Compact efficient centrifugal nozzle for multi-point lean oil direct injection combustion chamber

Abstract

The invention relates to the technical field of pressure atomizing nozzles, in particular to a compact efficient centrifugal nozzle for a multi-point lean oil direct injection combustion chamber. A contraction section, a straight pipe section and a nozzle which are sequentially communicated are arranged in the nozzle shell, the swirler is assembled in the nozzle shell, three tangential grooves are formed in the swirler at equal intervals, a cylindrical swirling chamber is arranged in the swirler, the compression nut is of a stepped structure and is provided with a first fuel oil channel and a fuel oil through hole, and the first fuel oil channel and the fuel oil through hole are communicated through the first fuel oil channel. And the first fuel channel and the second fuel channel of the nozzle shell form a complete fuel conveying channel. In the working process, fuel oil enters the rotational flow chamber through the tangential groove to form a high-speed rotating liquid film after being guided in and distributed, and is sprayed out from the nozzle to form hollow conical spray after being accelerated and thinned through the contraction section and crushed through the straight pipe section, and the hollow conical spray is rapidly mixed with air to form uniform and lean combustible mixed gas. The device is compact in structure, high in rotational flow efficiency and excellent in atomization quality, the multi-point arrangement requirement of an MLDI combustion system is met, the temperature of a combustion area can be effectively reduced, and nitrogen oxide emission is restrained.

Description

Technical Field

[0001] This invention relates to the field of pressure atomizing nozzle technology, and more specifically to a compact, high-efficiency centrifugal nozzle for multi-point lean direct injection combustion chambers. Background Technology

[0002] As aero-engine combustion technology evolves towards lower emissions, higher efficiency, and wider steady-state operating ranges, lean combustion has become the main trend for next-generation low-emission combustors. Multi-point lean direct injection (MLDI) technology effectively reduces local flame temperature and significantly suppresses nitrogen oxides (NOx) by creating a uniform, stable, and generally lean combustible mixture in the combustor inlet region. x The generation of advanced combustion chambers has become an important development direction.

[0003] In an MLDI combustion system, nozzles need to be positioned at multiple points in the combustion chamber head. Fuel must be rapidly broken into fine droplets near the nozzle outlet and quickly mixed with the air under the strong swirling action of the mainstream airflow. The nozzle body of an MLDI system only provides a fuel flow channel and lacks an air introduction structure. Fuel atomization is primarily achieved through an internal centrifugal swirling structure, while air is supplied by the external combustion chamber flow field to enhance fuel mist dispersion and mixing. Therefore, the swirling intensity, tangential momentum introduction method, and nozzle geometry within the nozzle directly determine the fuel atomization quality, thus affecting the fuel-air mixing characteristics.

[0004] MLDI technology places comprehensive demands on nozzle geometry, including miniaturization, high swirl intensity, and excellent atomization. However, existing swirl nozzles are mostly used in traditional combustion systems, resulting in relatively large structural dimensions. The matching relationship between the tangential groove and the swirl chamber is difficult to maintain efficiently at a small scale. Insufficient liquid film disruption in some nozzle orifice areas leads to larger and unevenly distributed droplets, affecting the stability of lean combustion and low-emission performance. Furthermore, due to installation space constraints, nozzles must simultaneously achieve reliable swirl formation, sufficient pressure drop, and effective liquid film disruption within a very small volume, placing higher demands on internal flow channel design. Summary of the Invention

[0005] The purpose of this invention is to provide a compact, high-efficiency centrifugal nozzle for multi-point lean direct injection combustion chambers, which has higher swirl formation efficiency and can achieve rapid liquid film breakup in the nozzle area, thus meeting the requirements of MLDI technology for nozzle miniaturization, high atomization efficiency and rapid mixing capability.

[0006] To achieve the above objectives, the technical solution of this application is: a compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber, comprising: The nozzle housing has an nozzle at one end for injecting fuel, and an internal mounting cavity for assembling components and an injection channel for fuel flow, wherein the injection channel is connected to the nozzle. A swirler is assembled in the mounting cavity of the nozzle housing. It has a swirling chamber inside for forming a rotating liquid film of fuel. A tangential groove is provided on the swirler. One end of the tangential groove is connected to the fuel delivery channel and the other end is connected to the swirling chamber, so as to allow fuel to flow into the swirling chamber tangentially. A clamping nut is fitted into the mounting cavity of the nozzle housing and engages with one end of the cyclone separator to achieve axial positioning of the cyclone separator within the mounting cavity.

[0007] In another embodiment of the present invention, a first fuel passage is provided on the clamping nut, and a second fuel passage is provided on the nozzle housing. The first fuel passage and the second fuel passage are connected to form a fuel delivery passage. The fuel delivery passage is connected to an upstream fuel supply pipeline for continuously delivering fuel into the nozzle.

[0008] In another implementation of the present invention, the hydrocyclone has three tangential grooves, which are arranged at equal intervals around the circumference of the hydrocyclone, and the included angle between adjacent tangential grooves is 120°.

[0009] In another embodiment of the present invention, the injection channel includes a converging section and a straight section connected in sequence, wherein the converging section is connected to the mounting cavity, and the end of the straight section away from the converging section forms a nozzle for injecting fuel.

[0010] In another embodiment of the present invention, the clamping nut is in the form of a stepped columnar structure, including an integrally formed thin section and a thick section; a plurality of through fuel through holes are uniformly opened along the circumference on the side wall of the thin section, and the interior of the thick section is a first fuel channel. The fuel through holes and the first fuel channel are interconnected to form a continuous and smooth fuel delivery channel.

[0011] In another embodiment of the present invention, the outer wall of the cyclone separator is provided with a positioning boss, and an annular gap for circumferential fuel distribution is formed between the positioning boss, the clamping nut and the inner wall of the nozzle housing. The fuel flowing out from the fuel through hole enters the tangential groove through the annular gap.

[0012] In another implementation of the present invention, the swirling chamber is a cylindrical cavity with a swirling radius of R and a swirling chamber diameter of D0, satisfying the design relationship D0≈2R+b, where b is the outlet width of the tangential groove.

[0013] In another implementation of the present invention, the swirl radius R of the swirling chamber and the nozzle radius r of the nozzle are... c Satisfying R=4r c The matching relationship.

[0014] In another embodiment of the present invention, the contraction section is a conical structure with an included angle of 60° between its two inner walls; the length L0 of the straight pipe section is 0.5 mm, and the outlet diameter of the nozzle is 0.5 mm.

[0015] In another embodiment of the present invention, the clamping nut and the nozzle housing are assembled by a threaded connection to form a detachable mating structure.

[0016] By adopting the above technical solution, the present invention can achieve the following technical effects: 1. Through the coordinated design of the tangential grooves, swirling chamber, and nozzle structure of the swirler, a highly efficient swirling generation mechanism was precisely constructed within a relatively small geometric scale. The scientific arrangement of the three tangential grooves ensures that the fuel receives sufficient tangential momentum when entering the swirling chamber. Combined with the optimized dimensions of the swirling chamber, a high-strength and stable rotating liquid film is rapidly formed, providing excellent initial conditions for subsequent droplet breakup and ensuring atomization effect from the source.

[0017] 2. The geometric adaptation design of the swirl chamber and the contraction section creates favorable conditions for the full expansion and acceleration of the rotating liquid film; the short straight pipe nozzle structure further constrains the movement of the liquid film, prompting it to break up efficiently near the nozzle outlet, ultimately forming a fine and uniformly distributed oil mist, effectively solving the problem of limited atomization quality of small-sized nozzles.

[0018] 3. The overall structure is compact and the flow channel boundary is stable. It integrates core functions such as swirl formation, liquid film acceleration, and break-up injection in a very small volume. It does not require additional complex structures and can meet the dense layout requirements of multi-point lean direct injection (MLDI) combustion systems, greatly improving the installation adaptability of nozzles in specific combustion scenarios.

[0019] 4. The excellent atomization effect and reasonable spray pattern enable the oil mist to mix quickly and evenly with the air outside the nozzle, which significantly improves the initial oil-air mixing conditions and ensures the formation of a generally lean and evenly distributed combustible mixture. This not only improves combustion stability but also effectively reduces the temperature of the combustion zone and suppresses nitrogen oxide emissions, which is in line with the development trend of low-pollution combustion technology.

[0020] 5. The matching design of the structure and parameters of each component has been precisely calculated, and the flow channel layout is reasonable. It not only ensures the balance between swirling intensity, pressure drop and liquid film breaking efficiency, but also has good structural stability and assembly reliability, providing a technical solution that combines high performance and practicality for practical applications. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 A cross-sectional view of a compact, high-efficiency centrifugal nozzle used in a multi-point lean direct injection combustion chamber; Figure 2 Side and cross-sectional views of the hydrocyclone; Figure 3 This is a cross-sectional view of the end face of the clamping nut; Figure 4 A three-dimensional exploded view of a compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber; The numbers in the diagram are explained as follows: 1. Nozzle housing; 11. Second fuel passage; 2. Swirl; 3. Compression nut; 4. Contraction section; 5. Straight pipe section; 6. Nozzle; 21. Positioning boss; 22. Tangential groove; 23. Swirl chamber; 31. First fuel passage; 32. Fuel through hole. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature marked with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0027] Example 1 like Figure 1 As shown, this embodiment provides a compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber. Its structural design revolves around the core requirements of "miniaturization, high swirl, and superior atomization," adapting to the multi-point arrangement and low emission requirements of MLDI combustion systems. The specific structure includes: The nozzle housing 1 has a stepped mounting cavity and an injection channel inside. The mounting cavity is used to assemble the swirler 2 and the clamping nut 3. The injection channel is connected to the nozzle 6 and is used to guide the fuel treated by the swirler 2 to flow along the nozzle axis and be sprayed out. The injection channel includes a converging section 4 and a straight section 5 connected in sequence: the converging section 4 has a conical structure with an included angle (full cone angle) of 60° between its two inner walls, used to axially accelerate and radially compress the rotating liquid film; the straight section 5 is arranged along the nozzle axis, preferably with a length L0 = 0.5 mm, and the end away from the converging section 4 forms the nozzle 6. The outlet diameter of the nozzle 6 is preferably 0.5 mm (nozzle radius r). c =0.25mm), the straight pipe section is used to further constrain and shape the rotating liquid film, so that the fuel forms a stable rotating injection state at the nozzle. The nozzle housing 1 has a second fuel passage 11 on its side wall. One end of the passage is adapted to the upstream fuel supply line, and the other end is connected to the first fuel passage 31 of the clamping nut 3, forming an important part of the fuel delivery path.

[0028] like Figure 2As shown, the cyclone separator 2 is the core component for centrifugal atomization of the nozzle and is assembled in the mounting cavity of the nozzle housing 1. Its outer wall is provided with an annular positioning boss 21, forming an annular gap between the positioning boss 21, the clamping nut 3, and the inner wall of the nozzle housing 1 for uniform circumferential fuel distribution. The cyclone separator 2 contains a cylindrical cyclone chamber 23, preferably with a cyclone radius R = 1 mm, corresponding to a cyclone chamber diameter D0 = 2.4 mm, satisfying the design relationship D0 ≈ 2R + b (where b is the outlet width of the tangential groove), providing sufficient space for the swirling liquid film to expand; the cyclone radius R of the cyclone chamber 23 is related to the nozzle radius r. c Satisfying R=4r c The matching relationship can significantly improve the centrifugal breaking capacity of the liquid film with a very small nozzle size. Three tangential grooves 22 are formed on the hydrocyclone 2, and the three tangential grooves 22 are arranged at equal intervals around the circumference of the hydrocyclone 2, with an included angle of 120° between adjacent tangential grooves 22 to ensure uniform circumferential force on the fuel. One end of the tangential groove 22 is connected to the annular gap, and the other end is connected to the cyclone chamber 23, used to allow the fuel to flow into the cyclone chamber 23 tangentially; the total flow area F of the three tangential grooves 22... d =0.78mm 2 The groove width and groove depth are designed to match the total flow area, so that the ratio of the equivalent cross-sectional area of ​​the tangential groove to the cross-sectional area of ​​the nozzle meets the theoretical requirements of the centrifugal nozzle. Under the premise of ensuring reasonable pressure drop (avoiding excessive energy loss), it provides sufficient tangential momentum for fuel.

[0029] like Figure 3 As shown, the clamping nut 3 has a stepped columnar structure, divided into a thin section and a thick section along its axial direction. The diameter of the thin section is smaller than that of the thick section, and multiple through-holes 32 are evenly distributed circumferentially on its sidewall for fuel diversion and discharge. The interior of the thick section is a hollow first fuel channel 31, which communicates with the second fuel channel 11 of the nozzle housing 1 and is interconnected with the fuel through-holes 32 of the thin section, forming a continuous and smooth fuel delivery channel. The outer wall of the thick section of the clamping nut 3 is provided with external threads, which are adapted to the internal threads of the inner wall of the nozzle housing 1 mounting cavity. The threaded connection enables a detachable fit, facilitating the installation, disassembly, and maintenance of the components. One end of the thin section abuts against the positioning boss 21 of the hydrocyclone 2. Tightening the threads enables the axial clamping and positioning of the hydrocyclone 2, ensuring the structural stability of the assembled components.

[0030] like Figure 4As shown, during assembly, first, the swirler 2 is installed into the mounting cavity of the nozzle housing 1, so that the swirling chamber 23 at the front end of the swirler 2 fits against the inner wall of the constriction section 4 of the nozzle housing 1; then, the thin section of the clamping nut 3 is oriented towards the swirler 2 and screwed into the mounting cavity of the nozzle housing 1 until the end face of the thin section of the clamping nut 3 is tightly abutted against the swirler 2, thus completing the fixing of the swirler 2; at this time, the first fuel passage 31 of the clamping nut 3 is precisely aligned with the second fuel passage 11 of the nozzle housing 1, and the tangential groove 22, the annular gap, and the swirling chamber 23 are all kept in communication, forming a complete fuel flow channel.

[0031] Example 2 This embodiment provides a working method adapted to the nozzle described in Embodiment 1. Through fuel delivery, swirl formation, liquid film breaking, and oil-gas mixing processes, it achieves efficient atomization and rapid mixing. The specific steps are as follows: Fuel in the upstream fuel supply line, under the action of fuel supply pressure (pressure range adapted to the working requirements of MLDI combustion system), enters the first fuel passage 31 of the clamping nut 3 through the second fuel passage 11 of the nozzle housing 1; fuel flows along the first fuel passage 31 to the thin section of the clamping nut 3, and is diverted and discharged through the fuel through holes 32 evenly arranged circumferentially on the side wall of the thin section, and enters the positioning boss 21 of the cyclone separator 2, the annular gap formed between the clamping nut 3 and the inner wall of the nozzle housing 1; within the annular gap, fuel diffuses evenly circumferentially, completing circumferential distribution and ensuring that the fuel intake of the three tangential grooves 22 is consistent.

[0032] After being evenly distributed through the annular gap, the fuel enters the three equally spaced tangential grooves 22 on the hydrocyclone 2 under continuous fuel supply pressure. Since the tangential grooves 22 are arranged tangentially, the fuel gains a significant tangential velocity when passing through the tangential grooves 22 and is guided tangentially into the cylindrical swirling chamber 23 of the hydrocyclone 2. The fuel entering the swirling chamber 23 flows along the chamber wall and forms a high-speed rotating liquid film that is tightly attached to the chamber wall under the combined action of centrifugal force and tangential momentum. The liquid film expands outward continuously during rotation and moves forward along the axial direction (towards the contraction section 4).

[0033] After the rotating liquid film flows out of the swirl chamber 23, it enters the conical contraction section 4. As the cross-sectional area of ​​the contraction section 4 gradually decreases along the fuel flow direction, the rotating liquid film is squeezed by the flow channel, and the axial velocity is further increased. At the same time, the liquid film continues to thin, the surface fluctuation amplitude continues to increase, and unstable rupture begins to occur, laying the foundation for subsequent complete rupture.

[0034] Subsequently, the initially ruptured liquid film enters a straight pipe section 5 with a length of only 0.5 mm. Inside the straight pipe section 5, the liquid film maintains a strong rotational state and is constrained by the inner wall of the straight pipe section 5, further enhancing the rotational intensity. As the liquid film forms an unstable liquid structure within a very short distance, it provides the initial conditions for the droplet to break up under the action of external air.

[0035] The swirling droplets, thoroughly broken up by the straight pipe section 5, are ejected from the nozzle 6 at the nozzle tip, forming a hollow cone-shaped spray. This spray pattern has a large diffusion angle and surface area, enabling it to quickly contact the swirling air provided by the combustion chamber flow field. Under the action of the air swirling, the fuel mist and air are fully mixed, forming a generally lean and spatially uniform combustible mixture. This provides favorable initial conditions for subsequent lean combustion, effectively reducing the combustion zone temperature and significantly suppressing nitrogen oxides (NOx). x The generation of ) is in line with the low emission and high efficiency requirements of MLDI combustion systems.

[0036] Throughout the entire operation, it ensures efficient atomization performance of the nozzle at a small size, achieves rapid and uniform mixing of oil and gas, and maintains reasonable pressure loss and structural stability, making it suitable for long-term operation of MLDI combustion systems.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A compact, high-efficiency centrifugal nozzle for multi-point lean direct injection combustion chambers, characterized in that, include: The nozzle housing (1) has an nozzle for injecting fuel at one end, and an internal mounting cavity for assembling components and an injection channel for fuel flow are formed inside, the injection channel being connected to the nozzle. The swirler (2) is installed in the mounting cavity of the nozzle housing (1). It has a swirling chamber (23) inside for forming a rotating liquid film of fuel. The swirler (2) has a tangential groove (22). One end of the tangential groove (22) is connected to the fuel delivery channel, and the other end is connected to the swirling chamber (23) for making the fuel flow into the swirling chamber (23) tangentially. The clamping nut (3) is fitted into the mounting cavity of the nozzle housing (1) and abuts against one end of the cyclone separator (2) to achieve axial positioning of the cyclone separator (2) in the mounting cavity.

2. The compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber according to claim 1, characterized in that, The clamping nut (3) has a first fuel passage (31), and the nozzle housing (1) has a second fuel passage (11). The first fuel passage (31) and the second fuel passage (11) are connected to form a fuel delivery passage. The fuel delivery passage is connected to the upstream fuel supply pipeline and is used to continuously deliver fuel to the nozzle.

3. The compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber according to claim 1, characterized in that, The number of tangential grooves (22) on the hydrocyclone (2) is three. The three tangential grooves (22) are arranged at equal intervals around the circumference of the hydrocyclone (2), and the included angle between adjacent tangential grooves (22) is 120°.

4. The compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber according to claim 1, characterized in that, The injection channel includes a converging section (4) and a straight section (5) connected in sequence, wherein the converging section (4) is connected to the mounting cavity, and the end of the straight section (5) away from the converging section (4) forms a nozzle (6) for injecting fuel.

5. A compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber according to claim 1, characterized in that, The clamping nut (3) has a stepped columnar structure, including an integrally formed thin section and a thick section; multiple through-holes (32) are evenly opened along the circumference on the side wall of the thin section, and the inside of the thick section is a first fuel channel (31). The fuel through-holes (32) and the first fuel channel (31) are interconnected to form a continuous and smooth fuel delivery channel.

6. The compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber according to claim 5, characterized in that, The outer wall (2) of the cyclone separator is provided with a positioning boss (21). The positioning boss (21), the clamping nut (3) and the inner wall of the nozzle housing form an annular gap for circumferential fuel distribution. The fuel flowing out from the fuel through hole enters the tangential groove through the annular gap.

7. The compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber according to claim 1, characterized in that, The swirling chamber (23) is a cylindrical cavity with a swirling radius of R and a swirling chamber diameter of D0, satisfying the design relationship D0≈2R+b, where b is the outlet width of the tangential groove (22).

8. The compact, high-efficiency centrifugal nozzle for a multi-point lean direct injection combustion chamber according to claim 4, characterized in that, The swirl radius R of the swirling chamber (23) and the nozzle radius r of the nozzle (6) c Satisfying R=4r c The matching relationship.

9. The compact, high-efficiency centrifugal nozzle according to claim 4, characterized in that, The contraction section (4) is a conical structure with an included angle of 60° between its two inner walls; the length L0 of the straight pipe section (5) is 0.5 mm, and the outlet diameter of the nozzle (6) is 0.5 mm.

10. The compact, high-efficiency centrifugal nozzle according to claim 1, characterized in that, The clamping nut (3) and the nozzle housing (1) are assembled by a threaded connection to form a detachable mating structure.

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