Pre-evaporation-direct mixing four-concave-cavity grading combustion chamber head

Abstract

The invention relates to the technical field of aero-engines, and discloses a pre-evaporation-direct mixing four-concave-cavity staged combustion chamber head. A four-cavity standing vortex field structure which is formed by a pre-combustion stage, a central stage and a third stage in the radial direction and is beneficial to ignition, efficient combustion and flame stabilization of the combustion chamber is arranged in an annular channel formed by an outer casing and an inner casing of a sudden expansion section of the combustion chamber; a direct mixing organization combustion mode is adopted in the center stage, high-working-condition oil gas uniform mixing can be guaranteed, efficient combustion and good outlet temperature distribution are achieved, an evaporation ring cavity is adopted in the pre-combustion stage and the third stage to achieve a pre-evaporation oil gas mixing mode, the length of the combustion chamber can be remarkably shortened, and the weight is reduced; the ignition and low-working-condition combustion stability boundary of the combustion chamber can be obviously widened; therefore, combustion chamber temperature rise and combustion efficiency are improved, and combustion chamber outlet temperature distribution quality is improved.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology and discloses a pre-evaporation-direct mixing four-cavity staged combustion chamber head. Background Technology

[0002] The ever-increasing performance requirements of future advanced aircraft engines necessitate that combustors not only maintain good lean combustion stability under low operating conditions but also achieve efficient, low-smoke combustion under high operating conditions, while meeting increasingly stringent exit temperature distribution requirements. To achieve these performance requirements, in addition to further exploring the potential of conventional swirl combustors, researchers both domestically and internationally have never ceased their exploration of novel combustor technologies, such as intelligent combustors, staged and zoned combustors, and trapped vortex combustors (TVC).

[0003] The vortex combustor represents a significant innovation compared to conventional swirl combustors, which rely on a central recirculation zone for stable combustion. Its fundamental principle is the formation of a stable recirculation zone within a specifically structured cavity / concave, thereby stabilizing the flame. Bench tests of the vortex combustor demonstrate that, compared to conventional combustors, the vortex combustor exhibits a significantly wider ignition-quenching stable combustion boundary and demonstrates great potential in improving combustion efficiency and reducing NOx emissions.

[0004] The combustion chamber head is a key component of combustion chamber design. Research on vortex combustion chambers has solved most of the technical challenges related to flow field and combustion organization, laying the technical foundation for reliable ignition, stable combustion under low operating conditions, and efficient combustion under high operating conditions. However, some shortcomings still exist, specifically including a complex combustion chamber structure and excessive weight; the head design is not conducive to controlling the interaction between the concave cavity and the mainstream airflow; and the concave cavity's front wall intake structure is complex. Summary of the Invention

[0005] The purpose of this invention is to provide a pre-evaporation-direct mixing four-cavity staged combustion chamber head, which can improve combustion chamber temperature rise and combustion efficiency, and improve the quality of combustion chamber outlet temperature distribution.

[0006] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: A pre-evaporation-direct mixing four-cavity staged combustion chamber head, located between the outer casing and the inner casing in an annular channel, includes: The central stage is composed of an outer concave cavity, an inner concave cavity, and a central flow guiding ring cone. The central flow guiding ring cone is located upstream of the outer concave cavity and the inner concave cavity of the central stage. The upstream sides of the outer concave cavity and the inner concave cavity of the central stage are connected to the central flow guiding ring cone. A pre-combustion stage is radially disposed on the outer periphery of the central stage for first-stage combustion. The pre-combustion stage is composed of an outer ring inclined concave cavity, the inner wall of which overlaps with the outer concave cavity of the central stage. An evaporation ring cavity is disposed on the outer ring inclined concave cavity. The third stage is radially disposed on the inner periphery of the central stage and is used to perform the second stage combustion simultaneously with the central stage. The third stage is composed of an inner ring oblique concave cavity, the outer wall of which overlaps the inner concave cavity of the central stage, and an evaporation ring cavity is provided on the inner ring oblique concave cavity. The outer ring oblique concave cavity, the inner ring oblique concave cavity, the outer concave cavity of the central stage, and the inner concave cavity of the central stage are each provided with a front jet hole for injecting fuel into the corresponding concave cavity through the fuel nozzle; Each of the evaporation annular cavities has several air inlets evenly distributed around its windward wall surface for supplying air to the corresponding evaporation annular cavity; the central guide annular cone has a cavity structure, and a central air inlet slit is formed at the leading edge of the central guide annular cone for supplying air to the front jet holes of the central stage outer concave cavity and the central stage inner concave cavity.

[0007] Furthermore, it also includes a fuel main and a series fuel lines, wherein the fuel main is mounted and fixed on the outer casing, and the series fuel lines include a secondary fuel line, a main fuel line, and a third fuel line; wherein: The auxiliary oil passage is connected to the main fuel line via a connecting pipeline, and the auxiliary oil passage is used to supply oil to the outer ring inclined concave cavity; The main oil circuit is located downstream of the auxiliary oil circuit and at the end of the fuel main pipe connecting pipeline. A constant pressure valve is provided at the oil inlet of the main oil circuit, which circumferentially passes through and is fixed on the central guide ring cone, for supplying oil to the outer concave cavity of the central stage and the inner concave cavity of the central stage. The third oil circuit is connected to the main oil circuit via a connecting pipeline and is used to supply oil to the inner ring oblique concave cavity.

[0008] Furthermore, the auxiliary oil passage, main oil passage, and third oil passage have a double-layer structure, and the oil passage is wrapped with a heat-insulating sleeve for heat insulation. The auxiliary oil passage and the third oil passage have several direct-shot nozzles evenly opened along the circumference. The direct-shot nozzles face the center of the air inlet, and the number of direct-shot nozzles corresponds one-to-one with the number of air inlets.

[0009] Furthermore, a central annular cavity is provided between the inner ring of the central stage outer concave cavity and the outer ring of the central stage inner concave cavity, and the central air inlet slit supplies air to the front jet holes of the central stage outer concave cavity and the central stage inner concave cavity through the central annular cavity.

[0010] Furthermore, the downstream of the main oil circuit extends to the central annular cavity through several connecting pipes in the circumferential direction. Several centrifugal nozzles are installed at the upper and lower ends of the connecting pipes, and the outlets of the centrifugal nozzles extend into the front jet holes of the outer concave cavity of the central stage and the inner concave cavity of the central stage.

[0011] Furthermore, the outer ring wall end of the outer ring concave cavity and the inner ring wall end of the inner ring concave cavity are uniformly provided with a number of identical rear jet holes along the circumferential direction.

[0012] Furthermore, the outer ring end of the central stage outer concave cavity and the inner ring end of the central stage inner concave cavity are uniformly provided with several identical rear jet holes along the circumferential direction.

[0013] Furthermore, cooling holes are provided on the walls of the outer ring oblique concave cavity, the inner ring oblique concave cavity, the central stage outer concave cavity, and the central stage inner concave cavity, and the cooling holes form an acute angle with the flow direction of the local oil-gas mixture in the corresponding concave cavity.

[0014] Compared with the prior art, the beneficial effects of this invention are: 1. This invention sets a head in the expansion section of the traditional combustion chamber and adopts a radially graded design of a pre-combustion stage, a central stage, and a third stage for the combustion chamber. The innovative structural form creates a stable four-cavity vortex flow field structure in the radial direction. Among them, the pre-combustion stage and the third stage adopt a pre-evaporation oil-gas mixing mode, which can significantly shorten the length of the combustion chamber, reduce the weight, and significantly widen the boundary of combustion chamber ignition and low-condition combustion stability. The central stage adopts a pneumatic centrifugal nozzle direct mixing combustion mode, which can ensure uniform oil-gas mixing under high conditions, achieve efficient combustion, and good outlet temperature distribution.

[0015] 2. The combustion chamber head designed in this invention adopts a pre-evaporation-direct mixing four-cavity vortex staged combustion mode, which forms a flow field structure that is conducive to ignition, efficient combustion and flame stability in the pre-combustion stage, central stage and third stage combustion zone. This can further meet the requirements of continuously widening the stable working boundary of the combustion chamber, continuously increasing the temperature rise and more stringent quality of the outlet temperature distribution. 3. The pre-evaporation-direct mixing four-cavity staged combustion chamber head designed in this invention has a streamlined flow-dividing channel formed by its windward surface and the inner surfaces of the outer and inner casings of the combustion chamber's sudden expansion section. Combined with the stable four-cavity vortex flow field structure formed by the head, it can adapt to higher incoming flow velocity intake conditions, thus eliminating the need for the pre-diffuser of the traditional combustion chamber. In addition, the overall structure of the head is moved forward to the sudden expansion section of the traditional combustion chamber, and the head layout is compact with high space utilization, freeing up more space for the downstream combustion zone. Therefore, the length of the downstream flame tube can be shortened, further making the entire combustion chamber shorter and lighter. Attached Figure Description

[0016] Figure 1This is a schematic diagram of the combustion chamber structure with a four-cavity staged combustion chamber head in the embodiment. Figure 2 This is a schematic diagram of the head structure of the pre-evaporation-direct mixing four-cavity staged combustion chamber in the embodiment; Figure 3 This is a schematic diagram of the fuel main and staged fuel circuit structure in the embodiment; Figure 4 This is a schematic diagram of the flow field at the head of the pre-evaporation-direct mixing four-cavity staged combustion chamber in the embodiment; The components are as follows: 1. Outer casing; 2. Inner casing; 3. Fuel main; 4. Auxiliary fuel passage; 5. Main fuel passage; 6. Third fuel passage; 7. Outer annular concave cavity; 8. Central stage outer concave cavity; 9. Central stage inner concave cavity; 10. Central guide ring cone; 11. Inner annular concave cavity; 12. Constant pressure valve; 13. Heat insulation sleeve; 14. Direct injection nozzle; 15. Centrifugal nozzle; 16. Evaporator annular cavity; 17. Air inlet; 18. Front jet orifice; 19. Rear jet orifice; 20. Cooling hole; 21. Flame tube outer ring; 22. Flame tube inner ring; 23. Ignition nozzle; 24. Central air inlet slot; 25. Central annular cavity; 26. Main combustion orifice; 27. Mixing orifice; 28. Combustion chamber outlet; 29. ​​Outer annular vortex; 30. Central stage outer annular vortex; 31. Central stage inner annular vortex; 32. Inner annular vortex. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0018] Example 1 See Figures 1 to 4 A pre-evaporation-direct mixing four-cavity staged combustion chamber head, located between the outer casing 1 and the inner casing 2 in an annular channel, characterized in that it comprises: The central stage is composed of a central stage outer concave cavity 8, a central stage inner concave cavity 9, and a central flow guiding ring cone 10. The central flow guiding ring cone 10 is located upstream of the central stage outer concave cavity 8 and the central stage inner concave cavity 9. The central stage outer concave cavity 8 and the central stage inner concave cavity 9 are connected to the central flow guiding ring cone 10 on their upstream sides. A pre-combustion stage is radially disposed on the outer periphery of the central stage for first-stage combustion. The pre-combustion stage is composed of an outer ring inclined concave cavity 7, the inner wall of which overlaps with the outer concave cavity 8 of the central stage. An evaporation ring cavity 16 is disposed on the outer ring inclined concave cavity 7. The third stage is radially arranged on the inner periphery of the central stage and is used to perform the second stage combustion simultaneously with the central stage. The third stage is composed of an inner ring inclined cavity 11. The outer wall of the inner ring inclined cavity 11 overlaps the inner cavity 9 of the central stage. An evaporation ring cavity 16 is provided on the inner ring inclined cavity 11. The front jet hole 18, the outer ring oblique concave cavity 7, the inner ring oblique concave cavity 11 evaporation ring cavity, the central stage outer concave cavity 8, and the central stage inner concave cavity 9 are respectively provided with front jet holes 18, which are used to inject fuel into the corresponding concave cavity through the fuel nozzle; Each of the evaporation annular cavity 16 has several air inlets 17 evenly distributed around its windward wall surface for supplying air to the corresponding evaporation annular cavity 16; the central guide annular cone 10 has a cavity structure, and a central air inlet slit 24 is opened at the front edge of the central guide annular cone 10 for supplying air to the front jet holes 18 of the central stage outer concave cavity 8 and the central stage inner concave cavity 9.

[0019] In this embodiment, a four-cavity vortex flow field structure is formed radially between the annular channel formed by the outer casing 1 and the inner casing 2 of the combustion chamber's expansion section. This structure, consisting of a pre-combustion stage, a central stage, and a third stage, facilitates combustion chamber ignition, efficient combustion, and flame stability. The pre-combustion stage is composed of an outer annular oblique concave cavity 7 and is radially positioned above the central stage for first-stage combustion. The central stage consists of an outer concave cavity 8, an inner concave cavity 9, and a central guide ring cone 10. The third stage is composed of an inner annular oblique concave cavity 11 and is radially positioned below the central stage, simultaneously performing second-stage combustion with the central stage. The central stage employs a direct-mixing combustion mode, ensuring uniform mixing of fuel and gas under high operating conditions, achieving efficient combustion and a good outlet temperature distribution. The pre-combustion stage and the third stage utilize an evaporation annular cavity 16 to achieve a pre-evaporation fuel-gas mixing mode, significantly shortening the combustion chamber length, reducing weight, and significantly widening the combustion chamber ignition and low-operation combustion stability boundaries. This improves combustion chamber temperature rise and combustion efficiency, and enhances the quality of the combustion chamber outlet temperature distribution.

[0020] Example 2 See Figure 1A pre-evaporation-direct mixing four-cavity staged combustion chamber head, located between the outer casing 1 and the inner casing 2 in an annular channel, includes a pre-combustion stage, a central stage, a third stage, a fuel main 3, and a staged fuel circuit structure. The pre-combustion stage is composed of an outer annular oblique concave cavity 7, which is radially positioned above the central stage. The lower right end of the outer annular oblique concave cavity 7 overlaps with the central stage structure. The central stage is composed of a central stage outer concave cavity 8, a central stage inner concave cavity 9, and a central guide ring cone 10. The central stage outer concave cavity 8 structure... The upper end overlaps with the outer ring inclined concave cavity 7, and the lower end is connected to the central stage inner concave cavity 9 as a whole. The left side of the central stage outer concave cavity 8 and the central stage inner concave cavity 9 are connected to the central guide ring cone 10. The central stage outer concave cavity 8 and the central stage inner concave cavity 9 form a central ring cavity 25 structure. The third stage is composed of an inner ring inclined concave cavity 11 structure and is radially arranged below the central stage. The upper right end of the inner ring inclined concave cavity 11 overlaps with the central stage inner concave cavity 9. The fuel main pipe 3 is installed and fixed on the outer casing 1.

[0021] The staged fuel circuit includes three annular fuel circuits: auxiliary fuel circuit 4, main fuel circuit 5, and third fuel circuit 6. Auxiliary fuel circuit 4 is radially arranged above main fuel circuit 5 and connected to fuel main line 3 via a connecting pipe. Main fuel circuit 5 is located at the end of the connecting pipe of fuel main line 3 downstream of auxiliary fuel circuit 4. A constant pressure valve 12 is installed at the fuel inlet of main fuel circuit 5, which runs circumferentially through and is fixed on the central guide ring cone 10. Third fuel circuit 6 is radially arranged below main fuel circuit 5 and connected to main fuel circuit 5 via a connecting pipe. The structure of each component, including fuel main line 3, auxiliary fuel circuit 4, main fuel circuit 5, third fuel circuit 6, outer annular oblique concave cavity 7, central stage outer concave cavity 8, central stage inner concave cavity 9, central guide ring cone 10, and inner annular oblique concave cavity 11, and the positional relationship between each component differs from the prior art.

[0022] like Figure 1As shown, the combustion chamber operates as follows: Fresh air enters through the combustion chamber inlet and flows in separate streams within the expansion zone formed by the outer casing 1 and the inner casing 2. Part of the air enters the pre-combustion stage combustion zone from the outer ring concave cavity 7; part of the air enters the main combustion stage combustion zone from the central stage outer concave cavity 8, the central stage inner concave cavity 9, and the central guide ring cone 10; and part of the air enters the third-stage combustion zone from the inner ring concave cavity 11. The remaining air enters the flame tube through the outer ring 21 and inner ring 22 of the flame tube via the main combustion port 26, mixing port 27, and flame tube cooling holes (not shown). Fuel is supplied to the combustion chamber via the fuel main pipe 3 in three paths. It first flows through the auxiliary fuel line 4 and into the outer ring concave cavity 7 to form a fuel-air mixture. The ignition spark 23 generates an electric spark, igniting the fuel-air mixture for the first stage of combustion. As the fuel supply pressure gradually increases, exceeding the constant pressure valve... 12. Pressure is applied, and fuel begins to enter the main fuel line 5 and the third fuel line 6. The main fuel line 5 supplies fuel to the outer concave cavity 8 and the inner concave cavity 9 of the central stage to form a fuel-air mixture. The third fuel line 6 supplies fuel to the inner ring oblique concave cavity 11 to form a fuel-air mixture. At this time, the high-temperature gas flowing out of the outer ring oblique concave cavity 7 first ignites the fuel-air mixture in the outer concave cavity 8 and the inner concave cavity 9 of the central stage. Then, the already burned mixture in the inner concave cavity 9 of the central stage ignites the fuel-air mixture in the inner ring oblique concave cavity 11 for the second stage of combustion. The unburned fuel-air mixture then flows into the main combustion zone located in front of the main combustion port 26, which is composed of the outer ring 21 and the inner ring 22 of the flame tube, to continue combustion. The air entering from the mixing port 27 mixes the already burned high-temperature gas to form the required combustion chamber outlet temperature field distribution. The fully burned high-temperature gas is finally discharged from the combustion chamber outlet 28.

[0023] This embodiment designs a pre-combustion stage, a central stage, and a third stage within the annular channel formed by the outer casing 1 and the inner casing 2 of the conventional combustion chamber's expansion section. These stages together radially form a stable four-cavity vortex flow field structure and combustion zone. Simultaneously, the pre-combustion stage and the third stage employ a pre-evaporation fuel-air mixing mode, significantly shortening the combustion chamber length, reducing weight, and widening the combustion chamber ignition and low-condition combustion stability boundaries. The central stage uses a pneumatic centrifugal nozzle direct mixing combustion mode to ensure uniform fuel-air mixing under high-condition conditions, achieving efficient combustion and a good outlet temperature distribution.

[0024] like Figures 2 to 4As shown, in this embodiment, the outer ring inclined concave cavity 7 of the pre-combustion stage and the left front edge of the inner ring inclined concave cavity 11 of the third stage are both equipped with an evaporation ring cavity 16 structure. Several air inlet holes 17 are evenly opened circumferentially on the windward wall surface of the evaporation ring cavity 16. Several front jet holes 18 are evenly opened circumferentially on the inner wall of the outer ring inclined concave cavity 7 and the inner ring inclined concave cavity 11 connected to the evaporation ring cavity 16. The upper wall surface of the outer ring inclined concave cavity 7 and the lower wall surface of the inner ring inclined concave cavity 11 are evenly opened with the same number of rear jet holes 19 as the aforementioned front jet holes 18. Cooling holes 20 are also opened on the remaining wall surfaces of the outer ring inclined concave cavity 7 and the inner ring inclined concave cavity 11. During operation, the air entering from the cooling hole 20 of the outer ring inclined concave cavity 7 forms a clockwise rotating wall-adhering air film on the inner wall surface of the outer ring inclined concave cavity 7. Under the combined action of the oblique jet formed by the air entering the front jet hole 18 through the air inlet 17 and the radial jet formed by the air entering the rear jet hole 19, an outer ring vortex 29 is formed in the outer ring inclined concave cavity 7. This vortex structure ensures good ignition performance of the combustion chamber and a large lean fuel quench margin.

[0025] Air entering through the cooling hole 20 of the inner ring inclined concave cavity 11 forms a counterclockwise rotating wall-attached air film on the inner wall surface of the inner ring inclined concave cavity 11. Under the combined action of the oblique jet formed by the air entering the front jet hole 18 through the air inlet 17 and the radial jet formed by the air entering the rear jet hole 19, an inner ring vortex 32 is formed in the inner ring inclined concave cavity 11. This vortex structure ensures good lean combustion stability of the combustion chamber and widens the stability boundary of the combustion chamber.

[0026] The central guide ring cone 10 of the main combustion stage has a cavity structure. A central air intake slit 24 is opened at the leading edge of the central guide ring cone 10, and the central air intake slit 24 is connected to the central ring cavity 25. The walls of the central stage outer concave cavity 8 and the central stage inner concave cavity 9 of the main combustion stage are evenly provided with several front jet holes 18 and rear jet holes 19 in the same number along the circumference. Cooling holes 20 are also provided on the other walls. During operation, a portion of the air enters the central annular cavity 25 directly through the central intake slot 24 at the leading edge of the central guide ring cone 10. Subsequently, it enters through the cooling holes 20 and the front jet hole 18 on the front and lower walls of the central stage outer concave cavity 8, forming a clockwise rotating wall-attached air film and a radial jet. Another portion of the incoming air enters through the cooling holes 20 and the rear jet hole 19 on the front and upper walls of the central stage outer concave cavity 8, forming a clockwise rotating wall-attached air film and a radial jet. Under the combined action of the above airflows, a central stage outer annular vortex 30 is formed in the central stage outer concave cavity 8. This vortex structure ensures good lean combustion stability, efficient combustion, and outlet temperature distribution in the combustion chamber.

[0027] Part of the air entering the central annular cavity 25 from the central intake slot 24 at the leading edge of the central guide ring cone 10 will simultaneously enter from the cooling holes 20 and the front jet hole 18 on the front and upper walls of the central stage concave cavity 9, forming a counterclockwise rotating wall-attached air film and radial jet. Another part of the incoming air will enter from the cooling holes 20 and the rear jet hole 19 on the front and lower walls of the central stage concave cavity 9, forming a counterclockwise rotating wall-attached air film and radial jet. Under the combined action of the above airflows, a central stage inner annular vortex 31 is formed in the central stage concave cavity 9. This vortex structure ensures good lean combustion stability and efficient combustion, as well as efficient combustion and outlet temperature distribution in the combustion chamber.

[0028] like Figures 2 to 4 As shown, in this embodiment, the auxiliary oil passage 4, main oil passage 5, and third oil passage 6 of the graded oil passage are all double-layer structures with external heat insulation by heat insulation sleeve 13. Among them, the auxiliary oil passage 4 and the third oil passage 6 have several direct-shot nozzles 14 evenly opened in the circumferential direction. The direct-shot nozzles 14 face the center of the air inlet 17, and the number corresponds one-to-one with the air inlet 17. The right side of the main oil passage 5 extends to the central annular cavity 25 in the circumferential direction through several connecting pipes. Several centrifugal nozzles 15 are installed at the top and bottom of the connecting pipes. The outlet of the centrifugal nozzles 15 extends into the front jet hole 18 of the central stage outer concave cavity 8 and the central stage inner concave cavity 9. During operation, the direct-injection nozzles 14 of the auxiliary oil passage 4 and the third oil passage 6 inject fuel into the air intake holes 17 at the left leading edge of the outer ring inclined concave cavity 7 and the inner ring inclined concave cavity 11, respectively. The fuel enters the evaporation ring cavity 16 with the airflow to achieve pre-evaporation. The evaporated fuel-air mixture is supplied to the outer ring vortex 29 and the inner ring vortex 32 regions for combustion through the front jet hole 18 with the airflow. The centrifugal nozzles 15 of the main oil passage 5 directly supply fuel into the front jet holes 18 of the central stage outer concave cavity 8 and the central stage inner concave cavity 9, respectively, and the fuel is burned in the central stage outer ring vortex 30 and the central stage inner ring vortex 31 regions, respectively.

[0029] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pre-evaporation-direct mixing four-cavity staged combustion chamber head, located between the outer casing and the inner casing in an annular channel, characterized in that, include: The central stage is composed of a central stage outer concave cavity (8), a central stage inner concave cavity (9), and a central flow guiding ring cone (10). The central flow guiding ring cone (10) is located upstream of the central stage outer concave cavity (8) and the central stage inner concave cavity (9). The central stage outer concave cavity (8) and the central stage inner concave cavity (9) are connected to the central flow guiding ring cone (10) on their upstream sides. A pre-combustion stage is radially arranged on the outer periphery of the central stage for first-stage combustion. The pre-combustion stage is composed of an outer ring inclined concave cavity (7), and the inner wall end of the outer ring inclined concave cavity (7) overlaps with the outer concave cavity (8) of the central stage. An evaporation ring cavity (16) is provided on the outer ring inclined concave cavity (7). The third stage is radially arranged on the inner periphery of the central stage and is used to perform the second stage combustion simultaneously with the central stage. The third stage is composed of an inner ring oblique concave cavity (11). The outer wall of the inner ring oblique concave cavity (11) overlaps the inner concave cavity (9) of the central stage. An evaporation ring cavity (16) is provided on the inner ring oblique concave cavity (11). The front jet hole (18), the evaporation ring cavity of the outer ring oblique concave cavity (7), the inner ring oblique concave cavity (11), the outer concave cavity of the central stage (8), and the inner concave cavity of the central stage (9) are respectively provided with front jet holes (18) for injecting fuel into the corresponding concave cavity through the fuel nozzle; Each of the evaporation ring chambers (16) has several air inlets (17) evenly distributed around its windward wall surface for supplying air to the corresponding evaporation ring chamber (16); the central guide ring cone (10) is a cavity structure, and a central air inlet slit (24) is opened at the front edge of the central guide ring cone (10), which is used to supply air to the front jet holes (18) of the central stage outer concave cavity (8) and the central stage inner concave cavity (9).

2. The pre-evaporation-direct mixing four-cavity staged combustion chamber head according to claim 1, characterized in that, It also includes a fuel main (3) and a series of fuel lines. The fuel main (3) is installed and fixed on the outer casing (1). The series of fuel lines includes a secondary fuel line (4), a main fuel line (5), and a third fuel line (6). The auxiliary oil passage (4) is connected to the main fuel line (3) via a connecting pipeline, and the auxiliary oil passage (4) is used to supply oil to the outer ring inclined cavity (7); The main oil passage (5) is located downstream of the auxiliary oil passage (4) and at the end of the connecting pipeline of the fuel main pipe (3). A constant pressure valve (12) is provided at the oil inlet of the main oil passage (5), which circumferentially passes through and is fixed on the central guide ring cone (10) for supplying oil to the central stage outer concave cavity (8) and the central stage inner concave cavity (9). The third oil passage (6) is connected to the main oil passage (5) and is used to supply oil to the inner ring oblique cavity (11).

3. The pre-evaporation-direct mixing four-cavity staged combustion chamber head according to claim 2, characterized in that, The auxiliary oil passage (4), main oil passage (5) and third oil passage (6) are double-layered structures. The oil passages are wrapped with heat insulation sleeves (13) for heat insulation. The auxiliary oil passage (4) and third oil passage (6) have several direct-shot nozzles (14) evenly opened in the circumference. The direct-shot nozzles (14) face the center of the air inlet (17). The number of direct-shot nozzles (14) corresponds one-to-one with the number of air inlet (17).

4. The pre-evaporation-direct mixing four-cavity staged combustion chamber head according to claim 2, characterized in that, A central annular cavity (25) is provided between the inner ring of the central stage outer concave cavity (8) and the outer ring of the central stage inner concave cavity (9). The central air inlet slit (24) supplies air to the front jet hole (18) of the central stage outer concave cavity (8) and the central stage inner concave cavity (9) through the central annular cavity (25).

5. The pre-evaporation-direct mixing four-cavity staged combustion chamber head according to claim 4, characterized in that, Downstream of the main oil passage (5), several connecting pipes extend circumferentially to the central annular cavity (25). Several centrifugal nozzles (15) are installed at the upper and lower ends of the connecting pipes. The outlet of the centrifugal nozzles (15) extends into the front jet hole (18) of the central stage outer concave cavity (8) and the central stage inner concave cavity (9).

6. The pre-evaporation-direct mixing four-cavity staged combustion chamber head according to claim 1, characterized in that, The outer ring wall end of the outer ring concave cavity (7) and the inner ring wall end of the inner ring concave cavity (11) are uniformly provided with a number of identical rear jet holes (19) along the circumference.

7. The pre-evaporation-direct mixing four-cavity staged combustion chamber head according to claim 1, characterized in that, The outer ring end of the central stage outer concave cavity (8) and the inner ring end of the central stage inner concave cavity (9) are uniformly provided with a number of identical rear jet holes (19) along the circumference.

8. The pre-evaporation-direct mixing four-cavity staged combustion chamber head according to claim 1, characterized in that, Cooling holes (20) are provided on the walls of the outer ring oblique concave cavity (7), the inner ring oblique concave cavity (11), the central stage outer concave cavity (8), and the central stage inner concave cavity (9). The cooling holes (20) form an acute angle with the flow direction of the local oil and gas mixture in the corresponding concave cavity.

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