A radial composite nozzle structure

Abstract

A radial composite nozzle structure belongs to the field of nozzle technology. The present invention realizes different combustion modes by redistributing the fuel and air entering the nozzle, which can improve the integrated design of the nozzle on the basis of existing needs; by setting inclined radial swirl blades and a first fuel channel with a variable cross-section design, it can easily blow the fuel downstream, prevent backfire, and facilitate the absorption of fuel from the first fuel injection hole; based on the setting of the first fuel channel with a variable cross-section, in conjunction with the radial swirl blades, it can not only form a larger recirculation zone, effectively reduce the velocity of the mixed gas flow, and improve the ignition success rate, but also form a diffusion swirl combustion mode, providing a stable ignition source for peripheral combustion; through the arrangement of the second fuel channel and the second fuel injection hole, it can facilitate the uniform distribution of fuel among multiple second fuel channels, forming a micro-mixed combustion mode, which can greatly reduce NOx emissions and avoid the occurrence of backfire.

Description

Technical Field

[0001] The invention belongs to the technical field of nozzles, and in particular relates to a radial composite nozzle structure. Background Art

[0002] The nozzles in aircraft engines or ground gas turbines need to meet the requirements of ignition performance in small states, pollution emission performance in large states, and combustion stability under all operating conditions. Currently, a mode of central diffuser nozzle and outer premixed nozzle is usually adopted, but the central diffuser nozzle needs to maintain a continuous combustion working state, which affects pollution emissions, while the outer premixed nozzle has risks such as backfire. In addition, its structural arrangement is not conducive to overall compact design, and has high requirements for the layout environment and layout method, which affects its wide application. Summary of the Invention

[0003] In view of the above problems existing in the prior art, the object of the present invention is to provide a radial composite nozzle structure.

[0004] The present invention provides the following technical solution: a radial composite nozzle structure, comprising a nozzle body; the nozzle body is provided with a first fuel channel, a first air channel, a second fuel channel, and a second air channel coaxially arranged in sequence from the center outward;

[0005] A group of radial swirl blade channels of equal width and inclined arrangement are formed on the sidewall of the first air channel, with radial swirl blades formed between adjacent radial swirl blade channels; the first fuel channel is a variable cross-section channel, so that a section of the first fuel channel is formed with a gradually increasing cross-sectional area along the fuel flow direction, and a section of the first air channel is formed with a gradually decreasing cross-sectional area along the air flow direction; the first fuel channel is connected to the first air channel, and the fuel passing through the first fuel channel mixes with the swirling air flowing into the first air channel to form a swirling mixed gas, and a recirculation zone is formed downstream of the nozzle;

[0006] The second air passage is communicated with the second fuel passage. Air flowing in through the second air passage is mixed with fuel flowing into the second air passage through the second fuel passage and then flows out.

[0007] Furthermore, the nozzle body is provided with a fuel inlet cavity located in the middle of the nozzle body and an air inlet cavity located outside the nozzle body; the fuel flows into the first fuel channel and the second fuel channel respectively through the fuel inlet cavity; the air flows into the first air channel and the second air channel respectively through the air inlet cavity.

[0008] Furthermore, a fuel distribution chamber is provided in the nozzle body, and the fuel passes through the fuel inlet chamber and is distributed to the first fuel channel and the second fuel channel via the fuel distribution chamber; the cross-sectional area of ​​the fuel distribution chamber is larger than the cross-sectional area of ​​the fuel inlet chamber; the fuel inlet chamber, the fuel distribution chamber and the first fuel channel are coaxially arranged.

[0009] Furthermore, a group of radial swirl blade channels are evenly distributed along the central axis of the first air channel and are inclined with a tangential angle of 30° to 60°; the width of the radial swirl blades is 1-5 mm and gradually decreases from the outside to the inside.

[0010] Furthermore, the outer side wall of the first fuel channel on the first fuel channel includes a first straight section, an expansion section and a second straight section in sequence along the fuel flow direction; the cross-sectional area of ​​the expansion section gradually increases along the fuel flow direction, and there is a smooth transition between the lower end of the first straight section and the upper end of the expansion section, and between the lower end of the expansion section and the upper end of the second straight section; a group of first fuel injection holes connected to the first air channel are provided on the second straight section.

[0011] Furthermore, a group of second fuel channels are arranged in the outer wall of the first air channel, away from the central axis of the fuel distribution cavity, and are evenly spaced along the central axis of the fuel distribution cavity to facilitate uniform distribution of fuel among the group of second fuel channels.

[0012] Furthermore, a second fuel injection hole communicating with the second air channel is provided at the end of the second fuel channel; a flow direction of the fuel through the second fuel injection hole is perpendicular to a flow direction of the air in the second air channel.

[0013] Furthermore, a group of air gate holes are provided at the bottom of the second air channel, the number of the radial swirl blade channels is the same as the number of the air gate holes, and the radial swirl blade channels are located between two air gate holes; the second fuel injection holes are arranged in a one-to-one correspondence with the air gate holes.

[0014] Furthermore, the fuel passing through the first fuel channel and the swirling air flowing into the first air channel form a diffusion swirling combustion mode downstream of the nozzle; the fuel passing through the second fuel channel and the air flowing into the second air channel form a micro-mixed combustion mode downstream of the nozzle.

[0015] By adopting the above technology, compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1) The present invention achieves different combustion modes by redistributing the fuel and air entering the nozzle, which can meet the requirements of ignition performance in a small state, pollution emission performance in a large state, and combustion stability under all operating conditions. It improves the integration and compactness of the nozzle design and facilitates processing and installation.

[0017] 2) In the present invention, by providing inclined radial swirl blades, a swirling airflow is formed in the first air channel. Furthermore, due to the provision of an expansion section on the first fuel channel, a section of the first air channel is formed with a gradually decreasing cross-sectional area along the direction of air flow. This increases the velocity of the airflow, makes it easier to blow the fuel downstream, and prevents backfire. Furthermore, based on the principle of the Bernoulli effect, where pressure increases with velocity and decreases with pressure, fuel is easily drawn from the first fuel injection hole.

[0018] 3) In the present invention, based on the setting of the variable-section first fuel channel, combined with the radial swirl blades, not only can a larger recirculation area be formed, the mixture flow velocity is effectively reduced, and the ignition success rate is improved, but also a diffusion swirl combustion mode can be formed, providing a stable ignition source for peripheral combustion; in addition, the diffusion swirl combustion is relatively stable, which can effectively reduce the thermal and acoustic oscillations of the entire nozzle and combustion chamber, and enhance combustion stability.

[0019] 4) In the present invention, the arrangement of the second fuel channels can facilitate the uniform distribution of fuel among multiple second fuel channels; and through the setting of the second fuel injection holes, the gas and air flow are cross-mixed to enhance the mixing between the fuel and air, forming a micro-mixing effect, and then forming a micro-mixing combustion mode, which can greatly reduce NOx emissions and avoid the occurrence of backfire. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the internal cross-sectional structure of the present invention;

[0021] Figure 2 for Figure 1 Schematic diagram of the structure of the AA section;

[0022] Figure 3 This is a schematic diagram of the internal structure of the diffusion swirl combustion mode of the present invention;

[0023] Figure 4 This is a schematic diagram of another embodiment of the internal structure of the diffusion swirl combustion mode of the present invention, wherein: a group of first fuel injection holes are obliquely arranged on the first fuel base plate;

[0024] Figure 5 Schematic diagram of the internal structure of the mild-mix combustion mode of the present invention.

[0025] In the figure: 10-fuel inlet chamber; 11-nozzle assembly hole; 20-fuel distribution chamber; 30-first fuel channel; 31-first fuel inlet hole; 32-first fuel injection hole; 33-first fuel bottom plate; 34-outer side wall of first fuel channel; 40-second fuel channel; 41-second fuel injection hole; 50-air inlet chamber; 51-nozzle mounting surface; 52-radial swirl blade channel; 60-first air channel; 61-radial swirl blade; 62-outer side wall of first air channel; 70-second air channel; 71-air door hole; 72-air plate. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] On the contrary, the present invention covers any alternatives, modifications, equivalents, and solutions that fall within the spirit and scope of the present invention as defined by the claims. Furthermore, to facilitate a better understanding of the present invention, certain specific details are described in detail below in the detailed description of the present invention. Those skilled in the art will be able to fully understand the present invention without these details.

[0028] See also Figure 1-5 A radial composite nozzle structure includes a nozzle body, which is provided with a fuel inlet cavity 10, a fuel distribution cavity 20, an air inlet cavity 50, and a first fuel channel 30, a first air channel 60, a second fuel channel 40 and a second air channel 70 coaxially arranged from the center to the outside.

[0029] Specifically, fuel enters the nozzle distribution chamber 20 through the fuel inlet chamber 10 and is distributed into the first fuel passage 30 and the second fuel passage 40 . Air is distributed into the first air passage 60 and the second air passage 70 through the air inlet chamber 50 .

[0030] Specifically, the cross-sectional area of ​​the fuel distribution chamber 20 is larger than the cross-sectional area of ​​the fuel inlet chamber, so that the flow rate of the fuel is reduced after entering the fuel distribution chamber 20, which is more conducive to reducing pressure loss and distributing the fuel. A portion (approximately 10%) of the fuel (which can be natural gas, hydrogen, ammonia or synthesis gas, etc.) enters the first fuel channel 30 through the first fuel inlet hole 31 at the end of the first fuel channel 30, and the remaining fuel (approximately 90%) enters the multiple second fuel channels 40, with the number of second fuel channels 40 being 6 to 20. The second fuel channels 40 are arranged away from the central axis of the fuel distribution chamber 20 so that the flow rate of the fuel in the second fuel channels 40 is further reduced compared to the central axis position, which is conducive to uniform distribution of the fuel among the multiple second fuel channels 40.

[0031] Specifically, the ratio of the flow rate flowing into the first fuel passage 30 and the second fuel passage 40 through the fuel inlet cavity is calculated according to the effective areas of the first fuel injection hole 32 and the second fuel injection hole 41 .

[0032] m1=m t *(A1*Cd1) / (A1*Cd1+A2*Cd2)

[0033] m1 is the flow rate flowing into the first fuel channel 30, m t is the total flow rate from the fuel inlet; A1 is the total area of ​​the first fuel injection port 32, A2 is the total area of ​​the second fuel injection port 41; Cd1 is the flow coefficient of the first fuel injection port 32; Cd2 is the flow coefficient of the second fuel injection port 41. The ratio of the flow rate through the first fuel channel 30 and the second fuel channel 40 is:

[0034] m1 / m2=A1Cd1 / A2Cd2

[0035] During the design process, the ratio of fuel flowing into the first fuel channel 30 and the second fuel channel 40 is usually designed first, and then the areas of the first fuel injection hole 32 and the second fuel injection hole 41 are designed based on this ratio.

[0036] Specifically, the ratio of air flowing through the air inlet cavity 50 into the first air passage 60 and the second air passage 70 is also determined according to the effective areas of the radial swirl blade passage 52 and the air door hole 71 .

[0037] Specifically, a group of radial swirl blade channels 52 of equal width and inclined arrangement are provided on the channel side wall of the first air channel 60, with a tangential angle of 30° to 60° and a number of channels of 4 to 10; radial swirl blades 61 are formed between two adjacent radial swirl blade channels 52; the width of the radial swirl blades 61 is 1-5 mm and gradually decreases from the outside to the inside.

[0038] The first fuel channel 30 is a variable cross-section channel. The first fuel channel outer wall 34 on the first fuel channel 30 includes a first straight section 341, an expansion section 342 and a second straight section 343 in sequence along the fuel flow direction; the cross-sectional area of ​​the expansion section 342 gradually increases along the fuel flow direction; a group of first fuel injection holes 32 connected to the first air channel 60 are provided on the second straight section 343.

[0039] Based on the structural design of the above-mentioned radial swirl blade channel 52, a swirling airflow is formed when the airflow enters the first air channel 60. Combined with the structural design of the first fuel channel 30, a section of channel with a gradually increasing cross-sectional area along the fuel flow direction is formed in the first fuel channel 30, and a section of channel with a gradually decreasing cross-sectional area along the air flow direction is formed in the first air channel 60. On the one hand, it can increase the air flow rate and easily blow the fuel downstream. On the other hand, according to the Bernoulli effect, the pressure flow rate increases and the pressure decreases, which facilitates the absorption of fuel from the first fuel injection hole 32.

[0040] Specifically, air enters the air inlet chamber 50, and a portion (about 5%) of the air turns from the radial swirl blade channel 52 to flow into the first air channel 60, and the vast majority (about 95%) of the air flows along the mainstream to the second air channel 70 and flows out from the air door holes 71 evenly distributed circumferentially at the bottom of the second air channel 70.

[0041] The plurality of radial swirl blade channels 52 are evenly distributed along the circumference of the first air channel 60. The number of radial swirl blade channels 52 matches the number of air ports 71. The radial swirl blade channels 52 are positioned between two adjacent air ports 71, and thus have little impact on the flow field distribution within the air ports 71. The number of second fuel channels 40 corresponds one-to-one to the number of air ports 71 in the second air channel.

[0042] Part of the air entering from the air inlet cavity 50 forms a swirling airflow within the first air passage 60 and mixes with the fuel flowing out through the first fuel injection hole 32, forming a large recirculation zone downstream of the first fuel base plate 33. This can effectively reduce the mixture speed and improve the ignition success rate. Moreover, since the fuel passing through the first fuel injection hole 32 accounts for approximately 10% of the total fuel volume and the air passing through the first air passage 60 accounts for 5% of the total air volume, the local equivalence ratio of the swirling mixture is twice the total equivalence ratio of the nozzle, which can also greatly improve the ignition success rate. In the small state, the air temperature is low and the air flow is small. However, the design of the first fuel injection hole 32 and the first air passage 60 forms an ignition-friendly zone downstream of the nozzle. This not only well meets the needs of small-state ignition, but also ensures stable combustion in the diffusion swirl combustion mode, providing a stable ignition source for combustion outside the nozzle, facilitating the continued combustion of the outer flame, and improving combustion stability. In addition, the diffusion swirl combustion is relatively stable, which can effectively reduce the thermal and acoustic oscillations of the entire nozzle and combustion chamber, enhancing combustion stability.

[0043] Specifically, a second fuel injection hole 41 is provided at the end of the second fuel passage 40. The second portion of fuel flowing through the second fuel injection hole 41 mixes with the second portion of air flowing from the second air passage 70 and through the air port 71. Because the fuel velocity and the air velocity are perpendicular to each other, this enhances the mixing of the fuel and air, creating a micro-mixing effect. After the inner swirl flame ignites, multiple independent, dispersed small flames form downstream of the second fuel injection hole 41, creating a micro-mixing combustion mode. Individual flames are shorter and weaker, significantly reducing NOx emissions. Furthermore, because the fuel and air are located in separate passages, flashback is avoided.

[0044] Specifically, the entire nozzle structure can be installed at multiple locations within the burner, such as the centerline of the burner head, near the outer wall of the burner head, or axially arranged on the burner's flame tube, primarily relying on the nozzle mounting surface 51 for positioning. A fuel pipeline is connected upstream of the nozzle and is screwed into the nozzle assembly hole 11 provided on the nozzle body.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A radial composite nozzle structure, comprising a nozzle body; characterized in that: The nozzle body is provided with a first fuel channel (30), a first air channel (60), a second fuel channel (40), and a second air channel (70) which are coaxially arranged in sequence from the center outward; A group of radial swirl blade channels (52) of equal width and inclined arrangement are provided on the channel side wall of the first air channel (60), and radial swirl blades (61) are formed between two adjacent radial swirl blade channels (52); the first fuel channel (30) is a variable cross-section channel, so that a section of the channel with a gradually increasing cross-sectional area along the fuel flow direction is formed in the first fuel channel (30), and a section of the channel with a gradually decreasing cross-sectional area along the air flow direction is formed in the first air channel (60); the first fuel channel (30) is connected to the first air channel (60), and the fuel passing through the first fuel channel (30) is mixed with the swirl air flowing into the first air channel (60) to form a swirl mixed gas, and a recirculation zone is formed downstream of the nozzle; The second air channel (70) is in communication with the second fuel channel (40), and the air flowing in through the second air channel (70) is mixed with the fuel flowing in through the second fuel channel (40) and then flows out; The outer side wall (34) of the first fuel channel (30) includes a first straight section (341), an expansion section (342), and a second straight section (343) in sequence along the fuel flow direction; the cross-sectional area of ​​the expansion section (342) gradually increases along the fuel flow direction, and there is a smooth transition between the lower end of the first straight section (341) and the upper end of the expansion section (342), and between the lower end of the expansion section (342) and the upper end of the second straight section (343); the second straight section (343) is provided with a group of first fuel injection holes (32) that are in communication with the first air channel (60); A second fuel injection hole (41) communicating with a second air channel (70) is provided at the end of the second fuel channel (40); A group of air gate holes (71) is provided at the bottom of the second air channel (70), the number of the radial swirl blade channels (52) is the same as the number of the air gate holes (71), and the radial swirl blade channels (52) are located between the two air gate holes (71); and the second fuel injection holes (41) are provided in a one-to-one correspondence with the air gate holes (71).

2. A radial composite nozzle structure according to claim 1, characterized in that: The nozzle body is further provided with a fuel inlet cavity (10) located in the middle of the nozzle body and an air inlet cavity (50) located outside the nozzle body; fuel flows into the first fuel channel (30) and the second fuel channel (40) respectively through the fuel inlet cavity (10); and air flows into the first air channel (60) and the second air channel (70) respectively through the air inlet cavity (50).

3. A radial composite nozzle structure according to claim 2, characterized in that: A fuel distribution chamber (20) is provided in the nozzle body, and fuel passes through the fuel inlet chamber (10) and is distributed to the first fuel channel (30) and the second fuel channel (40) via the fuel distribution chamber (20); the cross-sectional area of ​​the fuel distribution chamber (20) is larger than the cross-sectional area of ​​the fuel inlet chamber (10); and the fuel inlet chamber (10), the fuel distribution chamber (20) and the first fuel channel (30) are coaxially arranged.

4. A radial composite nozzle structure according to claim 3, characterized in that: A group of radial swirl blade channels (52) are evenly distributed along the central axis of the first air channel (60) and are inclined, with a tangential angle of 30° to 60°; the width of the radial swirl blades (61) is 1-5 mm and gradually decreases from the outside to the inside.

5. The radial composite nozzle structure according to claim 4, characterized in that: A group of second fuel channels (40) is arranged in the outer wall of the first air channel (60), away from the central axis of the fuel distribution cavity (20), and is evenly spaced along the central axis of the fuel distribution cavity (20) to facilitate uniform distribution of fuel among the group of second fuel channels (40).

6. The radial composite nozzle structure according to claim 5, characterized in that: The flow direction of the fuel through the second fuel injection hole (41) is perpendicular to the flow direction of the air in the second air passage (70).

7. A radial composite nozzle structure according to any one of claims 1 to 6, characterized in that: The fuel passing through the first fuel passage (30) and the swirling air flowing into the first air passage (60) form a diffusion swirling combustion mode downstream of the nozzle; the fuel passing through the second fuel passage (40) and the air flowing into the second air passage (70) form a micro-mixing combustion mode downstream of the nozzle.

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