Combustion chamber cooling structure, combustion heater and additive manufacturing method thereof

Abstract

The invention belongs to the technical field of combustion chambers and additive manufacturing, and discloses a combustion chamber cooling structure, a combustion heater and an additive manufacturing method of the combustion heater. The combustion chamber cooling structure comprises a liquid inlet end, a liquid outlet end and a first flow channel which are arranged in the side wall of the combustion chamber. The liquid inlet end comprises a liquid inlet hole and a first liquid inlet chamber which are sequentially arranged in the liquid inlet direction. The first liquid inlet chamber obliquely extends to the combustion chamber side wall area corresponding to the gas inlet end in the liquid inlet direction, and the included angle between the top wall of the first liquid inlet chamber and the horizontal plane is not smaller than 45 degrees; two ends of the first liquid inlet chamber are respectively communicated with the liquid inlet hole and the first flow channel; and the first flow channel is communicated with the liquid outlet end. The combustion heater includes a combustion chamber cooling structure. According to the additive manufacturing method of the combustion heater, the combustion heater is formed in a vertically upward layer-by-layer stacking mode. According to the invention, a cooling blind area can be eliminated, the cooling effect is obviously improved, and support-free forming is realized.

Description

Technical Field

[0001] The present invention relates to the technical fields of combustion chambers and additive manufacturing. Background Art

[0002] As the core hot-end component of the heating system of hypersonic aerodynamic / propulsion ground test equipment, the combustion heater is the main area where oxidizer and fuel burn to generate high-temperature and high-pressure gas. In order to improve the service performance of the combustion heater in a high-temperature and high-pressure working environment, multiple water-cooling channels are usually designed inside the side walls of the combustion chamber of the combustion heater for active cooling, which greatly increases the manufacturing difficulty.

[0003] The traditional process for manufacturing the combustion heater is welding. Restricted by the welding process, the cooling channel structure on the side wall of the combustion chamber should be as simple and regular as possible to facilitate welding and forming after machining. However, a simple channel structure is not sufficient to meet the cooling requirements of the combustion chamber. Therefore, in order to machine more complex cooling channels inside the side wall structure of the combustion chamber, the integrated forming of the combustion chamber can be achieved through additive manufacturing technology.

[0004] Currently, due to the limitations of additive manufacturing processes, the top of the confluence chamber inside the side wall of the combustion chamber needs to be designed as a spire structure to achieve integrated additive manufacturing and support-free forming. Due to the existence of this spire structure, a cooling blind area is formed in the area of the gas inlet end of the combustion chamber corresponding to the spire structure, that is, the coolant cannot reach this area. However, this cooling blind area is the area with the highest temperature and pressure. Summary of the Invention

[0005] The present application provides a combustion chamber cooling structure to solve the contradiction problem between additive manufacturing and cooling blind areas caused by the spire structure.

[0006] The present invention is realized through the following technical solutions:

[0007] A combustion chamber cooling structure, comprising:

[0008] A liquid inlet end, a liquid outlet end and a first flow channel arranged inside the side wall of the combustion chamber;

[0009] The liquid inlet end includes a liquid inlet hole and a first liquid inlet chamber arranged in sequence along the liquid inlet direction;

[0010] The first liquid inlet chamber extends obliquely along the liquid inlet direction to the area of the side wall of the combustion chamber corresponding to the gas inlet end, and the included angle between the top wall of the first liquid inlet chamber and the horizontal plane is not less than 45°;

[0011] Both ends of the first liquid inlet chamber are respectively communicated with the liquid inlet hole and the first flow channel; the first flow channel is communicated with the liquid outlet end.

[0012] The present invention removes the pointed top structure of the first liquid inlet chamber and designs the first liquid inlet chamber as an obliquely extending structure so that the coolant can be guided along the first liquid inlet chamber to the side wall area of the combustion chamber corresponding to the gas inlet end, thereby eliminating the cooling blind area. Moreover, the angle between the top wall of the first liquid inlet chamber and the horizontal plane is not less than 45°, which can ensure that the first liquid inlet chamber is formed without support during additive manufacturing.

[0013] Further, the first liquid inlet chamber is an annular cavity surrounding the combustion chamber.

[0014] The first liquid inlet chamber is an annular cavity so that the liquid inlet holes share the connection between the first liquid inlet chamber and the first flow channel, simplifying the structure and also ensuring circumferential cooling of the side wall area of the combustion chamber corresponding to the gas inlet end.

[0015] Further, the first flow channel extends along the axial direction of the combustion chamber. In this way, axial cooling of the side wall of the combustion chamber can be achieved through the first flow channel.

[0016] Further, a plurality of first flow channels are circumferentially distributed along the side wall of the combustion chamber. In this way, circumferential cooling of the side wall of the combustion chamber can be achieved.

[0017] Further, it further includes a second liquid inlet chamber and a second flow channel arranged in sequence along the liquid inlet direction;

[0018] The second flow channel is located outside the first flow channel; both ends of the second liquid inlet chamber are respectively connected to the liquid inlet hole and the second flow channel; the second flow channel is connected to the liquid outlet end;

[0019] The second liquid inlet chamber extends obliquely along the liquid inlet direction to the second flow channel, and the angle between the top wall of the second liquid inlet chamber and the horizontal plane is not less than 45°

[0020] Adding the second liquid inlet chamber and the second flow channel can achieve differential temperature cooling of the side wall of the combustion chamber: the first flow channel is close to the inner side of the side wall of the combustion chamber, and the coolant flowing through the first flow channel takes away a large amount of heat, and the temperature of the coolant is relatively high; the second flow channel is located outside the first flow channel and is relatively far from the inner side of the side wall of the combustion chamber, and the temperature of the coolant flowing through the second flow channel is relatively low, which can carry away the heat outside the first flow channel, thereby improving the overall cooling and heat dissipation effect.

[0021] Adding the second liquid inlet chamber and the second flow channel can also reduce the pressure drop between the liquid inlet end and the liquid outlet end: the first liquid inlet chamber, the first flow channel, the second liquid inlet chamber, and the second flow channel form a double-chamber double-row cooling structure. Compared with the single-row cooling structure, the total cross-sectional area of the inner flow channels increases, which can reduce the flow resistance of the inner flow channels, so that the coolant can be discharged from the liquid inlet chamber more timely.

[0022] Furthermore, the first flow channel and the second flow channel are circumferentially staggered along the side wall of the combustion chamber. This can make the wall thickness of the side wall of the combustion chamber more uniform and ensure the strength of the side wall of the combustion chamber.

[0023] Furthermore, a plurality of liquid inlet holes are distributed circumferentially along the side wall of the combustion chamber; the second liquid inlet chamber is an annular cavity surrounding the combustion chamber.

[0024] By arranging a plurality of liquid inlet holes, the liquid inlet flow rate is increased. The second liquid inlet chamber is an annular cavity for sharing, which simplifies the structure and is convenient for processing and manufacturing.

[0025] Furthermore, the liquid outlet end includes a liquid outlet confluence chamber and a liquid outlet hole arranged in sequence along the liquid outlet direction; the liquid outlet confluence chamber has a pointed top structure, and the included angle of the pointed top structure is not less than 45°; both the first flow channel and the second flow channel extend along the axis direction of the combustion chamber to the liquid outlet confluence chamber and are connected to the liquid outlet hole through the liquid outlet confluence chamber.

[0026] The first flow channel and the second flow channel share the liquid outlet confluence chamber, which simplifies the structure; the pointed top structure of the liquid outlet confluence chamber ensures unsupported forming during additive manufacturing.

[0027] The present invention also provides a combustion heater, including the above-mentioned combustion chamber cooling structure.

[0028] The present invention also provides an additive manufacturing method for a combustion heater, which vertically stacks and forms the above-mentioned combustion heater layer by layer, and first forms the liquid outlet end at the lower end and then forms the liquid inlet end at the upper end.

[0029] First form the liquid outlet end and then form the liquid inlet end to ensure that the included angle between the top wall of the liquid inlet chamber and the horizontal plane and the included angle of the pointed top structure can meet the process requirements of unsupported forming in additive manufacturing.

[0030] The additive manufacturing method of the present invention realizes integrated manufacturing with high efficiency, high quality and low cost. The combustion heater processed by the additive manufacturing method of the present invention can eliminate the cooling blind area, significantly improve the cooling effect, and the overall structural strength and quality stability are improved, thereby greatly improving the service life and service reliability of the combustion chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1is a quarter-sectional view of the combustion chamber side wall in the prior art;

[0033] Figure 2 is a quarter-sectional view of the combustion chamber side wall in Embodiment 1;

[0034] Figure 3 is a schematic cross-sectional view of the combustion chamber side wall in Embodiment 1;

[0035] Figure 4 is a quarter-sectional view of the combustion chamber side wall in Embodiment 2;

[0036] Figure 5 is a schematic cross-sectional view of the combustion chamber side wall in Embodiment 2;

[0037] Figure 6 is a temperature field distribution diagram of the combustion chamber side wall in the prior art;

[0038] Figure 7 is a temperature field distribution diagram of the combustion chamber side wall in Embodiment 2;

[0039] Figure 8 is a cooling water pressure distribution diagram of the combustion chamber side wall in the prior art;

[0040] Figure 9 is a cooling water pressure distribution diagram of the combustion chamber side wall in Embodiment 2. Detailed implementation manners

[0041] Reference Figure 1 As shown, in the prior art, the top of the manifold chamber 1A inside the combustion chamber side wall needs to be designed as a spire structure to achieve integrated additive manufacturing and unsupported forming. Due to the existence of this spire structure, a cooling blind area 1b is formed in the area of the gas inlet end of the combustion chamber corresponding to the spire structure, that is, the coolant cannot reach this area.

[0042] To solve the contradiction problem between additive manufacturing and the cooling blind area caused by the spire structure, the present invention provides a combustion chamber cooling structure, removes the spire structure, and diverts the coolant to the gas inlet end by changing the structure of the manifold chamber (liquid inlet chamber), and meets the requirements of unsupported forming.

[0043] Embodiment 1

[0044] This embodiment specifically describes the combustion chamber cooling structure.

[0045] Reference Figure 2 As shown, a combustion chamber cooling structure includes:

[0046] A liquid inlet end, a liquid outlet end and a first flow channel 103 arranged inside the combustion chamber side wall 1;

[0047] The liquid inlet end includes a liquid inlet hole 101 and a first liquid inlet chamber 102 arranged in sequence along the liquid inlet direction;

[0048] The first liquid inlet chamber 102 extends obliquely along the liquid inlet direction to the side wall area of the combustion chamber corresponding to the gas inlet end, and the angle α between the top wall of the first liquid inlet chamber 102 and the horizontal plane is not less than 45°;

[0049] Both ends of the first liquid inlet chamber 102 are respectively communicated with the liquid inlet hole 101 and the first flow channel 103; the first flow channel 103 is communicated with the liquid outlet end.

[0050] In this embodiment, the pointed top structure of the first liquid inlet chamber 102 is removed, and the first liquid inlet chamber 102 is designed as an obliquely extending structure, so that the coolant can be guided along the first liquid inlet chamber 102 to the side wall area of the combustion chamber corresponding to the gas inlet end, thereby eliminating the cooling blind area. Moreover, the angle between the top wall of the first liquid inlet chamber 102 and the horizontal plane is not less than 45°, which can ensure that the first liquid inlet chamber 102 is formed without support during additive manufacturing.

[0051] Reference Figure 3 As described above, in this embodiment, a plurality of liquid inlet holes 101 are circumferentially distributed along the side wall 1 of the combustion chamber; the first liquid inlet chamber 102 is an annular cavity surrounding the combustion chamber.

[0052] In addition, the first liquid inlet chamber can also be a plurality of independent chambers circumferentially distributed along the side wall of the combustion chamber. In this case, the smaller the interval between the independent chambers, the better the cooling effect on the side wall area of the combustion chamber corresponding to the gas inlet end.

[0053] A plurality of liquid inlet holes 101 can increase the flow rate of the coolant. The first liquid inlet chamber 102 is an annular cavity, so that the liquid inlet holes 101 share the communication between the first liquid inlet chamber 102 and the first flow channel 103, simplifying the structure and ensuring circumferential cooling of the side wall area of the combustion chamber corresponding to the gas inlet end.

[0054] In this embodiment, the first flow channel 103 extends along the axial direction of the combustion chamber. In this way, axial cooling of the side wall 1 of the combustion chamber can be achieved through the first flow channel 103.

[0055] In this embodiment, a plurality of first flow channels 103 are circumferentially distributed along the side wall 1 of the combustion chamber. In this way, circumferential cooling of the side wall 1 of the combustion chamber can be achieved, and the cooling effect is more uniform.

[0056] In this embodiment, the liquid outlet end includes a liquid outlet confluence chamber 104 and a liquid outlet hole 105 arranged in sequence along the liquid outlet direction; the liquid outlet confluence chamber has a spire structure, and the included angle γ of the spire structure is not less than 45°; the first flow channel 103 extends along the axis direction of the combustion chamber to the liquid outlet confluence chamber, and is communicated with the liquid outlet hole 105 through the liquid outlet confluence chamber 104.

[0057] All the first flow channels share the liquid outlet confluence chamber, which can simplify the structure and facilitate processing and manufacturing. The spire structure of the liquid outlet confluence chamber 104 ensures unsupported forming during additive manufacturing.

[0058] Embodiment 2

[0059] This embodiment specifically describes another combustion chamber cooling structure.

[0060] Reference Figure 4 As shown, a combustion chamber cooling structure includes:

[0061] A liquid inlet end, a liquid outlet end and a first flow channel 103 arranged in the side wall 1 of the combustion chamber;

[0062] The liquid inlet end includes a liquid inlet hole 101 and a first liquid inlet chamber 102 arranged in sequence along the liquid inlet direction;

[0063] The first liquid inlet chamber 102 extends obliquely along the liquid inlet direction to the area of the side wall of the combustion chamber corresponding to the gas inlet end, and the included angle between the top wall of the first liquid inlet chamber 102 and the horizontal plane is not less than 45°;

[0064] Both ends of the first liquid inlet chamber 102 are communicated with the liquid inlet hole 101 and the first flow channel 103 respectively; the first flow channel 103 is communicated with the liquid outlet end;

[0065] It further includes a second liquid inlet chamber 106 and a second flow channel 107 arranged in sequence along the liquid inlet direction;

[0066] The second flow channel 107 is located outside the first flow channel 103; both ends of the second liquid inlet chamber 106 are communicated with the liquid inlet hole 101 and the second flow channel 107 respectively; the second flow channel 107 is communicated with the liquid outlet end;

[0067] The second liquid inlet chamber 106 extends obliquely along the liquid inlet direction to the second flow channel 107, and the included angle β between the top wall of the second liquid inlet chamber 106 and the horizontal plane is not less than 45°.

[0068] Adding a second liquid inlet chamber 106 and a second flow channel 107 can achieve differential temperature cooling of the combustion chamber sidewall 1: The first flow channel 103 is close to the inner side of the combustion chamber sidewall 1, and a large amount of heat is carried away by the coolant flowing through the first flow channel 103, so the temperature of the coolant is relatively high; the second flow channel 107 is located outside the first flow channel 103 and is relatively far from the inner side of the combustion chamber sidewall 1, and the temperature of the coolant flowing through the second flow channel 107 is relatively low, which can carry the heat outside the first flow channel 103, thereby improving the overall cooling and heat dissipation effect.

[0069] Adding the second liquid inlet chamber and the second flow channel 107 can also reduce the pressure drop between the liquid inlet end and the liquid outlet end: The first liquid inlet chamber 102, the first flow channel 103, the second liquid inlet chamber 106, and the second flow channel 107 form a double-chamber and double-row cooling structure. Compared with the single-row cooling structure, the total cross-sectional area of the inner flow channels increases, which can reduce the flow resistance of the inner flow channels, so that the coolant can be discharged from the liquid inlet chamber more timely.

[0070] In this embodiment, a plurality of liquid inlet holes 101 are circumferentially distributed along the combustion chamber sidewall 1; the second liquid inlet chamber 106 is an annular cavity surrounding the combustion chamber 1. By providing a plurality of liquid inlet holes 101, the liquid inlet flow rate is increased. The second liquid inlet chamber 106 is an annular cavity for sharing, which simplifies the structure and is convenient for processing and manufacturing.

[0071] Reference Figure 5 As shown, in this embodiment, the first flow channel 103 and the second flow channel 107 are circumferentially staggered along the combustion chamber sidewall 1. This can make the wall thickness of the combustion chamber sidewall 1 more uniform and ensure the strength of the combustion chamber sidewall 1.

[0072] In this embodiment, the liquid outlet end includes a liquid outlet confluence chamber 104 and a liquid outlet hole 105 arranged in sequence along the liquid outlet direction; the liquid outlet confluence chamber has a spire structure, and the angle of the spire structure is not less than 45°; both the first flow channel 103 and the second flow channel 107 extend along the axis direction of the combustion chamber to the liquid outlet confluence chamber and are connected to the liquid outlet hole 105 through the liquid outlet confluence chamber 104.

[0073] The first flow channel 103 and the second flow channel 107 share the liquid outlet confluence chamber, which simplifies the structure; the spire structure of the liquid outlet confluence chamber ensures support-free forming during additive manufacturing.

[0074] Embodiment 3

[0075] This embodiment also provides a combustion heater, including the combustion chamber cooling structure of Embodiment 1 or 2.

[0076] This embodiment also provides an additive manufacturing method for a combustion heater, which vertically stacks and forms the above-mentioned combustion heater layer by layer, and first forms the liquid outlet end at the lower end and then forms the liquid inlet end at the upper end.

[0077] First, form the liquid outlet end, and then form the liquid inlet end to ensure that the angles between the top wall of the liquid inlet chamber and the horizontal plane and the tip structure can comply with the process requirements of additive manufacturing without support.

[0078] In this embodiment, selective laser melting technology is used for integrated additive manufacturing. The forming direction is that the liquid inlet end is on the upper side and the liquid outlet end is on the lower side, and it is stacked layer by layer vertically upward. The inclination angles of the first liquid inlet chamber and the second liquid inlet chamber with the horizontal plane are both designed to be 45°, realizing support-free printing. After post-treatment processes such as vibration powder cleaning, stress relief annealing, and wire cutting, a combustion heater with a new structure of double-chamber double-row differential temperature cooling is obtained.

[0079] The additive manufacturing method of this embodiment realizes high-efficiency, high-quality, and low-cost integrated manufacturing. The combustion heater processed by the additive manufacturing method of this embodiment can eliminate the cooling blind area, significantly improve the cooling effect, and the overall structural strength and quality stability are improved, thereby greatly improving the service life and service reliability of the combustion heater.

[0080] Embodiment 4

[0081] In this embodiment, finite element simulation is used to compare and verify the cooling effect of the combustion heater.

[0082] First, establish a finite element model of fluid-solid coupling for heat transfer between the water-cooled internal flow channel of the combustion chamber and the high-temperature and high-pressure gas on the wall surface (hereinafter referred to as the finite element model). The model material is selected as GH3625 nickel-based alloy, and the key finite element model parameters are shown in Table 1. Under the condition that the cooling water inlet flow rate is set to 60 kg / s, the SST k-Omega control equation is used for solution. The finite element model is calculated according to Equations (1), (2), and (3), so as to inversely deduce the required cooling water inlet pressure and obtain the temperature field of the combustion chamber and the cooling water pressure distribution in the flow channel.

[0083] Table 1 Model parameters

[0084]

[0085]

[0086] In the formula: P k is the turbulent production term; β * is the turbulent model parameter; σ k is the turbulent Prandtl number; u t is the turbulent viscosity coefficient (based on the turbulent shear stress); α, β, σ ω are the turbulent model parameters; R TIt is the turbulent interaction term. The SST model combines the advantages of the k-ω model and the k-∈ model, is used to better predict turbulent separation and boundary layer characteristics, realizes the combination of the two models, and finally introduces a correction term for turbulent shear stress to improve the prediction results.

[0087] According to the established finite element model, the temperature field distributions of the combustion heaters in the prior art ( Figure 1 ) and the combustion heaters including the combustion chamber cooling structure in Embodiment 2 are respectively simulated under the working condition of the water inlet flow rate of 60 kg / S in the combustion chamber, as shown in Figure 6 、 Figure 7 ; and the water pressure distributions of the combustion heaters in the prior art ( Figure 1 ) and the combustion heaters including the combustion chamber cooling structure in Embodiment 2 are respectively simulated, as shown in Figure 8 、 Figure 9 . Finally, the cooling effect under the working condition of the water inlet flow rate of 60 kg / S in the combustion chamber is obtained:

[0088] Table 1 Comparison of cooling effects

[0089]

[0090]

[0091] The combustion chamber (original model) in the prior art: the inlet cooling water pressure is 3.05 MPa, the outlet pressure is 0.38 MPa, the pressure drop is 2.27 MPa, the highest temperature of the combustion heating wall surface is 638.2 K, and the average temperature is 455.4 K.

[0092] The combustion chamber (double-chamber double-row) corresponding to Embodiment 2: the inlet cooling water pressure is 1.64 MPa, the inlet cooling water pressure is reduced to 53.8% of the original structure, the outlet pressure is 0.44 MPa, and the pressure drop is 1.05 MPa; the highest temperature of the combustion heating wall surface is 440.8 K, which is reduced to 69.1% of the original structure; the average wall temperature is 367.3 K, which is reduced to 80.7% of the original structure.

[0093] The present invention eliminates the cooling blind area by improving the structure of the liquid inlet chamber, makes the cooling effect more uniform, reduces the flow resistance and the pressure drop through the double-row flow channels, promotes the rapid circulation of the coolant, and thus significantly improves the cooling effect.

[0094] Obviously, the above embodiments are only examples clearly described and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A combustion chamber cooling structure, characterized in that: include: A liquid inlet end, a liquid outlet end and a first flow channel are arranged in the side wall of the combustion chamber; The liquid inlet end comprises a liquid inlet hole and a first liquid inlet chamber which are sequentially arranged along the liquid inlet direction; The first liquid inlet chamber extends obliquely along the liquid inlet direction to the combustion chamber side wall area corresponding to the gas inlet end, and the angle between the top wall of the first liquid inlet chamber and the horizontal plane is not less than 45°; Two ends of the first liquid inlet chamber are respectively communicated with the liquid inlet hole and the first flow channel; the first flow channel is communicated with the liquid outlet.

2. The combustion chamber cooling structure according to claim 1, characterized in that: The first liquid inlet chamber is an annular chamber surrounding the combustion chamber.

3. The combustion chamber cooling structure according to claim 1, characterized in that: The first flow channel extends along the axial direction of the combustion chamber.

4. The combustion chamber cooling structure according to claim 1, characterized in that: A plurality of first flow channels are distributed circumferentially along the side wall of the combustion chamber.

5. The combustion chamber cooling structure according to claim 1, characterized in that: It also includes a second liquid inlet chamber and a second flow channel which are sequentially arranged along the liquid inlet direction; The second flow channel is located outside the first flow channel; two ends of the second liquid inlet chamber are respectively connected to the liquid inlet hole and the second flow channel; the second flow channel is connected to the liquid outlet; The second liquid inlet chamber extends obliquely along the liquid inlet direction to the second flow channel, and the angle between the top wall of the second liquid inlet chamber and the horizontal plane is not less than 45°.

6. The combustion chamber cooling structure according to claim 4, characterized in that: The first flow channel and the second flow channel are staggeredly distributed along the circumferential direction of the combustion chamber side wall.

7. The combustion chamber cooling structure according to any one of claims 1 to 6, characterized in that: A plurality of liquid inlet holes are distributed circumferentially along the side wall of the combustion chamber; the second liquid inlet chamber is an annular cavity surrounding the combustion chamber.

8. The combustion chamber cooling structure according to claim 7, characterized in that: The liquid outlet end includes a liquid outlet confluence chamber and a liquid outlet hole which are arranged in sequence along the liquid outlet direction; the liquid outlet confluence chamber has a pointed top structure, and the angle of the pointed top structure is not less than 45°; the first flow channel and the second flow channel both extend along the axial direction of the combustion chamber to the liquid outlet confluence chamber, and are connected to the liquid outlet hole through the liquid outlet confluence chamber.

9. A combustion heater, characterized in that: It comprises a combustion chamber cooling structure as described in any one of claims 1 to 8.

10. A method for additive manufacturing of a combustion heater, characterized in that: The combustion heater as claimed in claim 9 is formed by stacking layers vertically upward, and the liquid outlet at the lower end is formed first, and then the liquid inlet at the upper end is formed.

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