Multi-head fan-shaped combustion chamber test piece with noise elimination cavity and noise elimination adjustment method

Abstract

The invention provides a multi-head fan-shaped combustion chamber test piece with a noise elimination cavity and a noise elimination adjustment method, and the test piece comprises a force bearing case which is located between an air inlet pipe and an exhaust pipe; the air inlet assembly is arranged in the force bearing casing and comprises a rectification pipeline and a diffusion pipeline, the rectification pipeline comprises an inlet baffle and a rectification pipe, the diffusion pipeline comprises a fixing plate, a flow guide pipe, a flow expansion pipe and a conical wall, the upper, lower, left and right ends of the rectification pipeline and the diffusion pipeline are connected with the force bearing casing, and a plurality of first acoustic damping holes are formed in the rectification pipe; a plurality of second acoustic damping holes are formed in the conical wall; and the flame tube assembly is located at the exhaust port of the air inlet assembly. Wherein the frequency of a first Helmoltz resonator formed by the rectification pipeline and the bearing casing is the same as the incoming flow disturbance frequency in the air inlet pipe; and the frequency of a second Helmoltz resonator formed by the diffusion pipeline and the bearing casing is the same as the combustion oscillation frequency in the flame tube assembly. Combustion oscillation can be effectively restrained, airflow is kept stable, and noise is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature and high-pressure combustion chamber test piece design, and in particular to a multi-headed fan-shaped combustion chamber test piece with a silencer cavity and a silencer adjustment method. Background Art

[0002] With the development of aviation technology, higher requirements are put forward for the temperature ratio, pressure ratio, thrust-to-weight ratio and combustion efficiency of aircraft engines. As a key component of aircraft engines, the combustion chamber undertakes the important task of converting chemical energy into power, which directly affects the performance of the engine. In the development process of aircraft engines, the combustion chamber of aircraft engines is designed on paper and applied to core engines / whole machine tests. In order to verify the performance indicators of combustion chamber components, such as combustion efficiency, temperature distribution, pressure changes, etc., to ensure that they meet the design requirements, it is necessary to carry out technical verification through single-head combustion chamber tests, multi-head fan-shaped combustion chamber tests, and full-ring combustion chamber tests.

[0003] Among these three tests, the single-head combustion chamber has a simple shape and layout, the combustion process is only carried out in one area, and the distribution of the combustion process in the combustion chamber is not uniform enough. It is generally used for multiple combustion chamber scheme screening, and one or more schemes with better comprehensive performance are selected from multiple schemes, so as to continue to carry out further test verification in the fan-shaped combustion chamber and even the full-ring combustion chamber. In the selection of multi-head fan-shaped combustion chamber and full-ring combustion chamber, although the full-ring combustion chamber test can realize the distribution of the combustion chamber around the entire engine and provide more comprehensive combustion, the structure is more complex and the manufacturing and maintenance costs are higher. Therefore, the multi-head fan-shaped combustion chamber test is more commonly used.

[0004] For low-emission combustion chambers, during the sector-shaped combustion chamber test, gas reflection and interference may cause pressure waves, leading to unstable combustion, which will cause fluctuations in engine thrust, power and fuel consumption rate, reduce combustion efficiency, and make it difficult for fuel supply parameters to meet expectations, affecting the accuracy and repeatability of the test, resulting in the test operating condition parameters being unable to meet verification requirements, test failure, and possible damage to the test equipment itself.

[0005] Chinese invention CN115930260A discloses an air bleed structure for an auxiliary power unit, which includes a casing and a flame tube. The casing is a double-layer shell structure, including an inner shell and an outer shell located on the outer periphery of the inner shell, and a casing inner cavity is formed between the outer shell and the inner shell. The inner shell is provided with an inner shell air bleed hole, and the outer shell is provided with an outer shell air bleed hole, and the outer shell air bleed hole supplies air to the main engine air supply channel through an air bleed pipe. The flame tube is located inside the inner shell, and the outer wall of the flame tube is provided with a flame tube air inlet hole, and an inlet flow channel is formed between the inner shell and the outer wall of the flame tube, and the angle between the opening direction of the inner shell air bleed hole and the air inlet direction of the inlet flow channel is not greater than 75°. For the airflow passing through the air duct of the inner shell, when the airflow passes through the air duct of the inner shell, since the inner shell and the outer shell are integrated, and the opening angle of the air duct of the inner shell is consistent with the direction of the airflow, the airflow is evenly dispersed by the air duct of the inner shell after passing through the air duct of the inner shell, avoiding the disorderly flow of the airflow in the casing, increasing the orderliness of the airflow, and effectively reducing the excitation effect caused by the initial vibration and unevenness of the air duct. The above invention disperses the instability of the mainstream flow through the design of the inner and outer double-layer casings, thereby reducing the initial disturbance of the flow. The structural complexity is high, which will also increase the design cost. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-headed fan-shaped combustion chamber test piece with a silencer cavity and a silencer adjustment method to solve the above-mentioned problems, which can effectively suppress combustion oscillations, maintain stable gas flow in the combustion chamber, and reduce noise during combustion chamber operation.

[0007] The present invention proposes a multi-head sector-shaped combustion chamber test piece with a muffler cavity, comprising:

[0008] The load-bearing casing is located between the intake and exhaust pipes;

[0009] An air intake assembly is arranged in the load-bearing casing, and introduces airflow and performs pressure expansion. The air intake assembly includes a rectifying duct and a pressure expansion duct. The rectifying duct includes an inlet baffle and a rectifying tube. The pressure expansion duct includes a fixed plate, a guide tube, a flow expansion tube and a cone wall. The inlet baffle includes two vertical plates, and one end of each of the two vertical plates is connected to the load-bearing casing, and the other end is connected to one end of the rectifying tube. The other end of the rectifying tube is connected to the fixed plate. The upper and lower ends of the fixed plate are respectively connected to the load-bearing casing. One end of the guide tube is connected to the fixed plate, and the other end is connected to one end of the flow expansion tube. The cone wall is circumferentially arranged around the outer wall of the flow expansion tube and close to the inner wall of the load-bearing casing. The rectifying tube is provided with a plurality of first acoustic damping holes, and the cone wall is provided with a plurality of second acoustic damping holes.

[0010] A flame tube assembly is arranged in the load-bearing casing, located at the exhaust port of the air intake assembly, and receives the expanded pressure airflow;

[0011] Among them, the rectifying duct and the load-bearing casing form a first Helmoltz resonator, the frequency of the first Helmoltz resonator is the same as the incoming flow disturbance frequency in the intake pipe, and the diffuser duct and the load-bearing casing form a second Helmoltz resonator, the frequency of the second Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly.

[0012] In one embodiment, the load-bearing casing includes a first transition casing, an air bleed section casing, a test section casing, a measurement section casing and a second transition casing;

[0013] One end of the first transfer casing is connected to the air intake pipe, and the other end is connected to one end of the air bleed section casing, the other end of the air bleed section casing is connected to one end of the test section casing, the other end of the test section casing is connected to one end of the measuring section casing, the other end of the measuring section casing is connected to one end of the second transfer casing, and the other end of the second transfer casing is connected to the exhaust pipe;

[0014] The cross-section of the first adapter casing gradually decreases from one end connected to the air intake pipe to the other end connected to the air bleed section casing, the cross-sections of the air bleed section casing, the test section casing and the measuring section casing remain unchanged along the axial direction, and the cross-section of the second adapter casing gradually increases from one end connected to the measuring section casing to the other end connected to the exhaust pipe.

[0015] In one embodiment, the cross-sections of the air bleed section casing and the test section casing are both fan-shaped;

[0016] The air bleed section casing comprises a first outer ring casing, a first inner ring casing and two first side casings, the first outer ring casing and the first inner ring casing are both arc-shaped, the arc radius of the first outer ring casing is greater than the arc radius of the first inner ring casing, and the two first side casings are both semicircular, respectively connecting the two ends of the first outer ring casing and the first inner ring casing, and forming a closed pipeline with the first outer ring casing and the first inner ring casing;

[0017] The test section casing includes a second outer ring casing, a second inner ring casing and two second side casings. The second outer ring casing and the second inner ring casing are both arc-shaped. The arc radius of the second outer ring casing is larger than the arc radius of the second inner ring casing. The two second side casings are both semicircles, which respectively connect the two ends of the second outer ring casing and the second inner ring casing, and form a closed pipeline with the second outer ring casing and the second inner ring casing.

[0018] In one embodiment, the rectifying duct is arranged inside the air bleed section casing, the rectifying duct also includes a mounting plate, the inlet baffle also includes two transverse plates, the two transverse plates respectively face the first outer ring casing and the first inner ring casing, and there is a gap G1 between the two transverse plates and the first outer ring casing and the first inner ring casing respectively, the two vertical plates are respectively connected to the transverse plate at one end and connected to one end of the rectifying tube at the other end, the other end of the rectifying tube is connected to the mounting plate, the cross-section of the rectifying tube remains unchanged along the axial direction, and the mounting plate is bolted to the fixing plate.

[0019] In one embodiment, the cross section of the rectifier tube is fan-shaped, including an outer ring rectifier plate, an inner ring rectifier plate and two side rectifier plates, and the first acoustic damping hole includes a first outer ring damping hole and a first inner ring damping hole;

[0020] The outer ring rectifying plate and the inner ring rectifying plate are both arc-shaped, the arc radius of the outer ring rectifying plate is greater than the arc radius of the inner ring rectifying plate, the first outer ring damping hole is arranged on the outer ring rectifying plate, and the first inner ring damping hole is arranged on the inner ring rectifying plate;

[0021] Two side rectifying plates are respectively connected to two ends of the outer ring rectifying plate and the inner ring rectifying plate, and extend in a radial direction to be connected to the first outer ring casing and the first inner ring casing;

[0022] The outer ring rectifier plate, the first outer ring casing and the rectifier plates on both sides form a third cavity V 1 , forming a first outer ring Helmoltz resonator, the inner ring rectifier plate, the first inner ring casing and the rectifier plates on both sides form a fourth cavity V 2 , forming a first inner ring Helmoltz resonator.

[0023] In one embodiment, the pressure diffuser pipe is arranged inside the test section casing, and two ends of the fixing plate are respectively bolted to the second outer ring casing and the second inner ring casing;

[0024] The cross section of the guide tube is fan-shaped and remains unchanged along the axial direction. The guide tube comprises an outer ring guide plate, an inner ring guide plate and two side guide plates. The outer ring guide plate and the inner ring guide plate are both arc-shaped. The arc radius of the outer ring guide plate is greater than the arc radius of the inner ring guide plate. The two side guide plates are respectively connected to the two ends of the outer ring guide plate and the inner ring guide plate, and extend in the radial direction to be connected to the second outer ring casing and the second inner ring casing.

[0025] The other end of the flow diffuser is toward the flame tube assembly, and the cross section of the flow diffuser gradually increases from the end connected to the guide tube to the other end toward the flame tube assembly, so as to expand the airflow and guide the expanded airflow into the flame tube assembly;

[0026] The outer ring guide plate, the second outer ring casing and the guide plates on both sides form a fifth cavity V. 3 , forming a second outer ring Helmoltz resonator, the inner ring guide plate, the second inner ring casing and the guide plates on both sides form a sixth cavity V 4 , forming a second inner ring Helmoltz resonator.

[0027] In one embodiment, the cone wall includes an outer cone wall and an inner cone wall, the outer cone wall is close to the second outer casing, and there is a gap G2 between the outer cone wall and the second outer casing, and the inner cone wall is close to the second inner casing, and there is a gap G2 between the inner cone wall and the second inner casing;

[0028] The second acoustic damping hole comprises a second outer ring damping hole and a second inner ring damping hole, the second outer ring damping hole is arranged on the outer ring cone wall, and the second inner ring damping hole is arranged on the inner ring cone wall.

[0029] In one embodiment, the flame tube assembly includes a flame tube outer wall, a flame tube inner wall and two flame tube side walls;

[0030] The outer wall of the flame tube and the inner wall of the flame tube are both arc-shaped, and the arc radius of the outer wall of the flame tube is greater than the arc radius of the inner wall of the flame tube;

[0031] The two flame tube side walls are respectively connected to the two ends of the flame tube outer wall and the flame tube inner wall, and extend in the radial direction to be connected to the second outer ring casing and the second inner ring casing;

[0032] The flame tube assembly further comprises a plurality of flame tube heads, which are located inside a region surrounded by an outer wall of the flame tube, an inner wall of the flame tube and two side walls of the flame tube and are evenly arranged along the circumference of the flame tube assembly.

[0033] In one embodiment, the multi-head sector combustion chamber test piece with a muffler cavity further includes a fuel nozzle, an ignition nozzle and a pulsating pressure sensing portion, and the fuel nozzle, the ignition nozzle and the pulsating pressure sensing portion are all arranged on the second outer ring casing;

[0034] The fuel nozzle is connected to the flame tube assembly to spray the fuel into the flame tube assembly to mix with the diffuser airflow for combustion;

[0035] The ignition nozzle is installed on the head of the flame tube in the middle position and is used to ignite the fuel and expand the air flow;

[0036] The pulsating pressure sensing parts are respectively installed on the flame tube heads at non-middle positions and are used to measure the dynamic pressure of the gas during combustion.

[0037] The present invention also proposes a method for adjusting noise reduction, which is applied to the multi-head sector-shaped combustion chamber test piece with a noise reduction cavity as described above, and comprises the following steps:

[0038] The frequency of the first outer ring Helmoltz resonator is adjusted by adjusting the volume of the third cavity, the diameter and the number of the first outer ring damping holes, so that the frequency of the first outer ring Helmoltz resonator is the same as the frequency of the incoming flow disturbance in the intake pipe;

[0039] The frequency of the first inner ring Helmoltz resonator is adjusted by adjusting the volume of the fourth cavity, the diameter and the number of the first inner ring damping holes, so that the frequency of the first inner ring Helmoltz resonator is the same as the frequency of the incoming flow disturbance in the intake pipe;

[0040] The frequency of the second outer ring Helmoltz resonator is adjusted by adjusting the volume of the fifth cavity, the diameter and the number of the second outer ring damping holes, so that the frequency of the second outer ring Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly;

[0041] The frequency of the second inner ring Helmoltz resonator is adjusted by adjusting the volume of the sixth cavity, the diameter and the number of the second inner ring damping holes, so that the frequency of the second inner ring Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly.

[0042] Compared with the prior art, the multi-head sector-shaped combustion chamber test piece with a muffler cavity and the muffler adjustment method of the present invention have the following beneficial effects:

[0043] 1) The present invention can effectively suppress combustion oscillations, help maintain stable gas flow in the combustion chamber, reduce noise during combustion chamber operation, maintain combustion efficiency, and ensure that the performance of the engine remains at the designed level, thereby ensuring that the combustion chamber operating conditions can achieve the expected verification goals.

[0044] 2) The present invention helps to reduce the vibration amplitude of combustion chamber components and related structures, improve the stability of the entire combustion test, maintain the controllability of the engine under various operating conditions, reduce the risk of instability, thereby reducing the risk of fatigue and stress concentration, and improving the reliability and life of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic structural diagram of a multi-head sector-shaped combustion chamber test piece with a muffler cavity according to an embodiment of the present invention;

[0046] Figure 2 for Figure 1 Enlarged view of M in the middle;

[0047] Figure 3 for Figure 2Middle AA section view;

[0048] Figure 4 It is a schematic structural diagram of a rectifying duct in a multi-head sector-shaped combustion chamber test piece with a muffler cavity according to an embodiment of the present invention;

[0049] Figure 5 It is a schematic structural diagram of a pressure diffuser pipe in a multi-head sector-shaped combustion chamber test piece with a muffler cavity according to an embodiment of the present invention;

[0050] Figure 6 for Figure 2 Middle BB section view;

[0051] Figure 7 for Figure 2 Middle CC section view;

[0052] Figure 8 It is a schematic diagram of the first outer ring damping hole, the first inner ring damping hole, the second outer ring damping hole and the second inner ring damping hole in a multi-head sector-shaped combustion chamber test piece with a silencer cavity according to an embodiment of the present invention.

[0053] Reference numerals

[0054] 1. Intake pipe, 10. First cavity, 2. Exhaust pipe, 20. Second cavity, 31. First transfer casing, 32. Bleeding section casing, 321. First outer ring casing, 322. First inner ring casing, 323. First side casing, 33. Test section casing, 331. Second outer ring casing, 332. Second inner ring casing, 333. Second side casing, 34. Measuring section casing, 35. Second transfer casing, 4. Fuel nozzle, 5. Flame tube assembly, 50. Combustion cavity, 51. Flame tube outer wall, 52. Flame tube inner wall, 53. Flame tube side wall, 61. Ignition nozzle, 62. Pulsating pressure sensing part, 7. Intake assembly, 71. Rectification pipe, 711. Inlet baffle, 712. Rectification pipe, 7121. Outer ring rectifier plate, 7122. Inner ring rectifier plate, 7123. Side rectifier plate, 713. Mounting plate, 72. Diffuser pipe, 721. Fixing plate, 722. Guide pipe, 7221. Outer ring guide plate, 7222. Inner ring guide plate, 7223. Side guide plate, 723. Diffuser, 724. Cone wall, 7241. Outer ring cone wall, 7242. Inner ring cone wall, P, Intake chamber, V 1 , the third chamber, V 2 , the fourth chamber, V 3 , the fifth chamber, V 4 , the sixth cavity, G1, the gap between the inlet baffle and the first outer ring casing and the first inner ring casing, G2, the gap between the cone wall and the second outer ring casing and the second inner ring casing, f up , the frequency of the flow disturbance in the intake pipe, f c, the combustion oscillation frequency within the flame tube assembly. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the specific embodiments described herein are used to help understand the present invention, but do not constitute a limitation of the present invention.

[0056] The present invention proposes a multi-headed sector-shaped combustion chamber test piece with a muffler cavity, comprising a load-bearing casing, an air intake assembly 7 and a flame tube assembly 5, see Figure 1 .

[0057] The load-bearing casing is composed of a plurality of casings arranged in an arrangement and is located between the intake pipe 1 and the exhaust pipe 2.

[0058] The air intake assembly 7 is arranged in the load-bearing casing, and is used to introduce airflow and perform pressure expansion. The air intake assembly 7 includes a rectifying duct 71 and a pressure expansion duct 72. The rectifying duct 71 includes an inlet baffle 711 and a rectifying tube 712, and the pressure expansion duct 72 includes a fixed plate 721, a guide tube 722, a flow expansion tube 723 and a cone wall 724. The inlet baffle 711 includes two vertical plates, and one end of the two vertical plates is connected to the load-bearing casing, and the other end is connected to one end of the rectifying tube 712. The other end of the rectifying tube 712 is connected to the fixed plate 721, and the upper and lower ends of the fixed plate 721 are respectively connected to the load-bearing casing. One end of the guide tube 722 is connected to the fixed plate 721, and the other end is connected to one end of the flow expansion tube 723. The cone wall 724 is circumferentially arranged around the outer wall of the flow expansion tube 723 and is close to the inner wall of the load-bearing casing. The rectifier tube 712 is provided with a plurality of first acoustic damping holes, and the cone wall 724 is provided with a plurality of second acoustic damping holes.

[0059] The flame tube assembly 5 is arranged in the load-bearing casing and is located at the exhaust port of the air intake assembly 7 , that is, the air intake assembly 7 is located upstream of the flame tube assembly 5 .

[0060] The inner flow passage of the intake pipe 1 forms a first cavity 10 for conveying intake air. The flame tube assembly 5 forms a combustion cavity 50, and the fuel injected from the fuel nozzle 4 and the diffuser airflow from the intake assembly 7 are burned in the combustion cavity 50. The inner flow passage of the exhaust pipe 2 forms a second cavity 20 for outputting the combusted gas.

[0061] Among them, the rectifying duct 71 and the load-bearing casing form a first Helmoltz resonator, the frequency of the first Helmoltz resonator is the same as the incoming flow disturbance frequency in the intake pipe 1, and the diffuser duct 72 and the load-bearing casing form a second Helmoltz resonator, the frequency of the second Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly 5.

[0062] It should be noted that the Helmoltz resonator is a device for adjusting acoustic frequency. It controls the frequency of sound waves by the relative size and shape between the neck and the cavity of the container. When the sound wave enters the resonator, it interacts with the air inside the resonator, causing the resonator to resonate at a specific frequency. This specific frequency is usually called the resonant frequency, which can be changed by adjusting the geometric parameters of the resonator. The Helmholtz resonator exhibits a strong resonant response to sound waves of a specific frequency, which makes it widely used in fields such as acoustic engineering and architectural acoustics for purposes such as sound absorption, noise reduction and tuning.

[0063] The following is a detailed description of the various components of the multi-head sector-shaped combustion chamber test piece with a silencer cavity described above.

[0064] The load-bearing casing of one embodiment of the present invention comprises a first transition casing 31 , an air bleed section casing 32 , a test section casing 33 , a measurement section casing 34 and a second transition casing 35 .

[0065] One end of the first adapter casing 31 is connected to the air intake pipe 1, and the other end is connected to one end of the air bleed section casing 32, the other end of the air bleed section casing 32 is connected to one end of the test section casing 33, the other end of the test section casing 33 is connected to one end of the measuring section casing 34, the other end of the measuring section casing 34 is connected to one end of the second adapter casing 35, and the other end of the second adapter casing 35 is connected to the exhaust pipe 2;

[0066] The cross-section of the first adapter casing 31 gradually decreases from one end connected to the air intake pipe 1 to the other end connected to the air bleed section casing 32, the cross-sections of the air bleed section casing 32, the test section casing 33 and the measuring section casing 34 remain unchanged along the axial direction, and the cross-section of the second adapter casing 35 gradually increases from one end connected to the measuring section casing 34 to the other end connected to the exhaust pipe 2.

[0067] like Figure 3 , Figure 6 , Figure 7 As shown, the cross-sections of the air bleed section casing 32 and the test section casing 33 of one embodiment of the present invention are both fan-shaped.

[0068] The air bleed section casing 32 includes a first outer ring casing 321, a first inner ring casing 322 and two first side casings 323. The first outer ring casing 321 and the first inner ring casing 322 are both arc-shaped, and the arc radius of the first outer ring casing 321 is greater than the arc radius of the first inner ring casing 322. The two first side casings 323 are both semicircular, respectively connecting the two ends of the first outer ring casing 321 and the first inner ring casing 322, and forming a closed pipeline with the first outer ring casing 321 and the first inner ring casing 322.

[0069] The test section casing 33 includes a second outer ring casing 331, a second inner ring casing 332 and two second side casings 333. The second outer ring casing 331 and the second inner ring casing 332 are both arc-shaped, and the arc radius of the second outer ring casing 331 is greater than the arc radius of the second inner ring casing 332. The two second side casings 333 are both semicircular, respectively connecting the two ends of the second outer ring casing 331 and the second inner ring casing 332, and forming a closed pipeline with the second outer ring casing 331 and the second inner ring casing 332.

[0070] like Figure 2 , Figure 4 As shown, a rectifying duct 71 of an embodiment of the present invention is arranged inside the air bleed section casing 32, and the rectifying duct 71 also includes a mounting plate 713. The inlet baffle 711 also includes two transverse plates, which face the first outer ring casing 321 and the first inner ring casing 322 respectively, and there is a certain mounting gap G1 between the two transverse plates and the first outer ring casing 321 and the first inner ring casing 322 respectively, in order to ensure that the rectifying duct 71 can be smoothly installed inside the air bleed section casing 32, but this gap G1 must be small enough. One end of the two vertical plates is connected to the transverse plate, and the other end is connected to one end of the rectifying tube 712. The other end of the rectifying tube 712 is connected to the mounting plate 713, and the cross section of the rectifying tube 712 remains unchanged along the axial direction, and the mounting plate 713 is bolted to the fixing plate 721.

[0071] like Figure 7 As shown, the cross section of the rectifier tube 712 of one embodiment of the present invention is fan-shaped, including an outer ring rectifier plate 7121, an inner ring rectifier plate 7122 and two side rectifier plates 7123. The outer ring rectifier plate 7121 and the inner ring rectifier plate 7122 are both arc-shaped, and the arc radius of the outer ring rectifier plate 7121 is greater than the arc radius of the inner ring rectifier plate 7122. The wall thickness of the outer ring rectifier plate 7121 is b 1 , the wall thickness of the inner ring rectifier 7122 is b 2 The two side rectifying plates 7123 are respectively connected to the two ends of the outer ring rectifying plate 7121 and the inner ring rectifying plate 7122 , and extend in the radial direction to be connected to the first outer ring casing 321 and the first inner ring casing 322 .

[0072] like Figure 8 As shown, the first acoustic damping hole includes a first outer ring damping hole and a first inner ring damping hole, and the first outer ring damping hole and the first inner ring damping hole are both circular through holes. The first outer ring damping holes are evenly arranged on the outer ring rectifier plate 7121, and the diameter of the first outer ring damping holes is d 1 , the number is N 1 The first inner ring damping holes are evenly arranged on the inner ring rectifier plate 7122, and the diameter of the first inner ring damping holes is d 2 , the number is N 2 .

[0073] The outer ring rectifying plate 7121, the first outer ring casing 321 and the rectifying plates 7123 on both sides form a third cavity V 1 , forming a first outer ring Helmoltz resonator; the inner ring rectifier plate 7122, the first inner ring casing 322 and the rectifier plates 7123 on both sides form a fourth cavity V 2 , forming a first inner ring Helmoltz resonator.

[0074] like Figure 2 , Figure 5 , Figure 6 As shown, the diffuser pipe 72 of one embodiment of the present invention is arranged inside the test section casing 33. The two ends of the fixing plate 721 are bolted to the second outer ring casing 331 and the second inner ring casing 332 respectively, and the connection needs to be sealed to prevent the air in the first chamber 10 from leaking to the combustion chamber 50 from the connection.

[0075] The guide tube 722 has a fan-shaped cross section and remains unchanged along the axial direction, and includes an outer ring guide plate 7221, an inner ring guide plate 7222 and two side guide plates 7223. The outer ring guide plate 7221 and the inner ring guide plate 7222 are both arc-shaped, and the arc radius of the outer ring guide plate 7221 is greater than the arc radius of the inner ring guide plate 7222. The two side guide plates 7223 are respectively connected to the two ends of the outer ring guide plate 7221 and the inner ring guide plate 7222, and extend in the radial direction to connect with the second outer ring casing 331 and the second inner ring casing 332.

[0076] The outer ring guide plate 7221, the second outer ring casing 331 and the guide plates 7223 on both sides form a fifth cavity V 3 , forming a second outer ring Helmoltz resonator; the inner ring guide plate 7222, the second inner ring casing 332 and the guide plates 7223 on both sides form a sixth cavity V 4 , forming a second inner ring Helmoltz resonator.

[0077] The other end of the diffuser 723 faces the flame tube assembly 5 , and the cross-section of the diffuser 723 gradually increases from one end connected to the guide tube 722 to the other end facing the flame tube assembly 5 , thereby diffusing the airflow and guiding the diffused airflow into the flame tube assembly 5 .

[0078] The inner flow passages of the rectifying tube 712 and the guide tube 722 form an air intake cavity P for rectifying and conveying gas. The joint between the mounting plate 713 and the fixing plate 721 needs to be sealed to prevent the third cavity V 1 , the fourth chamber V 2 The air inside leaks from the connection to the air intake chamber P.

[0079] like Figure 5As shown, the cone wall 724 of one embodiment of the present invention includes an outer cone wall 7241 and an inner cone wall 7242. The outer cone wall 7241 is close to the second outer ring casing 331 and has a wall thickness of b. 3 There is a certain installation gap G2 between the inner ring wall 7242 and the second outer ring casing 331. The inner ring cone wall 7242 is close to the second inner ring casing 332, and its wall thickness is b 4 There is a certain installation gap G2 between the second inner ring casing 332. The installation gap G2 is designed to ensure that the diffuser pipe 72 can be smoothly installed inside the test section casing 33, but this gap G2 should be small enough to simulate the real combustion chamber as much as possible.

[0080] like Figure 8 As shown, the second acoustic damping hole includes a second outer ring damping hole and a second inner ring damping hole, and the second outer ring damping hole and the second inner ring damping hole are both circular through holes. The second outer ring damping holes are evenly arranged on the outer ring cone wall 7241, and the diameter of the second outer ring damping holes is d 3 , the number is N 3 The second inner ring damping holes are evenly arranged on the inner ring cone wall 7242, and the diameter of the second inner ring damping holes is d 4 , the number is N 4 .

[0081] like Figure 3 As shown, a flame tube assembly 5 of an embodiment of the present invention includes a flame tube outer wall 51, a flame tube inner wall 52 and two flame tube side walls 53. The flame tube outer wall 51 and the flame tube inner wall 52 are both arc-shaped, and the arc radius of the flame tube outer wall 51 is greater than the arc radius of the flame tube inner wall 52. The two flame tube side walls 53 are respectively connected to the two ends of the flame tube outer wall 51 and the flame tube inner wall 52, and extend in the radial direction to be connected with the second outer ring casing 331 and the second inner ring casing 332. The flame tube assembly 5 also includes a plurality of flame tube heads, which are located inside the area surrounded by the flame tube outer wall 51, the flame tube inner wall 52 and the two flame tube side walls 53, and are evenly arranged along the circumference of the flame tube assembly 5 for receiving the expanded pressure airflow.

[0082] A multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to an embodiment of the present invention further includes a fuel nozzle 4, an ignition nozzle 61 and a pulsating pressure sensing portion 62, and the fuel nozzle 4, the ignition nozzle 61 and the pulsating pressure sensing portion 62 are all arranged on the second outer ring casing 331. The fuel nozzle 4 is connected to the flame tube assembly 5, and the fuel is sprayed into the flame tube assembly 5 to mix with the diffuser airflow for combustion. The ignition nozzle 61 is installed on the flame tube head at the middle position, and is used to ignite the fuel and the diffuser airflow. The pulsating pressure sensing portion 62 is respectively installed on the flame tube heads at non-middle positions, and is used to measure the dynamic pressure of the gas during combustion. Figure 35 flame tube heads and 4 pulsating pressure sensing parts 62 are shown in the figure. The ignition nozzle 61 faces the center of the flame tube head in the middle position, and the 4 pulsating pressure sensing parts 62 face the centers of the other 4 flame tube heads respectively. Of course, the number of flame tube heads and the number of pulsating pressure sensing parts 62 can be adjusted according to actual conditions.

[0083] The present invention also proposes a muffler adjustment method, which is applied to the above-mentioned multi-head sector-shaped combustion chamber test piece with a muffler cavity, and comprises the following steps:

[0084] The frequency of the first outer ring Helmoltz resonator is adjusted by adjusting the volume of the third cavity, the diameter and the number of the first outer ring damping holes, so that the frequency of the first outer ring Helmoltz resonator is the same as the frequency of the incoming flow disturbance in the intake pipe;

[0085] The frequency of the first inner ring Helmoltz resonator is adjusted by adjusting the volume of the fourth cavity, the diameter and the number of the first inner ring damping holes, so that the frequency of the first inner ring Helmoltz resonator is the same as the frequency of the incoming flow disturbance in the intake pipe;

[0086] The frequency of the second outer ring Helmoltz resonator is adjusted by adjusting the volume of the fifth cavity, the diameter and the number of the second outer ring damping holes, so that the frequency of the second outer ring Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly;

[0087] The frequency of the second inner ring Helmoltz resonator is adjusted by adjusting the volume of the sixth cavity, the diameter and the number of the second inner ring damping holes, so that the frequency of the second inner ring Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly.

[0088] The following is a detailed explanation of the noise reduction adjustment method.

[0089] The airflow from the tester inlet pipe 1 is unstable, and its characteristic frequency, that is, the disturbance frequency of the incoming flow, is f up , propagates downstream in the form of convection. The frequency of the incoming flow disturbance is f up The calculation formula is: Among them, Sr is the Strouhal number, U up is the average flow velocity in the intake pipe 1, D up is the characteristic diameter of the intake pipe 1. The Strouhal number Sr can be obtained by cold large eddy simulation.

[0090] The inherent thermoacoustic instability in the combustion chamber flame tube 5 has a characteristic frequency, that is, the combustion oscillation frequency, f c , propagates upstream or downstream in the form of sound waves, and is "absorbed", "emitted", "scattered", etc. at the solid wall boundary. The combustion oscillation frequency is fc It can be obtained through three-dimensional thermoacoustic finite element, among which the flame transfer function required in the three-dimensional thermoacoustic finite element tool can be obtained through thermal large eddy simulation.

[0091] The third cavity V 1 , the fourth chamber V 2 、Fifth chamber V 3 and the sixth chamber V 4 A first outer ring Helmoltz resonator, a first inner ring Helmoltz resonator, a second outer ring Helmoltz resonator and a second inner ring Helmoltz resonator are respectively formed, and these Helmoltz resonators can eliminate disturbances of corresponding frequencies.

[0092] The frequency f of the Helmoltz resonator H,i The calculation formula is: Where: c is the speed of sound, which is related to the temperature of the air flowing into the test piece; N i d i are the number and diameter of openings on the wall with acoustic damping holes; V i is the volume of the i-th cavity; the value range of i is 1 or 2 or 3 or 4.

[0093] When i = 1 or 2, by designing N i d i and V i , so that f H,i With f up Similarly, the instability disturbance of the flow coming from the upstream of the intake duct is weakened, and the convection of the disturbance to the combustion chamber triggers the thermoacoustic instability.

[0094] When i = 3 or 4, by designing N i d i and V i , so that f H,i With f c Similarly, it is to weaken the emission of sound waves from the inherent thermal-acoustic instability of the combustion chamber on the cone wall and weaken the influence of reflected waves on the combustion chamber flame tube.

[0095] In short, multiple acoustic cavities are formed between the air intake assembly 7 and the load-bearing casing by design, an array of acoustic damping holes is opened on the wall surface, and the characteristic frequency of the acoustic cavity upstream of the air intake assembly is designed to be the same as the incoming flow disturbance frequency, and the characteristic frequency of the acoustic cavity downstream of the air intake assembly is designed to be the same as the combustion oscillation frequency. Through acoustic design, the purpose of suppressing combustion oscillation is achieved.

[0096] It should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inside" and "outside" are all based on the directions or positional relationships shown in the drawings. Such expressions are only intended to make the description of the present invention simpler and more convenient, and do not indicate or imply that the referred parts must have a specific direction or be constructed and operated in a specific direction.

[0097] In addition, in this application, unless otherwise clearly specified and limited, the terms such as "installation", "connection", "setting" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. Those skilled in the art can understand the specific meanings of the above terms in this application according to the specific circumstances. In addition, the terms "first", "second", "third", "fourth", "fifth", and "sixth" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0098] The present invention has the following beneficial effects:

[0099] 1) The present invention can effectively suppress combustion oscillations, help maintain stable gas flow in the combustion chamber, reduce noise during combustion chamber operation, maintain combustion efficiency, and ensure that the performance of the engine remains at the designed level, thereby ensuring that the combustion chamber operating conditions can achieve the expected verification goals.

[0100] 2) The present invention helps to reduce the vibration amplitude of combustion chamber components and related structures, improve the stability of the entire combustion test, maintain the controllability of the engine under various operating conditions, reduce the risk of instability, thereby reducing the risk of fatigue and stress concentration, and improving the reliability and life of the structure.

[0101] The above-described embodiments are only further explanations of the present invention, and are not intended to limit the present invention in other forms. The present invention may also have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding modifications and changes according to the present invention, but these corresponding modifications and changes should all fall within the protection scope of the present invention.

Claims

1. A multi-headed sector combustion chamber test piece with a muffler cavity, It is characterized in that include: The load-bearing casing is located between the intake and exhaust pipes; An air intake assembly is arranged in the load-bearing casing, and introduces airflow and performs pressure expansion. The air intake assembly includes a rectifying duct and a pressure expansion duct. The rectifying duct includes an inlet baffle and a rectifying tube. The pressure expansion duct includes a fixed plate, a guide tube, a flow expansion tube and a cone wall. The inlet baffle includes two vertical plates, and one end of each of the two vertical plates is connected to the load-bearing casing, and the other end is connected to one end of the rectifying tube. The other end of the rectifying tube is connected to the fixed plate. The upper and lower ends of the fixed plate are respectively connected to the load-bearing casing. One end of the guide tube is connected to the fixed plate, and the other end is connected to one end of the flow expansion tube. The cone wall is circumferentially arranged around the outer wall of the flow expansion tube and close to the inner wall of the load-bearing casing. The rectifying tube is provided with a plurality of first acoustic damping holes, and the cone wall is provided with a plurality of second acoustic damping holes. A flame tube assembly is arranged in the load-bearing casing, located at the exhaust port of the air intake assembly, and receives the expanded pressure airflow; Among them, the rectifying duct and the load-bearing casing form a first Helmoltz resonator, the frequency of the first Helmoltz resonator is the same as the incoming flow disturbance frequency in the intake pipe, and the diffuser duct and the load-bearing casing form a second Helmoltz resonator, the frequency of the second Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly.

2. The multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to claim 1, It is characterized in that The load-bearing casing includes a first transition casing, an air bleed section casing, a test section casing, a measurement section casing and a second transition casing; One end of the first transfer casing is connected to the air intake pipe, and the other end is connected to one end of the air bleed section casing, the other end of the air bleed section casing is connected to one end of the test section casing, the other end of the test section casing is connected to one end of the measuring section casing, the other end of the measuring section casing is connected to one end of the second transfer casing, and the other end of the second transfer casing is connected to the exhaust pipe; The cross-section of the first adapter casing gradually decreases from one end connected to the air intake pipe to the other end connected to the air bleed section casing, the cross-sections of the air bleed section casing, the test section casing and the measuring section casing remain unchanged along the axial direction, and the cross-section of the second adapter casing gradually increases from one end connected to the measuring section casing to the other end connected to the exhaust pipe.

3. The multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to claim 2, It is characterized in that The cross sections of the air bleed section casing and the test section casing are both fan-shaped; The air bleed section casing comprises a first outer ring casing, a first inner ring casing and two first side casings, the first outer ring casing and the first inner ring casing are both arc-shaped, the arc radius of the first outer ring casing is greater than the arc radius of the first inner ring casing, and the two first side casings are both semicircular, respectively connecting the two ends of the first outer ring casing and the first inner ring casing, and forming a closed pipeline with the first outer ring casing and the first inner ring casing; The test section casing includes a second outer ring casing, a second inner ring casing and two second side casings. The second outer ring casing and the second inner ring casing are both arc-shaped. The arc radius of the second outer ring casing is larger than the arc radius of the second inner ring casing. The two second side casings are both semicircles, which respectively connect the two ends of the second outer ring casing and the second inner ring casing, and form a closed pipeline with the second outer ring casing and the second inner ring casing.

4. The multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to claim 3, It is characterized in that The rectifier duct is arranged inside the air bleed section casing, and the rectifier duct also includes a mounting plate. The inlet baffle also includes two transverse plates, which face the first outer ring casing and the first inner ring casing respectively, and have a gap G1 between the two transverse plates and the first outer ring casing and the first inner ring casing respectively. The two vertical plates are respectively connected to the transverse plate at one end and connected to one end of the rectifier tube at the other end. The other end of the rectifier tube is connected to the mounting plate. The cross-section of the rectifier tube remains unchanged along the axial direction, and the mounting plate is bolted to the fixing plate.

5. The multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to claim 3, It is characterized in that The cross section of the rectifier tube is fan-shaped, and includes an outer ring rectifier plate, an inner ring rectifier plate and two side rectifier plates; the first acoustic damping hole includes a first outer ring damping hole and a first inner ring damping hole; The outer ring rectifying plate and the inner ring rectifying plate are both arc-shaped, the arc radius of the outer ring rectifying plate is greater than the arc radius of the inner ring rectifying plate, the first outer ring damping hole is arranged on the outer ring rectifying plate, and the first inner ring damping hole is arranged on the inner ring rectifying plate; Two side rectifying plates are respectively connected to two ends of the outer ring rectifying plate and the inner ring rectifying plate, and extend in a radial direction to be connected to the first outer ring casing and the first inner ring casing; The outer ring rectifier plate, the first outer ring casing and the rectifier plates on both sides form a third cavity V 1 , forming a first outer ring Helmoltz resonator, the inner ring rectifier plate, the first inner ring casing and the rectifier plates on both sides form a fourth cavity V 2 , forming a first inner ring Helmoltz resonator.

6. The multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to claim 3, It is characterized in that The pressure diffuser pipe is arranged inside the test section casing, and two ends of the fixing plate are respectively connected with the second outer ring casing and the second inner ring casing by bolts; The cross section of the guide tube is fan-shaped and remains unchanged along the axial direction. The guide tube comprises an outer ring guide plate, an inner ring guide plate and two side guide plates. The outer ring guide plate and the inner ring guide plate are both arc-shaped. The arc radius of the outer ring guide plate is greater than the arc radius of the inner ring guide plate. The two side guide plates are respectively connected to the two ends of the outer ring guide plate and the inner ring guide plate, and extend in the radial direction to be connected to the second outer ring casing and the second inner ring casing. The other end of the flow diffuser is toward the flame tube assembly, and the cross section of the flow diffuser gradually increases from the end connected to the guide tube to the other end toward the flame tube assembly, so as to expand the airflow and guide the expanded airflow into the flame tube assembly; The outer ring guide plate, the second outer ring casing and the guide plates on both sides form a fifth cavity V. 3 , forming a second outer ring Helmoltz resonator, the inner ring guide plate, the second inner ring casing and the guide plates on both sides form a sixth cavity V 4 , forming a second inner ring Helmoltz resonator.

7. The multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to claim 3, It is characterized in that The cone wall includes an outer cone wall and an inner cone wall, the outer cone wall is close to the second outer casing, and there is a gap G2 between the outer cone wall and the second outer casing, and the inner cone wall is close to the second inner casing, and there is a gap G2 between the inner cone wall and the second inner casing; The second acoustic damping hole comprises a second outer ring damping hole and a second inner ring damping hole, the second outer ring damping hole is arranged on the outer ring cone wall, and the second inner ring damping hole is arranged on the inner ring cone wall.

8. The multi-headed sector-shaped combustion chamber test piece with a muffler cavity according to claim 3, It is characterized in that The flame tube assembly comprises a flame tube outer wall, a flame tube inner wall and two flame tube side walls; The outer wall of the flame tube and the inner wall of the flame tube are both arc-shaped, and the arc radius of the outer wall of the flame tube is greater than the arc radius of the inner wall of the flame tube; The two flame tube side walls are respectively connected to the two ends of the flame tube outer wall and the flame tube inner wall, and extend in the radial direction to be connected to the second outer ring casing and the second inner ring casing; The flame tube assembly further comprises a plurality of flame tube heads, which are located inside a region surrounded by an outer wall of the flame tube, an inner wall of the flame tube and two side walls of the flame tube and are evenly arranged along the circumference of the flame tube assembly.

9. The multi-head sector-shaped combustion chamber test piece with a muffler cavity according to claim 8, It is characterized in that It also includes a fuel nozzle, an ignition nozzle and a pulsating pressure sensing part, wherein the fuel nozzle, the ignition nozzle and the pulsating pressure sensing part are all arranged on the second outer ring casing; The fuel nozzle is connected to the flame tube assembly to spray the fuel into the flame tube assembly to mix with the diffuser airflow for combustion; The ignition nozzle is installed on the head of the flame tube in the middle position and is used to ignite the fuel and expand the air flow; The pulsating pressure sensing parts are respectively installed on the flame tube heads at non-middle positions and are used to measure the dynamic pressure of the gas during combustion.

10. A method for adjusting noise reduction, It is characterized in that The method is applied to a multi-headed sector-shaped combustion chamber test piece with a muffler cavity as described in any one of claims 1 to 9, comprising the following steps: The frequency of the first outer ring Helmoltz resonator is adjusted by adjusting the volume of the third cavity, the diameter and the number of the first outer ring damping holes, so that the frequency of the first outer ring Helmoltz resonator is the same as the frequency of the incoming flow disturbance in the intake pipe; The frequency of the first inner ring Helmoltz resonator is adjusted by adjusting the volume of the fourth cavity, the diameter and the number of the first inner ring damping holes, so that the frequency of the first inner ring Helmoltz resonator is the same as the frequency of the incoming flow disturbance in the intake pipe; The frequency of the second outer ring Helmoltz resonator is adjusted by adjusting the volume of the fifth cavity, the diameter and the number of the second outer ring damping holes, so that the frequency of the second outer ring Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly; The frequency of the second inner ring Helmoltz resonator is adjusted by adjusting the volume of the sixth cavity, the diameter and the number of the second inner ring damping holes, so that the frequency of the second inner ring Helmoltz resonator is the same as the combustion oscillation frequency in the flame tube assembly.

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