A pure hydrogen fuel injection device and combustion chamber for a micro turbojet engine

Abstract

The present application provides a fuel injection device which can sufficiently mix air and hydrogen fuel, improve the stability and combustion efficiency of hydrogen fuel combustion, and avoid the problem of local overheating of the hydrogen fuel combustion chamber. The pure hydrogen fuel injection device of the micro turbojet engine comprises an annular nozzle arranged in the combustion chamber and a hydrogen fuel supply pipe. The annular nozzle comprises a plurality of micro mixing units, each of which comprises an air channel and a fuel injection hole arranged perpendicular to each other. A fuel gas path network is arranged inside the annular nozzle, which comprises a first gas path channel, a second gas path channel and a gas hole. The first gas path channel and the second gas path channel are arranged staggered in the axial direction of the annular nozzle, and the gas hole communicates the first gas path channel and the second gas path channel. Each micro mixing unit is communicated with the second gas path channel through the fuel injection hole, and the first gas path channel is communicated with the hydrogen fuel supply pipe.

Description

Technical Field

[0001] This invention relates to aircraft engines, and more particularly to a pure hydrogen fuel injection device and combustion chamber for a micro turbojet engine. Background Technology

[0002] Hydrogen fuel, characterized by high calorific value, low pollution, and renewability, is a crucial energy source to replace traditional fossil fuels and plays a significant role in decarbonization and zero-carbonization. In the aviation field, research on hydrogen fuel engines is of paramount importance. Hydrogen fuel turbojet engines offer advantages such as high power density and low emissions, contributing to improved aircraft performance and environmental friendliness. Hydrogen fuel micro turbojet engines show broad application prospects in fields such as unmanned aerial vehicles (UAVs) and small aircraft. However, directly replacing aviation kerosene with hydrogen fuel in engines can cause serious consequences such as backfire, localized high temperatures, and increased nitrogen oxide formation. Therefore, the combustion of hydrogen fuel in the combustion chamber of an aircraft engine differs significantly from that of traditional aviation kerosene. Thus, the development of hydrogen fuel aero engines necessitates a redesign of traditional fuel injection methods in the combustion chamber to adapt to the unique characteristics of hydrogen fuel combustion. Summary of the Invention

[0003] The purpose of this invention is to provide a pure hydrogen fuel injection device for a micro turbojet engine, which solves the problem of backfire during existing hydrogen fuel combustion and organizes efficient combustion of hydrogen fuel.

[0004] To address the aforementioned technical problems, this invention provides a pure hydrogen fuel injection device for a micro turbojet engine, comprising an annular nozzle and a hydrogen fuel supply pipe disposed within a combustion chamber; the annular nozzle includes multiple micro-mixing units, each of which includes an air passage and a fuel injection orifice arranged perpendicularly to each other;

[0005] A fuel gas path network is provided inside the annular nozzle. The fuel gas path network includes a first gas path channel, a second gas path channel, and a gas hole. The first gas path channel and the second gas path channel are arranged alternately back and forth along the axial direction of the annular nozzle. The gas hole connects the first gas path channel and the second gas path channel.

[0006] Each micro-hybrid unit is connected to the second gas passage through a fuel injection port, and the first gas passage is connected to the hydrogen fuel supply pipe.

[0007] In a preferred embodiment, three groups of micro-mixing units are distributed from the inside out along the center of the annular nozzle, and the multiple micro-mixing units in each group are evenly distributed along the circumference.

[0008] In a preferred embodiment, the number of micro-mixing units in each group is the same; each micro-mixing unit is a cylindrical micro-mixing cavity with a diameter of 5 mm and a length of 15 mm, and an air channel with a cross-sectional diameter of 5-8 mm and a length of 15 mm is provided on it.

[0009] In a preferred embodiment, the three sets of micro-hybrid units are arranged sequentially from the center of the ring outwards, with the micro-hybrid unit located in the inner ring having two fuel injection holes; and the micro-hybrid units located in the outer and middle rings having four fuel injection holes.

[0010] The second gas path channel is provided with multiple branch channels connecting each of the fuel injection holes; two adjacent micro-mixing units are connected by a branch channel, and the branch channels are distributed on the line connecting the centers of the micro-mixing units.

[0011] In a preferred embodiment, the cross-sectional area of ​​the first air passage and the second air passage is larger than the cross-sectional area of ​​the air hole; the air hole is distributed at the center of each branch passage.

[0012] In a preferred embodiment, the air passages are arranged in a ring shape along the center of the annulus; the fuel injection holes are disposed on the side of the micro-mixing unit; the first air passage and the second air passage are arranged in a ring shape inside the annular nozzle.

[0013] In a preferred embodiment, the hydrogen fuel supply pipe is divided into an inner ring pipe and an outer ring pipe, and gas supply pipes are provided on both the inner and outer ring pipes; the gas supply pipes are distributed radially.

[0014] The first gas path is divided into an inner ring gas path and an outer ring gas path. Both the inner and outer ring gas paths are connected to the corresponding inner and outer ring pipes through connecting channels.

[0015] In a preferred embodiment, multiple connecting channels are arrayed along the center of the ring on both the inner and outer ring tubes;

[0016] The width and thickness of the inner and outer ring pipes are both 3-4 mm; the width and thickness of the gas supply pipe are both 3-4 mm; the width and thickness of the connecting channel are both 3-4 mm.

[0017] In a preferred embodiment, the width of the first air passage is 3-4 mm and the thickness is 3-4 mm; the air hole is a circular air hole with a diameter of 0.4 mm-0.8 mm and a depth of 3 mm; the width of the second air passage is 2 mm-3 mm and the thickness is 3-4 mm.

[0018] The present invention also provides a combustion chamber, which applies the aforementioned micro turbojet engine pure hydrogen fuel injection device; the combustion chamber includes an air intake passage, a hydrogen fuel supply pipe, an annular nozzle, a combustion chamber wall, a combustion flame tube, and a combustion chamber outlet; the combustion flame tube has cooling holes and air supply holes.

[0019] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0020] 1. A pure hydrogen fuel injection device for a micro turbojet engine is provided, which can fully mix air and hydrogen fuel, improve the stability and efficiency of hydrogen fuel combustion, and avoid the problem of local overheating in the hydrogen fuel combustion chamber.

[0021] 2. By setting up an annular nozzle, a hydrogen fuel supply pipe, and a fuel gas network, the annular nozzle includes multiple micro-mixing units. The fuel gas network is divided into a first gas channel and a second gas channel. The micro-mixing unit includes an air channel and a fuel injection hole arranged perpendicularly to each other. The fuel is injected by vertical airflow. In order to make the hydrogen fuel injection in each micro-mixing unit uniform, the distribution between each micro-mixing unit group is uniform, and the injection hole method is the same, so that the hydrogen fuel injection effect of each micro-mixing unit is consistent.

[0022] 3. Through this pure hydrogen fuel injection device, the fuel blending process is dispersed to each micro-mixing unit by utilizing the fuel gas network, and the air and hydrogen fuel are fully mixed, thereby effectively organizing the combustion of pure hydrogen, improving combustion efficiency, avoiding the generation of local high-temperature hot spots, which is beneficial for thermal protection and reducing the formation of thermal NOx; the micro-mixing unit can rectify and accelerate the incoming airflow to match the high-level flow flame velocity of hydrogen fuel, which can effectively suppress combustion backfire. Attached Figure Description

[0023] Figure 1 This is an axial cross-sectional view of the pure hydrogen fuel injection device and combustion chamber of the micro turbojet engine in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the flow field in the combustion chamber after hydrogen fuel enters the nozzle in an embodiment of the present invention;

[0025] Figure 3 This is a front view of the connection method between the hydrogen fuel supply pipe and the nozzle in an embodiment of the present invention for implementing a pure hydrogen fuel injection device;

[0026] Figure 4 This is a layout diagram of the hydrogen fuel gas passage network inside the annular nozzle in an embodiment of the present invention;

[0027] Figure 5 This is an axial cross-sectional view of the annular nozzle and a schematic diagram of hydrogen fuel flow in an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the internal hydrogen fuel gas passage structure of the annular nozzle in an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached drawings: 100, intake passage; 200, hydrogen fuel supply pipe; 210, outer ring pipe; 211, external gas supply pipe; 212, external connection passage; 220, inner ring pipe; 221, internal gas supply pipe; 222, internal connection passage; 300, annular nozzle; 301, air passage; 302, first gas path passage; 303, air vent; 304, second gas path passage; 305, micro-mixing unit; 306, branch passage; 400, combustion chamber wall; 500, combustion flame tube; 600, combustion chamber outlet. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0033] refer to Figures 1-6 This embodiment provides a pure hydrogen fuel injection device for a micro turbojet engine. This device is assembled in the combustion chamber and provides a pure hydrogen fuel injection scheme for a micro turbojet engine. For example... Figure 1The main components of the combustion chamber include an intake passage 100, a hydrogen fuel supply pipe 200, an annular nozzle 300, a combustion chamber wall 400, a combustion flame tube 500, and a combustion chamber outlet 600. Among them, the hydrogen fuel supply pipe 200, which supplies hydrogen fuel from outside the nozzle, and the annular nozzle 300 are the main injection devices to realize the pure hydrogen fuel injection scheme of the micro turbojet engine.

[0034] The combustion flame tube 500 is equipped with cooling holes and air supply holes to prevent localized overheating in the combustion chamber. This facilitates air supply and makes combustion more repetitive. The air intake passage 100, combustion flame tube 500, and hydrogen fuel supply pipe 200 can all be designed and modified according to the actual working conditions and usage requirements of the combustion chamber, and are not limited to this embodiment. Figure 1 The structure in.

[0035] Both the annular nozzle 300 and the hydrogen fuel supply pipe 200 are located within the combustion chamber, with the hydrogen fuel supply pipe 200 positioned on the outer side of the annular nozzle 300. The annular nozzle 300 includes multiple micro-mixing units 305. Each micro-mixing unit 305 includes mutually perpendicular air channels 301 and fuel injection holes. The air channels 301 are arranged in a ring around the center of the annulus, and the fuel injection holes are located on the side of the micro-mixing unit 305. A fuel gas network is provided inside the annular nozzle 300 to connect to the hydrogen fuel supply pipe 200. Hydrogen fuel can enter the fuel gas network through the hydrogen fuel supply pipe 200 and then be transported into the nozzle via the fuel gas network. Incoming air enters through the intake channel 100 and is divided into multiple small air streams by the annular nozzle 300, entering the air channels 301 of each micro-mixing unit 305 to fully mix with the hydrogen fuel, which can be hydrogen gas.

[0036] The fuel gas network includes a first gas passage 302, a second gas passage 304, and a gas port 303. The first gas passage 302 and the second gas passage 304 are arranged alternately along the axial direction of the annular nozzle 300, and the gas port 303 connects the first gas passage 302 and the second gas passage 304. Each micro-mixing unit 305 is connected to the second gas passage 304 through a fuel injection port, and the first gas passage 302 is connected to the hydrogen fuel supply pipe 200.

[0037] The annular nozzle 300 has three groups of micro-mixing units 305 distributed from the center of the ring outwards. Each group has multiple micro-mixing units 305 evenly distributed along the circumference, and the number of micro-mixing units 305 in each group is the same. Each micro-mixing unit 305 is a cylindrical micro-mixing cavity. The dimensions of a single micro-mixing unit 305 are set to a diameter of 5 mm and a length of 15 mm. The air channel 301 on the micro-mixing unit 305 has a cross-sectional diameter of 5-8 mm and a length of 15 mm.

[0038] The annular nozzle 300 provided in this embodiment has a thickness of 15mm. There are a total of 36 micro-mixing units 305 on the annular nozzle 300. To facilitate the arrangement of the hydrogen fuel transportation path, they are divided into three groups of micro-mixing units 305, with 12, 12 and 12 micro-mixing units 305 being offset outwards in sequence.

[0039] The second gas path passage 304 is provided with multiple branch passages 306 connecting various fuel injection holes, and two adjacent micro-mixing units 305 are connected through a branch passage 306. The branch passages 306 are distributed on the line connecting the centers of the micro-mixing units 305. The connection distribution of the multiple micro-mixing units 305 and the branch passages 306 is as follows: the three groups of micro-mixing units 305 are arranged sequentially from the center of the ring outwards. The micro-mixing unit 305 located in the inner ring is provided with two fuel injection holes, and the four branch passages 306 converge in pairs to connect the two fuel injection holes; the micro-mixing units 305 located in the outer ring and the middle ring are provided with four fuel injection holes, and the four branch passages 306 are connected to one micro-mixing unit 305.

[0040] like Figure 3 The connection between the hydrogen fuel supply pipe 200 and the annular nozzle 300 is configured such that the hydrogen fuel supply pipe 200 is divided into an inner annular pipe 220 and an outer annular pipe 210. An inner gas supply pipe 221 and an outer gas supply pipe 211 are correspondingly provided on the inner and outer annular pipes (220, 210), respectively. The gas supply pipes are radially distributed and vertically distributed, used to supply hydrogen fuel into the inner and outer annular pipes (220, 210). The first gas passage 302 is divided into an inner annular gas passage and an outer annular gas passage. Both the inner and outer annular gas passages are connected to the corresponding inner and outer annular pipes (220, 210) through connecting channels. Multiple connecting channels are arrayed along the center of the annulus on both the inner and outer annular pipes (220, 210). In this embodiment, the inner annular pipe 220 may have 12 inner connecting channels 222, and the outer annular pipe 210 may have 6 outer connecting channels 212, all arrayed along the center of the annulus.

[0041] Hydrogen fuel is injected from the gas supply pipe, diffuses through the inner and outer annular pipes (220, 210), reaches each connecting channel on the circumference, and then flows into the first gas passage 302 inside the annular nozzle 300. The inner and outer annular pipes (220, 210) are both 3-4 mm wide and 3-4 mm thick; the gas supply pipe is 3-4 mm wide and 3-4 mm thick; and the connecting channels are 3-4 mm wide and 3-4 mm thick.

[0042] like Figure 4The internal gas passage layout of the annular nozzle 300 consists of a front first gas passage 302, a rear second gas passage 304, and cylindrical gas holes 303, forming a hydrogen fuel gas passage network. The first gas passage 302 is divided into an inner annular gas passage and an outer annular gas passage, used to connect with the inner and outer annular pipes (220, 210). The width and thickness of the first gas passage 302 are 3-4 mm. The first gas passage 302 is then connected to the rear second gas passage 304 through cylindrical gas holes 303 with a diameter of 0.4 mm-0.8 mm and a depth of 3 mm.

[0043] The second gas passage 304 connects every two adjacent micro-hybrid units 305, and the multiple branch passages 306 of the second gas passage 304 serve as the hydrogen fuel injection channels for the micro-hybrid units. The width of the second gas passage 304 is 2mm-3mm, and the thickness is 3-4mm.

[0044] The first gas path channel 302 and the second gas path channel 304 are arranged in a ring shape inside the annular nozzle 300. To ensure consistent fuel injection volume from each fuel injection orifice, the cross-sectional areas of the first gas path channel 302 and the second gas path channel 304 are larger than the cross-sectional area of ​​the cylindrical gas orifice 303. The diameter of the cylindrical gas orifice 303 is 0.4-0.8 mm, and the depth is 3 mm. Simultaneously, to ensure consistent hydrogen fuel distribution to each micro-mixing unit 305 from the second gas path channel 304, cylindrical gas orifices 303 are distributed at the center of each branch channel 306. The distance from the cylindrical gas orifice 303 to the two micro-mixing units 305 is equal, ensuring uniform distribution of hydrogen fuel to each micro-mixing unit 305.

[0045] Because the internal channel structure of the annular nozzle 300 is complex and difficult to manufacture, therefore, in this embodiment, as Figure 6 Both the first air passage 302 and the second air passage 304 are designed as square pipes with a width of 3-4 mm and a thickness of 4 mm. 3D printing technology can be used to manufacture the nozzles.

[0046] The pure hydrogen fuel injection scheme for the micro turbojet engine provided in this embodiment is achieved through a hydrogen fuel supply pipe 200, an annular nozzle 300, and a hydrogen fuel gas path network composed of a first gas path channel 302, a second gas path channel 304, and a gas hole 303 disposed within the annular nozzle 300. Figure 5 Hydrogen fuel enters the annular nozzle 300 from the hydrogen fuel supply pipe 200, and then sequentially enters the first gas passage 302, the cylindrical gas hole 303, and the second gas passage 304, and finally enters the micro-mixing unit 305 to be mixed with air.

[0047] To ensure consistent fuel injection rates across all injection orifices, in this embodiment, the hydrogen fuel, after being injected into the annular nozzle 300, preferentially fills the first gas channel 302 before passing through the cylindrical orifice 303 into the second gas channel 304. Due to the smaller size of the cylindrical orifice 303, the flow velocity increases, resulting in more uniform gas pressure. The gas then rapidly enters the second gas channel 304. Combined with the location of the cylindrical orifice 303 (at the center of the branch channels 306 connecting the micro-mixing units 305), the gas injected into the micro-mixing unit 305 is relatively uniform. The uniform distribution and identical injection orifice patterns among the micro-mixing units 305 ensure consistent hydrogen fuel injection, allowing for thorough mixing of air and hydrogen fuel during injection. This improves the stability and efficiency of hydrogen fuel combustion and avoids localized overheating in the hydrogen fuel combustion chamber.

[0048] The above description is merely a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention by those skilled in the art within the scope of the technology disclosed in the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A pure hydrogen fuel injection device for a micro turbojet engine, characterized in that: It includes an annular nozzle and a hydrogen fuel supply pipe disposed in the combustion chamber; the annular nozzle includes multiple micro-mixing units, and the micro-mixing unit includes air passages and fuel injection holes arranged perpendicularly to each other; A fuel gas path network is provided inside the annular nozzle. The fuel gas path network includes a first gas path channel, a second gas path channel, and a gas hole. The first gas path channel and the second gas path channel are arranged alternately back and forth along the axial direction of the annular nozzle. The gas hole connects the first gas path channel and the second gas path channel. Each micro-hybrid unit is connected to the second gas passage through a fuel injection port, and the first gas passage is connected to the hydrogen fuel supply pipe.

2. The micro turbojet engine pure hydrogen fuel injection device according to claim 1, characterized in that: Three groups of micro-mixing units are distributed from the inside out along the center of the ring on the annular nozzle, and multiple micro-mixing units in each group are evenly distributed along the circumference.

3. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 2, characterized in that: The number of micro-mixing units in each group is the same; each micro-mixing unit is a cylindrical micro-mixing cavity with a diameter of 5mm and a length of 15mm, and the air channel on it has a cross-sectional diameter of 5-8mm and a length of 15mm.

4. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 3, characterized in that: The three sets of micro-mixing units are arranged sequentially from the center of the ring outwards, with the micro-mixing unit located in the inner ring having two fuel injection holes; and the micro-mixing units located in the outer and middle rings having four fuel injection holes. The second gas path channel is provided with multiple branch channels connecting each of the fuel injection holes; two adjacent micro-mixing units are connected by a branch channel, and the branch channels are distributed on the line connecting the centers of the micro-mixing units.

5. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 4, characterized in that: The cross-sectional area of ​​the first air passage and the second air passage is larger than the cross-sectional area of ​​the air hole; the air hole is distributed at the center of each branch passage.

6. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 1, characterized in that: The air passages are arranged in a ring shape along the center of the ring; the fuel injection holes are located on the side of the micro-mixing unit; the first air passage and the second air passage are arranged in a ring shape inside the annular nozzle.

7. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 1, characterized in that: The hydrogen fuel supply pipe is divided into an inner ring pipe and an outer ring pipe, and gas supply pipes are provided on both the inner and outer ring pipes; the gas supply pipes are distributed radially. The first gas path is divided into an inner ring gas path and an outer ring gas path. Both the inner and outer ring gas paths are connected to the corresponding inner and outer ring pipes through connecting channels.

8. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 7, characterized in that: Multiple connection channels are arrayed along the center of the inner and outer ring tubes. The width and thickness of the inner and outer ring pipes are both 3-4 mm; the width and thickness of the gas supply pipe are both 3-4 mm; the width and thickness of the connecting channel are both 3-4 mm.

9. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 1, characterized in that: The width of the first air passage is 3-4 mm and the thickness is 3-4 mm; the air hole is a circular air hole with a diameter of 0.4 mm-0.8 mm and a depth of 3 mm; the width of the second air passage is 2 mm-3 mm and the thickness is 3-4 mm.

10. A combustion chamber, characterized in that: A micro turbojet engine pure hydrogen fuel injection device according to any one of claims 1-9; the combustion chamber includes an air intake passage, a hydrogen fuel supply pipe, an annular nozzle, a combustion chamber wall, a combustion flame tube, and a combustion chamber outlet; the combustion flame tube is provided with cooling holes and air supply holes.

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