Center-staged low-emission combustion chamber head with efficient anti-backfire structure

Abstract

The invention discloses a center-staged low-emission combustion chamber head with an efficient anti-backfire structure, and belongs to the technical field of low-emission combustion chamber heads. Comprising a pre-combustion stage part, a main combustion stage part and an anti-backfire structure located between the pre-combustion stage part and the main combustion stage part. Fuel oil in the pre-combustion-stage component is ejected out through a pre-combustion-stage centrifugal nozzle, so that a solid conical atomization field is formed; fuel oil in the main combustion stage component is injected into a main combustion stage annular channel through a main combustion stage transverse fuel oil direct injection hole to form an annular atomization field, and combustible premixed oil gas is formed after the fuel oil is mixed with air in a main combustion stage first-stage radial swirler. The anti-backfire structure provides an anti-backfire air wall for the interior of the main combustion stage annular channel, an output port of the anti-backfire air wall is located on the inner wall face of the main combustion stage, the included angle between the output port and the inner wall of the main combustion stage on the outlet side of the main combustion stage annular channel is an acute angle, and the output port and the inner wall of the main combustion stage are used for preventing main combustion stage flames from extending towards upstream premixed oil gas. The tempering phenomenon is efficiently prevented, and therefore potential safety hazards caused by tempering are prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of low-emission combustion chamber heads, and in particular relates to a centrally graded low-emission combustion chamber head with a high-efficiency anti-flashback structure. Background Art

[0002] With the increasing global environmental awareness, the performance optimization and pollutant emission control of aircraft engines have become the focus of common concern in the scientific research community. As one of the core components of aircraft engines, the design and performance of the combustion chamber directly determine the overall efficiency, economy and environmental protection of the engine. In recent years, the central staged combustion chamber has been widely used and studied in the field of aircraft engines due to its efficient combustion organization, low pollutant emissions and good stability.

[0003] The design of the center-staged swirl combustor aims to improve combustion efficiency, reduce pollutant generation and enhance combustion stability by optimizing the mixing process of fuel and air and the layout of the combustion area. The unique aerodynamic structure design of this combustion organization helps to suppress the formation of local high-temperature areas, reduce the generation of thermal NOx, and promote the oxidation of soot, reducing pollutant emissions. However, the center-staged combustor has a serious flashback problem due to the setting of the main combustion stage premixing section.

[0004] In summary, in order to reduce pollutant emissions and effectively prevent the occurrence of flashback, the present invention designs a centrally graded low-emission combustion chamber head with a highly effective anti-flashback structure. Summary of the invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the prior art, the present invention provides a centrally staged low-emission combustion chamber head with an efficient anti-flashback structure, an annular channel is provided between the pre-combustion stage component and the main combustion stage component, and the air in the annular channel is introduced into the main combustion stage channel through the jet hole to form a high-speed flowing "air wall", which isolates the main combustion stage flame from extending to the upstream premixed oil and gas, and effectively prevents the occurrence of flashback, thereby preventing the safety hazards caused by flashback. At the same time, the present invention adopts a centrally staged combustion organization mode to maintain combustion stability under small working conditions and widen the flameout boundary; and reduce pollutant emissions, especially NOx emissions, under large working conditions. The present invention solves the flashback problem caused by the centrally staged combustion organization technology while reducing pollutant emissions, and can both ensure the reduction of pollutant generation and prevent the occurrence of flashback.

[0007] The technical solution of the present invention is: a centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure, characterized in that: it includes a pre-combustion stage component, a main combustion stage component and an anti-flashback structure located therebetween, which are arranged in sequence from the inside to the outside; the pre-combustion stage component ejects the internal fuel oil through a pre-combustion stage centrifugal nozzle to form a solid conical atomization field; the main combustion stage component ejects the internal fuel oil into the main combustion stage annular channel through a main combustion stage transverse fuel straight injection hole to form an annular atomization field, which is mixed with the air in the first-stage radial swirler of the main combustion stage to form combustible premixed oil and gas; the anti-flashback structure provides an anti-flashback air wall into the main combustion stage annular channel, and the output port of the anti-flashback air wall is located on the inner wall of the main combustion stage, and the angle with the inner wall of the main combustion stage on the outlet side of the main combustion stage annular channel is acute, so as to isolate the main combustion stage flame from extending to the upstream premixed oil and gas.

[0008] A further technical solution of the present invention is: the pre-combustion stage component includes a pre-combustion stage centrifugal nozzle, a pre-combustion stage two-stage axial swirler, a venturi, and a pre-combustion stage oil supply pipe, the pre-combustion stage two-stage axial swirler is arranged on the outer periphery of the pre-combustion stage centrifugal nozzle to introduce reverse swirling air; the outer wall of the first-stage swirler of the pre-combustion stage two-stage axial swirler extends toward the downstream direction of the pre-combustion stage centrifugal nozzle, and the extended part is the venturi; the input end of the pre-combustion stage oil supply pipe is connected to the centrifugal nozzle for introducing fuel; the flow range of the pre-combustion stage centrifugal nozzle is 1 to 15 g / s, the spray type is solid cone, hollow cone or semi-solid cone, and the spray angle is 45°, 60° or 80°.

[0009] A further technical solution of the present invention is: the pre-combustion stage two-stage axial swirler adopts axial flow straight blades, the two-stage blades have opposite rotation directions, and the number of blades is 12; the internal and external blade swirl angles are 30° and 45° respectively; the air flow ratio of the inner and outer two-stage swirlers is 0.43~1.5.

[0010] A further technical solution of the present invention is that the convergent section angle of the venturi tube is the same as the cone angle of the centrifugal nozzle head, the included angle with the axis is 22.5°, and the included angle with the expansion section is 11.5°.

[0011] A further technical solution of the present invention is: the main combustion stage component is an annular structure, and a main combustion stage oil delivery passage and a main combustion stage annular channel are arranged in its annular wall; a main combustion stage oil collecting ring is provided at the input end of the main combustion stage oil delivery passage, which is connected to the main combustion stage oil supply pipe; the inlet of the main combustion stage annular channel is connected to the main combustion stage first-level radial swirler, and swirling air is introduced radially through the main combustion stage first-level radial swirler, and its outlet is located on the downstream end face, on the same side as the pre-combustion stage centrifugal nozzle; the main combustion stage oil delivery passage and the main combustion stage annular channel are connected through the main combustion stage transverse fuel straight injection hole, and the fuel in the main combustion stage oil delivery passage is sprayed into the main combustion stage annular channel.

[0012] A further technical solution of the present invention is: the angle between the main combustion stage transverse fuel straight spray hole and the axial direction is 75°~120°, the spray hole diameter is 0.2~0.4mm, the spray hole aspect ratio is 2.5~5, and the number of spray holes is 8~16; the swirl angle of the main combustion stage first-stage radial swirler is 30°~45°, the number of blades is 30, and the blade height is 12mm.

[0013] A further technical solution of the present invention is: the main combustion stage oil collecting ring is an annular flow channel inside the front end of the main combustion stage, with a ring height of 6mm and a ring width of 2mm. There are 8 to 16 deep holes with a diameter of 1mm inside the oil collecting ring, which are connected to the main combustion stage lateral fuel straight injection hole to supply oil to it.

[0014] A further technical solution of the present invention is: the anti-backfire structure includes an interstage channel arranged between the pre-combustion stage component and the main combustion stage component, a main combustion stage transverse air jet hole connecting the interstage channel and the main combustion stage annular channel, and a head cooling hole leading to the downstream end face of the interstage channel; the outlet of the main combustion stage transverse air jet hole is located on the inner wall of the main combustion stage annular channel, with an axial angle of 45° with the head of the centrally-staged low-emission combustion chamber, a diameter of 1.9 mm, and two rows of inclined holes, arranged crosswise, for a total of 80.

[0015] A further technical solution of the present invention is: the interstage channel is an air channel between the pre-combustion stage and the main combustion stage, and the channel ring height is 5 mm.

[0016] A further technical solution of the present invention is: the head cooling holes are located on the interstage steps between the pre-combustion stage and the main combustion stage, and are distributed in 4 concentric and staggered circles, with 20 microholes with a diameter of 0.5 mm in each circle.

[0017] Beneficial Effects

[0018] The beneficial effects of the present invention are as follows: the present invention proposes a centrally staged low-emission combustion chamber head with an efficient anti-backfire structure, which is mainly composed of a pre-combustion stage component, a main combustion stage component, an interstage channel and a head cooling hole. The pre-combustion stage component is located at the center of the head, and is composed of a centrifugal nozzle, a two-stage axial swirler, a venturi, and a pre-combustion stage oil supply pipe. The blades of the two-stage axial swirler rotate in opposite directions, and a central reflow zone with a strong shear layer is formed downstream thereof, which helps the oil film to break up and atomize and stabilize the flame. Under small operating conditions, the pre-combustion stage works alone and burns stably in the form of a diffusion flame. At the same time, the local oil-rich state also greatly broadens the flame stabilization working boundary. The main combustion stage component is arranged in a concentric circle, annularly surrounding the pre-combustion stage component, and mainly includes a transverse fuel direct injection hole, a first-stage radial swirler, a transverse air jet hole, an oil supply pipe and an oil collecting ring. The main combustion stage components are opened under large operating conditions, and cooperate with the pre-combustion stage components to regulate the flow field temperature distribution in the combustion chamber, and the oil and gas distribution of the main / pre-combustion stage can be adjusted according to different operating conditions to achieve the best combustion performance and emission performance. The multiple lateral fuel direct injection holes of the main combustion stage atomize the fuel injection, and the annular swirl formed by the first-stage radial swirler is quickly mixed in the premixing channel to form a uniform combustible mixture. The inner wall of the main combustion stage is provided with a 45° lateral air jet hole, which is located downstream of the fuel injection hole. This design can provide close velocity distribution in the radial and axial directions, among which the radial component velocity can effectively block the direct contact between the upstream fuel flowing close to the inner wall and the downstream high-temperature fuel gas, avoid the extension of the high-temperature flame to the premixing channel, and thus prevent the occurrence of flashback. At the same time, the design of the axial component velocity increases the axial velocity of the mainstream airflow, shortens the stagnation time, and thus significantly reduces NOx emissions. The specific advantages are as follows:

[0019] (1) Enhanced ignition and stability. The diameter of the pre-combustion stage nozzle is 0.2-0.6 mm. The smaller nozzle diameter can fully atomize the fuel under the action of high oil pressure, making it easy to ignite and the flame stability is strong.

[0020] (2) Lower pollutant emissions. The main combustion stage is evenly arranged with 16 transverse fuel injection holes with a diameter of 0.2 to 0.4 mm, which has better fuel penetration depth and atomization effect, and more uniform oil and gas mixing in the premixing section. Multiple transverse air injection holes with a 45° jet angle are set on the inner wall of the main combustion stage. The axial component velocity provided by them can increase the axial velocity of the mainstream gas, shorten the stagnation time, and significantly reduce NOx emissions.

[0021] (3) Highly effective flashback prevention. The 45° jet angle can provide a radial velocity equal to the axial velocity. This radial velocity can prevent the direct contact between the upstream fuel oil flowing near the inner wall and the downstream high-temperature combustion gas while ensuring that the mainstream axial velocity is not greatly affected, thus preventing the high-temperature flame from extending to the premixing channel and flashing.

[0022] (4) The combustion chamber has a wider stable working margin. The central staged combustion organization technology is adopted. The pre-combustion stage works alone under small working conditions to form a stable diffusion flame. The main combustion stage works simultaneously with the pre-combustion stage under large working conditions. Through oil and gas matching, staged and zoned combustion, the combustion is more stable.

[0023] (5) Flexible head structure. The multiple parts of the combustion chamber head are assembled by extrusion and threaded fastening. The parts can be disassembled and replaced. The main combustion stage blade installation angle, the number of fuel direct injection holes, the position of the fuel direct injection holes, the atomization angle of the pre-combustion stage centrifugal nozzle, etc. can all be replaced according to research needs, which has a wide range of research applications.

[0024] Proven, Figure 7 The results of the temperature field simulation of the initial model (a) and the optimized existing model (b) are shown. It can be seen that the 45° air jet hole structure designed on the inner wall of the main combustion stage effectively eliminates the flashback phenomenon. Figure 8 The results of the initial model (a) and the optimized existing model (b) in the NO concentration field simulation are shown. It can be seen that the 45° air jet hole structure designed on the inner wall of the main combustion stage effectively reduces the NO generation. The air jet hole angle is designed to be 45° to take into account the functions of anti-flashback and low NOx emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural cross-sectional view of the head of the center-staged low-emission combustion chamber with a high-efficiency anti-flashback structure of the present invention;

[0026] Figure 2 A cross-sectional view of a pre-combustion stage component of a center-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure of the present invention;

[0027] Figure 3 It is one of the partial structural schematic diagrams of the pre-combustion stage component of the head of the centrally-staged low-emission combustion chamber with a high-efficiency anti-flashback structure of the present invention;

[0028] Figure 4 A cross-sectional view of a main combustion stage component of a center-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure of the present invention;

[0029] Figure 5 This is one of the partial structural schematic diagrams of the main combustion stage components of the head of the centrally-staged low-emission combustion chamber with a high-efficiency anti-flashback structure of the present invention;

[0030] Figure 6 The front view (a), left view (b) and positive triaxial view (c) of the center-staged low-emission combustion chamber head structure with a high-efficiency anti-flashback structure of the present invention;

[0031] Figure 71 and 1 are the results of the temperature field simulation of the initial model (a) and the optimized existing model (b) in the embodiment of the present invention.

[0032] Figure 8 1 and 1 are the results of the initial model (a) and the optimized existing model (b) in the NO concentration field simulation in the embodiment of the present invention.

[0033] Explanation of the reference numerals: 1. Pre-combustion stage component; 2. Main combustion stage component; 3. Interstage channel; 4. Head cooling hole; 11. Pre-combustion stage centrifugal nozzle; 12. Pre-combustion stage two-stage axial swirler; 13. Venturi tube; 14. Pre-combustion stage oil supply pipe; 21. Main combustion stage lateral fuel straight injection hole; 22. Main combustion stage first-stage radial swirler; 23. Main combustion stage lateral air jet hole; 24. Main combustion stage oil supply pipe; 25. Main combustion stage oil collecting ring; 26. Main combustion stage oil delivery channel. DETAILED DESCRIPTION

[0034] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0036] Based on the fact that the existing central staged combustion organization technology reduces pollutant emissions while also bringing about the problem of flashback, the present invention provides a central staged low emission combustion chamber head with a high-efficiency anti-flashback structure, comprising a pre-combustion stage component, a main combustion stage component and an anti-flashback structure located therebetween, which are arranged in sequence from the inside to the outside; the pre-combustion stage component ejects the internal fuel oil through a pre-combustion stage centrifugal nozzle to form a solid conical atomization field; the main combustion stage component ejects the internal fuel oil into the main combustion stage annular channel through the main combustion stage transverse fuel straight injection hole to form an annular atomization field, which is mixed with the air in the first radial swirler of the main combustion stage to form combustible premixed oil and gas; the anti-flashback structure provides an anti-flashback air wall into the main combustion stage annular channel, and the output port of the anti-flashback air wall is located on the inner wall of the main combustion stage, and the included angle with the inner wall of the main combustion stage on the outlet side of the main combustion stage annular channel is acute, so as to isolate the main combustion stage flame from extending to the upstream premixed oil and gas.

[0037] Specifically, the pre-combustion stage components include a pre-combustion stage centrifugal nozzle, a pre-combustion stage two-stage axial swirler, a venturi tube, and a pre-combustion stage oil supply pipe. The pre-combustion stage two-stage axial swirler is arranged on the periphery of the pre-combustion stage centrifugal nozzle to introduce reverse swirling air; the outer wall of the first-stage swirler of the pre-combustion stage two-stage axial swirler extends toward the downstream direction of the pre-combustion stage centrifugal nozzle, and the extended part is the venturi tube; the input end of the pre-combustion stage oil supply pipe is connected to the centrifugal nozzle to introduce fuel;

[0038] Specifically, the main combustion stage component is an annular structure, and a main combustion stage oil delivery channel and a main combustion stage annular channel are arranged in its annular wall. A main combustion stage oil collecting ring is provided at the input end of the main combustion stage oil delivery channel, which is connected to the main combustion stage oil supply pipe; the inlet of the main combustion stage annular channel is connected to the main combustion stage first-level radial swirler, and swirling air is introduced radially through the main combustion stage first-level radial swirler, and its outlet is located on the downstream end face, on the same side as the pre-combustion stage centrifugal nozzle; the main combustion stage oil delivery channel and the main combustion stage annular channel are connected through the main combustion stage transverse fuel straight injection hole, and the fuel in the main combustion stage oil delivery channel is sprayed into the main combustion stage annular channel.

[0039] Specifically, the anti-backfire structure includes an interstage channel arranged between the pre-combustion stage component and the main combustion stage component, a main combustion stage transverse air jet hole connecting the interstage channel and the main combustion stage annular channel, and a head cooling hole leading to the downstream end face of the interstage channel; the outlet of the main combustion stage transverse air jet hole is located on the inner wall of the main combustion stage annular channel.

[0040] The first feature of the head of the present invention is that the center-stage combustion organization technology greatly improves the flame stability under small working conditions and significantly reduces the pollutant emissions under large working conditions. The second feature is that a transverse air jet hole structure is designed at the outlet of the main combustion stage premixing section to form an "air wall" that isolates the premixed gas from the flame, effectively preventing the occurrence of flashback, thereby preventing the safety hazards caused by flashback.

[0041] The above technical solution is further described below in conjunction with the accompanying drawings and embodiments:

[0042] Reference Figure 1-Figure 6 As shown, the centrally staged low emission combustion chamber head with a high-efficiency anti-flashback structure in this embodiment includes a pre-combustion stage component 1, a main combustion stage component 2, an interstage channel 3 and a head cooling hole 4. The head adopts centrally staged low emission technology and anti-flashback structure design, and is made of high-temperature alloy steel GH3536 material as a whole, and is assembled and formed by welding and threaded fastening.

[0043] The pre-combustion stage component 1 is located in the center of the head, and is composed of a centrifugal nozzle 11, a two-stage axial swirler 12, a venturi 13, and a pre-combustion stage oil supply pipe 14. The two-stage axial swirler 12 and the venturi 13 are integrally formed by 3D printing technology; the pre-combustion stage oil supply pipe 14 and the centrifugal nozzle 11 are machined and connected together by welding, and the end faces are pressed and sealed in the central channel of the swirler by threaded fastening, and the downstream end face of the nozzle is flush with the downstream end face of the central channel of the swirler.

[0044] The blades of the pre-combustion stage double-stage axial swirler 12 rotate in opposite directions, and a central recirculation zone with a strong shear layer is formed downstream thereof, which helps the oil film to break up and atomize and stabilize the flame. Under small working conditions, the pre-combustion stage works alone and burns stably in the form of a diffusion flame. At the same time, the local oil-rich state also greatly broadens the working boundary of flame stability.

[0045] The main combustion stage component 2 is arranged in a concentric circle, annularly surrounding the pre-combustion stage component, and mainly includes a transverse fuel injection hole 21, a first-stage radial swirler 22, a transverse air jet hole 23, an oil supply pipe 24 and an oil collecting ring 25. The main combustion stage component 2 is made by machining, and the pre-combustion stage component 1 is concentrically placed inside the main combustion stage. The downstream outer end face of the pre-combustion stage is pressed to the downstream inner end face of the main combustion stage to form an inter-stage channel 3 and an inter-stage step, and the inter-stage step is machined with a head cooling hole 4. The inner and outer rings of the main combustion stage are connected with long bolts through the threaded holes on the front end face, and are fixed to the combustion chamber head baffle as a whole with a pressure plate.

[0046] The main combustion stage component 2 is turned on under large operating conditions, and cooperates with the pre-combustion stage component 1 to regulate the temperature distribution of the flow field in the combustion chamber, and can adjust the oil and gas distribution of the main / pre-combustion stage according to different operating conditions to achieve optimal combustion performance and emission performance. The multiple transverse fuel direct injection holes 21 of the main combustion stage atomize the fuel injection, and the annular swirl formed by the first-stage radial swirler 22 is quickly mixed in the premixing channel to form a uniform combustible mixture. The transverse air jet hole 23 forms an "air wall" upstream of the main combustion stage outlet, which effectively blocks the direct contact between the flame and the combustible mixture, and increases the axial jet speed of the mixture, effectively preventing the occurrence of flashback. In addition, the transverse jet shortens the gas stagnation time, which can further reduce the emission of pollutants such as NOx.

[0047] Reference Figure 1As shown, the air flowing through the combustion chamber head structure is divided into three streams: main combustion stage swirl gas, pre-combustion stage swirl gas and inter-stage channel gas. The first stream of air is introduced through the two-stage axial swirler 12 of the pre-combustion stage. This stream of air further breaks up and atomizes the fuel sprayed from the centrifugal nozzle 11 in the form of reverse swirl, and forms a central reflow zone in the downstream area of ​​the combustion chamber head, thereby stabilizing the combustion of the flame. The second stream of air enters the premixing channel of the swirler through the primary radial swirler 22 of the main combustion stage, forming an annular swirl. This swirl is quickly mixed with the fuel sprayed from the main combustion stage transverse fuel direct injection hole 21 to form a uniform premixed oil and gas. As for the third stream of air, it is mainly injected into the main combustion stage channel in large quantities through the transverse air injection hole 23 of the main combustion stage. This stream of air constructs two layers of air barriers upstream of the channel outlet, like an "air wall", which effectively prevents the occurrence of flashback. In addition, the addition of transverse jet air also reduces the swirl intensity of the main combustion stage air and the stagnation time of the premixed gas, thereby significantly reducing the generation of NOx. The remaining small amount of air flows into the combustion chamber through the head cooling holes 4 on the interstage steps, using a highly efficient porous heat exchange cooling method to ensure that the steps are protected from erosion by high-temperature flames.

[0048] Reference Figure 2 As shown, the pre-combustion stage two-stage axial swirler 12 is integrally formed by 3D printing technology, using axial flow straight blades, the two-stage blades have opposite rotation directions, and the number of blades is 12. The swirl angles of the inner and outer blades are 30° and 45°, respectively. The ring heights of the inner and outer two-stage swirlers are 4.55mm and 3.25mm, respectively, and the ring heights are geometrically adjustable, and the two-stage air flow ratio is 1. It should be pointed out that the diameter of the upper half of the middle channel of the swirler is 15.2mm, and the diameter of the lower half of the channel is 13.2mm, forming a step with a width of 1mm, which is used to form an end face compression seal with the boss of the centrifugal nozzle 11.

[0049] Reference Figure 3 As shown, the pre-combustion stage oil supply pipe 14 and the centrifugal nozzle 11 are machined and connected together by welding. The inner diameter of the oil supply pipe is 2 mm and the outer diameter is 4 mm. The outer diameter of the centrifugal nozzle 11 is 13 mm and the diameter of the spray hole is 0.4 mm. There is a 1 mm high and 4 mm wide boss in the middle of the centrifugal nozzle 11. When assembled with the pre-combustion stage cyclone, the boss is pressed and sealed with the step end face of the pre-combustion stage central channel.

[0050] Reference Figure 4As shown, the main combustion stage transverse fuel straight injection hole 21 of the main combustion stage component 2 has an angle of 90° with the axial direction, a nozzle diameter of 0.2mm, a nozzle aspect ratio of 5, and 16 nozzles. The swirl angle of the main combustion stage first-stage radial swirler 22 is 35°, the number of blades is 30, and the blade height is 12mm. The main combustion stage transverse air jet hole 23 has an angle of 45° with the axial direction, a diameter of 1.9mm, and two rows of inclined holes, arranged crosswise, for a total of 80. The main combustion stage premixing channel is a tapered type, with a contraction angle of about 5° and a channel length of 17mm.

[0051] Reference Figure 5 As shown, the oil collecting ring of the main combustion stage component is an annular flow channel inside the front end of the main combustion stage, with a ring height of 6 mm and a ring width of 2 mm. There are 16 deep holes with a diameter of 1 mm inside the oil collecting ring, which are connected to the main combustion stage lateral fuel straight injection holes to serve as the main combustion stage oil delivery channel 26.

[0052] Reference Figure 6 As shown, the maximum outer diameter of the combustion chamber head structure is 102mm and the axial length is 38.5mm. In Figure (b), the end face of the head is provided with multiple threaded holes for assembling various components of the head. Combined with the threads on the outer ring wall of the main combustion stage in Figure (c), the entire head can be fixed on the front baffle of the combustion chamber.

[0053] Reference Figure 7 As shown, (a) and (b) are the temperature field calculation results of the old model before the optimization design of the present invention and the low-emission combustion chamber head model with an efficient anti-flashback structure of the present invention, respectively. It can be seen that the general low-emission combustion chamber head is prone to spontaneous combustion and flashback due to the presence of premixed gas in its premixing channel, which greatly ablates the head structure and seriously affects the safety and reliability of the combustion chamber. The head of Figure (a) is optimized and 80 45° air jet holes are set downstream of the fuel injection hole on the inner wall of the main combustion stage, which can provide a close velocity distribution in the radial and axial directions. Among them, the radial component velocity can effectively block the direct contact between the upstream fuel flowing close to the inner wall and the downstream high-temperature fuel gas, avoid the high-temperature flame from extending to the premixing channel, and thus prevent the occurrence of flashback. At the same time, the design of the axial component velocity increases the axial velocity of the mainstream airflow, shortens the stagnation time, and thus significantly reduces NOx emissions. The air jet hole angle is designed to be 45°, which takes into account the functions of anti-flashback and low NOx emissions.

[0054] Reference Figure 8 The figure shows the results of the initial model (a) and the optimized existing model (b) in the NO concentration field simulation. It can be seen that the 45° air jet hole structure designed on the inner wall of the main combustion stage effectively reduces the NO generation. The air jet hole angle is designed to be 45° to take into account the functions of anti-flashback and low NOx emissions.

[0055] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A centrally graded low emission combustion chamber head with a highly efficient anti-flashback structure, characterized in that: It comprises a pre-combustion stage component, a main combustion stage component and an anti-flashback structure located therebetween, which are arranged in sequence from the inside to the outside; the pre-combustion stage component ejects the internal fuel oil through a pre-combustion stage centrifugal nozzle to form a solid conical atomization field; the main combustion stage component ejects the internal fuel oil into a main combustion stage annular channel through a main combustion stage transverse fuel straight injection hole to form an annular atomization field, which is mixed with the air in a first-stage radial swirler of the main combustion stage to form combustible premixed oil and gas; the anti-flashback structure provides an anti-flashback air wall into the main combustion stage annular channel, the output port of the anti-flashback air wall is located on the inner wall of the main combustion stage, and forms an acute angle with the inner wall of the main combustion stage on the outlet side of the main combustion stage annular channel, so as to isolate the main combustion stage flame from extending to the upstream premixed oil and gas.

2. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 1, characterized in that: The pre-combustion stage components include a pre-combustion stage centrifugal nozzle, a pre-combustion stage two-stage axial swirler, a venturi, and a pre-combustion stage oil supply pipe. The pre-combustion stage two-stage axial swirler is arranged on the outer periphery of the pre-combustion stage centrifugal nozzle to introduce reverse swirling air; the outer wall of the first-stage swirler of the pre-combustion stage two-stage axial swirler extends toward the downstream direction of the pre-combustion stage centrifugal nozzle, and the extended part is the venturi; the input end of the pre-combustion stage oil supply pipe is connected to the centrifugal nozzle for introducing fuel; the flow range of the pre-combustion stage centrifugal nozzle is 1 to 15 g / s, the spray type is solid cone, hollow cone or semi-solid cone, and the spray angle is 45°, 60° or 80°.

3. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 2, characterized in that: The pre-combustion stage two-stage axial swirler adopts axial flow straight blades, the two-stage blades rotate in opposite directions, and the number of blades is 12; the swirl angles of the inner and outer blades are 30° and 45° respectively; the ratio of the air flow rates of the inner and outer two-stage swirlers is 0.43-1.

5.

4. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 2, characterized in that: The convergent section angle of the venturi tube is the same as the cone angle of the centrifugal nozzle head, with the included angle of 22.5° to the axis, and the included angle of the expansion section to the axis is 11.5°.

5. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 1, characterized in that: The main combustion stage component is an annular structure, and a main combustion stage oil delivery passage and a main combustion stage annular channel are arranged in its annular wall. A main combustion stage oil collecting ring is arranged at the input end of the main combustion stage oil delivery passage, which is connected to the main combustion stage oil supply pipe; the inlet of the main combustion stage annular channel is connected to the main combustion stage first-level radial swirler, and swirling air is introduced radially through the main combustion stage first-level radial swirler, and its outlet is located on the downstream end face, on the same side as the pre-combustion stage centrifugal nozzle; the main combustion stage oil delivery passage and the main combustion stage annular channel are connected through the main combustion stage transverse fuel straight injection hole, and the fuel in the main combustion stage oil delivery passage is sprayed into the main combustion stage annular channel.

6. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 5, characterized in that: The included angle between the main combustion stage transverse fuel straight spray hole and the axial direction is 75° to 120°, the spray hole diameter is 0.2 to 0.4 mm, the spray hole aspect ratio is 2.5 to 5, and the number of spray holes is 8 to 16; the swirl angle of the main combustion stage first-stage radial swirler is 30° to 45°, the number of blades is 30, and the blade height is 12 mm.

7. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 6, characterized in that: The main combustion stage oil collecting ring is an annular flow channel inside the front end of the main combustion stage, with a ring height of 6 mm and a ring width of 2 mm. There are 8 to 16 deep holes with a diameter of 1 mm inside the oil collecting ring, which are connected to the main combustion stage lateral fuel direct injection holes to supply oil to them.

8. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 7, characterized in that: The anti-backfire structure includes an interstage channel arranged between the pre-combustion stage component and the main combustion stage component, a main combustion stage transverse air jet hole connecting the interstage channel and the main combustion stage annular channel, and a head cooling hole leading to the downstream end face of the interstage channel; the outlet of the main combustion stage transverse air jet hole is located on the inner wall of the main combustion stage annular channel, with an axial angle of 45° with the head of the centrally staged low-emission combustion chamber, a diameter of 1.9 mm, and two rows of inclined holes, arranged crosswise, for a total of 80.

9. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 8, characterized in that: The interstage channel is an air channel between the pre-combustion stage and the main combustion stage, and the channel ring height is 5mm.

10. A centrally-staged low-emission combustion chamber head with a high-efficiency anti-flashback structure according to claim 8, characterized in that: The head cooling holes are located on the interstage steps between the pre-combustion stage and the main combustion stage, and are distributed in 4 concentric circles, each circle having 20 microholes with a diameter of 0.5 mm.

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