Two-stage rotational flow hydrogen fuel nozzle and combustion chamber thereof

Abstract

The invention discloses a two-stage rotational flow hydrogen fuel nozzle and a combustion chamber thereof. The nozzle comprises a main hydrogen flow path, an auxiliary hydrogen flow path and an air flow path; the hydrogen main flow path is provided with a plurality of main spray holes which are distributed in a circumferential array; the air flow path is provided with a two-stage cyclone; the hydrogen auxiliary flow path comprises a hollow annular flow divider, the flow divider is coaxially arranged around the periphery of the hydrogen main flow path, and a plurality of injection holes are formed in the inner wall and the outer wall of the flow divider and communicated with the first-stage rotational flow channel and the second-stage rotational flow channel respectively. In the using process, efficient mixing of fuel and air is achieved through the synergistic effect of graded injection of main and auxiliary hydrogen and two-stage rotational flow air. According to the combustion chamber provided with the nozzle, large-scale flames are decomposed into a plurality of small flames through micro-scale injection, two-stage rotational flow is combined for strengthening mixing, the backfire risk is effectively restrained, the combustion temperature is lowered, NOx emission is remarkably reduced, meanwhile, the combustion stability is improved, and a reliable solution is provided for hydrogen fuel combustion of an aero-engine.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine technology, specifically relating to a two-stage swirling hydrogen fuel nozzle and its combustion chamber. Background Technology

[0002] Hydrogen fuel, due to its zero-carbon emission characteristics, has become an important component of the clean energy system. Theoretically, hydrogen has a higher thermal efficiency than traditional gasoline engines, and hydrogen engines have unique advantages compared to traditional fuel engines and hydrogen fuel cells. Hydrogen engines have a fast combustion speed, and their lean-burn characteristics allow them to maintain high combustion efficiency even under partial load conditions, reducing energy consumption.

[0003] Hydrogen fuel nozzles are a crucial component of hydrogen energy power systems. Their design must balance high-pressure sealing, mixing efficiency, combustion control, and reliability, making them a key technology for promoting the large-scale application of hydrogen energy. Traditional hydrogen fuel nozzles typically employ a single-path injection method, resulting in insufficient fuel-air mixing intensity, which can easily lead to problems such as hydrogen combustion instability, backfire, and NOx emissions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a two-stage swirling hydrogen fuel nozzle and its combustion chamber. By setting a two-stage swirling flow and a micro-scale nozzle, backfire is avoided at the structural level, and more efficient and stable combustion and nitrogen oxide control are achieved. This is adapted to the characteristics of hydrogen fuel combustion and can be used to modify existing combustion chambers to meet the requirements of efficient and reliable combustion organization and low nitrogen oxide emissions. This improves the high-performance combustion of the combustion chamber and solves the shortcomings of the single-path injection and single-stage swirling mixing intensity of traditional hydrogen fuel nozzles. It achieves precise mixing of fuel and air, thereby solving the problems of instability, backfire and reduced NOx emissions during hydrogen combustion.

[0005] One of the technical solutions adopted by this invention to solve its technical problem is as follows: a two-stage swirling hydrogen fuel nozzle is provided, including a main hydrogen flow path, a secondary hydrogen flow path, and an air flow path; the main hydrogen flow path is provided with a plurality of main nozzles arranged in a circumferential array; the air flow path is provided with a two-stage swirler; the secondary hydrogen flow path includes a hollow annular splitter, which is coaxially arranged around the outer circumference of the main hydrogen flow path, and the downstream air flow path of the two-stage swirler is divided into a primary swirling channel and a secondary swirling channel by the splitter; a plurality of injection holes are opened on the inner and outer walls of the splitter and respectively connected to the primary swirling channel and the secondary swirling channel.

[0006] In a preferred embodiment of the present invention, the main nozzle is an elliptical nozzle; the elliptical nozzle forms an angle of 10 to 30° with the central ray, the major axis radius is 0.3 to 0.6 mm, the minor axis radius is between 0.1 and 0.4 mm, and the nozzle spacing is 0.9 mm.

[0007] In a preferred embodiment of the present invention, a plurality of spray holes are provided at equal and perpendicular angles on the inner and outer walls, with the spacing between each spray hole being 10 to 20° and the radius being 0.3 to 0.5 mm.

[0008] In a preferred embodiment of the present invention, an air inlet is further included, wherein the air inlet is provided with a hydrogen main flow inlet and an annular air inlet chamber coaxially arranged around the outer periphery of the hydrogen main flow.

[0009] In a preferred embodiment of the present invention, the annular intake chamber is connected to the annular diversion chamber downstream, and two-stage cyclones are arranged in the annular diversion chamber, including two annular partitions with a gap between the annular partitions.

[0010] In a preferred embodiment of the present invention, each stage of the two-stage hydrocyclone consists of 18 blades with a blade angle of 30° to 55°.

[0011] In a preferred embodiment of the present invention, the hydrogen auxiliary flow path is connected to a fuel chamber, which is located outside the nozzle body and is provided with an independent gas supply pipe.

[0012] In a preferred embodiment of the present invention, the fuel chamber is connected to the splitter through through holes on the blades of the two-stage cyclone separator.

[0013] In a preferred embodiment of the present invention, an air outlet is further included, which is located downstream of the main nozzle, the primary swirling channel and the secondary swirling channel and is in the shape of a gradually expanding cone.

[0014] The second technical solution adopted by this invention to solve its technical problem is: providing a combustion chamber, including a two-stage swirling hydrogen fuel nozzle as described above. The main hydrogen flow path is directly connected to the intermediate fuel chamber, and the secondary hydrogen flow path is configured with a fuel chamber.

[0015] In a preferred embodiment of the present invention, the combustion chamber includes a diffuser, an intake passage, a hydrogen fuel supply pipe, a swirling nozzle, an inner channel, a combustion chamber wall, a combustion flame tube, and a combustion chamber outlet; the combustion flame tube has mixing holes and cooling holes; the swirling nozzle is a two-stage swirling hydrogen fuel nozzle as described in any one of claims 1-9.

[0016] Compared with the prior art, this technical solution has the following advantages:

[0017] 1. This invention employs a pure hydrogen fuel supply system, focusing on staged fuel supply to ensure stable and efficient fuel delivery. Through the deep coupling of geometric innovation and fluid dynamics optimization, it systematically solves the three core contradictions of hydrogen fuel combustion, realizing micro-mixing injection of pure hydrogen fuel and secondary swirl of air, improving the mixing efficiency of hydrogen and air and the fuel utilization efficiency, and providing strong support for the development of the aero-engine field.

[0018] 2. The nozzle size of this invention is less than 1 mm, which can effectively improve the injection speed of hydrogen to adapt to the fast-flowing air, ensure the effective injection penetration depth of fuel, and achieve rapid and thorough mixing of fuel and air: ① The main hydrogen flow path adopts an elliptical main nozzle, with the major half-axis controlled between 0.3 mm and 0.6 mm and the minor half-axis controlled between 0.1 mm and 0.4 mm. A total of six layers are set, increasing sequentially from the center of the main nozzle outwards. The distance between different nozzles is 0.9 mm, which can achieve a jet coverage rate of >95%; ② The circular injection holes of the hydrogen secondary flow path are evenly distributed on both sides, with the radius controlled between 0.3 mm and 0.5 mm, and a micro-hole every 10° in the circumferential direction.

[0019] 3. Each stage of the two-stage air cyclone separator of this invention consists of 18 blades. The angle between a single blade and the center of the circle is controlled between 30° and 55°. By increasing the angle of the cyclone separator, the radial velocity of the air is increased, allowing it to mix better with the downstream hydrogen. The first-stage cyclone forms a preliminary vortex ring, and the second-stage cyclone adjusts the size and position of the recirculation zone through tangential momentum injection, confining the high-concentration hydrogen to the shear layer rather than the recirculation core area, thus avoiding problems such as flashback caused by local hydrogen accumulation.

[0020] 4. In this invention, the main hydrogen flow path and the secondary flow path use different gas supply pipes. The main hydrogen flow path is directly connected to the intermediate fuel chamber, while the secondary hydrogen flow path has a fuel chamber that surrounds the lower end of the main body. Holes are opened on the cyclone separator, allowing the hydrogen to flow into the secondary fuel channel. This allows for convenient adjustment of the flow ratio between the main and secondary hydrogen flows. The secondary flow path eliminates low-speed vortex regions, while the main flow path, with its swirling elliptical micropore array, enhances turbulent kinetic energy, reduces mixing distance and mixing inhomogeneity, and eliminates localized hydrogen-rich and hydrogen-poor zones, resulting in more uniform hydrogen mixing and combustion with air. This design not only ensures sufficient fuel supply to each component but also achieves precise control of fuel supply, thereby improving the overall system's operating efficiency and stability. Attached Figure Description

[0021] Figure 1 This is a perspective view of Example 1;

[0022] Figure 2 This is a side view of Example 1;

[0023] Figure 3 This is a front view of Example 1;

[0024] Figure 4 This is a diagram showing the circumferential array arrangement of the main nozzles in Example 1;

[0025] Figure 5 for Figure 3 A sectional view along line AA.

[0026] Figure 6 for Figure 5 Enlarged view at point B in the middle;

[0027] Figure 7 for Figure 5 Enlarged view at point C;

[0028] Figure 8 This is a structural diagram of the secondary hydrocyclone blades in Example 1;

[0029] Figure 9 for Figure 8 Enlarged view at point D;

[0030] Figure 10 This is a structural diagram of Example 2.

[0031] Among them, 1-inlet, 2-main hydrogen flow path, 21-main nozzle, 3-diverter, 31-inner wall, 32-outer wall, 33-injection hole, 4-annular inlet chamber, 41-first-stage swirl channel, 42-second-stage swirl channel, 43-annular diverter chamber, 51-partition plate, 52-blade, 53-through hole, 54-microgroove, 6-fuel chamber, 61-independent gas supply pipe, 7-outlet, 81-inlet channel, 82-diffuser, 83-mixing hole, 84-cooling hole, 85-inner channel, 86-combustion flame tube, 87-combustion chamber outlet, 88-hydrogen fuel supply pipe, 9-two-stage swirl hydrogen fuel nozzle. Detailed Implementation

[0032] To more clearly illustrate the purpose, technical solution, and effects of this invention, the following description, in conjunction with the accompanying drawings and examples, will provide further insight. It should be noted that the specific embodiments mentioned herein are for illustrative purposes only and are not intended to limit the invention.

[0033] Example 1

[0034] This embodiment discloses a two-stage swirling hydrogen fuel nozzle, the main body of which is provided with an inlet 1 and an outlet 7, as well as a main hydrogen flow path 2, a secondary hydrogen flow path, and an air flow path between them; the main hydrogen flow path 2 is provided with a plurality of main nozzles 21 arranged in a circumferential array; the air flow path is provided with a two-stage swirler; the secondary hydrogen flow path includes a hollow annular splitter 3, which is coaxially arranged around the outer periphery of the main hydrogen flow path 2, and the downstream air flow path of the two-stage swirler is divided by the splitter 3 into a primary swirling channel 41 and a secondary swirling channel 42; the inner wall 31 and the outer wall 32 of the splitter 3 are provided with a plurality of injection holes 33 respectively connected to the primary swirling channel 41 and the secondary swirling channel 42.

[0035] In this embodiment, the main hydrogen flow path 2 is directly connected to the intermediate fuel chamber, and at its end is a six-layer circumferential array of main nozzles 21, which are elliptical orifices, numbered 5, 10, 18, 25, 28, and 30 from the inside out, totaling 116 elliptical orifices. Each elliptical orifice has a major axis radius of 0.3~0.6 mm and a minor axis radius of 0.1~0.4 mm, and they are uniformly and tightly arranged at the end of the main flow path. The spacing between each micro-orifice stage is 0.9 mm, and all micro-orifices maintain the same size. The major axis of the micro-orifices forms a 20° angle with the circumferential tangent, and the orifice coverage is >9%. The elliptical orifices enhance shear mixing with the swirling air, and by adjusting their size, ensure the jet achieves a certain penetration depth. Through the synergistic effect of the main / secondary flow, the large-scale flame is decomposed into multiple micro-scale flames, controlling the non-uniformity of combustion, and significantly reducing NOx emissions compared to traditional nozzles.

[0036] In this embodiment, the splitter 3 of the hydrogen secondary flow path is a hollow annular structure. The guide plate formed by the inner wall 31 and the outer wall 32 is connected at the end and extends to the upstream of the main combustion zone. Several injection holes 33 are opened at equal angles (every 10°) and vertically on the inner wall 31 and the outer wall 32, forming a double row of micro-holes with a radius of 0.4 mm, which inject fuel into the radial inner and outer channels respectively, forming a fuel concentration gradient. The splitter 3 is connected to a fuel chamber 6, which is located outside the nozzle body and is equipped with an independent gas supply pipe 61. The risk of hydrogen enrichment in the low-speed vortex zone can be eliminated through independent pipeline control.

[0037] In this embodiment, the air inlet 1 is provided with a hydrogen main flow path 2 inlet and an annular air intake chamber 4 coaxially arranged around the outer periphery of the hydrogen main flow path 2. After compression, the airflow enters the annular air intake chamber 4 and reaches the downstream annular split chamber 43. Two-stage cyclones are arranged in the annular split chamber 43. The cyclones adopt a split design, including two annular baffles 51. The edges of the annular baffles 51 are left with gaps between them and the annular split chamber 43 to allow air to pass through. Blades 52 are provided between the two annular baffles 51. The blades 52 are coupled to the baffles, and the gaps between the blades 52 form microgrooves 54. Each stage consists of 18 blades 52, and the blade angles of the blades 52 are 30°~55°. The blades 52 of the second-stage cyclone are provided with through holes 53. Hydrogen gas introduced into the fuel chamber 6 through an independent pipe is connected to the splitter 3 through the through holes 53 on the blades 52 of the two-stage cyclones. Under the guidance of the baffle 51 and the inner and outer walls 31 and 32 of the distributor 3, the air is premixed with the hydrogen by the first-stage swirl channel 41, while the second-stage swirl channel 42 delivers more air to the main combustion zone. The microgrooves 54 between the swirl blades 52 further break up the airflow, improving the mixing efficiency with the microscale fuel jet and reducing mixing inhomogeneity. The blades 52 of the second-stage swirl converter have the same angle, but the increased radial velocity enhances the tangential momentum and adjusts the position of the recirculation zone. Since the inlet 1 and the fuel nozzle are coaxially arranged, the airflow is ensured to be orthogonal to the fuel injection path, preventing flow separation. The blade angle can be optimized using fluid dynamics to match the airflow velocity with the hydrogen injection velocity. Air enters through two paths via a secondary cyclone separator. The primary cyclone separator creates a preliminary (low-speed) premixed vortex, while the secondary cyclone separator enhances the kinetic energy of the turbulence, greatly increasing the tangential velocity of the air. This confines the high-concentration hydrogen gas in the main nozzle 21 to the shear layer rather than the backflow core region, thus avoiding problems such as backfire caused by local hydrogen accumulation.

[0038] In this embodiment, the outlet 7 is located downstream of the main nozzle 21, the primary swirl channel 41, and the secondary swirl channel 42, and is a gradually expanding cone shape. This accelerates the outflow velocity of the mixed gas to prevent backfire. The expanding cone structure also increases the combustion area of ​​the mixed hydrogen, preventing the accumulation of high-temperature zones. A high-temperature recirculation zone can be formed at the outlet to stabilize the flame, while the secondary hydrogen jet suppresses the expansion of the recirculation zone, ensuring that the core combustion temperature remains below 1800 K and inhibiting NOx formation.

[0039] Example 2

[0040] like Figure 10In this embodiment, the combustion chamber includes a diffuser 82, an intake passage 81, a hydrogen fuel supply pipe 88, an inner channel 85, a combustion chamber wall, a combustion flame tube 86, and a combustion chamber outlet 87. The combustion flame tube 86 has mixing holes 83 and cooling holes 84. The swirling nozzle is a two-stage swirling hydrogen fuel nozzle 9 as described in Embodiment 1. Applying the nozzle of Embodiment 1 to the combustion chamber, where the main hydrogen flow path 2 and the secondary flow path use different gas supply pipes, ensures that each part of the combustion chamber receives sufficient fuel supply and achieves precise control of the fuel supply, thereby improving the overall system's operating efficiency and stability. Combustion process:

[0041] First, the air required for combustion enters the combustion chamber through the diffuser 82 and intake passage 81. The diffuser 82 effectively slows down the airflow, increases static pressure, and provides stable and sufficient air for subsequent fuel-gas mixing. In this main airflow, a hydrogen auxiliary stream is pre-mixed with a portion of the main air through its dedicated independent supply pipe 61. The purpose of this pre-mixing is to initially form a relatively uniform lean hydrogen mixture before entering the main combustion zone, to suppress the formation of nitrogen oxides and provide a stable ignition source for subsequent main combustion. Subsequently, this pre-mixed airflow is further fully mixed with the main hydrogen stream injected through the main hydrogen nozzle 21 in the main combustion zone. The design of the main nozzle 21 ensures that hydrogen can be efficiently and quickly mixed uniformly with the remaining air from the intake port to achieve the optimal stoichiometric ratio or lean combustion condition, thereby maximizing combustion efficiency. To further improve combustion efficiency and effectively control wall temperature, additional air is introduced into the combustion chamber through mixing holes 83 and cooling holes 84. Mixing holes 83 introduce secondary air to ensure complete fuel combustion and reduce unburned emissions. Cooling holes 84 utilize the principle of film cooling to form a relatively low-temperature air film on the combustion chamber wall, effectively reducing the high-temperature zone on the wall, protecting the combustion chamber structure from high-temperature corrosion, and extending component life. Finally, the high-temperature exhaust gas produced by combustion is ejected through the optimized combustion chamber outlet 87, and is usually directed to the turbine stage or other downstream components for energy recovery.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A two-stage swirling hydrogen fuel nozzle, characterized in that: It includes a main hydrogen flow path, a secondary hydrogen flow path, and an air flow path; the main hydrogen flow path is provided with a number of main nozzles arranged in a circular array; the air flow path is provided with a two-stage cyclone separator; the secondary hydrogen flow path includes a hollow annular splitter, which is coaxially arranged around the outer periphery of the main hydrogen flow path, and the downstream air flow path of the two-stage cyclone separator is divided into a primary cyclone channel and a secondary cyclone channel by the splitter; The inner and outer walls of the distributor have several injection holes that are respectively connected to the primary vortex channel and the secondary vortex channel.

2. The two-stage swirling hydrogen fuel nozzle according to claim 1, characterized in that: The main nozzle is an elliptical nozzle; the elliptical nozzle forms an angle of 10~30° with the central ray, the major axis radius is 0.3~0.6mm, the minor axis radius is between 0.1~0.4mm, and the nozzle spacing is 0.9mm.

3. The two-stage swirling hydrogen fuel nozzle according to claim 1, characterized in that: Several injection holes are opened at equal and vertical intervals on the inner and outer walls, with the interval between each injection hole being 10~20° and the radius being 0.3~0.5mm.

4. A two-stage swirling hydrogen fuel nozzle according to claim 1, characterized in that: It also includes an air inlet, which has a hydrogen main flow inlet and an annular air inlet chamber coaxially arranged around the outer periphery of the hydrogen main flow.

5. A two-stage swirling hydrogen fuel nozzle according to claim 4, characterized in that: Downstream of the annular intake chamber is an annular flow divider chamber, and two-stage cyclones are arranged in the annular flow divider chamber, including two annular baffles with a gap between the annular baffles.

6. A two-stage swirling hydrogen fuel nozzle according to claim 5, characterized in that: Each stage of the two-stage hydrocyclone consists of 18 blades with blade angles ranging from 30° to 55°.

7. A two-stage swirling hydrogen fuel nozzle according to claim 6, characterized in that: The hydrogen auxiliary flow path is connected to a fuel chamber, which is located outside the nozzle body and has an independent gas supply pipe.

8. A two-stage swirling hydrogen fuel nozzle according to claim 7, characterized in that: The fuel chamber is connected to the splitter through through holes on the blades of the two-stage cyclone separator.

9. A two-stage swirling hydrogen fuel nozzle according to claim 1, characterized in that: It also includes an air outlet, which is located downstream of the main nozzle, the primary swirling channel and the secondary swirling channel and is in the shape of a gradually expanding cone.

10. A combustion chamber, characterized in that: It includes a diffuser, an intake passage, a hydrogen fuel supply pipe, a swirling nozzle, an inner channel, a combustion chamber wall, a combustion flame tube, and a combustion chamber outlet; the combustion flame tube has mixing holes and cooling holes; the swirling nozzle is a two-stage swirling hydrogen fuel nozzle as described in any one of claims 1-9.

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