thickening of vibration damping screens often comes at a significant cost: increased weight and heat load, limited cooling design, increased structural stress and thermal deformation risks, and increased processing and assembly costs. Furthermore, overall thickening affects the geometry of the vibration damping screen and its back cavity, as well as installation space and reliability boundaries. In particular, reducing structural weight is a crucial indicator for the optimized design of afterburners in aero-engines, and designing vibration damping screens with thick plates would increase their weight by more than five times.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A vibration damping screen for an afterburner chamber with an insertion tube, characterized in that, It includes a vibration damper (1), a flame stabilizer (2), and a center cone (3); among which, the vibration damper (1) is located at the downstream end of the outer bypass channel, closely attached to the inner wall of the afterburner shell, forming a double-wall structure. The outer bypass cold air flows through it, which cools the wall surface and absorbs the oscillation energy, suppressing the high-frequency vibration of the combustion chamber; the flame stabilizer (2) is located in the inner channel, and its inner end is connected to the center cone (3). The inner channel and part of the outer bypass airflow meet here to form a low-speed recirculation zone, realizing oil-gas mixing and stable ignition; the center cone (3) is completely located on the central axis of the afterburner, extending from the rear frame of the turbine to the rear, and the tail expands to form a sudden expansion section, providing the recirculation core for the flame stabilizer and guiding the main flow of the inner channel; The vibration damping screen (1) is installed in the afterburner chamber to isolate the internal airflow from the external airflow, and together with the external cavity, forms a vibration damping screen sound-absorbing back cavity structure to absorb and suppress the oscillation pressure generated in the afterburner chamber. The vibration damping screen (1) is made with a hole, which is a deep hole structure with an insertion tube. The insertion tube is set in the hole of the vibration damping screen base, so that the vibration damping screen can obtain a significantly increased equivalent hole neck length without changing the thickness of the main plate, thereby realizing the shift of the sound absorption peak frequency to the low frequency direction and improving the absorption capacity of the vibration damping screen for the low frequency oscillation mode in the afterburner.

2. The vibration damping screen for the afterburner chamber with an insertion tube according to claim 1, characterized in that, The vibration damping screen (1) includes a vibration damping screen base (101) and vibration damping screen insertion holes (102) distributed on the vibration damping screen base (101); the vibration damping screen base (101) is in the form of a plate or a screen body; the vibration damping screen insertion holes (102) include several through hole structures and insertion tubes; The insertion tube of the vibration damping screen insertion hole (102) is a short tube that is inserted into the opening of the vibration damping screen base (101). Each of the vibration damping screen insertion holes (102) is located on the side close to the main flow of the afterburner. The structure of the anti-vibration screen substrate (101) opening and the anti-vibration screen insertion hole (102) can be divided into different hole types and different hole boundary forms; the anti-vibration screen insertion hole (102) can increase the effective hole depth by locally thickening or locally protruding, or the anti-vibration screen insertion hole (102) can be used in conjunction with rolled edge or alone.

3. The vibration damping screen for the afterburner chamber with an insertion tube according to claim 2, characterized in that, The vibration damping screen is a circular straight-edge insertion tube type vibration damping screen, that is, the opening of the vibration damping screen base (101) is a circular straight-edge base hole (201), and the structure of the vibration damping screen insertion hole (102) is a circular straight-edge insertion tube (202); the circular straight-edge insertion tube (202) cooperates with the circular straight-edge base hole (201) of the vibration damping screen, and the circular straight-edge insertion tube (202) is placed on one side of the afterburner.

4. The vibration damping screen for the afterburner chamber with an insertion tube according to claim 2, characterized in that, The vibration damping screen is a circular rolled-edge insert tube type vibration damping screen, that is, the opening of the vibration damping screen base (101) is a circular rolled-edge base hole (301); the structure of the vibration damping screen insertion hole (102) is a circular rolled-edge insert tube (302); the circular rolled-edge insert tube (302) cooperates with the circular rolled-edge base hole (301) of the vibration damping screen, and the circular rolled edge (303) is set at the outlet of the circular insert tube 302. The circular rolled-edge insert tube (302) and the circular rolled edge (303) are placed on the main flow side of the afterburner; the circular rolled edge (303) includes: single-sided rolled edge structure, double-sided rolled edge, inner flange, outer flange, rounded corner rolled edge, and flared mouth rolled edge.

5. The vibration damping screen for the afterburner chamber with an insertion tube according to claim 2, characterized in that, The vibration damping screen is an elliptical straight-edge insertion tube type vibration damping screen; that is, the opening of the vibration damping screen base (101) is an elliptical straight-edge base hole (401); the structure of the vibration damping screen insertion hole (102) is an elliptical straight-edge insertion tube (402), the elliptical straight-edge insertion tube (402) cooperates with the elliptical straight-edge base hole (401) of the vibration damping screen, and the elliptical straight-edge insertion tube (402) is placed on one side of the afterburner chamber.

6. The vibration damping screen for the afterburner chamber with an insertion tube according to claim 2, characterized in that, The vibration damping screen is an elliptical rolled-edge insert tube type vibration damping screen; that is, the opening of the vibration damping screen base (101) is the vibration damping screen elliptical rolled-edge base hole (501), the vibration damping screen insertion hole (102) structure is an elliptical rolled-edge insert tube (502), the elliptical rolled-edge insert tube (502) cooperates with the vibration damping screen elliptical rolled-edge base hole 501, the elliptical rolled edge (503) is set at the outlet of the elliptical rolled-edge insert tube (502), the elliptical rolled-edge insert tube (502) and the elliptical rolled edge (503) are placed on one side of the afterburner, and the direction of the major axis of the ellipse is consistent with the direction of the central axis of the afterburner; the elliptical rolled edge (503) includes: single-sided rolled edge structure, double-sided rolled edge, inner flange, outer flange, rounded corner rolled edge, and flared mouth rolled edge.

7. The vibration damping screen for the afterburner chamber with an insertion tube according to claim 2, characterized in that, The vibration damping screen is a triangular straight-edge / rolled-edge insert tube type vibration damping screen; when the vibration damping screen is a triangular straight-edge insert tube type vibration damping screen, that is, the opening of the vibration damping screen base (101) is the vibration damping screen triangular base hole (601); the structure of the vibration damping screen insertion hole (102) is a triangular insertion tube (602), the triangular insertion tube (602) cooperates with the vibration damping screen triangular base hole (601), the triangular insertion tube (602) is placed on one side of the afterburner, and the apex of the triangle is aligned with the upstream direction of the central axis of the afterburner.

8. The vibration damping screen for the afterburner chamber with an insertion tube according to claim 2, characterized in that, The vibration damping screen insertion hole (102) is used to increase the equivalent thickness of the vibration damping screen substrate (101), so that the sound absorption peak frequency of the vibration damping screen moves towards the low frequency direction, and improves the absorption capacity of the vibration damping screen for the low frequency oscillation mode in the afterburner; the height parameter range of the vibration damping screen insertion hole (102) is 4–8 mm; when the vibration damping screen substrate (101) adopts the vibration damping screen main plate, the thickness t of the vibration damping screen main plate is 0.8 mm; The opening ratio φ can be designed according to the target mode and sound absorption requirements (reference value is about 3%), and the back cavity depth H is determined according to the actual engine outer cavity structure and spatial boundary; the vibration damping screen substrate (101) also includes other irregular holes to resist grazing and mixing, including elongated holes, star-shaped holes and square holes; the hole diameter or equivalent hydraulic diameter d of the vibration damping screen substrate (101) is 4–12 mm.

9. The vibration damping screen for an afterburner chamber with an insertion tube according to claim 2, characterized in that, The manufacturing process of the afterburner vibration damper includes: stamping and flanging, rolling and rolling, laser cutting + secondary flanging, additive manufacturing integral forming, and brazing or welding sleeve.

10. The vibration damping screen for an afterburner chamber with an insertion tube according to any one of claims 1 to 9, characterized in that, The working mode of the afterburner vibration damping screen is as follows: The vibration damping base (101) is installed circumferentially downstream of the afterburner flame stabilizer (2) and coaxial with the central cone (3) to isolate the high-temperature combustion gas inside the casing from the cooling airflow outside the casing. The vibration damping base (101) is provided with several vibration damping insertion holes (102), and is combined with the outer cavity to form a sound-absorbing back cavity to absorb and suppress the oscillation pressure generated in the afterburner. A short tube is inserted into the insertion hole (102) of the vibration damping screen. The insertion tube is arranged on the side close to the main flow of the afterburner, so that the vibration damping screen can obtain a local deep hole / local thick plate effect, increase the equivalent thickness of the vibration damping screen substrate (101), shift the peak frequency of sound absorption to a lower frequency, and enhance the absorption capacity of the vibration damping screen for the low-frequency oscillation mode in the afterburner. The outlet end of the insertion tube may be provided with a rolled edge, and the vibration damping screen insertion hole (102) is an irregular hole, which is used to protect the oscillating jet at the orifice, suppress the swirling bend and vortex shedding, and improve the nonlinear acoustic impedance characteristics. By adjusting the type of the rolled edge, the shape of the irregular hole and the height of the insertion tube, the sound absorption coefficient can be improved in the target frequency band and the vibration damping effect can be further enhanced, thereby improving the stability margin of the afterburner.

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