Micro turbojet engine pure hydrogen fuel injection device and combustion chamber

Abstract

The invention provides a fuel injection device capable of fully mixing air and hydrogen fuel, the combustion stability and the combustion efficiency of the hydrogen fuel are improved, the problem of local overheating of a hydrogen fuel combustion chamber is avoided, and the pure hydrogen fuel injection device of the micro turbojet engine comprises an annular nozzle and a hydrogen fuel supply pipe which are arranged in the combustion chamber; the annular nozzle comprises a plurality of micro-mixing units, and each micro-mixing unit comprises an air channel and a fuel injection hole which are perpendicular to each other; a fuel gas road network is arranged in the annular nozzle and comprises a first gas path channel, a second gas path channel and gas holes; the first air channel and the second air channel are arranged in a front-back staggered mode in the axial direction of the annular nozzle, and the first air channel and the second air channel are communicated through the air holes. Each micro-mixing unit is communicated with the second gas path channel through a fuel injection hole, and the first gas path channel is communicated with the hydrogen fuel supply pipe.

Description

Technical Field

[0001] The present invention and an aero-engine particularly relate to a pure hydrogen fuel injection device and a combustion chamber of a micro turbojet engine. Background Art

[0002] Hydrogen fuel has the characteristics of high calorific value, low pollution and renewable. It is one of the important energy sources to replace traditional fossil fuels. It is also of great significance for low carbonization and zero carbonization. In the field of aviation, the research of hydrogen fuel engines is of great significance. Hydrogen fuel turbojet engines have the advantages of high power density and low emissions, which help to improve the performance and environmental performance of aircraft. In the fields of drones, small aircraft, etc., hydrogen fuel micro turbojet engines have broad application prospects. However, the direct replacement of aviation kerosene by hydrogen fuel in the engine will cause serious consequences such as backfire, local high temperature, and increased nitrogen oxide generation. Therefore, the combustion of hydrogen fuel in the combustion chamber of an aircraft engine is significantly different from that of traditional aviation kerosene. Therefore, the development of hydrogen fuel aircraft engines must redesign the traditional fuel injection method of the combustion chamber to adapt to the characteristics of hydrogen fuel combustion. Summary of the invention

[0003] The purpose of the present invention is to provide a pure hydrogen fuel injection device for a micro turbojet engine, so as to solve the problem of flashback during the combustion of the existing hydrogen fuel and organize the efficient combustion of the hydrogen fuel.

[0004] In order to solve the above technical problems, the present invention provides a pure hydrogen fuel injection device for a micro turbojet engine, comprising an annular nozzle and a hydrogen fuel supply pipe arranged in a combustion chamber; the annular nozzle comprises a plurality of micro-mixing units, and the micro-mixing units comprise air channels and fuel injection holes arranged perpendicularly to each other;

[0005] A fuel gas path network is arranged inside the annular nozzle, and the fuel gas path network includes a first gas path channel, a second gas path channel and an air hole; the first gas path channel and the second gas path channel are arranged alternately front and back along the axial direction of the annular nozzle, and the air hole connects the first gas path channel with the second gas path channel;

[0006] Each micro-mixing unit is communicated with the second gas path channel through a fuel injection hole, and the first gas path channel is communicated with the hydrogen fuel supply pipe.

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

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

[0009] In a preferred embodiment, the three groups of micro-mixing units are arranged in sequence from the center of the ring outwards: the micro-mixing unit located in the inner ring is provided with two fuel injection holes; the micro-mixing unit located in the outer ring and the middle ring is provided with four fuel injection holes;

[0010] The second gas path channel is divided into a plurality of branch channels connected to the respective fuel injection holes; two adjacent micro-mixing units are connected via a branch channel, and the branch channels are distributed on a line connecting the centers of the micro-mixing units.

[0011] In a preferred embodiment, the cross-sectional areas of the first gas path channel and the second gas path channel are larger than the cross-sectional area of ​​the air holes; and the air holes are distributed at the center position of each branch channel.

[0012] In a preferred embodiment, the air passage is distributed in a ring shape along the center of the ring; the fuel injection hole is arranged on the side of the micro-mixing unit; the first air path channel and the second air path channel 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 both the inner and outer ring pipes are provided with gas supply pipes; the gas supply pipes are distributed in the radial direction;

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

[0015] In a preferred embodiment, a plurality of connecting channels are distributed along the center array of the circular ring on both the inner and outer ring tubes;

[0016] The width of the inner and outer ring tubes is 3-4mm, and the thickness is 3-4mm; the width of the air supply pipe is 3-4mm, and the thickness is 3-4mm; the width of the connecting channel is 3-4mm, and the thickness is 3-4mm.

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

[0018] The present invention also provides a combustion chamber, which uses the pure hydrogen fuel injection device of a micro turbojet engine; the combustion chamber includes an air intake channel, 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.

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

[0020] 1. Provide a pure hydrogen fuel injection device for a micro turbojet engine, which can fully 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.

[0021] 2. By setting an annular nozzle, a hydrogen fuel supply pipe and a fuel gas network, the annular nozzle includes a plurality of micro-mixing units, the fuel gas network is divided into a first gas path channel and a second gas path channel in the front and rear, the micro-mixing unit includes an air channel and a fuel injection hole arranged perpendicular to each other, and the fuel is injected perpendicular to the air flow. In order to make the hydrogen fuel injection in each micro-mixing unit uniform, the micro-mixing unit groups are evenly distributed, and the injection hole mode is the same, so that the hydrogen fuel injection effect of each micro-mixing unit is consistent.

[0022] 3. Through the pure hydrogen fuel injection device, the fuel gas network is used to disperse the fuel mixing process to each micro-mixing unit, and the air and hydrogen fuel can be fully mixed, thereby effectively organizing the combustion of pure hydrogen, improving combustion efficiency, avoiding the generation of local high-temperature hotspots, and being beneficial to thermal protection and reducing thermal NOx generation; the micro-mixing unit can rectify and accelerate the incoming air to match the high-level flow flame speed of the hydrogen fuel, which can effectively suppress the combustion flashback phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0025] Figure 3 It is a front view of the connection mode between the hydrogen fuel supply pipe and the nozzle of the pure hydrogen fuel injection device in the embodiment of the present invention;

[0026] Figure 4 It is a layout diagram of the hydrogen fuel gas path channel network inside the annular ring nozzle in the embodiment of the present invention;

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

[0028] Figure 6 Schematic diagram of the structure of the hydrogen fuel gas path channel inside the annular nozzle in an embodiment of the present invention.

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

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. 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 the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] refer to Figure 1-Figure 6 This embodiment provides a pure hydrogen fuel injection device for a micro turbojet engine, which is installed in a combustion chamber and provides a pure hydrogen fuel injection scheme for a micro turbojet engine. Figure 1The main parts of the combustion chamber include an air intake channel 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 and the annular nozzle 300 that supply hydrogen fuel from the outside of the nozzle 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 provided with cooling holes and air supply holes 303, which avoid the problem of local overheating in the combustion chamber. This is conducive to replenishing air to make the combustion more repeated. The air intake channel 100, the combustion flame tube 500 and the hydrogen fuel supply pipe 200 can be designed and modified according to the actual working conditions and use requirements of the combustion chamber, and are not limited to the present embodiment. Figure 1 The structure in .

[0035] The annular nozzle 300 and the hydrogen fuel supply pipe 200 are both arranged in the combustion chamber, and the hydrogen fuel supply pipe 200 is arranged outside the annular nozzle 300. The annular nozzle 300 includes a plurality of micro-mixing units 305, each of which includes an air channel 301 and a fuel injection hole arranged perpendicularly to each other. The air channel 301 is distributed in a ring shape along the center of the ring, and the fuel injection hole is arranged on the side of the micro-mixing unit 305. A fuel gas network is arranged inside the annular nozzle 300 for connecting the hydrogen fuel supply pipe 200. The hydrogen fuel can enter the fuel gas network through the hydrogen fuel supply pipe 200 and enter the nozzle through the transportation of the fuel gas network. After the incoming air enters from the air intake channel 100, it is divided into multiple small air flows by the annular nozzle 300 and enters the air channel 301 of each micro-mixing unit 305, and is fully integrated with the hydrogen fuel. The hydrogen fuel can be hydrogen.

[0036] The fuel gas path network includes a first gas path channel 302, a second gas path channel 304 and a gas hole 303, wherein the first gas path channel 302 and the second gas path channel 304 are arranged in a staggered manner in the axial direction of the annular nozzle 300, and the gas hole 303 connects the first gas path channel 302 and the second gas path channel 304. Each micro-mixing unit 305 is connected to the second gas path channel 304 through a fuel injection hole, and the first gas path channel 302 is connected to the hydrogen fuel supply pipe 200.

[0037] The annular nozzle 300 is provided with three groups of micro-mixing units 305 distributed from the inside to the outside according to the center of the annulus, and the multiple micro-mixing units 305 of each group are evenly distributed along the circumference, and the number of micro-mixing units 305 of each group is the same; each micro-mixing unit 305 is a cylindrical micro-mixing cavity. The size of a single micro-mixing unit 305 is set to a diameter of 5 mm and a length of 15 mm, and the cross-sectional diameter of the air channel 301 provided on the micro-mixing unit 305 is 5-8 mm and the length is 15 mm.

[0038] The annular nozzle 300 provided in this embodiment has a thickness of 15 mm. There are 36 micro-mixing units 305 arranged on the annular nozzle 300. To facilitate the layout of the hydrogen fuel transport path, they are divided into three circles of micro-mixing units 305, with 12, 12 and 12 micro-mixing units 305 offset to the periphery in sequence.

[0039] The second gas path channel 304 is divided into a plurality of branch channels 306 connected to each fuel injection hole, and two adjacent micro-mixing units 305 are connected through a branch channel 306, and the branch channel 306 is distributed on the center line of the micro-mixing unit 305. The connection distribution of the plurality of micro-mixing units 305 and the branch channel 306 is that the three groups of micro-mixing units 305 are arranged in sequence from the center of the ring to the outside, the micro-mixing unit 305 located in the inner ring is provided with two fuel injection holes, and the four branch channels 306 are merged in pairs to connect the two fuel injection holes; the micro-mixing unit 305 located in the outer ring and the middle ring is provided with four fuel injection holes, and four branch channels 306 are connected to one micro-mixing unit 305.

[0040] like Figure 3 , the connection mode of the hydrogen fuel supply pipe 200 and the annular nozzle 300 is set as follows: the hydrogen fuel supply pipe 200 is divided into an inner annular pipe 220 and an outer annular pipe 210, and an inner gas supply pipeline 221 and an outer gas supply pipeline 211 are correspondingly arranged on the inner and outer annular pipes (220, 210), and the gas supply pipelines are distributed radially, and the gas supply pipelines are vertically distributed, for supplying hydrogen fuel into the inner and outer annular pipes (220, 210). The first gas path channel 302 is divided into an inner ring gas path and an outer ring gas path, and the inner and outer ring gas paths are connected to the corresponding inner and outer annular pipes (220, 210) through connecting channels, and multiple connecting channels are distributed along the center array of the annular pipes (220, 210) on the inner and outer annular pipes (220, 210). In the present embodiment, the inner annular pipe 220 can be selected to have 12 inner connecting channels 222, and the outer annular pipe 210 can have 6 outer connecting channels 212, and they are all distributed along the center array of the annular pipe.

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

[0042] like Figure 4The gas path channel layout inside the annular nozzle 300 is realized by a hydrogen fuel gas path network composed of a first gas path channel 302 at the front, a second gas path channel 304 at the rear, and a cylindrical air hole 303. The first gas path channel 302 is divided into an inner ring gas path and an outer ring gas path, which are used to communicate with the inner and outer ring pipes (220, 210). The gas path channel width of the first gas path channel 302 is 3-4mm, and the thickness is 3-4mm. The first gas path channel 302 is connected to the second gas path channel 304 at the rear through a cylindrical air hole 303 with a diameter of 0.4mm-0.8mm and a depth of 3mm.

[0043] The second gas path channel 304 is responsible for connecting every two adjacent micro-mixing units 305. The multi-channel branch channels 306 of the second gas path channel 304 are hydrogen fuel injection channels of the micro-mixing units. The width of the second gas path channel 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 that the fuel injection amount of each fuel injection hole is consistent, the cross-sectional area of ​​the first gas path channel 302 and the second gas path channel 304 is greater than the cross-sectional area of ​​the cylindrical air hole 303. The diameter of the cylindrical air hole 303 is 0.4-0.8mm and the depth is 3mm. At the same time, to ensure that the amount of hydrogen fuel distributed to each micro-mixing unit 305 by the second gas path channel 304 is consistent, the cylindrical air hole 303 is distributed at the center of each branch channel 306, and the distance from the cylindrical air hole 303 to the two micro-mixing units 305 is equal, which ensures that the hydrogen fuel is evenly distributed to each micro-mixing unit 305.

[0045] Since the internal channel structure of the annular nozzle 300 is complex and difficult to process, in this embodiment, Figure 6 The first gas path channel 302 and the second gas path channel 304 are both designed as square pipes with a width of 3-4 mm and a thickness of 4 mm. It is possible to consider using 3D printing technology to manufacture the nozzle.

[0046] The pure hydrogen fuel injection scheme of the micro turbojet engine provided in this embodiment is realized by the hydrogen fuel supply pipe 200, the annular nozzle 300, and the hydrogen fuel gas path network composed of the first gas path channel 302, the second gas path channel 304 and the gas hole 303 arranged in the annular nozzle 300. Figure 5 The hydrogen fuel enters the annular nozzle 300 from the hydrogen fuel supply pipe 200, and then enters the first gas path channel 302, the cylindrical air hole 303 and the second gas path channel 304 in sequence, and finally enters the micro-mixing unit 305 to be mixed with the air.

[0047] In order to ensure that the fuel injection amount of each injection hole is consistent, in this embodiment, through the setting of the first gas path channel 302 and the second gas path channel 304, after the hydrogen fuel is injected into the annular nozzle 300, it will first fill the first gas path channel 302, and then enter the second gas path channel 304 through the cylindrical air hole 303. Since the size of the cylindrical air hole 303 is small, the flow rate increases at this time, the gas pressure is uniform, and then quickly enters the second gas path channel 304. With the distribution position of the cylindrical air hole 303 (the center position of the branch channel 306 connecting the micro-mixing units 305), the gas injected in the micro-mixing unit 305 will be relatively uniform. The micro-mixing units 305 are evenly distributed between the groups, and the injection hole mode is the same, so that the hydrogen fuel injection effect of each micro-mixing unit 305 is consistent, and the air and hydrogen fuel can be fully mixed for injection, thereby improving the stability and combustion efficiency of hydrogen fuel combustion and avoiding the problem of local overheating of the hydrogen fuel combustion chamber.

[0048] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention shall be deemed to infringe 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 arranged in the combustion chamber; the annular nozzle includes a plurality of micro-mixing units, and the micro-mixing units include air channels and fuel injection holes arranged perpendicular to each other; A fuel gas path network is arranged inside the annular nozzle, and the fuel gas path network includes a first gas path channel, a second gas path channel and an air hole; the first gas path channel and the second gas path channel are arranged alternately front and back along the axial direction of the annular nozzle, and the air hole connects the first gas path channel with the second gas path channel; Each micro-mixing unit is communicated with the second gas path channel through a fuel injection hole, and the first gas path channel is communicated with the hydrogen fuel supply pipe.

2. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 1, characterized in that: Three groups of micro-mixing units are distributed on the annular nozzle from the inside to the outside according to the center of the annular ring, and the 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 the micro-mixing units in each group is the same; each of the micro-mixing units is a cylindrical micro-mixing cavity with a diameter of 5 mm and a length of 15 mm, and an air channel section arranged thereon has a diameter of 5-8 mm and a length of 15 mm.

4. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 3, characterized in that: The three groups of micro-mixing units are arranged in sequence from the center of the ring to the outside, the micro-mixing unit located in the inner ring is provided with two fuel injection holes; the micro-mixing units located in the outer ring and the middle ring are provided with four fuel injection holes; The second gas path channel is divided into a plurality of branch channels connected to the respective fuel injection holes; two adjacent micro-mixing units are connected via a branch channel, and the branch channels are distributed on a 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 areas of the first gas path channel and the second gas path channel are larger than the cross-sectional areas of the air holes; and the air holes are distributed at the center position of each branch channel.

6. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 1, characterized in that: The air passage is distributed in a ring shape along the center of the ring; the fuel injection hole is arranged on the side of the micro-mixing unit; the first gas path channel and the second gas path channel 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 both the inner and outer ring pipes are provided with gas supply pipes; the gas supply pipes are distributed in the radial direction; The first gas path channel is divided into an inner ring gas path and an outer ring gas path, and the inner and outer ring gas paths are connected to the corresponding inner and outer ring pipes through a connecting channel.

8. A pure hydrogen fuel injection device for a micro turbojet engine according to claim 7, characterized in that: The inner and outer ring tubes are provided with a plurality of connecting channels arranged along the center array of the ring; The width of the inner and outer ring tubes is 3-4mm, and the thickness is 3-4mm; the width of the air supply pipe is 3-4mm, and the thickness is 3-4mm; the width of the connecting channel is 3-4mm, and the thickness is 3-4mm.

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 path channel is 3-4mm, and the thickness is 3-4mm; the air holes are circular holes with a diameter of 0.4mm-0.8mm and a depth of 3mm; the width of the second air path channel is 2mm-3mm, and the thickness is 3-4mm.

10. A combustion chamber, characterized in that: A pure hydrogen fuel injection device for a micro turbojet engine according to any one of claims 1 to 9; the combustion chamber comprises 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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