A swirl- straight-flow coupling short-distance reinforced mixing hydrogen fuel nozzle

Abstract

The application provides a swirl-DC coupling short-distance reinforced mixing hydrogen fuel nozzle, and belongs to the technical field of aero-engine / gas turbine combustion, and specifically comprises a fuel pipe, an external straight pipe and a ring plate arranged coaxially, the external straight pipe is wrapped around the outer periphery of the fuel pipe, and the ring plate is sealingly connected with the fuel pipe and the external straight pipe on the side of the inlet end of the fuel pipe; a plurality of fuel injection holes are arranged on the outer peripheral side wall of the fuel pipe and spaced apart along the circumference of the fuel pipe, a plurality of oblique cutting holes are arranged on the outer wall of the external straight pipe and spaced apart along the circumference of the external straight pipe, and a plurality of straight injection holes are arranged on the outer wall of the external straight pipe and spaced apart along the circumference of the external straight pipe; in the axial direction of the external straight pipe, all the oblique cutting holes are located on the side of the fuel injection holes facing the ring plate, and all the straight injection holes are located on the side of the fuel injection holes facing away from the ring plate, so that the mixing uniformity of hydrogen fuel and oxidant or air in a short distance is improved, and a uniform temperature field is realized to reduce NOx emission.

Description

Technical Field

[0001] This application relates to the field of combustion in aero-engines / gas turbines, and more particularly to a swirling DC-coupled short-pitch enhanced mixing hydrogen fuel nozzle. Background Technology

[0002] Aero engines and gas turbines are crucial equipment in the energy and power sector. Driven by the dual-carbon development goals, the application of green, low-carbon, and zero-carbon fuels, represented by hydrogen fuel, in aero engines and gas turbines has gained attention. However, due to the significant differences in the physicochemical properties of hydrogen fuel, such as density, combustion temperature, and flame velocity, compared to traditional fuels, traditional large-size swirl burners can only accommodate hydrogen-blended combustion with a hydrogen volume ratio of less than 30%. Pure hydrogen combustion requires the development of new combustion technologies to adapt to the fuel's characteristics. Micro-mixing combustion technology, which improves the mixing quality of hydrogen fuel by reducing the mixing scale of fuel and oxidizer, has received considerable attention.

[0003] Currently, different research institutions have developed micro-mixing nozzles based on premixed combustion and diffusion combustion modes. From the perspective of reducing NOx emissions, the premixed combustion mode is better, as the fuel and oxidant or air mix in a relatively long premixing section to form a uniform premixed gas. However, this requires a long premixing channel and has a higher risk of backfire. Micro-mixing nozzles using the diffusion mode have strong flame stability and avoid backfire problems, but current designs are mostly based on simple transverse jet and coaxial jet schemes, resulting in poor mixing of fuel and oxidant or air, which easily generates more high-temperature zones and increases NOx emissions. Summary of the Invention

[0004] In view of this, this application provides a swirl-DC coupled short-distance enhanced mixing hydrogen fuel nozzle, which solves the problem of difficult hydrogen fuel mixing in the prior art, improves the mixing uniformity of hydrogen fuel and oxidant or air in a short distance, so as to achieve a uniform temperature field and reduce NOx emissions.

[0005] The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing provided in this application adopts the following technical solution:

[0006] A swirl-DC coupled short-pitch enhanced mixing hydrogen fuel nozzle includes a fuel tube, an outer straight tube, and an annular plate arranged coaxially. The outer straight tube surrounds the outer periphery of the fuel tube. One end of the fuel tube is open as an inlet end, and the other end of the fuel tube is closed. The annular plate is sealed to the fuel tube and the outer straight tube on the inlet end side of the fuel tube. The outer peripheral sidewall of the fuel pipe is provided with a plurality of fuel injection holes spaced apart along the circumference of the fuel pipe. The outer wall of the outer straight pipe is provided with a plurality of oblique holes spaced apart along the circumference of the outer straight pipe. The outer wall of the outer straight pipe is provided with a plurality of direct injection holes spaced apart along the circumference of the outer straight pipe. On the projection of the circumferential cross section of the outer straight pipe, the angle between the axial direction of the oblique hole and the radial direction of the outer straight pipe at the oblique hole position is greater than 0°. The direct injection holes are arranged along the radial direction of the outer straight pipe. The oblique holes and direct injection holes are used to allow oxidant or air to enter the space between the outer straight pipe and the fuel pipe from the outside of the outer straight pipe. In the axial direction of the outer straight pipe, all the oblique holes are located on the side of the fuel injection holes facing the annular plate, and all the direct injection holes are located on the side of the fuel injection holes facing away from the annular plate.

[0007] Optionally, the outer straight pipe is provided with at least one ring of multiple oblique holes and at least one ring of multiple direct injection holes. The oblique holes in the same ring are located at the same axial position of the outer straight pipe, and the circumferential inclination direction of the oblique holes in the same ring is the same, so that the oxidant or air entering between the outer straight pipe and the fuel pipe through the oblique holes in the same ring forms a co-directional swirling airflow. The direct injection holes in the same ring are located at the same axial position of the outer straight pipe.

[0008] Optionally, the distance between adjacent beveled holes and direct-fire holes along the axial direction of the outer straight pipe is less than or equal to the inner diameter of the outer straight pipe.

[0009] Optionally, the oblique holes in the same circle are evenly distributed along the circumference of the outer straight pipe, and the direct-fire holes in the same circle are evenly distributed along the circumference of the outer straight pipe.

[0010] Optionally, the oblique holes and direct holes are staggered in the circumferential direction of the outer straight pipe.

[0011] Optionally, the fuel pipe is provided with at least one ring of fuel injection holes, and the fuel injection holes in the same ring are evenly distributed along the circumference of the fuel pipe.

[0012] Optionally, the inner diameter of the outer straight pipe is 4-20mm, the axial length of the outer straight pipe is 10-50mm, the outer diameter of the fuel pipe is 2-6mm, the diameter of the oblique cut hole is 1-6mm, and the diameter of the direct injection hole is 1-6mm.

[0013] Optionally, the inner diameter of the fuel injection orifice is 0.2-2 mm.

[0014] In summary, this application includes the following beneficial technical effects: In this application, hydrogen fuel is injected into the nozzle channel from a fuel nozzle located between an oblique orifice and a direct injection orifice. Part of the oxidant or air enters the nozzle channel through the oblique orifice, forming a swirling airflow that circumferentially agitates the downstream discretely injected hydrogen fuel, enhancing the circumferential uniformity of the hydrogen fuel. Part of the oxidant or air enters the inner annular cavity channel of the nozzle through the direct injection orifice, forming a direct injection flow that radially impacts the incoming hydrogen fuel and oxidant or air mixture, strengthening the mixing effect with the hydrogen fuel jet and improving the radial uniformity of the hydrogen fuel. Through two stages of agitation and mixing in different directions, uniform mixing of hydrogen fuel and oxidant or air is achieved over a short distance, and finally, the mixture is ejected from the hydrogen fuel nozzle for combustion.

[0015] Compared with straight-tube micro-mixing nozzles that use premixing, the solution provided in this application can achieve rapid and uniform mixing of hydrogen fuel and oxidant or air over an ultra-short distance through two-stage jets. Under the same mixing uniformity, it can significantly reduce nozzle length and weight, and reduce the risk of backfire that may be caused by premixing.

[0016] Compared with micro-mixing nozzles using a diffusion mode, the solution provided in this application significantly improves the mixing uniformity of hydrogen fuel with oxidant or air without a significant change in nozzle length, effectively reducing the formation of high-temperature zones and thus achieving lower NOx emissions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the hydrogen fuel nozzle with swirl-DC coupling short-pitch enhanced mixing according to this application. Figure 2 This is a schematic cross-sectional view of the hydrogen fuel nozzle with swirl-DC coupling short-pitch enhanced mixing according to this application.

[0019] Explanation of reference numerals in the attached diagram: 1. Fuel pipe; 2. External straight pipe; 3. Annular plate; 4. Fuel injection hole; 5. Angled hole; 6. Direct injection hole. Detailed Implementation

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0023] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0024] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0025] This application provides a hydrogen fuel nozzle with swirling DC coupling and short-pitch enhanced mixing.

[0026] like Figure 1 and Figure 2As shown, a swirl-DC coupled short-pitch enhanced mixing hydrogen fuel nozzle includes a fuel tube 1, an outer straight tube 2, and an annular plate 3 arranged coaxially. The outer straight tube 2 surrounds the outer periphery of the fuel tube 1. One end of the fuel tube 1 is open as an inlet end, and the other end of the fuel tube 1 is closed. The annular plate 3 is sealed to the fuel tube 1 and the outer straight tube 2 on the inlet end side of the fuel tube 1. In one embodiment, the circumferential cross-section of the fuel tube 1 and the outer straight tube 2 is circular, and an annular nozzle flow channel is formed between the outer straight tube 2 and the fuel tube 1. The end of the nozzle flow channel facing away from the annular plate 3 serves as the outlet of the hydrogen fuel nozzle.

[0027] The outer peripheral wall of the fuel pipe 1 is provided with a plurality of fuel injection holes 4 spaced apart along the circumference of the fuel pipe 1. The outer wall of the outer straight pipe 2 is provided with a plurality of oblique holes 5 spaced apart along the circumference of the outer straight pipe 2. The outer wall of the outer straight pipe 2 is provided with a plurality of direct injection holes 6 spaced apart along the circumference of the outer straight pipe 2. On the projection of the circumferential cross section of the outer straight pipe 2, the angle between the axial direction of the oblique hole 5 and the radial direction of the outer straight pipe 2 at the position of the oblique hole 5 is greater than 0°. The direct injection holes 6 are arranged along the radial direction of the outer straight pipe 2. The oblique holes 5 and the direct injection holes 6 are used to allow oxidant or air to enter the space between the outer straight pipe 2 and the fuel pipe 1 from the outside of the outer straight pipe 2. In the axial direction of the outer straight pipe 2, all the oblique holes 5 are located on the side of the fuel injection holes 4 facing the annular plate 3, and all the direct injection holes 6 are located on the side of the fuel injection holes 4 facing away from the annular plate 3.

[0028] In this application, hydrogen fuel is injected into the nozzle channel from the fuel nozzle 4 located between the oblique orifice 5 and the direct injection orifice 6. Part of the oxidant or air enters the nozzle channel through the oblique orifice 5, forming a swirling airflow that circumferentially agitates the downstream discretely injected hydrogen fuel, enhancing the circumferential uniformity of the hydrogen fuel. Part of the oxidant or air enters the inner annular cavity channel of the nozzle through the direct injection orifice 6, forming a direct injection flow that radially impacts the incoming hydrogen fuel and oxidant or air mixture, strengthening the mixing effect with the hydrogen fuel jet and improving the radial uniformity of the hydrogen fuel. Through two stages of agitation and mixing in different directions, uniform mixing of hydrogen fuel and oxidant or air is achieved over a short distance, and finally, the mixture is ejected from the hydrogen fuel nozzle for combustion. The hydrogen fuel nozzle of this application achieves uniform mixing of hydrogen fuel and oxidant or air over a short distance while shortening the size of the hydrogen fuel nozzle, thereby reducing the weight of the hydrogen fuel nozzle. This has a significant positive effect on the lightweight and miniaturization design of aero-engines.

[0029] Compared with straight-tube micro-mixing nozzles that use premixing, the solution provided in this application can achieve rapid and uniform mixing of hydrogen fuel and oxidant or air over an ultra-short distance through two-stage jets. Under the same mixing uniformity, it can significantly reduce nozzle length and weight, and reduce the risk of backfire that may be caused by premixing.

[0030] Compared with micro-mixing nozzles using a diffusion mode, the solution provided in this application significantly improves the mixing uniformity of hydrogen fuel with oxidant or air without a significant change in nozzle length, effectively reducing the formation of high-temperature zones and thus achieving lower NOx emissions.

[0031] In this embodiment, the inner and outer diameters of the fuel pipe 1 are uniform in the axial direction. In other embodiments, the fuel pipe 1 may also be configured with a gradually expanding or contracting outer diameter from the inlet end to the closed end of the other end. If the outer diameter of the fuel pipe 1 is gradually expanding from the inlet end to the closed end of the other end, a nozzle flow channel that gradually narrows from upstream to downstream of the hydrogen fuel nozzle can be formed, which can accelerate the airflow and better suppress backfire; if the outer diameter of the fuel pipe 1 is gradually narrowing from the inlet end to the closed end of the other end, a nozzle flow channel that gradually expands from upstream to downstream of the hydrogen fuel nozzle can be formed, which can reduce the airflow velocity and improve flame stability. The overall shape of the fuel pipe 1 can be designed according to actual needs. In addition, a turbulence structure can be installed on the inner wall of the fuel pipe 1 away from the inlet end to enhance heat transfer. The turbulence structure can be a raised structure. Alternatively, the fuel pipe 1 can be designed as a double-layer structure, with the inner and outer spaces of the fuel pipe 1 connected on the side away from the inlet end. The fuel nozzle 4 is connected to the outer space. After the fuel enters the inner space from the inlet end, it reaches the downstream end of the fuel pipe 1 and then turns back into the outer space, where it is sprayed out through the fuel nozzle 4. This can better enhance the cooling effect at the end of the fuel pipe 1 away from the inlet end.

[0032] The fuel pipe 1 described in this application is provided with at least one ring of fuel injection holes 4. The fuel injection holes 4 in the same ring are evenly distributed along the circumference of the fuel pipe 1. In a specific embodiment, the number of rings of fuel injection holes 4 can be 1-3 rings, and the number of fuel injection holes 4 in each ring can be 2-10.

[0033] The outer straight pipe 2 is provided with at least one ring of multiple obliquely cut holes 5 and at least one ring of multiple direct injection holes 6. The obliquely cut holes 5 in the same ring are located at the same axial position of the outer straight pipe 2, and the circumferential inclination direction of the obliquely cut holes 5 in the same ring is the same, so that the oxidant or air entering between the outer straight pipe 2 and the fuel pipe 1 through the obliquely cut holes 5 in the same ring forms a co-directional swirling airflow. The direct injection holes 6 in the same ring are located at the same axial position of the outer straight pipe 2. In a specific embodiment, the obliquely cut holes 5 can be round holes, elliptical holes, irregularly shaped holes, or grooves, and the specific inclination angle of the obliquely cut holes 5 is designed according to the actual mixing uniformity requirements; the direct injection holes 6 are round holes.

[0034] The distance between adjacent beveled holes 5 and direct-fire holes 6 along the axial direction of the outer straight pipe 2 is less than or equal to the inner diameter of the outer straight pipe 2.

[0035] The oblique holes 5 in the same circle are evenly distributed along the circumference of the outer straight pipe 2, and the direct injection holes 6 in the same circle are evenly distributed along the circumference of the outer straight pipe 2.

[0036] The oblique holes 5 and the direct-fire holes 6 are staggered in the circumferential direction of the outer straight pipe 2.

[0037] In one example, the number of beveled holes 5 on the outer straight pipe 2 can be 1-3 turns, and the number of beveled holes 5 in each turn can be 2-6. The number of direct injection holes 6 on the outer straight pipe 2 can be 1-3 turns, and the number of direct injection holes 6 in each turn can be 2-6.

[0038] In one embodiment, the inner diameter of the outer straight pipe 2 is 4-20 mm, the axial length of the outer straight pipe 2 is 10-50 mm, the outer diameter of the fuel pipe 1 is 2-6 mm, the diameter of the oblique cut hole 5 is 1-6 mm, the diameter of the direct injection hole 6 is 1-6 mm, and the inner diameter of the fuel injection hole 4 is 0.2-2 mm.

[0039] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing, characterized in that, It includes a fuel pipe (1), an outer straight pipe (2) and an annular plate (3) arranged coaxially. The outer straight pipe (2) surrounds the outer periphery of the fuel pipe (1). One end of the fuel pipe (1) is open as the inlet end, and the other end of the fuel pipe (1) is closed. The annular plate (3) is sealed to the fuel pipe (1) and the outer straight pipe (2) on the inlet end side of the fuel pipe (1). The outer peripheral sidewall of the fuel pipe (1) is provided with a plurality of fuel injection holes (4) spaced apart along the circumference of the fuel pipe (1), the outer wall of the outer straight pipe (2) is provided with a plurality of oblique holes (5) spaced apart along the circumference of the outer straight pipe (2), and the outer wall of the outer straight pipe (2) is provided with a plurality of direct injection holes (6) spaced apart along the circumference of the outer straight pipe (2). On the projection of the circumferential cross section of the outer straight pipe (2), the angle between the axial direction of the oblique hole (5) and the radial direction of the outer straight pipe (2) at the position of the oblique hole (5) is greater than 0°. The direct injection holes (6) are arranged along the radial direction of the outer straight pipe (2). The oblique holes (5) and the direct injection holes (6) are used to allow oxidant or air to enter the space between the outer straight pipe (2) and the fuel pipe (1) from the outside of the outer straight pipe (2). In the axial direction of the outer straight pipe (2), all the oblique holes (5) are located on the side of the fuel injection hole (4) facing the annular plate (3), and all the direct injection holes (6) are located on the side of the fuel injection hole (4) facing away from the annular plate (3).

2. The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing according to claim 1, characterized in that, The outer straight pipe (2) is provided with at least one ring of multiple oblique holes (5) and at least one ring of multiple direct injection holes (6). The oblique holes (5) in the same ring are located at the same axial position of the outer straight pipe (2), and the circumferential inclination direction of the oblique holes (5) in the same ring is the same, so that the oxidant or air entering between the outer straight pipe (2) and the fuel pipe (1) through the oblique holes (5) in the same ring forms a unidirectional swirling airflow. The direct injection holes (6) in the same ring are located at the same axial position of the outer straight pipe (2).

3. The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing according to claim 2, characterized in that, The distance between adjacent beveled holes (5) and direct-fire holes (6) along the axial direction of the outer straight pipe (2) is less than or equal to the inner diameter of the outer straight pipe (2).

4. The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing according to claim 2, characterized in that, The oblique holes (5) of the same ring are evenly distributed along the circumference of the outer straight pipe (2), and the direct-fire holes (6) of the same ring are evenly distributed along the circumference of the outer straight pipe (2).

5. The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing according to claim 2, characterized in that, The oblique holes (5) and direct holes (6) are staggered in the circumferential direction of the outer straight pipe (2).

6. The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing according to claim 1, characterized in that, The fuel pipe (1) is provided with at least one ring of fuel injection holes (4), and the fuel injection holes (4) in the same ring are evenly distributed along the circumference of the fuel pipe (1).

7. The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing according to claim 1, characterized in that, The inner diameter of the outer straight pipe (2) is 4-20mm, the axial length of the outer straight pipe (2) is 10-50mm, the outer diameter of the fuel pipe (1) is 2-6mm, the diameter of the oblique hole (5) is 1-6mm, and the diameter of the direct injection hole (6) is 1-6mm.

8. The hydrogen fuel nozzle with swirl-DC coupling and short-pitch enhanced mixing according to claim 7, characterized in that, The inner diameter of the fuel injection hole (4) is 0.2-2 mm.

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