A large-size water-cooled combustion chamber with a three-layer structure and a manufacturing method thereof

Abstract

The present invention discloses a large-sized water-cooled combustion chamber with a three-layer structure and a manufacturing method thereof. The large-sized water-cooled combustion chamber has a three-layer structure of an inner wall, an outer wall and a pressure-bearing shell. The outer wall surface of the inner wall or the inner wall surface of the outer wall is provided with a plurality of longitudinal cooling grooves parallel to the central axis, and the two ends of the three-layer circular tube are blocked by annular plugs. In the manufacturing method of the large-sized water-cooled combustion chamber, the inner wall and the outer wall are fixedly connected by brazing, and after forming an assembly, the pressure-bearing shell is fixedly connected by interference fit. The large-sized water-cooled combustion chamber can meet the requirements of high working parameters and large-sized combustion chambers, achieve a gas temperature of 2000~3000K, a working pressure of more than 10MPa, and a combustion chamber inner diameter dimension greater than 500mm, which exceeds the current largest rocket engine thrust chamber size, and has engineering practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature combustion wind tunnels, and in particular relates to a large-size water-cooled combustion chamber with a three-layer structure and a manufacturing method thereof. Background Art

[0002] The combustion chamber is a key component of high-temperature equipment such as ground gas flow and arc, and wind tunnel devices. With the increase in the scale of aerospace engines / aircraft, the working parameters of the combustion chamber need to be continuously expanded, especially for high enthalpy, large dynamic pressure and long-term simulation conditions. The internal gas temperature of the combustion chamber is required to be as high as 1600K~3000K, and the working pressure exceeds 10MPa. This brings new challenges to the design and manufacture of combustion chamber cooling, especially as the scale of the combustion chamber increases, this challenge becomes more intense.

[0003] For reusable combustion chambers, when the temperature is higher than 1300K and the working time is longer than 30s, circulating water is usually used for cooling. There are two typical structures: one is an assembly structure, that is, a closed cooling channel is formed between the assembly blocks to achieve the purpose of cooling the combustion chamber wall; the other is a welding structure, that is, the inner and outer walls are welded to form a closed cooling channel. The cooling channel can be processed on the inner or outer wall side. At this time, the welding process generally adopts the brazing process.

[0004] The first assembly structure has two main shortcomings. First, after long-term use due to thermal expansion and contraction, the seal between the assembly structures is prone to failure, resulting in water leakage. Second, since the inner wall and the outer wall are not combined, when the combustion chamber is large enough, the inner wall cannot withstand the high-pressure cooling water pressure. In order to maintain effective cooling under high heat flow conditions, the wall thickness of the inner wall is generally only 2mm~5mm.

[0005] The second type of welding structure is mainly brazing structure. The main problem is that when the combustion chamber is too large, the outer wall is thicker due to the pressure requirement, resulting in a large overall weight, which exceeds the upper limit of the vacuum brazing furnace. When the weight is too large, uneven temperature rise of the test piece can easily lead to poor brazing quality, thereby increasing the scrap rate. The upper limit of the current maximum-scale brazing furnace is about 500kg. When the combustion chamber diameter exceeds 450mm, the length exceeds 800mm, and the gas pressure exceeds 8MPa, the designed inner and outer wall weight will generally reach more than 1t, making it impossible to weld.

[0006] Currently, there is an urgent need to develop a large-sized water-cooled combustion chamber with a three-layer structure and a manufacturing method thereof. Summary of the invention

[0007] One technical problem to be solved by the present invention is to provide a large-sized water-cooled combustion chamber with a three-layer structure. Another technical problem to be solved by the present invention is to provide a method for manufacturing a large-sized water-cooled combustion chamber with a three-layer structure.

[0008] The large-sized water-cooled combustion chamber with a three-layer structure of the present invention is characterized in that the large-sized water-cooled combustion chamber comprises three layers of circular tubes from the inside to the outside with the same central axis, the inner circular tube is the inner wall, the middle circular tube is the outer wall, the outer circular tube with flange is the pressure-bearing shell, the outer wall surface of the inner wall or the inner wall surface of the outer wall is provided with a plurality of longitudinal cooling grooves parallel to the central axis, the inner wall and the outer wall are fixedly connected by brazing, and the longitudinal cooling grooves are closed, isolated and not connected;

[0009] Annular grooves are provided at both ends of the pressure shell for cooling water confluence. The annular groove at the front end and the annular plug block I at the front end, as well as the annular groove at the rear end and the annular plug block II at the rear end are sealed by vacuum electron beam welding. An annular cooling water supply manifold is fixed to the circumference of the flange at the front end of the pressure shell. A cooling water inlet is provided on the cooling water supply manifold, and the cooling water supply manifold is connected to the annular groove at the front end through a number of cooling water supply branches distributed along the circumference. An annular cooling water outlet manifold is fixed to the circumference of the flange at the rear end of the pressure shell. A cooling water outlet is provided on the cooling water outlet manifold, and the cooling water outlet manifold is connected to the annular groove at the rear end through a number of cooling water outlet branches distributed along the circumference.

[0010] The large-sized water-cooled combustion chamber is also equipped with two pressure sensors for measuring the combustion chamber pressure.

[0011] The method for manufacturing a large-sized water-cooled combustion chamber with a three-layer structure of the present invention comprises the following steps:

[0012] S1. Processing a plurality of longitudinal cooling grooves parallel to the central axis on the outer wall surface of the inner wall or the inner wall surface of the outer wall, and then silver-plating;

[0013] S2. The inner wall and the outer wall are assembled together and placed in a vacuum brazing furnace for brazing to obtain assembly I. Assembly I is subjected to a water pressure test until it meets the design requirements;

[0014] S3. Process the outer surface of the outer wall until the outer surface of assembly I meets the surface accuracy requirements;

[0015] S4. Repair the assembly I and the pressure shell with interference fit until the design requirements are met;

[0016] S5. Cooling the assembly I in liquid nitrogen, and then performing interference fit with the pressure-bearing shell to obtain assembly II;

[0017] S6. A ring plug I is machined at the front end of assembly II, a ring plug II is machined at the rear end of assembly II, and assembly II, ring plug I, ring plug II and pressure shell are welded into assembly III by electron beam or fusion welding;

[0018] S7. Weld cooling water supply branches and corresponding cooling water supply manifolds distributed along the circumferential direction on the front flange, weld cooling water outlet branches and corresponding cooling water outlet manifolds distributed along the circumferential direction on the rear flange, and check all contact surfaces that need to be sealed and seal them to obtain assembly IV;

[0019] S8. Two mounting holes for pressure sensors are processed on the tube body of assembly IV, with one pressure sensor installed in each mounting hole; after the processing is completed, a large-sized water-cooled combustion chamber with a three-layer structure is obtained.

[0020] Furthermore, the inner wall and the outer wall are made of copper alloy, and the pressure-bearing shell is made of stainless steel.

[0021] The large-sized water-cooled combustion chamber with a three-layer structure of the present invention has the following characteristics:

[0022] a. It adopts a three-layer structure: inner wall, outer wall and pressure-bearing shell. The inner wall and outer wall are fixedly connected by brazing. After forming an assembly, it is fixedly connected to the pressure-bearing shell by interference fit;

[0023] b. After the inner wall, outer wall and pressure shell are assembled, annular plugs are used to seal the cooling water at both ends.

[0024] The large-sized water-cooled combustion chamber with a three-layer structure of the present invention can significantly reduce the brazing weight by more than 80% compared to the traditional two-layer welded structure combustion chamber, thereby reducing the load-bearing requirements of the large-sized combustion chamber for the brazing furnace, making it possible to use brazing for combustion chambers of larger scale and higher working parameters.

[0025] The inner wall and outer wall of the large-sized water-cooled combustion chamber with a three-layer structure of the present invention are heat-bearing structures as a whole, and the interference fit with the pressure-bearing shell is conducive to increasing the gas pressure. The pressure-bearing shell is the main pressure-bearing component. The heat-bearing and pressure-bearing separation design facilitates the selection of materials and improves the working parameters. For example, the inner wall material can be made of copper alloy with good thermal conductivity, and the pressure-bearing shell adopts a stainless steel structure. The heat-bearing and pressure-bearing designs have achieved a certain degree of decoupling.

[0026] Compared with the traditional two-layer welded structure combustion chamber, the large-sized water-cooled combustion chamber with a three-layer structure of the present invention has no flanges and other components, and the inner and outer walls have uniform sizes. The material in the brazing furnace is heated evenly, which is convenient for improving the brazing quality and ensuring the success rate.

[0027] For large-scale, high-operating-parameter (high-temperature and high-pressure) combustion chambers, the large-scale water-cooled combustion chamber with a three-layer structure of the present invention has a three-layer structure of inner wall, outer wall, and pressure-bearing shell. On the one hand, it avoids the shortcomings of insufficient pressure bearing and unreliable cooling water sealing of the traditional two-layer welded combustion chamber assembly structure, and at the same time avoids the shortcomings of excessive weight and uneven heating of the traditional two-layer welded combustion chamber brazing structure. It can meet the needs of high-operating-parameter, large-scale combustion chambers, achieve a gas temperature of 2000~3000K, an operating pressure of more than 10MPa, and a combustion chamber inner diameter of more than 500mm, which exceeds the current largest rocket engine thrust chamber size, and has engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram (front cross-sectional view) of a large-sized water-cooled combustion chamber with a three-layer structure of the present invention;

[0029] Figure 2 It is a structural schematic diagram of a large-sized water-cooled combustion chamber with a three-layer structure of the present invention (a side partial cross-sectional view);

[0030] Figure 3 It is a schematic diagram of the partial cross-sectional structure of the large-sized water-cooled combustion chamber with a three-layer structure after the inner wall and the outer wall are assembled.

[0031] In the figure, 1. inner wall; 2. outer wall; 3. annular plug block I; 4. pressure-bearing shell; 5. cooling water supply branch pipe; 6. cooling water supply manifold; 7. pressure sensor; 8. cooling water outlet manifold; 9. cooling water outlet branch pipe; 10. annular plug block II; 11. cooling water inlet; 12. cooling water outlet; 13. longitudinal cooling groove. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] like Figure 1~Figure 3 As shown, the large-sized water-cooled combustion chamber with a three-layer structure in this embodiment includes three layers of circular tubes from the inside to the outside with the same central axis, the inner circular tube is the inner wall 1, the middle circular tube is the outer wall 2, and the outer circular tube with flange is the pressure shell 4. The outer wall surface of the inner wall 1 or the inner wall surface of the outer wall 2 is provided with a plurality of longitudinal cooling grooves 13 parallel to the central axis, the inner wall 1 and the outer wall 2 are fixedly connected by brazing, and the longitudinal cooling grooves 13 are closed, isolated and not connected;

[0035] Annular grooves are provided at both ends of the pressure shell 4 for cooling water confluence. The annular groove at the front end and the annular plug block Ⅰ3 at the front end, and the annular groove at the rear end and the annular plug block Ⅱ10 at the rear end are sealed by vacuum electron beam welding. An annular cooling water supply manifold 6 is fixed to the circumference of the flange at the front end of the pressure shell 4. A cooling water inlet 11 is provided on the cooling water supply manifold 6. The cooling water supply manifold 6 is connected to the annular groove at the front end through a number of cooling water supply branch pipes 5 distributed along the circumference. An annular cooling water outlet manifold 8 is fixed to the circumference of the flange at the rear end of the pressure shell 4. A cooling water outlet 12 is provided on the cooling water outlet manifold 8. The cooling water outlet manifold 8 is connected to the annular groove at the rear end through a number of cooling water outlet branch pipes 9 distributed along the circumference.

[0036] Two pressure sensors 7 for measuring the combustion chamber pressure are also installed on the large-sized water-cooled combustion chamber.

[0037] The method for manufacturing a large-sized water-cooled combustion chamber with a three-layer structure in this embodiment includes the following steps:

[0038] S1. A plurality of longitudinal cooling grooves 13 are processed parallel to the central axis on the outer wall surface of the inner wall 1 or the inner wall surface of the outer wall 2, and then silver-plated;

[0039] S2. The inner wall 1 and the outer wall 2 are assembled together and placed in a vacuum brazing furnace for brazing to obtain an assembly Ⅰ, and the assembly Ⅰ is subjected to a water pressure test until the design requirements are met;

[0040] S3. Processing the outer surface of the outer wall 2 until the outer surface of the assembly Ⅰ meets the surface accuracy requirements;

[0041] S4. Repair the assembly I and the pressure-bearing shell 4 by interference fit until the design requirements are met;

[0042] S5. The assembly Ⅰ is placed in liquid nitrogen for cooling, and then interference fit is performed with the pressure shell 4 to obtain the assembly Ⅱ;

[0043] S6. A circular plug Ⅰ3 is processed at the front end of the assembly Ⅱ, a circular plug Ⅱ10 is processed at the rear end of the assembly Ⅱ, and the assembly Ⅱ, the circular plug Ⅰ3, the circular plug Ⅱ10 and the pressure shell 4 are welded into an assembly Ⅲ by electron beam or fusion welding;

[0044] S7. Weld the cooling water supply branch pipe 5 and the corresponding cooling water supply manifold 6 distributed along the circumferential direction on the front flange, and weld the cooling water outlet branch pipe 9 and the corresponding cooling water outlet manifold 8 distributed along the circumferential direction on the rear flange, and check all the contact surfaces that need to be sealed and seal them to obtain assembly IV;

[0045] S8. Two mounting holes for the pressure sensors 7 are processed on the tube body of the assembly IV, with one pressure sensor 7 installed in each mounting hole; after the processing is completed, a large-sized water-cooled combustion chamber with a three-layer structure is obtained.

[0046] Furthermore, the inner wall 1 and the outer wall 2 are made of copper alloy, and the pressure-bearing shell 4 is made of stainless steel.

[0047] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and the embodiments, and can be fully applied to various technical fields suitable for the present invention. For those familiar with the art, additional improvements and modifications can be easily realized, so without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the legends shown and described here.

Claims

1. A large-sized water-cooled combustion chamber with a three-layer structure, characterized in that: The large-sized water-cooled combustion chamber comprises three layers of circular tubes from the inside to the outside with the same central axis, the inner circular tube being the inner wall (1), the middle circular tube being the outer wall (2), and the outer circular tube with flange being the pressure-bearing shell (4), the outer wall surface of the inner wall (1) or the inner wall surface of the outer wall (2) being provided with a plurality of longitudinal cooling grooves (13) parallel to the central axis, the inner wall (1) and the outer wall (2) being fixedly connected by brazing, and the longitudinal cooling grooves (13) being closed, isolated and not connected; Annular grooves are provided at both ends of the pressure shell (4), and the annular grooves are used for cooling water confluence. The annular groove at the front end and the annular plug block I (3) at the front end, and the annular groove at the rear end and the annular plug block II (10) at the rear end are sealed by vacuum electron beam welding. An annular cooling water supply manifold (6) is fixed to the circumference of the flange at the front end of the pressure shell (4), and a cooling water inlet (11) is provided on the cooling water supply manifold (6). The cooling water supply manifold (6) is connected to the annular groove at the front end through a plurality of cooling water supply branch pipes (5) distributed along the circumference. An annular cooling water outlet manifold (8) is fixed to the circumference of the flange at the rear end of the pressure shell (4), and a cooling water outlet (12) is provided on the cooling water outlet manifold (8). The cooling water outlet manifold (8) is connected to the annular groove at the rear end through a plurality of cooling water outlet branch pipes (9) distributed along the circumference. Two pressure sensors (7) for measuring the combustion chamber pressure are also installed on the large-sized water-cooled combustion chamber.

2. The method for manufacturing a large-sized water-cooled combustion chamber with a three-layer structure according to claim 1, wherein the method is used to manufacture a large-sized water-cooled combustion chamber with a three-layer structure, and is characterized in that: The following steps are involved: S1. Processing a plurality of longitudinal cooling grooves (13) parallel to the central axis on the outer wall surface of the inner wall (1) or the inner wall surface of the outer wall (2), and then performing a silver plating process; S2. The inner wall (1) and the outer wall (2) are set together and placed in a vacuum brazing furnace for brazing to obtain an assembly Ⅰ, and the assembly Ⅰ is subjected to a water pressure test until the design requirements are met; S3. Processing the outer surface of the outer wall (2) until the outer surface of the assembly I meets the surface accuracy requirements; S4. Repair the assembly I and the pressure housing (4) by interference fit until the design requirements are met; S5. The assembly Ⅰ is placed in liquid nitrogen for cooling, and then interference fit is performed with the pressure shell (4) to obtain an assembly Ⅱ; S6. A circular plug Ⅰ (3) is processed at the front end of the assembly Ⅱ, a circular plug Ⅱ (10) is processed at the rear end of the assembly Ⅱ, and the assembly Ⅱ, the circular plug Ⅰ (3), the circular plug Ⅱ (10) and the pressure shell (4) are welded into the assembly Ⅲ by electron beam or fusion welding; S7. Weld the cooling water supply branch pipe (5) and the corresponding cooling water supply manifold (6) distributed along the circumferential direction on the front flange, weld the cooling water outlet branch pipe (9) and the corresponding cooling water outlet manifold (8) distributed along the circumferential direction on the rear flange, and check all the contact surfaces that need to be sealed and seal them to obtain assembly IV; S8. Two mounting holes for the pressure sensors (7) are processed on the tube body of the assembly IV, with one pressure sensor (7) being installed in each mounting hole; after the processing is completed, a large-sized water-cooled combustion chamber with a three-layer structure is obtained.

3. The method for manufacturing a large-sized water-cooled combustion chamber with a three-layer structure according to claim 2, characterized in that: The inner wall (1) and the outer wall (2) are made of copper alloy, and the pressure-bearing shell (4) is made of stainless steel.

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