Combustion chamber dual-mode injection structure

Abstract

The invention discloses a dual-mode injection structure of a combustion chamber, which comprises a head shell connected with a flame tube; the spraying module is positioned on the head shell; the injection module comprises a premixing module and a diffusion direct injection module; the premixing module is provided with a gas mixing channel, one end of the gas mixing channel communicates with a cavity between the cartridge receiver and the flame tube, and the other end of the gas mixing channel communicates with an inner cavity of the flame tube; the diffusion direct injection module is provided with a fuel input port, a first fuel output port and a second fuel output port, the fuel input port is connected with a fuel supply system, the first fuel output port is communicated with the flame tube inner cavity, the second fuel output port is communicated with the premixing module, and the center line of the second fuel output port is not collinear with the center line of the gas mixing channel. According to the injection module, premixing supply and diffusion direct injection supply of hydrogen are achieved at the same time, NOx emission can be reduced through dual-mode gas supply, tempering erosion damage can be effectively controlled, the stable combustion boundary of a combustion chamber is widened, and the stability of an engine during variable-state work is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbine engines, and particularly to a dual-mode injection structure for a combustion chamber. Background Art

[0002] Hydrogen has a relatively fast combustion speed, concentrated heat release, and a relatively high flame temperature, making it easier to produce thermal nitrogen oxides (NOx) emissions. The currently widely adopted technical means to reduce NOx emissions in hydrogen fuel combustion chambers is the premixed combustion mode, in which the fuel is pre-mixed with air evenly, so that the spatial distribution of the fuel is relatively dispersed, there is no local fuel enrichment area, and the heat release during combustion is also relatively dispersed, thus making it less likely to generate local high-temperature areas. However, premixed flames are prone to flashback, and related components are prone to ablation. In contrast, the diffusion combustion mode is not prone to flashback, but is prone to local fuel enrichment, and it is necessary to achieve the spatial discrete distribution of the fuel by reducing the fuel flow rate of a single injection hole, increasing the number and dispersion area of the injection holes.

[0003] The currently available hydrogen fuel combustion chambers generally achieve the premixing of hydrogen and air by arranging a premixing section at the head of the combustion chamber and arranging multiple premixing pipes in the premixing section. The stability of the premixed flame is poor, the ignition and extinction performance is poor, and thermoacoustic oscillations are likely to occur when the engine state changes, and in severe cases, it may lead to engine damage. Summary of the Invention

[0004] In view of this, the present invention provides a dual-mode injection structure for a combustion chamber to solve the problems of poor stability of the premixed flame and poor ignition and extinction performance of the current hydrogen fuel combustion chamber.

[0005] The present invention provides a dual-mode injection structure for a combustion chamber, including:

[0006] A head housing, which is adapted to be connected to a flame tube;

[0007] An injection module, which is positioned on the head housing; the injection module includes a premixing module and a diffusion direct injection module; the premixing module has a gas mixing channel, one end of the gas mixing channel is communicated with the cavity between the casing and the flame tube, and the other end of the gas mixing channel is communicated with the inner cavity of the flame tube; the diffusion direct injection module has a fuel input port, a first fuel output port, and a second fuel output port, the fuel input port is connected to a fuel supply system, the first fuel output port is communicated with the inner cavity of the flame tube, the second fuel output port is communicated with the premixing module, and the center line of the second fuel output port is not collinear with the center line of the gas mixing channel.

[0008] The beneficial effects of the above dual-mode injection structure of the combustion chamber are as follows: The premixing module achieves sufficient mixing of fuel and air through the mixing gas channel, ensuring a high-efficiency and stable combustion process; the diffusion direct injection module provides an additional fuel supply path to ensure a stable combustion state under different operating conditions. The diffusion direct injection module itself has the function of preventing flashback. In the invention, the center line of the second fuel outlet is not collinear with the center line of the mixing gas channel, which can effectively prevent the flame in the flame tube from spreading into the premixing module through the diffusion direct injection module. The non-collinear design makes it difficult for the flame to directly enter the internal structure of the diffusion direct injection module when propagating in the combustion chamber, thereby reducing the risk of flashback spread. In this way, the entire device has stronger flashback prevention ability, ensuring that the premixing tube will not be ablated due to flashback during small engine operating conditions or operating condition transitions.

[0009] The injection module of the present invention realizes both the premixed supply and the diffusion direct injection supply of hydrogen. The dual-mode gas supply can not only reduce NOx emissions, but also effectively control flashback ablation damage, broaden the stable combustion boundary of the combustion chamber, and enhance the stability of the engine during variable operating conditions.

[0010] In an alternative embodiment, the diffusion direct injection module includes:

[0011] At least one fuel supply pipe, one end of the fuel supply pipe is the fuel input port, and the other end of the fuel supply pipe is connected to an annular pipe;

[0012] An annular pipe, the annular pipe has at least one fuel input hole, at least one first fuel output hole and at least one second fuel output hole, the first fuel output hole is connected to a swirl structure, and the second fuel output hole is the second fuel outlet;

[0013] At least one swirl structure, the first fuel outlet is arranged on the swirl structure.

[0014] The beneficial effects of the above technical solution are as follows: The fuel supply pipe is connected to the annular pipe, and the fuel supply pipe transports the fuel to the annular pipe, and then the annular pipe distributes it to each fuel outlet. Swirl air is introduced through the swirl structure to better mix the fuel and air, forming a stable vortex combustion area, further improving the combustion efficiency and stability, and the swirl air generated by the swirl structure helps to isolate the flame from the fuel input path, further reducing the flashback risk.

[0015] In an alternative embodiment, the swirl structure includes a swirl gasket. One end of the swirl gasket is provided with a direct injection fuel hole connected to the first fuel output hole, the other end of the swirl gasket is provided with a confluence chamber, and a plurality of swirl air holes are arranged on the side wall of the swirl gasket; the confluence chamber is a cylindrical cavity, and the opening directions of the swirl air holes are tangent to the cylindrical wall surface of the confluence chamber.

[0016] The beneficial effects of the above technical solution are as follows: The confluence chamber is a cylindrical cavity, and the opening directions of the swirling air holes are tangent to the cylindrical wall surface of the confluence chamber. Air enters the confluence chamber through the swirling air holes on the swirling gasket and generates a wall-attached swirl, blocking the fuel from attaching to the wall, reducing the risk of flashback in the boundary layer, and generating a swirl downstream to stabilize the flame. Air enters the confluence chamber in a tangential direction through these swirling air holes and rotates forward along the wall surface in the chamber, which can produce an eddy current effect, making the fuel and air mix more evenly and forming a stable swirling combustion area.

[0017] In an alternative embodiment, one end of the swirling gasket is inserted into the interior of the annular pipe, and the other end of the swirling gasket is inserted into the interior of the head housing. The swirling gasket separates the annular pipe from the head housing.

[0018] In an alternative embodiment, the swirling gasket includes a first cylinder, a convex waist, and a second cylinder connected therebetween. The first cylinder is in small clearance fit with the round hole on the head housing, and the second cylinder is in interference fit or welded with the first fuel outlet hole.

[0019] In an alternative embodiment, the annular pipe is concentric with the engine main shaft. The centerlines of the first fuel outlets and the centerline of the air mixing channel are all parallel to the axis of the engine main shaft. A plurality of first fuel outlets are provided and the first fuel outlets are circumferentially spaced apart. A plurality of air mixing channels are provided and the air mixing channels are circumferentially spaced apart.

[0020] The beneficial effects of the above technical solution are as follows: It ensures the uniformity and symmetry of fuel supply, making the combustion process more stable. The fuel is evenly distributed to each outlet hole through the annular pipe, reducing problems such as local overheating and incomplete combustion.

[0021] In an alternative embodiment, the premixing module includes:

[0022] At least one premixing pipe group, the premixing pipe group is arranged on the head housing. The premixing pipe group includes two premixing pipes, and the two premixing pipes clamp the annular pipe and are fixedly connected to the outer wall surface of the annular pipe. The air mixing channel is arranged in the premixing pipe, and at least one fuel injection hole is arranged on the outer wall of the premixing pipe. The fuel injection hole is correspondingly communicated with the second fuel outlet hole.

[0023] In an alternative embodiment, a hoop is arranged on the periphery of the outer premixing pipe. A plurality of first bolt holes are arranged on the hoop. An annular groove is arranged on the surface of the head housing away from the flame tube. A clamping groove rib is arranged in the annular groove. A plurality of second bolt holes corresponding to the first bolt holes in sequence are arranged on the clamping groove rib. The hoop and the clamping groove rib are connected by bolts.

[0024] In an alternative embodiment, the premixing tube is divided into a straight section and a contraction section along the air flow direction, and the cross-sectional area of the contraction section gradually decreases along the air flow direction, so that the air flow is gradually accelerated.

[0025] In an alternative embodiment, the length of the contraction section is processed based on the equivalence ratio of fuel and air in the premixing tube, and the local fuel temperature downstream is adjusted by controlling the length of the contraction section.

[0026] The beneficial effects of the above technical solutions are as follows: By processing the length of the contraction section of a certain premixing tube as required, the equivalence ratio of hydrogen and air in the premixing tube can be finely adjusted, so as to adjust the local gas temperature downstream and reduce the generation of thermal NOx. The air flow rate in the premixing tube can be adjusted by replacing premixing tubes with different contraction section lengths, so as to finely adjust the local equivalence ratio and reduce the generation of thermal NOx.

[0027] In an alternative embodiment, a plurality of fuel injection holes are provided, the inner diameters of the fuel injection holes are different, and they are respectively arranged at different positions in the straight section and the contraction section. Then, after the fuel and air are mixed in the premixing tube, they are injected into the combustion chamber, and the fuel distribution is relatively uniform, and the NOx emission is low.

[0028] In an alternative embodiment, cooling guide vanes are provided on the wall surface of the inner cavity of the head shell located in the flame tube;

[0029] And / or, a first mounting edge is provided on the head shell, a second mounting edge is provided at the end of the flame tube, and the first mounting edge and the second mounting edge are fixedly connected.

[0030] In summary, the technical solution of the present invention has the following advantages:

[0031] The present invention can simultaneously achieve premixed injection and diffusion injection of fuel. Compared with the prior art, it has the advantages of small volume, light weight, simple processing, low cost, wide stable combustion boundary, and low combustion pollutant emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is an assembly relationship diagram of the present invention and the inner and outer rings of the flame tube;

[0034] Figure 2 This is an assembly relationship diagram of the head housing and the flame tube of the present invention;

[0035] Figure 3 This is a cross-sectional view of the injection module of the present invention;

[0036] Figure 4 This is a structural schematic diagram of the head housing of the present invention;

[0037] Figure 5 This is a structural schematic diagram of the swirl gasket of the present invention;

[0038] Figure 6 This is a structural schematic diagram of the premixing tube of the present invention;

[0039] Figure 7 This is a structural schematic diagram of the injection module of the present invention;

[0040] Figure 8 This is a front view cross-sectional view of the injection module of the present invention.

[0041] Explanation of reference numerals:

[0042] 1. Fuel supply pipe; 2. Annular pipe; 201. Fuel input hole; 202. First fuel output hole; 203. Second fuel output hole; 3. Swirl gasket; 301. Swirl air hole; 302. Direct injection fuel hole; 303. Confluence chamber; 304. First cylinder; 305. Convex waist; 306. Second cylinder; 4. Premixing tube; 401. Contraction surface; 402. Bottom surface; 403. Fuel injection hole; 5. Hoop; 501. First bolt hole; 6. Head housing; 601. Card slot rib; 602. Cooling guide vane; 603. First mounting edge; 604. Third bolt hole; 605. Square hole; 606. Round hole; 607. Cooling hole; 7. Flame tube, 701. Second mounting edge; 8. Casing. Detailed implementation manners

[0043] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Hydrogen has a relatively fast combustion speed, concentrated heat release, and a relatively high flame temperature, making it easier to produce thermal NOx emissions. The currently widely used technical means to reduce NOx emissions in hydrogen fuel combustors is the premixed combustion mode, where the fuel is pre-mixed evenly with air, resulting in a more dispersed spatial distribution of the fuel, no local fuel enrichment zones, and more dispersed heat release during combustion, thus making it less likely to generate local high-temperature zones. However, premixed flames are prone to flashback, and related components are liable to ablation. In contrast, the diffusion combustion mode is not prone to flashback, but is prone to local fuel enrichment, and it is necessary to achieve a discrete spatial distribution of the fuel by reducing the fuel flow rate per injection hole, increasing the number and dispersion area of injection holes.

[0045] The hydrogen fuel combustors of current technologies generally achieve the premixing of hydrogen and air by setting a premixing section at the head of the combustor and arranging multiple premixing tubes in the premixing section. However, the premixing section of the hydrogen fuel combustor is thick, heavy, and has a relatively long axial length, with both large weight and volume, making it unsuitable for use in aviation products. During small engine operating conditions or engine operating condition transitions, the premixing tubes are prone to flashback, resulting in ablation and damage to engine structural components. Additionally, the stability of the premixed flame is poor, the ignition and extinction performance is poor, and thermoacoustic oscillations are likely to occur when the engine state changes, seriously damaging the engine in severe cases.

[0046] Among them, the poor stability of the premixed flame means that when the premixing tubes are under small engine operating conditions or operating condition transitions, the change in air flow rate will break the mixing balance, triggering flashback or blow-off, resulting in combustion interruption or unevenness, and seriously damaging structural components such as the premixing tubes in severe cases.

[0047] The poor ignition and extinction performance means that premixed combustion has extremely high requirements for mixing accuracy. The existing premixing tube structures are difficult to quickly adjust the mixing ratio under transitional operating conditions, resulting in ignition delay or abnormal extinction.

[0048] Thermoacoustic oscillations refer to the coupling between the heat release rate of premixed combustion and the acoustic characteristics of the combustor when the engine state changes, triggering periodic pressure and temperature oscillations.

[0049] Based on this, the present invention provides a hydrogen injection structure applicable to hydrogen fuel gas turbine engines, which has the characteristics of small volume, light weight, simple processing, low cost, a wide stable combustion boundary, and low combustion pollutant emissions. It is beneficial to improve the disadvantages of relatively high NOx emissions in the hydrogen fuel combustor, relatively high local wall temperature of the flame tube, and the unsuitability of the engine for variable operating states.

[0050] According to an embodiment of the present invention, a dual-mode injection structure for a combustor is provided, which is arranged at the head of the flame tube to supply fuel to the combustor, and is particularly suitable for hydrogen fuel gas turbine engines with a wide operating range. For the convenience of description, in the illustrations, a rectangular array arrangement is used instead of the annular array arrangement of the actual invention solution.

[0051] Combined with Figure 1 and Figure 8 As shown, the dual-mode injection structure of the combustion chamber includes a head housing 6 and an injection module. The head housing 6 is adapted to be connected to the flame tube 7. The injection module is positioned on the head housing 6. The injection module includes a premixing module and a diffusion direct injection module. The premixing module has a mixing gas passage, one end of the mixing gas passage is communicated with the cavity between the casing 8 and the flame tube 7, a "secondary air passage" is formed between the casing 8 and the flame tube 7, the mixing gas passage is communicated with the "secondary air passage", and the other end of the mixing gas passage is communicated with the inner cavity of the flame tube 7; the diffusion direct injection module has a fuel input port, a first fuel output port and a second fuel output port, the fuel input port is connected to the fuel supply system, the first fuel output port is communicated with the inner cavity of the flame tube 7, the second fuel output port is communicated with the premixing module, and the center line of the second fuel output port is not collinear with the center line of the mixing gas passage.

[0052] For the above dual-mode injection structure of the combustion chamber, the premixing module realizes the full mixing of fuel and air through the mixing gas passage, ensuring a high-efficiency and stable combustion process; the diffusion direct injection module provides an additional fuel supply path to ensure a stable combustion state under different working conditions. The diffusion direct injection module itself has the function of preventing flashback. In this embodiment, the center line of the second fuel output port is not collinear with the center line of the mixing gas passage, which can effectively prevent the flame in the flame tube 7 from spreading to the inside of the premixing module through the diffusion direct injection module. The non-collinear design makes it difficult for the flame to directly enter the internal structure of the diffusion direct injection module when spreading in the combustion chamber, thus reducing the risk of flashback spread. In this way, the whole device has stronger flashback prevention ability, ensuring that the premixing pipe will not be ablated due to flashback during small working conditions or working condition transitions of the engine.

[0053] The injection module realizes the premixed supply and diffusion direct injection supply of hydrogen at the same time. The dual-mode gas supply can not only reduce NOx emissions, but also effectively control flashback ablation damage, broaden the stable combustion boundary of the combustion chamber, enhance the stability of the engine during variable state operation, and enable the diffusion direct injection to maintain stable combustion even when there are fluctuations in the premixed section during small working conditions or working condition transitions of the engine.

[0054] In some embodiments, referring to Figure 1 , the diffusion direct injection module includes a fuel supply pipe 1, an annular pipe 2 and a swirl structure.

[0055] At least one fuel supply pipe 1 is provided. One end of the fuel supply pipe 1 passes through the casing 8 and the end passing through the casing 8 is the fuel input port, and the fuel input port is connected to the external hydrogen supply pipeline of the engine. The other end of the fuel supply pipe 1 is communicated with the annular pipe 2. More specifically, the fuel supply pipe 1 is welded to the annular pipe 2, thereby introducing fuel from the outside of the engine into the combustion chamber.

[0056] Referring toFigure 7 , the annular duct 2 has at least one fuel input hole 201, at least one first fuel output hole 202 and at least one second fuel output hole 203. The first fuel output hole 202 communicates with the swirl structure, and the second fuel output hole 203 is the second fuel outlet. The fuel supply pipe 1 is inserted into the first fuel output hole 202 and welded to the annular duct 2 as a whole. The opening pattern of the first fuel output holes 202 is the same as that of the fuel injection holes 403 on the premixing pipe 4, the holes correspond to each other one by one, and the diameter of each first fuel output hole 202 is slightly larger than that of its corresponding fuel injection hole 403. The second fuel output hole 203 is in interference fit or welded with the second cylinder 306 of the swirl gasket 3.

[0057] At least one swirl structure is provided, and the first fuel outlet is arranged on the swirl structure. The annular duct 2 is a hollow tubular and annular member, and the cross-sectional shape of the annular duct 2 includes but is not limited to rectangle, rounded rectangle, circle, ellipse, kidney shape, etc. For the convenience of description, the cross-section of the annular duct 2 in the legend is a rounded rectangle. The cold air side ( Figure 3 the right side of the rounded rectangle in the figure) of the rounded rectangle is connected to the fuel supply pipe 1 by welding, and the gas side ( Figure 3 the left side of the rounded rectangle in the figure) is in interference connection or welded with the swirl gasket 3, and the other two sides ( Figure 3 the upper and lower sides of the rounded rectangle in the figure) are welded to the premixing pipe 4.

[0058] In this embodiment, the fuel supply pipe 1 communicates with the annular duct 2. The fuel supply pipe 1 transports the fuel to the annular duct 2, and then the annular duct 2 distributes the fuel to each fuel outlet. The swirl air is introduced through the swirl structure, so that the fuel and air are better mixed to form a stable vortex combustion area, further improving the combustion efficiency and stability. Moreover, the swirl air generated by the swirl structure helps to isolate the flame from the fuel input path, further reducing the risk of flashback.

[0059] In some embodiments, the annular duct 2 is concentrically arranged with the engine main shaft. The center lines of the first fuel outlets and the center line of the air-fuel mixture passage are all parallel to the axis of the engine main shaft. A plurality of the first fuel outlets are provided and the first fuel outlets are circumferentially spaced apart. A plurality of the air-fuel mixture passages are provided and the air-fuel mixture passages are circumferentially spaced apart. This design ensures the uniformity and symmetry of fuel supply, making the combustion process more stable. The fuel is evenly distributed to each output hole through the annular duct 2, reducing the problems of local overheating and incomplete combustion.

[0060] In some embodiments, see Figure 5, the swirl structure includes a swirl gasket 3. In addition to being a swirl gasket, the swirl structure can also be other types of structures that generate swirl, such as a vane-type swirler. One end of the swirl gasket 3 is provided with a direct injection fuel hole 302 communicating with the first fuel output hole 202 to ensure that fuel can enter the confluence chamber 303 and mix with air. The other end of the swirl gasket 3 is provided with a confluence chamber 303, and a plurality of swirl air holes 301 are provided on the side wall of the swirl gasket 3. The annular pipe and the head shell are separated by the swirl gasket, and the fuel can be directly injected into the combustion chamber after passing through the direct injection fuel hole and the confluence chamber on the swirl gasket.

[0061] The confluence chamber 303 is a cylindrical cavity, and the opening direction of each swirl air hole 301 is tangent to the cylindrical wall surface of the confluence chamber 303. Air enters the confluence chamber through the swirl air holes on the swirl gasket and generates a wall-attached swirl, blocking the fuel from attaching to the wall, reducing the risk of boundary layer flashback, and generating a swirl downstream to stabilize the flame. Air enters the confluence chamber 303 in a tangential direction through these swirl air holes and rotates forward along the wall surface in the cavity, which can produce a vortex effect, making the fuel and air mix more evenly and forming a stable swirl combustion region. During operation, the fuel is directly injected into the combustion chamber along the axis from the direct injection fuel hole 302, and swirl air holes 301 are opened on the convex waist 305. Air can enter the confluence chamber 303 through the swirl air holes 301 and rotate forward along the wall surface, forming an air layer against the wall to prevent the fuel from attaching to the wall.

[0062] One end of the swirl gasket 3 is inserted into the annular pipe 2, and the other end of the swirl gasket 3 is inserted into the head shell 6. The swirl gasket 3 separates the annular pipe 2 from the head shell 6.

[0063] More specifically, the swirl gasket 3 includes a first cylinder 304, a convex waist 305, and a second cylinder 306 connected therebetween. The first cylinder 304 is a cylinder structure at one end of the convex waist 305 close to the gas side, and the second cylinder 306 is a cylinder structure at one end of the convex waist 305 close to the cold gas side. See Figure 1 , Figure 7 , during assembly, the first cylinder 304 has a small clearance fit with the round hole 606 on the head shell 6, and the second cylinder 306 has an interference fit or is welded to the first fuel output hole 202. The convex waist 305 separates the annular pipe 2 from the head shell 6, and the height of the convex waist 305 is the separated distance.

[0064] In some embodiments, the premixing module includes a premixing pipe group. There is at least one premixing pipe group, which is arranged on the head housing 6. The premixing pipe group includes two premixing pipes 4. The two premixing pipes 4 clamp the annular pipe 2 and are fixedly connected to the outer wall surface of the annular pipe 2. The gas mixing channel is arranged in the premixing pipe 4. There is at least one fuel injection hole 403 on the outer wall of the premixing pipe 4, and the fuel injection hole 403 is correspondingly communicated with the second fuel output hole 203. In this embodiment, the fuel is fed into the annular pipe 2 through the fuel supply pipe 1, and then is divided into three streams along the annular pipe and flows to the premixing pipe and the swirl gasket.

[0065] In some embodiments, a hoop 5 is arranged on the periphery of the outer premixing pipe 4. There are a plurality of first bolt holes 501 on the hoop 5. There are two hoops 5, and the two hoops 5 are respectively arranged on the inner and outer sides of two rows of premixing pipes 4 and are welded to the premixing pipes 4.

[0066] Figure 2 is an assembly relationship diagram of the head housing 6 and the flame tube 7. The outer shape of the head housing 6 is plate-shaped and annular. There is an annular groove on the side of the head housing 6 away from the flame tube 7. There is a clamping groove rib 601 in the annular groove. There are a plurality of second bolt holes on the clamping groove rib 601 that correspond to the first bolt holes 501 in sequence. Refer to Figure 1 , the injection module is clamped between the two clamping groove ribs 601 of the head housing 6. The hoop 5 and the clamping groove rib 601 are connected by bolts, so that the injection module is connected to the head housing 6. In addition to being connected by bolts between the head housing and the injection module, other connection methods can also be used, such as tenon grooves, buckles, hinges, welding, screw threading, etc.

[0067] There is a first mounting edge 603 on the head housing 6. There is a second mounting edge 701 at the end of the flame tube 7. There are a plurality of third bolt holes 604 on the first mounting edge 603. There are a plurality of fourth bolt holes on the second mounting edge 701 that correspond to the third bolt holes 604. The first mounting edge 603 and the second mounting edge 701 are fixedly connected by bolts. In addition to being connected by bolts between the head housing 6 and the flame tube 7, other connection methods can also be used, such as tenon grooves, buckles, hinges, welding, screw threading, etc.

[0068] There are cooling guide vanes 602 on the wall surface of the head housing 6 located in the inner cavity of the flame tube 7. The cooling guide vanes 602 play a role in guiding the flow. There are also a plurality of cooling holes 607 on the head housing 6 for heat dissipation.

[0069] Refer to Figure 4 , square holes 605 and round holes 606 are evenly distributed in the circumferential direction on the head housing 6. One row of round holes 606 is arranged in the middle position, and two rows of square holes 605 are respectively arranged on the inner side ( Figure 4 in the lower middle) and the outer side (Figure 4 in the upper middle position. Refer to Figure 1 , Figure 4 , Figure 8 , the end face of the contraction section is inserted into the square hole 605 on the head shell 6.

[0070] In some embodiments, refer to Figure 6 , the premixing tube 4 is divided into a straight section and a contraction section along the air flow direction. The cross-sectional shape of the straight section includes but is not limited to rectangle, rounded rectangle, circle, ellipse, kidney shape, etc. For the convenience of description, the cross-sectional shape of the straight section in the figure is a rectangle. The cross-sectional area of the contraction section gradually decreases along the air flow direction, so that the air flow gradually accelerates.

[0071] For the convenience of description, Figure 4 , the contraction section in

[0072] It should be noted that the contraction section of the premixing tube can be not only three-sided contraction and regular surface, but also multi-sided contraction, irregular surface, or even no contraction.

[0073] There are multiple fuel injection holes 403. The inner diameters of the fuel injection holes 403 are different and are respectively arranged at different positions in the straight section and the contraction section. Then, the fuel and air are mixed in the premixing tube and injected into the combustion chamber, and the fuel distribution is relatively uniform, and the NOx emission is relatively low.

[0074] In the above combustion chamber dual-mode injection structure, when the engine is in a small working condition, the air flow rate decreases, and the flow rate in the premixing tube decreases. Traditional premixed combustion is prone to flashback because the flow rate is lower than the flame propagation speed. In the present invention, the premixing tube still provides part of the premixed gas (to maintain low NOx emissions), and at the same time, the direct injection hydrogen holes of the swirl gasket directly inject hydrogen into the combustion chamber (diffusion combustion mode). Diffusion combustion does not require premixing. The flame is located inside the combustion chamber and does not enter the premixing tube, fundamentally avoiding the risk of flashback; and diffusion combustion is not sensitive to changes in air flow rate and can stably maintain the flame.

[0075] During the engine operating condition transition, a sudden change in air flow rate may cause the equivalence ratio in the premixing tube to become unbalanced (too rich or too lean), leading to flameout or thermoacoustic oscillations. The diffusely direct-injected hydrogen burns while mixing with the surrounding air, forming a buffer combustion zone, alleviating the instantaneous fluctuations in the premixing section, ensuring a smooth transition of heat release during combustion, and suppressing the oscillations caused by sudden changes in the mixing ratio.

[0076] The premixing tube is divided into a straight section and a contraction section along the air flow direction. At low engine operating conditions, by lengthening the contraction section, the air flow rate in this premixing tube is reduced, avoiding an overly lean equivalence ratio caused by excessive air, and maintaining a reasonable mixing ratio in the premixing section. During the engine operating condition transition, the length of the contraction section of different premixing tubes is adjusted as needed to finely tune the local equivalence ratio, making the gas temperature distribution in the entire combustion region more uniform. While reducing the generation of thermal NOx, it avoids flame instability caused by local overheating or overcooling.

[0077] The swirling air holes 301 on the swirling gasket guide air into the confluence chamber 303, forming an attached swirling air layer. At low engine operating conditions, even if the total amount of air decreases, the swirling air can still wrap the direct-injected hydrogen, preventing it from directly contacting the head housing wall surface. At the same time, a stable swirling flow field is formed at the flame root, enhancing the flame anchoring ability. During the engine operating condition transition, the momentum stabilizing effect of the swirling air suppresses the high-frequency fluctuations of the combustion chamber flow field, reducing the excitation conditions for thermoacoustic oscillations.

[0078] The traditional premixing section has a long axial length and a large heat capacity, resulting in a lag in response when the operating conditions change. The present invention shortens the axial dimension and reduces the inertia of the combustion system through the layout of the annular head hydrogen ring and modular premixing tubes. At low engine operating conditions / transition: The fuel distribution (the flow ratio between the premixing tube and direct injection) can be quickly adjusted to avoid the mixing ratio imbalance caused by structural lag, improve the dynamic response speed of the system, and reduce the oscillation risk.

[0079] See Figure 7 、 Figure 8 , taking hydrogen fuel as an example, the specific working process of the dual-mode injection structure of the combustion chamber of the present invention will be described below.

[0080] During operation, hydrogen enters the annular pipeline 2 through a number of circumferentially evenly distributed fuel supply pipes 1. After the hydrogen fills the annular pipeline 2, it is divided into three streams and flows out: The first stream flows to the outside of the engine ( Figure 8 directly above in the Figure 8Directly below, it enters the pre-mixing pipe 4 arranged inside through the second fuel output hole 203 and the fuel injection hole 403. The third stream enters the confluence chamber 303 along the engine axis through the direct injection fuel hole 302 and is then injected into the combustion chamber from the confluence chamber 303. Air enters along the straight section of the pre-mixing pipe 4, flows downstream through the contraction section and then enters the combustion chamber, where it is pre-mixed with hydrogen in the pre-mixing pipe 4. Refer to Figure 7 A small part of the air flows through the circumferential gap between adjacent pre-mixing pipes 4 to the periphery of the swirl gasket 3 and enters the confluence chamber 303 along the swirl air hole 301, and moves forward along the wall of the confluence chamber and enters the combustion chamber.

[0081] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A dual-mode injection structure for a combustion chamber, characterized in that Comprising: A head housing (6), which is adapted to be connected to a combustion chamber (7); An injection module, which is positioned on the head housing (6); the injection module includes a premixing module and a diffusion direct injection module; The premixing module has a gas mixing channel, one end of the gas mixing channel communicates with the cavity between the casing (8) and the combustion chamber (7), and the other end of the gas mixing channel communicates with the inner cavity of the combustion chamber (7); the diffusion direct injection module has a fuel input port, a first fuel output port and a second fuel output port, the fuel input port is connected to a fuel supply system, the first fuel output port communicates with the inner cavity of the combustion chamber (7), the second fuel output port communicates with the premixing module, and the center line of the second fuel output port is not collinear with the center line of the gas mixing channel.

2. The dual-mode injection structure of the combustion chamber according to claim 1, characterized in that, The diffusion direct injection module includes: At least one fuel supply pipe (1), one end of the fuel supply pipe (1) is the fuel input port, and the other end of the fuel supply pipe (1) communicates with an annular pipe (2); The annular pipe (2) has at least one fuel input hole (201), at least one first fuel output hole (202) and at least one second fuel output hole (203), the first fuel output hole (202) communicates with a swirl structure, and the second fuel output hole (203) is the second fuel output port; At least one swirl structure, and the first fuel output port is arranged on the swirl structure.

3. The dual-mode injection structure of the combustion chamber according to claim 2, wherein The swirl structure includes a swirl gasket (3), one end of the swirl gasket (3) is provided with a direct injection fuel hole (302) communicating with the first fuel output hole (202), the other end of the swirl gasket (3) is provided with a confluence cavity (303), and a plurality of swirl air holes (301) are arranged on the side wall of the swirl gasket (3); the confluence cavity (303) is a cylindrical cavity, and the opening directions of the swirl air holes (301) are tangent to the cylindrical wall surface of the confluence cavity (303), so that air rotates forward along the wall surface in the confluence cavity (303) and forms an air layer against the wall surface to block the fuel from sticking to the wall.

4. The combustion chamber dual-mode injection structure according to claim 3, characterized in that, One end of the swirl gasket (3) is inserted into the annular pipe (2), and the other end of the swirl gasket (3) is inserted into the head housing (6), and the swirl gasket (3) separates the annular pipe (2) from the head housing (6).

5. The dual-mode injection structure of the combustion chamber according to claim 4, wherein The swirl gasket (3) includes a first cylinder (304), a convex waist (305) and a second cylinder (306) connected therebetween. The first cylinder (304) has a small clearance fit with a circular hole (606) on the head housing (6), and the second cylinder (306) has an interference fit or welding with the first fuel output hole (202).

6. The combustion chamber dual-mode injection structure according to claim 2, wherein, The annular pipe (2) is concentric with the engine main shaft, the center lines of the first fuel output port and the gas mixing channel are both parallel to the axis of the engine main shaft, there are multiple first fuel output ports and the first fuel output ports are circumferentially spaced, and there are multiple gas mixing channels and the gas mixing channels are circumferentially spaced.

7. The dual-mode injection structure of the combustion chamber according to any one of claims 2-6, characterized in that, The premixing module includes: At least one premixing tube group, the premixing tube group is arranged on the head housing (6), the premixing tube group includes two premixing tubes (4), and the two premixing tubes (4) clamp the annular pipe (2) and are fixedly connected to the outer wall surface of the annular pipe (2); the air mixing channel is arranged in the premixing tube (4), at least one fuel injection hole (403) is arranged on the outer wall of the premixing tube (4), and the fuel injection hole (403) is correspondingly communicated with the second fuel output hole (203).

8. The dual-mode injection structure of the combustion chamber according to claim 7, wherein, A hoop (5) is arranged on the periphery of the outer premixing tube (4); a circular groove is arranged on the surface of the head housing (6) away from the flame tube (7), and a clamping groove rib plate (601) is arranged in the circular groove, and the hoop (5) is connected with the clamping groove rib plate (601).

9. The dual-mode injection structure of the combustion chamber according to claim 7, wherein The premixing tube (4) is divided into a straight section and a contraction section along the air flow direction, and the cross-sectional area of the contraction section gradually decreases along the air flow direction.

10. The combustion chamber dual-mode injection structure according to claim 9, characterized in that, The length of the contraction section is processed based on the equivalence ratio of fuel and air in the premixing tube, and the local fuel temperature downstream is adjusted by controlling the length of the contraction section; And / or, a plurality of fuel injection holes (403) are arranged, the inner diameters of the fuel injection holes (403) are different and are respectively arranged at different positions in the straight section and the contraction section.

11. The dual-mode injection structure of the combustion chamber according to any one of claims 2-6, characterized in that, Cooling guide vanes (602) are arranged on the wall surface of the head housing (6) located in the inner cavity of the flame tube (7); And / or, a first mounting edge (603) is arranged on the head housing (6), a second mounting edge (701) is arranged at the end of the flame tube (7), and the first mounting edge (603) is fixedly connected with the second mounting edge (701).

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