Coaxial double-swirl combustion chamber nozzle structure with vacuum heat insulation layer

Abstract

The invention discloses a coaxial double-rotational-flow combustion chamber nozzle structure with a vacuum heat insulation layer, and belongs to the field of aero-engines. Comprising multiple stages of rotational flow units which are coaxially arranged and used for forming a graded rotational flow air field; the at least one fuel oil nozzle is arranged on the inner side or the downstream of the multi-stage rotational flow unit and is used for spraying fuel oil into the rotational flow air field; the vacuum heat insulation cavity is arranged on the periphery of the fuel nozzle; wherein an air exhaust hole is formed in the vacuum heat insulation cavity, and the air exhaust hole is sealed to enable the vacuum heat insulation cavity to keep a high-vacuum state, so that radiant heat transfer from a high-temperature environment of a combustion chamber to the fuel nozzle is effectively blocked. Heat radiation of flames of a combustion chamber to fuel oil in the nozzle is reduced through the vacuum heat insulation characteristic, the heat resistance of the nozzle is improved, and coking of the fuel oil in the nozzle is restrained.

Description

Technical Field

[0001] This invention belongs to the field of aero-engines, and specifically relates to a coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer. Background Technology

[0002] In the design of aero-engine combustors, the performance of fuel nozzles has a significant impact on combustion efficiency, emission characteristics, and engine life. Traditional fuel nozzles operate under high temperature and high pressure conditions and are directly affected by the combustion chamber flame. This can cause the fuel inside the nozzle to coke due to heat, affecting spray quality and leading to unstable combustion. To address this issue, the heat insulation design of fuel nozzles has become a key direction in current combustor technology research and development.

[0003] Currently, aircraft engine fuel nozzles are mainly divided into direct-injection nozzles and centrifugal nozzles. Direct-injection nozzles can provide higher fuel jet penetration and are suitable for combustion environments with high airflow velocities, while centrifugal nozzles rely on a swirling structure to form fine fuel droplets, improving fuel evaporation and combustion efficiency. Under high-temperature environments, the fuel inside centrifugal nozzles may coke and deposit due to heat conduction, affecting long-term reliability.

[0004] To reduce the heat exposure of fuel nozzles in high-temperature environments, an effective method is to employ thermal insulation technology. Currently, thermal insulation designs mainly include ceramic coatings, air insulation layers, and vacuum insulation layers. While ceramic coatings offer some thermal resistance, their thermal shock resistance is weak, making them prone to cracking during long-term operation. Air insulation layers rely on specific flow channel designs, requiring precise control of airflow to ensure good insulation performance. In contrast, vacuum insulation layers, due to their lower thermal conductivity, have become an important research direction in the thermal insulation technology of aero-engine fuel nozzles.

[0005] In summary, existing nozzle structures lack sufficient thermal protection capabilities in high-temperature environments, have limited insulation methods, and cannot effectively block the heat radiation path of high-temperature combustion gases to the fuel inside the nozzle, resulting in the continued risk of coking. Therefore, there is an urgent need for a new nozzle structure that combines efficient heat insulation, compact structure, manufacturability, and suitability for high-temperature combustion environments. Summary of the Invention

[0006] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides a coaxial dual-swirling combustor nozzle structure with a vacuum insulation layer. This nozzle structure combines a primary mold secondary swirling system and a secondary mold primary swirling system. A vacuum insulation annular cavity is set outside both the direct-injection nozzle and the centrifugal nozzle. After vacuuming through an extraction port, the cavity is welded and sealed to form a high-vacuum heat insulation barrier, significantly reducing heat conduction and radiation. This invention aims to optimize the nozzle's heat insulation performance, improve its heat resistance, and effectively prevent fuel coking; thereby achieving efficient thermal protection, optimized atomization performance, and suppression of nozzle coking problems, meeting the stringent operating requirements of next-generation aero-engines.

[0007] The technical solution of this invention is: a coaxial dual-swirl combustion chamber nozzle structure with a vacuum insulation layer, comprising: Coaxially arranged multi-stage swirl units are used to form a graded swirl air field; At least one fuel nozzle is disposed inside or downstream of the multi-stage swirl unit for injecting fuel into the swirling air field; And, a vacuum insulation cavity disposed around the fuel nozzle; The vacuum insulation cavity is provided with an air extraction hole, which is sealed to keep the vacuum insulation cavity in a high vacuum state, thereby effectively blocking the radiative heat transfer from the high temperature environment of the combustion chamber to the fuel nozzle.

[0008] A further technical solution of the present invention is: the multi-stage swirl unit includes: The main mold secondary cyclone unit 100 includes an outer wall surface 104 and an inner wall surface 110 of the main mold secondary cyclone separator. There are multiple cyclone blades 106 between the inner and outer wall surfaces. A non-cyclone air channel is formed between the inner wall surface 110 and the outer wall surface 112 of the secondary mold primary cyclone separator. Some air is cooled to the end face through several cooling holes 114. The secondary mold primary cyclone unit 200 includes the inner wall surface 212 of the secondary mold primary cyclone separator and the centrifugal nozzle mounting base 214 of the secondary mold primary cyclone separator. There are several secondary mold primary cyclone separator blades 210 between them. One fuel supply is provided through the duty oil inlet pipe 208, and another fuel supply is provided from the main combustion stage oil inlet pipe 204 through the main combustion stage oil collecting ring 216 to multiple direct injection nozzles 218. The inlet air passes through the atomizing air flow channel 206, part of which helps atomize the fuel inside the direct injection nozzle, and part of which cools the end face through several cooling holes 222.

[0009] A further technical solution of the present invention is: the fuel nozzle includes a plurality of direct-shot nozzles 218 disposed circumferentially on the sub-mold primary swirling unit 200 and a single-oil-path centrifugal fuel nozzle 300 disposed on its central axis; the vacuum insulation cavity includes a sub-mold primary swirling unit vacuum insulation ring cavity 220 opened on the inner wall surface 212 of the sub-mold primary swirling unit 200, and a nozzle vacuum insulation ring cavity 304 opened on the nozzle outer shell 302 of the single-oil-path centrifugal fuel nozzle 300.

[0010] A further technical solution of the present invention is: the vacuum insulation ring cavity 220 of the secondary mold first-stage cyclone separator is provided with a plurality of columnar beams 226 evenly distributed along the circumference. The columnar beams are used to support the inner and outer wall structures of the vacuum insulation ring cavity 220 of the secondary mold first-stage cyclone separator and to isolate the gas heat transfer path between the external atomizing air flow path 206 and the vacuum insulation ring cavity 220 of the secondary mold first-stage cyclone separator.

[0011] A further technical solution of the present invention is that the vacuum insulation ring cavity evacuation hole 224 of the sub-mold first-stage cyclone separator on the sub-mold first-stage cyclone separator vacuum insulation ring cavity 220 and the nozzle vacuum insulation ring cavity evacuation hole 306 of the nozzle vacuum insulation ring cavity 304 are sealed by vacuum electron beam welding to form a closed high vacuum structure.

[0012] A further technical solution of the present invention is that the vacuum degree in the vacuum insulation annular cavity 220 of the secondary mold first-stage cyclone separator and the vacuum insulation annular cavity 304 of the nozzle is less than 10. -2 Pa is used to cut off the radiative heat transfer of high-temperature gas to the fuel path of the nozzle.

[0013] A further technical solution of the present invention is that the radial thickness of the vacuum insulation annular cavity 220 of the secondary mold primary hydrocyclone and the vacuum insulation annular cavity 304 of the nozzle is 1mm to 2mm.

[0014] A further technical solution of the present invention is: the nozzle housing 302 and the inner wall surface 212 of the sub-mold first-stage cyclone unit 200 are integrally formed by additive manufacturing to form the sub-mold first-stage cyclone vacuum insulation ring cavity 220 and the nozzle vacuum insulation ring cavity 304.

[0015] A further technical solution of the present invention is: the main mold secondary swirl unit 100 and the secondary mold primary swirl unit 200 constitute a coaxial dual swirl structure, wherein the main mold provides secondary swirl airflow and the secondary mold provides primary swirl airflow, and the two swirls interact to enhance the fuel atomization effect.

[0016] A further technical solution of the present invention is that the direct-fire nozzle 218 and the columnar beam 226 are arranged in a one-to-one correspondence, and a minimum distance d is provided between them to accommodate thermal expansion.

[0017] Beneficial effects The beneficial effects of this invention are as follows: The swirling structure of this invention is a coaxial dual-swirling combination of a main mold secondary swirling unit and a secondary mold primary swirling unit. The main mold provides a strong swirling airflow, while the secondary mold cooperates to achieve efficient mixing of fuel and air. Furthermore, vacuum-insulated annular cavities are opened on the inner wall of the secondary mold surrounding the direct-injection nozzle and on the outer shell of the centrifugal nozzle, solving the problem of fuel coking in the nozzle due to heat radiation / heat conduction under high-temperature environments, while ensuring fuel atomization efficiency and lightweight structure. Specific effects are analyzed as follows: 1. The coaxial dual-swirl combustor nozzle structure with a vacuum insulation layer provided by the present invention achieves effective thermal isolation between the nozzle shell and the high-temperature gas flow of the flame by setting a vacuum insulation annular cavity outside the direct-injection nozzle and the centrifugal nozzle, and using a columnar beam structure to isolate the atomized air from the insulation layer. This vacuum annular cavity is evacuated through an air extraction port and then welded and sealed, maintaining a high vacuum state for a long time, significantly reducing the nozzle temperature rise caused by thermal radiation and heat conduction, effectively suppressing the thermal oxidation reaction of the fuel inside the nozzle, and avoiding high-temperature coking. At the same time, this structure is lightweight and compact, making it suitable for aero-engine combustors with a compact multi-nozzle layout.

[0018] 2. According to the nozzle structure with a vacuum insulation layer provided by the present invention, the main and auxiliary mold swirl units form a coaxial swirl coupling structure. The high-speed rotating air generated by the main mold enters the auxiliary mold through a non-swirl channel and undergoes synergistic atomization with the fuel inside the auxiliary mold. The direct-injection nozzle is suitable for atomization in the high-flow main combustion zone, while the centrifugal nozzle undertakes emergency fuel supply and flame stability maintenance. The separation of structure and function improves the nozzle's ability to adapt to multiple operating conditions. Under idle conditions, even with low injection pressure, a good atomized mist cone can still be formed because the nozzle is located in the high-speed swirl airflow region; the spray zone is close to the igniter, further enhancing the low-condition ignition boundary and expanding the working envelope of the combustion chamber.

[0019] 3. According to the nozzle structure provided by the present invention, an annular columnar beam is provided outside the direct-injection nozzle as a structural support and hot airflow barrier, which not only enhances the strength of the sub-mold structure but also prevents high-speed atomizing air from disturbing the vacuum insulation cavity. Multiple cooling holes are provided on the nozzle end face, enabling active cooling of the nozzle end by the incoming airflow, reducing the peak heat load, improving the high-temperature stress distribution, and helping to prevent end ablation. Furthermore, the duty nozzle housing also adopts a vacuum insulation design, with an internal cyclone separator and filter. The structure is replaceable and easy to maintain, and the internal temperature of the nozzle is always controlled. Combining the dual mechanisms of vacuum insulation and film cooling, the lifespan and operational reliability of the combustion chamber structure are comprehensively improved.

[0020] 4. This invention innovatively introduces a vacuum-insulated annular cavity into the nozzle structure, combined with columnar beam support and vacuum sealing technology, achieving effective thermal isolation between the nozzle fuel supply structure and the high-temperature combustion environment. This effectively prevents fuel from coking inside the nozzle due to thermal radiation. Simultaneously, the dual-swirling design of the main and auxiliary molds enhances the coupling efficiency of air disturbance and atomization processes, adapting to various combustion conditions and improving ignition and combustion stability under low injection pressure. The overall structure is compact and possesses strong thermal protection performance, suitable for the comprehensive requirements of high-performance aero-engines for nozzle heat resistance, reliability, and lightweight design, demonstrating broad engineering application prospects and promotional value. Attached Figure Description Figure 1 This is an exploded view of the coaxial dual-swirl combustion chamber nozzle structure with a vacuum insulation layer according to an embodiment of the present invention.

[0021] Figure 2 This is a full sectional view of the main mold secondary cyclone separator in an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of the secondary swirl blade of the main mold in an embodiment of the present invention.

[0023] Figure 4 This is a half-sectional view of the primary hydrocyclone of the secondary module in an embodiment of the present invention.

[0024] Figure 5 for Figure 4 A partial magnified front view of part A.

[0025] Figure 6 for Figure 4 A magnified front view of part B.

[0026] Figure 7 This is a schematic diagram of the structure of the first-stage swirl blade of the secondary module in an embodiment of the present invention.

[0027] Figure 8 This is a full sectional view of a single-oil-circuit centrifugal fuel nozzle according to an embodiment of the present invention.

[0028] Figure 9 for Figure 8 A partial magnified front view of part A.

[0029] Figure 10 This is a physical diagram of an embodiment of the present invention.

[0030] Figure 11 The following are the calculation results of the wet wall temperature distribution of the centrifugal nozzle of the sub-mold under different insulation layer thicknesses in the embodiments of the present invention. (a) Base configuration, (b) δ=0.1mm, (c) δ=0.2mm, (d) δ=0.3mm.

[0031] Figure 12The following are the calculated results of the wet wall temperature distribution of the direct-fired nozzle of the main mold under different vacuum levels of the insulation layer in the embodiments of the present invention. (a) Base configuration, (b) Air layer, (c) 0.995 atm vacuum layer.

[0032] Explanation of reference numerals in the attached drawings: 100, Secondary cyclone separator of the main mold; 102, Connection and mounting edge between the secondary cyclone separator of the main mold and the head of the flame tube; 104, Outer wall surface of the secondary cyclone separator of the main mold; 106, Blade of the secondary cyclone separator of the main mold; 108, Mounting rib between the secondary cyclone separator of the main mold and the primary cyclone separator of the secondary mold; 110, Inner wall surface of the secondary cyclone separator of the main mold; 112, Outer wall surface of the primary cyclone separator of the secondary mold; 114, Cooling holes on the end face of the secondary cyclone separator of the main mold; 200, Primary cyclone separator of the secondary mold; 202, Connection and mounting edge between the primary cyclone separator of the secondary mold and the secondary cyclone separator of the main mold; 204, Main combustion stage oil inlet pipe of the primary cyclone separator of the secondary mold; 206, Atomizing air flow path channel of the primary cyclone separator of the secondary mold; 208, Shift oil inlet pipe of the primary cyclone separator of the secondary mold; 210, Blade of the primary cyclone separator of the secondary mold; 2 12. Inner wall of the primary stage hydrocyclone of the secondary mold; 214. Centrifugal nozzle mounting seat for the primary stage hydrocyclone of the secondary mold; 216. Oil collecting ring of the main combustion stage of the primary stage hydrocyclone of the secondary mold; 218. Direct-injection nozzle of the main combustion stage of the primary stage hydrocyclone of the secondary mold; 220. Vacuum insulation ring cavity of the primary stage hydrocyclone of the secondary mold; 222. Cooling holes on the end face of the primary stage hydrocyclone of the secondary mold; 224. Air extraction hole of the vacuum insulation ring cavity of the primary stage hydrocyclone of the secondary mold; 226. Columnar beam of the vacuum insulation ring cavity of the primary stage hydrocyclone of the secondary mold; 300. Single-circuit centrifugal fuel nozzle; 302. Nozzle housing; 304. Vacuum insulation ring cavity of the nozzle; 306. Air extraction hole of the vacuum insulation ring cavity of the nozzle; 308. Nozzle hydrocyclone; 310. Nozzle spring; 312. Nozzle plug; 314. Nozzle retaining ring; 316. Nozzle filter. Detailed Implementation The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] Currently, to solve the problem of high-temperature coking in nozzles, existing technologies mainly employ the following methods: One approach is to use a heat-insulating coating or an air insulation layer. For example, the dual-oil-path nozzle proposed in CN112254172A reduces heat conduction by setting a heat insulation cover and a heat-insulating cavity outside the housing. However, the heat insulation effect of this type of structure is limited, the air layer has a high thermal conductivity, and the coating is prone to peeling off under thermal shock conditions, making it difficult to meet the heat insulation requirements under long-term high-temperature conditions.

[0035] Secondly, optimizing the swirl and fuel supply structure improves atomization. For example, CN118347016A uses a combined swirl-non-swirl intake method, CN103123122B uses a combination of a main-stage direct-injection nozzle and a shift-stage diffusion combustion, and CN117053234A uses a tower-type multi-stage swirl and multi-path fuel supply structure. While these solutions can improve atomization quality and combustion stability, they do not fundamentally solve the problem of fuel coking inside the nozzle due to high-temperature radiation.

[0036] Addressing the problems of poor heat insulation performance, easy fuel coking inside the nozzle, and short service life of existing aero-engine combustor nozzle designs in high-temperature environments, this invention provides a coaxial dual-swirl combustor nozzle structure with a vacuum insulation layer, comprising: Coaxially arranged multi-stage swirl units are used to form a graded swirl air field; At least one fuel nozzle is disposed inside or downstream of the multi-stage swirl unit for injecting fuel into the swirling air field; And, a vacuum insulation cavity disposed around the fuel nozzle; The vacuum insulation cavity is provided with an air extraction hole, which is sealed to keep the vacuum insulation cavity in a high vacuum state, thereby effectively blocking the radiative heat transfer from the high temperature environment of the combustion chamber to the fuel nozzle.

[0037] The multi-stage swirling unit includes a primary mold secondary swirling unit and a secondary mold primary swirling unit. The fuel nozzle includes multiple direct-shot nozzles arranged circumferentially on the secondary mold primary swirling unit and a single-oil-path centrifugal fuel nozzle arranged on its central axis. The vacuum insulation cavity includes a secondary mold primary swirling unit vacuum insulation ring cavity formed on the inner wall of the secondary mold primary swirling unit, and a nozzle vacuum insulation ring cavity formed on the nozzle housing of the single-oil-path centrifugal fuel nozzle.

[0038] The main mold secondary swirl unit, the secondary mold primary swirl unit, and the single-oil-path centrifugal fuel nozzle are arranged coaxially from the outside to the inside. The main mold secondary swirl unit is located on the outermost side, the secondary mold primary swirl unit is located in the middle and connected to the combustion chamber head, and the centrifugal nozzle is installed on the central axis of the secondary mold.

[0039] The secondary mold's first-stage cyclone separator is internally equipped with multiple cyclone blades, forming a stable first-stage cyclone structure. It also features two independent fuel supply systems: one for the main combustion stage and one for the duty stage. Fuel from the main combustion stage enters the secondary mold's fuel collecting ring through the main combustion stage inlet pipe, ultimately being delivered to multiple circumferentially arranged direct-injection nozzles. The duty stage fuel is directly supplied to single-path centrifugal nozzles through the duty stage inlet pipe. Both the direct-injection and centrifugal nozzles are externally equipped with vacuum-insulated annular cavities. Multiple columnar support beams are arranged within these cavities, and evacuation holes are opened on the outer walls, which are then welded and sealed after vacuuming, forming a stable vacuum cavity structure. This vacuum structure effectively cuts off the heat conduction path between the high-temperature flame and the nozzle fuel channel, thus achieving a long-term stable heat insulation effect.

[0040] This invention effectively reduces the degree of fuel heating by enclosing the fuel passage within a vacuum insulation structure, thus preventing coking in a high-temperature combustion environment. The main and auxiliary cyclone structures work together to form a dual swirling gas field, which improves fuel atomization while also providing cooling, combustion assistance, and thermal protection. This invention solves the problems of poor atomization stability, high heat load, and complex structural maintenance of existing nozzles, and has significant engineering practical value.

[0041] The above technical solution will be further explained below with reference to the accompanying drawings: In one embodiment, refer to Figure 1 As shown, this embodiment presents a coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer, comprising a primary mold secondary swirler 100, a secondary mold primary swirler 200, and a single-oil-path centrifugal nozzle 300, all three arranged coaxially. Multiple inclined swirler blades 106 are installed between the outer wall surface 104 and the inner wall surface 110 of the primary mold secondary swirler 100 to guide air from outside the combustion chamber into a rotating flow with a tangential velocity component. This rotating flow improves the mixing ability of fuel and air and creates a strong shear flow field, which is beneficial for subsequent atomization and combustion. A non-swirling air channel is provided between the inner wall surface 110 of the primary mold and the outer wall surface 112 of the secondary mold, allowing some incoming air to pass through in a straight line, creating a disturbance gradient in the secondary mold inlet area. During the flow, some of the non-swirling air is introduced into the end face of the secondary mold through multiple cooling holes 114, forming end-face air cooling, effectively reducing the heat load at the nozzle tip and delaying structural thermal fatigue.

[0042] The secondary mold primary cyclone unit 200 includes an inner wall surface 212 of the secondary mold primary cyclone separator and a centrifugal nozzle mounting base 214 for the secondary mold primary cyclone separator. Several secondary mold primary cyclone separator blades 210 are located between them. One fuel supply is provided through the duty oil inlet pipe 208, and another fuel supply is provided from the main combustion stage oil inlet pipe 204 through the main combustion stage oil collecting ring 216 to multiple direct-injection nozzles 218. Inlet air passes through the atomizing air flow channel 206, part of which helps atomize the fuel inside the direct-injection nozzles, and part of which cools the end face through several cooling holes 222. The inner wall surface 212 of the secondary mold primary cyclone separator has a vacuum insulation annular cavity 220 and a vacuum insulation annular cavity extraction hole 224. Several vacuum insulation annular cavity columnar beams 226 are located inside the annular cavity.

[0043] The single-oil-path centrifugal fuel nozzle 300 includes a nozzle vortex 308, a nozzle spring 310, a nozzle plug 312, a nozzle retaining ring 314, a nozzle filter screen 316, and a nozzle housing 302, wherein the housing 302 has a nozzle vacuum insulation annular cavity 304 and a nozzle vacuum insulation annular cavity extraction hole 306.

[0044] In one embodiment, refer to Figures 2 to 4 As shown, the secondary mold primary cyclone separator 200 is tightly connected to the primary mold secondary cyclone separator 100 via the connecting mounting edge 202, forming a composite cyclone structure. Multiple radially distributed secondary mold cyclone separator blades 210 are installed within the secondary mold. These blades guide the rotating air from the primary mold a second time, constructing a stable secondary cyclone field, thereby achieving high turbulent energy injection and a fully disturbed atomization environment. The secondary mold is equipped with a dual-path fuel supply system. Primary combustion stage fuel is input through the primary combustion stage inlet pipe 204 and uniformly distributed to multiple direct-injection nozzles 218 via the internal fuel collecting ring 216. These nozzles are evenly distributed circumferentially to achieve atomization coverage of the primary combustion zone. Shift fuel enters the nozzle mounting seat 214 located at the center of the secondary mold through an independent shift fuel inlet pipe 208, supplying a single centrifugal nozzle 300, mainly used for low-condition combustion maintenance, ignition, and emergency combustion. The secondary mold is also equipped with an atomizing air flow channel 206, which is responsible for guiding the rotating air from the main mold into the nozzle area. Part of the air is used for fuel atomization in the main nozzle, and the other part is sprayed out through small holes 222 evenly distributed on the end face of the secondary mold for end face cooling and temperature regulation.

[0045] Reference Figures 5 to 7As shown, to achieve external thermal protection of the nozzle and thermal isolation of the internal fuel structure, this invention designs an annular vacuum insulation cavity 220 around the direct-fire nozzle area. This cavity is located between the inner wall 212 and the outer wall of the primary cyclone separator of the secondary mold, and is supported and fixed by multiple vacuum insulation annular columnar beams 226. The columnar beams 226 maintain structural strength to prevent deformation of the cavity wall caused by high-temperature combustion gases, and block heat exchange and gas permeation between the atomizing air flow path 206 and the insulation annular cavity 220, ensuring the insulation effect of the vacuum cavity. An evacuation hole 224 is provided on the outer wall of the annular cavity. During the manufacturing process, a vacuum is applied through the evacuation hole, and the hole is sealed by welding to ensure a long-lasting and stable vacuum state. This significantly reduces the thermal radiation and thermal load of the high-temperature flame gases on the internal fuel path of the nozzle, extends the nozzle's coking-free operating time, and improves the long-term safety and reliability of the nozzle.

[0046] Reference Figures 8 to 9 As shown, the centrifugal nozzle 300 is installed in the nozzle mounting seat 214 in the middle of the primary cyclone separator of the secondary mold. A nozzle vacuum insulation annular cavity 304 is arranged around the nozzle housing 302 to isolate the nozzle body from direct heating by the high-temperature environment of the combustion chamber. An extraction port 306 is provided outside the nozzle vacuum insulation annular cavity 304 for extraction and welding sealing during manufacturing. The internal structure of the nozzle includes a cyclone separator 308, a spring 310, a plug 312, a retaining ring 314, and a filter screen 316. The cyclone separator 308 forms a rotating flow of fuel, achieving a conical atomization effect; the spring 310 maintains stable nozzle opening under different fuel supply pressures; the plug 312 and retaining ring 314 constitute a limiting and sealing assembly, controlling the nozzle response time and rebound accuracy; the filter screen 316 filters impurities in the fuel, preventing clogging of the nozzle orifice and ensuring uniform injection. The nozzle has a simple structure and compact components, facilitating assembly and maintenance, while possessing good atomization performance and anti-pollution capabilities, making it suitable for high-frequency start-up or variable operating condition applications.

[0047] Specifically, the nozzle vacuum insulation annular cavity 304 of the centrifugal nozzle housing 302 has specific structural dimensions, and its radial width d 3 is significantly larger than the minimum diameter of the outlet channel. d 4. To ensure the vacuum chamber fully covers the fuel delivery area of ​​the nozzle. This structural design effectively reduces the possibility of heat being conducted from the outer shell to the internal piping of the nozzle, achieving all-around thermal protection for the nozzle's fuel path. The evacuation port 306 is designed on the rear side wall of the housing. During manufacturing, evacuation is performed at this location, followed by welding to form a permanent vacuum chamber, ensuring thermal insulation during prolonged nozzle operation. The nozzle's shape adopts a transitional conical structure, ensuring structural strength while also considering airflow linearity and low-resistance characteristics.

[0048] In one embodiment, the outer diameter of the coaxial double swirl combustion chamber nozzle structure with a vacuum insulation layer is determined to be 120 mm and the total length is 35 mm according to the overall structural layout requirements.

[0049] The swirl angle of the blades in the main mold secondary hydrocyclone is 30°, the average gap between the outer and inner walls is 4.5 mm, the number of blades is 18, the axial length is 10.85 mm, the blade height is 16.26 mm, the thickness is 1.25 mm, and the blade material is a nickel-based high-temperature alloy to ensure swirl strength and thermal stability.

[0050] The inner diameter of the primary hydrocyclone of the secondary mold is 12 mm. The secondary mold hydrocyclone has 16 blades (210), a swirl angle of 45°, an axial length of 13.31 mm, a blade height of 22.35 mm, and a thickness of 1.25 mm. The mounting transition rib between the secondary mold and the primary mold is 5 mm thick and 5 mm long, used for installation, fixation, and enhancing structural stability.

[0051] The outer diameter of the main combustion stage fuel inlet pipe 204 is 8 mm and the inner diameter is 6 mm; the outer diameter of the oil collecting ring 216 is 53 mm, the inner diameter is 45 mm, and the length is 19 mm; the nozzle 218 has an outlet diameter of 0.6 mm and 18 nozzles distributed on the circumference with a spacing angle of 20°.

[0052] The diameter of the oil inlet pipe 208 is 8 mm, the outer diameter of the nozzle mounting seat 214 is 9.6 mm, and the length is 12.97 mm. This ensures that after the centrifugal nozzle 300 is installed, the nozzle end face is flush with the outlet end face of the primary hydrocyclone 200 of the secondary mold. The mounting seat material is a nickel-based high-temperature alloy.

[0053] 220mm height of vacuum insulation annular cavity inside the sub-mold d 1 is 1.5 mm, and the angle of inclination with the axial horizontal line is 1.5 mm. α The angle is 45°, and the distance between it and the atomizing airflow path 206 is 206. d 2 is 0.5 mm, and there are 18 circumferentially distributed columnar beams 226. The cross-section of the beam has an outer diameter of 4 mm, an inner diameter of 3 mm, and a height of 1.5 mm. Each columnar beam is distributed with a corresponding direct-fire nozzle at a spacing angle of 20°.

[0054] The diameter of the vent 224 d The number of holes is 1 mm, and there are 2 of them, symmetrically distributed along the outer wall of the cavity. A bevel structure with a bevel angle of 45° is provided between the evacuation hole and the vacuum welding area to facilitate vacuum welding sealing.

[0055] The centrifugal nozzle 300 has an outer diameter of 9.6 mm and an axial length of 10.13 mm; the internal cyclone separator 308 has a... The channel angle is 45°, the vortex cavity diameter is 1.78 mm; the free length of the nozzle spring 310 is 6.7 mm, the elastic coefficient is 22.46±2 N / mm, the nozzle retaining ring 314 has a diameter of 5 mm, and the block 312 has a height of 1.6 mm.

[0056] The numerical height of the annular cavity of the nozzle vacuum insulation annular cavity 304 d 3 is 1.5 mm, horizontal width near the nozzle d 4 is 0.5mm, and the diameter of the 306 suction port is... d 0 represents 1 mm, and there is only one such port located at the rear end of the housing. The air extraction port is positioned at a 90° angle to the horizontal axis.

[0057] The vacuum insulation annular cavity 220 and 304 are designed to have a vacuum level range of 10. -2 ~10 -5 Pa, the cavity is sealed by vacuum electron beam welding after maintaining a stable vacuum in the vacuum sealing furnace for at least 1 hour.

[0058] Based on the above, an embodiment of the present invention can be determined. It is worth noting that this embodiment adopts all the preferred parameter schemes of the present invention.

[0059] Reference Figure 10 As shown, the physical assembly diagram of this invention shows the main mold secondary cyclone separator and the secondary mold primary cyclone centrifugal nozzle. Both are first formed by additive manufacturing and then machined to ensure the diameter and surface roughness of the fuel injection holes. The red circle in the figure represents the holes retained during the additive manufacturing process and are sealed in a vacuum electron beam welding furnace.

[0060] In one embodiment, refer to Figures 11 to 12Numerical calculations were performed on the fluid domains of the direct nozzle of the primary mold's secondary cyclone separator and the centrifugal nozzle of the secondary mold's primary cyclone separator. Comparison of the numerical calculations revealed the following temperature distribution on the wetted wall surface of the nozzle with different insulation thicknesses (δ=0.1 mm, 0.2 mm, and 0.3 mm) for the selected baseline configuration without insulation: The highest wall temperature was approximately 860 K, and the average temperature was approximately 810 K. When δ=0.1 mm, the highest wall temperature decreased to approximately 835 K, and the average temperature decreased to 790 K, a decrease of approximately 25 K (about 2.9%). When δ=0.2 mm, the highest wall temperature further decreased to approximately 815 K, and the average temperature was approximately 770 K, a decrease of approximately 45 K (about 5.2%) compared to the baseline. When δ=0.3 mm, the highest wall temperature was approximately 800 K, and the average temperature was approximately 755 K, a decrease of approximately 60 K (about 7.0%). Comparing the nozzle wet wall temperature distribution with the baseline configuration and under different vacuum levels (at atmospheric pressure and 0.995 atm vacuum): In the baseline configuration, the highest wall temperature is approximately 860 K, and the average temperature is approximately 810 K. When using an atmospheric pressure air layer, the highest wall temperature drops to approximately 830 K, and the average temperature is 785 K, a decrease of approximately 30 K (about 3.5%). When using a 0.995 atm vacuum layer, the highest wall temperature further decreases to approximately 805 K, and the average temperature is approximately 765 K, a decrease of approximately 55 K (about 6.4%) compared to the baseline. The vacuum insulation layer structure proposed in this invention can effectively reduce the wet wall temperature of the nozzle under different parameters. Compared with the baseline configuration, increasing the insulation layer thickness or improving the vacuum level can significantly weaken heat transfer, reducing the maximum wall temperature by 25–60 K and the average temperature by approximately 20–45 K, thereby significantly mitigating the risk of fuel coking due to heat. This fully verifies the improvement effect of the technical solution of this invention compared with the prior art.

[0061] The present invention comprises a dual-swirling combustion structure consisting of a main mold and a secondary mold swirler, providing rotating turbulent airflow externally and internally respectively; a dual-path fuel supply structure enables separation of main combustion and emergency fuel supply, improving the response of the combustion regulation process; multi-point nozzles work together to improve spray uniformity; a vacuum-insulated annular cavity is embedded around the nozzle to achieve thermal isolation in the core area, effectively suppressing the coking process; and a columnar beam structure not only improves strength but also controls gas path flow. The overall structure combines the advantages of thermal protection, atomization stability, and lightweight design, making it suitable for the high reliability and high heat resistance requirements of nozzle systems in next-generation high-performance aero engines.

[0062] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer, characterized in that, include: Coaxially arranged multi-stage swirl units are used to form a graded swirl air field; At least one fuel nozzle is disposed inside or downstream of the multi-stage swirl unit for injecting fuel into the swirling air field; And, a vacuum insulation cavity disposed around the fuel nozzle; The vacuum insulation cavity is provided with an air extraction hole, which is sealed to keep the vacuum insulation cavity in a high vacuum state, thereby effectively blocking the radiative heat transfer from the high temperature environment of the combustion chamber to the fuel nozzle.

2. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 1, characterized in that: The multi-stage swirl unit includes: The main mold secondary swirling unit (100) includes the outer wall surface (104) and inner wall surface (110) of the main mold secondary swirling unit. There are multiple swirling unit blades (106) between the inner and outer wall surfaces. A non-swirling air channel is formed between the inner wall surface (110) and the outer wall surface (112) of the secondary mold primary swirling unit. Some air is cooled to the end face through several cooling holes (114). The secondary mold first-stage cyclone unit (200) includes the inner wall surface (212) of the secondary mold first-stage cyclone and the centrifugal nozzle mounting seat (214) of the secondary mold first-stage cyclone. There are several secondary mold first-stage cyclone blades (210) between them. One fuel supply is provided through the duty oil inlet pipe (208), and another fuel supply is provided from the main combustion stage oil inlet pipe (204) through the main combustion stage oil collecting ring (216) to multiple direct-injection nozzles (218). The inlet air passes through the atomizing air flow channel (206) to partially atomize the fuel inside the direct-injection nozzle, and partially cools the end face through several cooling holes (222).

3. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 2, characterized in that: The fuel nozzles include a plurality of direct-fire nozzles (218) disposed circumferentially on the sub-mold primary swirling unit (200) and a single-oil-path centrifugal fuel nozzle (300) disposed on its central axis; the vacuum insulation cavity includes a sub-mold primary swirling unit vacuum insulation ring cavity (220) opened on the inner wall (212) of the sub-mold primary swirling unit (200) and a nozzle vacuum insulation ring cavity (304) opened on the nozzle housing (302) of the single-oil-path centrifugal fuel nozzle (300).

4. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 3, characterized in that: The vacuum insulation ring cavity (220) of the sub-mold first-stage cyclone separator is provided with a plurality of columnar beams (226) evenly distributed along the circumference. The columnar beams are used to support the inner and outer wall structures of the vacuum insulation ring cavity (220) of the sub-mold first-stage cyclone separator and to isolate the gas heat transfer path between the external atomizing air flow path (206) and the vacuum insulation ring cavity (220) of the sub-mold first-stage cyclone separator.

5. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 3, characterized in that: The vacuum insulation ring cavity evacuation hole (224) on the primary cyclone separator vacuum insulation ring cavity (220) and the nozzle vacuum insulation ring cavity evacuation hole (306) on the nozzle vacuum insulation ring cavity (304) are sealed by vacuum electron beam welding to form a closed high vacuum structure.

6. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 5, characterized in that: The vacuum level in the vacuum insulation annular cavity (220) of the secondary module primary cyclone separator and the vacuum insulation annular cavity (304) of the nozzle is less than 10. - 2 Pa is used to cut off the radiative heat transfer of high-temperature gas to the fuel path of the nozzle.

7. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 5, characterized in that: The radial thickness of the vacuum insulation ring cavity (220) of the primary cyclone separator and the vacuum insulation ring cavity (304) of the nozzle is 1 mm to 2 mm.

8. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 3, characterized in that: The nozzle housing (302) and the inner wall surface (212) of the sub-mold first-stage cyclone unit (200) are integrally formed by additive manufacturing of the sub-mold first-stage cyclone vacuum insulation ring cavity (220) and the nozzle vacuum insulation ring cavity (304).

9. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 2, characterized in that: The main mold secondary swirl unit (100) and the secondary mold primary swirl unit (200) form a coaxial dual swirl structure, wherein the main mold provides secondary swirl airflow and the secondary mold provides primary swirl airflow, and the two swirls interact to enhance the fuel atomization effect.

10. The coaxial dual-swirling combustion chamber nozzle structure with a vacuum insulation layer according to claim 9, characterized in that: The direct-fire nozzle (218) is provided in a one-to-one correspondence with the columnar beam (226), and a minimum distance d is provided between them to accommodate thermal expansion.

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