A swirler suitable for a reflow combustion chamber

Abstract

The present invention relates to the field of gas turbine technology, and in particular to a swirler suitable for a reflow combustion chamber, comprising: a main combustion stage swirler, a pre-combustion stage swirler, a venturi tube and an outlet stabilizer; the venturi tube is axially arranged at one end of the pre-combustion stage swirler, the main combustion stage swirler is sleeved with the pre-combustion stage swirler and the venturi tube, and the outlet stabilizer is axially arranged at one end of the main combustion stage swirler; the main combustion stage swirler comprises a first base and a plurality of first blades, the first blades are arranged on the axial sidewall of the first base, and the plurality of first blades are evenly arranged circumferentially with the center of the first base as the center of the circle; an annular pipeline is arranged in the first base, a fuel cavity is arranged in the first blade, a first fuel inlet is arranged on the surface of the first blade facing the first base, and the first fuel inlet connects the annular pipeline and the fuel cavity. In this way, the two-stage swirler can realize efficient combustion of fuel, the first blade is hollow and stores fuel and sprays it out circumferentially, thereby enhancing the mixing effect with air.

Description

Technical Field

[0001] The invention relates to the technical field of gas turbines, and in particular to a swirler suitable for a reflow combustion chamber. Background Art

[0002] The main development trend of gas turbine combustors is low-pollution combustion. Newly developed gas turbine combustors must meet increasingly stringent pollutant emission standards. The main pollutant emitted by gas turbine combustors is NOx. In order to obtain lower NOx emissions without increasing the concentration of carbon dioxide and unburned hydrocarbons in the tail gas, low-emission combustion forms such as lean oil premixing preevaporation and rich oil quenching lean oil combustion have been widely studied and applied in gas turbines and aircraft engines.

[0003] The centrally staged combustion chamber is one of the main development directions of low-emission combustion chambers today. The fuel enters the pre-combustion stage and the main combustion stage through the auxiliary oil circuit and the main oil circuit respectively. Most of the fuel is sprayed into the main combustion stage to achieve premixed and partially premixed combustion, thereby reducing the temperature of the main combustion zone and further reducing nitrogen oxide emissions; a small part of the fuel is supplied to the combustion chamber through the pre-combustion stage nozzle.

[0004] At present, swirlers are installed at the main combustion stage or pre-combustion stage nozzles to improve the mixing effect with air, but the effect is not good. It is necessary to study more efficient and low-emission combustion chambers and nozzle structures. Moreover, with the development of lightweight gas turbines, how to make full use of the space in the micro-turbine recirculation combustion chamber while achieving efficient combustion and low emissions is also a difficulty that needs to be overcome. Summary of the invention

[0005] The object of the present invention is to solve at least one of the problems in the above-mentioned background technology and to provide a swirler suitable for a reflow combustion chamber.

[0006] To achieve the above object, the present invention provides a swirler suitable for a reflow combustion chamber, comprising:

[0007] Main combustion stage swirler, pre-combustion stage swirler, venturi tube and outlet flame stabilizer;

[0008] The venturi tube is axially arranged at one end of the pre-combustion stage swirler, the main combustion stage swirler is sleeved on the pre-combustion stage swirler and the venturi tube, the outlet flame stabilizer is axially arranged at one end of the main combustion stage swirler close to the venturi tube, and the outlet flame stabilizer is used to assist the stable combustion of the fuel;

[0009] The main combustion stage swirler comprises a first base and a plurality of first blades, the first base is sleeved on the pre-combustion stage swirler, the plurality of first blades are arranged on the axial side wall of the first base, and the plurality of blades are evenly arranged along the circumference of the pre-combustion stage swirler;

[0010] An annular pipeline is arranged in the first base, and the annular pipeline is used for the main combustion stage fuel to enter. A fuel cavity is arranged in the first blade, and a first fuel inlet is arranged on the surface of the first blade facing the first base, and the first fuel inlet communicates the annular pipeline with the fuel cavity;

[0011] A first fuel outlet is arranged on a circumferential side wall of the first blade, a first air flow channel is arranged between the first blades and between the first base and the venturi tube, and the first fuel outlet is communicated with the first air flow channel.

[0012] Preferably, the pre-combustion stage swirler comprises a second base, a second blade and a pre-combustion stage nozzle;

[0013] The second base is sleeved on the pre-combustion stage nozzle, and the second blade is axially arranged in the second base;

[0014] A plurality of the second blades are provided, a second air flow channel is provided between every two of the second blades, and the second air flow channel axially penetrates the base;

[0015] The base is connected to the venturi tube, and one end of the pre-combustion stage nozzle passes through the base and extends into the venturi tube;

[0016] One end of the pre-combustion stage nozzle extending into the venturi tube is provided with a second fuel outlet, and the other end is provided with a second fuel inlet.

[0017] Preferably, a protrusion is provided on the inner wall of the Venturi tube, the protrusion is arranged along the circumference of the Venturi tube, and the diameter of the protrusion gradually increases from the center of the Venturi tube to both ends;

[0018] A third air flow channel is provided at the maximum diameter of the protrusion, the third air flow channel radially penetrates the venturi tube and the protrusion, and the third air flow channel is communicated with the first air flow channel.

[0019] Preferably, the outlet flame stabilizer comprises a plurality of petals, the plurality of petals are fixedly connected to each other, the plurality of petals are evenly arranged along the circumference of the first base, and there is a gap between every two petals;

[0020] The petals are arranged obliquely from the center of the first base to the surrounding areas.

[0021] Preferably, the first blades are arranged in an arc shape, and a plurality of the first blades are bent with the center of the first base as the center of the circle, and the bending angles and directions of the plurality of the first blades are consistent.

[0022] Preferably, the second blade is arranged to be inclined along the circumference of the second base from one end close to the Venturi tube to the other end.

[0023] Preferably, the pre-combustion stage nozzle comprises a straight tube section and a contraction tube section, the straight tube section is fixedly connected to the contraction tube section, and the diameter of the contraction tube section gradually decreases from one end close to the straight tube section to the other end;

[0024] The maximum diameter of the contraction tube section is equal to the diameter of the straight tube section;

[0025] The second fuel outlet is arranged at an end of the contraction tube section away from the straight tube section.

[0026] Preferably, the edge of the petal is arranged to be arc-shaped.

[0027] Preferably, the second fuel outlet is arranged close to the third air flow channel.

[0028] Preferably, a main combustion stage nozzle is provided at one end of the first base away from the pre-combustion stage swirler, the main combustion stage nozzle is connected to the annular pipeline, and the main combustion stage nozzle is used to provide main combustion stage fuel.

[0029] Based on this, the beneficial effects of the present invention are:

[0030] 1. According to the solution of the present invention, the swirler includes a main combustion stage swirler and a pre-combustion stage swirler. The main combustion stage is a radial swirler, which can be well adapted to the recirculation combustion chamber and can achieve efficient combustion utilization in a limited space. The pre-combustion stage is an axial swirler, which can make full use of the central space that must exist in the radial swirler and reduce the pressure loss of the swirler, thereby achieving efficient combustion of liquid fuel.

[0031] 2. According to the solution of the present invention, a fuel cavity is provided in the first blade, the fuel cavity is connected to the annular pipeline, and a first fuel outlet is provided on the circumferential side wall of the first blade. When the main fuel enters the annular pipeline, the main fuel enters the fuel cavity through the first fuel inlet and is ejected from the first fuel inlet, which can form a counter-attack with the air between the two first blades, thereby improving the mixing effect and achieving efficient combustion;

[0032] 3. According to the scheme of the present invention, a venturi tube is provided at one axial end of the pre-combustion stage swirler, and the flow rate of the pre-combustion stage fuel sprayed from the pre-combustion stage swirler can be increased through the venturi tube. At the same time, a third air flow channel is provided at the center of the protrusion of the venturi tube, and the third air flow channel is connected with the first air flow channel, so that the air in the first air flow channel can enter the venturi tube and collide with the pre-combustion stage fuel, thereby improving the mixing effect;

[0033] 4. Through the scheme of the present invention, the outlet flame stabilizer is formed by a plurality of petals arranged evenly in the circumference, and there is a gap between every two petals. Since there is no air flow in the space between the outlet flame stabilizer and the corners of the inner wall of the combustion chamber, a dead corner will be formed, causing the accumulation of fuel. The gap between every two petals of the present invention can allow air to enter the dead corner area, thereby driving the flow of fuel in the dead corner, and can improve the ignition performance of the combustion chamber by eliminating the existence of the dead corner. At the same time, the edge of the petal is set to an arc shape, which can form a plurality of air vortices of different sizes due to the different curvatures of the petals after the fuel is sprayed out, which is conducive to flame stabilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A diagram schematically showing the use status of a two-stage cyclone according to an embodiment of the present invention;

[0035] Figure 2 A schematic diagram schematically showing the structure of a two-stage cyclone according to an embodiment of the present invention;

[0036] Figure 3 A schematic radial cross-sectional view of a two-stage cyclone according to an embodiment of the present invention;

[0037] Figure 4 A schematic axial cross-sectional view of a two-stage cyclone according to an embodiment of the present invention;

[0038] Explanation of the reference numerals: main combustion stage swirler 10, first base 101, annular pipeline 1011, first blade 102, fuel cavity 1021, first fuel inlet 1022, first fuel outlet 1023, first air flow channel 103, main combustion stage nozzle 104, pre-combustion stage swirler 20, second base 201, second blade 202, pre-combustion stage nozzle 203, straight tube section 2031, contracting tube section 2032, second fuel inlet 2033, second fuel outlet 2034, second air flow channel 204, venturi tube 30, protrusion 301, third air flow channel 302, outlet stabilizer 40, petal 401, combustion chamber 50, air inlet 501, fuel outlet 502, casing 503, flame tube 504. DETAILED DESCRIPTION

[0039] The content of the present application will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the content of the present application, rather than implying any limitation on the scope of the present application.

[0040] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0041] Figure 1 A schematic diagram showing the use state of a two-stage cyclone according to an embodiment of the present invention is shown in FIG. Figure 1 As shown:

[0042] In this scheme, a two-stage swirler is applied to the reflow combustion chamber 50, and the reflow combustion chamber 50 includes an air inlet 501, a fuel outlet 502, a casing 503 and a flame tube 504. The two-stage swirler runs through the casing 503 and the flame tube 504, and passes the swirled fuel into the flame tube 504. The air in the reflow combustion chamber 50 is supplied by the compressor, enters through the air inlet 501 and enters the interior of the flame tube 504 along the opening on the flame tube 504, and is connected with the two-stage swirler. When the fuel and air are mixed and burned in the flame tube 504, they are discharged through the fuel outlet 502 to drive the turbine to work.

[0043] Further, Figure 2 A schematic diagram schematically shows the structure of a two-stage cyclone according to an embodiment of the present invention, Figure 3 A schematic radial cross-sectional view of a two-stage cyclone according to an embodiment of the present invention is shown. Figure 4 A schematic axial cross-sectional view of a two-stage cyclone according to an embodiment of the present invention is shown as follows: Figure 2-4 As shown, a two-stage cyclone suitable for a micro gas turbine of the present invention comprises:

[0044] A main combustion stage swirler 10, a pre-combustion stage swirler 20, a venturi tube 30 and an outlet flame stabilizer 40;

[0045] The venturi tube 30 is axially arranged at one end of the pre-combustion stage swirler 20, the main combustion stage swirler 10 is sleeved on the pre-combustion stage swirler 20 and the venturi tube 30, and the outlet stabilizer 40 is axially arranged at one end of the main combustion stage swirler 10 close to the venturi tube 30, and the outlet stabilizer 40 is used to replicate the stable combustion of fuel;

[0046] The main combustion stage swirler 10 comprises a first base 101 and a plurality of first blades 102. The first base 101 is sleeved on the pre-combustion stage swirler 20. The plurality of first blades 102 are arranged on the axial sidewall of the first base 101. The plurality of first blades 102 are evenly arranged along the circumference of the pre-combustion stage swirler 20.

[0047] An annular pipeline 1011 is provided in the first base 101, and the annular pipeline 1011 is used for the main combustion stage fuel to enter. A fuel cavity 1021 is provided in the first blade 102, and a first fuel inlet 1022 is provided on the surface of the first blade 102 facing the first base 101, and the first fuel inlet 1022 communicates the annular pipeline 1011 with the fuel cavity 1021;

[0048] A first fuel outlet 1023 is provided on a circumferential side wall of the first blade 102 , a first air flow channel 103 is provided between the plurality of first blades 102 , and the first fuel outlet 1023 is in communication with the first air flow channel 103 .

[0049] Specifically, the main combustion stage swirler 10 includes a first blade 102, a fuel cavity 1021 is arranged in the first blade 102, and the fuel cavity 1021 is connected to the annular pipeline 1011; a main combustion stage nozzle 104 is arranged at one end of the first base 101 away from the pre-combustion stage swirler 20, and the main combustion stage nozzle 104 is connected to the annular pipeline 1011, and the main combustion stage nozzle 104 is used to provide main combustion stage fuel.

[0050] When the annular pipeline 1011 is supplied with main combustion stage fuel by the main combustion stage nozzle 104 , the main combustion stage fuel enters the fuel cavity 1021 through the first fuel inlet 1022 , and is discharged from the first fuel outlet 1023 on the circumferential side wall of the first blade 102 .

[0051] In this way, the two-stage swirler includes a main combustion stage swirler 10 and a pre-combustion stage swirler 20, and the first blades 102 are evenly arranged along the circumference of the first base 101 as the center of the circle, so that the main combustion stage swirler 10 is a radial swirler, which can be applied to the reflow combustion chamber;

[0052] Furthermore, the central space that is inevitably present in the radial swirler is utilized to arrange the pre-combustion stage swirler 20 therein, thereby realizing efficient utilization of the limited space.

[0053] By providing a fuel cavity 1021 in the first blade 102 and providing a first fuel outlet 1023 on the circumferential side wall of the first blade 102, when the main combustion stage fuel is sprayed out, it can collide with the air in the first air flow channel 103 between the two first blades 102, thereby improving the mixing effect of fuel and air;

[0054] At the same time, since the temperature of the first blade 102 will increase when the main combustion stage swirler 10 runs for a long time, reducing the service life of the first blade 102, a fuel cavity 1021 is opened in the first blade 102, so that the main combustion stage fuel can flow through the first blade 102, which has a cooling effect on the first blade 102 and further protects the first blade 102.

[0055] A venturi tube 30 is provided at one axial end of the pre-combustion stage swirler 20. After being ejected from the pre-combustion stage swirler 20, the pre-combustion stage fuel oil can increase its flow velocity after passing through the venturi tube 30, thereby increasing the impact force with the air and improving the mixing effect.

[0056] An outlet flame stabilizer 40 is provided at one axial end of the main combustion stage swirler 10. The outlet flame stabilizer 40 is configured to be expansion type, which can constrain the mixed fuel sprayed through the main combustion stage swirler 10 and the pre-combustion stage swirler 20, and control the central reflow zone to a suitable size, which is beneficial to subsequent efficient combustion.

[0057] Further, the pre-combustion stage swirler 20 includes a second base 201, a second blade 202 and a pre-combustion stage nozzle 203;

[0058] The second base 201 is sleeved on the pre-combustion stage nozzle 203, and the second blade 202 is axially arranged in the second base 201;

[0059] A plurality of second blades 202 are provided, and a second air flow channel 204 is provided between every two second blades 202. The second air flow channel 204 axially penetrates the second base 201;

[0060] The second base 201 is connected to the venturi tube 30 , and one end of the pre-combustion stage nozzle 203 passes through the second base 201 and extends into the venturi tube 30 . The pre-combustion stage nozzle 203 is used to provide pre-combustion stage fuel.

[0061] Specifically, the second blade 202 is arranged in the second base 201, and the second blade 202 is arranged to be inclined along the circumference of the second base 201 from one end close to the venturi tube 30 to the other end, so that the pre-combustion stage nozzle 203 becomes an axial swirler, forming a better shearing effect with the main combustion stage swirler 10, forming a better crushing atomization effect.

[0062] Furthermore, the outlet flame stabilizer 40 includes a plurality of petals 401, the plurality of petals 401 are fixedly connected to each other, the plurality of petals 401 are evenly arranged along the circumference of the first base 101, and there is a gap between every two petals 401;

[0063] The petals 401 are arranged tilted, and the tilting direction of the petals 401 is tilted from the center of the first base 101 to the surroundings, forming a reduced-expansion opening as a whole.

[0064] In this way, the outlet flame stabilizer 40 is configured to be formed by a plurality of flaps 401 arranged evenly in the axial direction, such as Figure 1 As shown, when the outlet stabilizer 40 is inserted into the combustion chamber 50, a dead angle is formed between the outlet stabilizer 40 and the corner of the combustion chamber 50, and the mixed fuel sprayed from the outlet stabilizer 40 directly moves axially toward the downstream of the combustion chamber 50, so that the fuel in the dead angle will not be taken away, thereby causing the accumulation of fuel, which is easy to form a deflagration phenomenon during ignition, which is not conducive to the stable propagation of the flame;

[0065] In this solution, by setting the flaps 401, there is a gap between every two flaps 401. While restricting the recirculation zone, the mixed fuel will also flow out from the gap when sprayed, thereby opening up the dead-angle recirculation zone and the main combustion stage swirl air, eliminating the existence of the dead-angle recirculation zone in the combustion chamber 50, and improving the ignition performance of the combustion chamber 50.

[0066] At the same time, the edge of the flap 401 is set to be arc-shaped, and the airflow is disturbed by the different curvatures of the edge of the flap 401 to form air vortices of different sizes, which is conducive to stabilizing the flame and becomes another measure to stabilize combustion in addition to the central recirculation area.

[0067] At the same time, the edge length of the flap 401 can be changed to reduce the turbulence and shear strength of the edge airflow, thereby achieving a noise reduction effect.

[0068] Furthermore, the first blades 102 are configured to be arc-shaped, and the bending angles and directions of the plurality of first blades 102 are consistent. With such a configuration, the first blades 102 can be streamlined as a whole, thereby reducing air flow losses and improving swirler performance.

[0069] Furthermore, a protrusion 301 is provided on the inner wall of the venturi tube 30, and the protrusion 301 is arranged along the circumference of the venturi tube 30, and the diameter of the protrusion 301 increases from the center of the venturi tube 30 to the main units at both ends;

[0070] A third air flow channel 302 is provided at the maximum diameter of the protrusion 301 . The third air flow channel 302 radially penetrates the venturi tube 30 and the protrusion 301 . The third air flow channel 302 is communicated with the first air flow channel 103 .

[0071] In this way, the protrusion 301 is provided to reduce the diameter of the Venturi tube 30, thereby compressing the fuel and air, increasing their flow rate, and thus enhancing the subsequent mixing effect. The provision of the third air flow channel 302 can allow the air in the first air flow channel 103 to be supplemented into the Venturi tube 30, increase the air content in the Venturi tube 30, and thus improve the mixing effect of the pre-combustion stage fuel.

[0072] Furthermore, the pre-combustion stage nozzle 203 includes a straight tube section 2031 and a contraction tube section 2032, the straight tube section 2031 is fixedly connected to the contraction tube section 2032, and the diameter of the contraction tube section 2032 gradually decreases from one end close to the straight tube section 2031 to the other end;

[0073] The maximum diameter of the contraction tube section 2032 is equal to the diameter of the straight tube section 2031 .

[0074] A second fuel inlet 2033 is provided at one end of the pre-combustion stage nozzle 203, and a second fuel outlet 2034 is provided at the other end;

[0075] The second fuel outlet 2034 is disposed at an end of the contraction tube section 2032 away from the straight tube section 2031 .

[0076] With such a configuration, the diameter of the contraction tube section 2032 gradually decreases, which can further compress the fuel, thereby increasing the fuel flow rate. When the fuel is sprayed out from the second fuel outlet 2034, the mixing effect with the air can be enhanced.

[0077] Furthermore, the second fuel outlet 2034 is arranged close to the third air flow channel 302, so that the pre-combustion level fuel comes into contact with the air of the third air flow channel 302 immediately after coming out of the second fuel outlet 2034, and the two collide with each other, thereby enhancing the mixing effect.

[0078] To sum up, through the scheme of the present invention, the two-stage swirler includes a radial main combustion stage swirler 10 and an axial pre-combustion stage swirler 20. The pre-combustion stage swirler 20 is located at the center of the main combustion stage swirler 10, and can make full use of the central space that must exist in its radial swirler to achieve efficient use of space; a good organization of the fuel is achieved through a first-stage radial and a first-stage axial swirler, thereby achieving efficient combustion of the fuel; at the same time, the first blade 102 in the main combustion stage swirler 10 is provided with a fuel cavity 1021, and the main combustion stage fuel can be stored in the fuel cavity 1021 and ejected from the circumference of the first blade 102, forming a counter-attack with the air in the first air flow channel 103 in the circumference of the first blade 102, thereby enhancing the mixing effect.

[0079] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

[0080] It should be understood that the size of the serial numbers of the steps in the invention content and embodiments of the present application does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

Claims

1. A swirler suitable for a recirculation combustion chamber, characterized in that: include: Main combustion stage swirler, pre-combustion stage swirler, venturi tube and outlet flame stabilizer; The venturi tube is axially arranged at one end of the pre-combustion stage swirler, the main combustion stage swirler is sleeved on the pre-combustion stage swirler and the venturi tube, the outlet flame stabilizer is axially arranged at one end of the main combustion stage swirler close to the venturi tube, and the outlet flame stabilizer is used to assist the stable combustion of the fuel; The main combustion stage swirler comprises a first base and a plurality of first blades, the first base is sleeved on the pre-combustion stage swirler, the plurality of first blades are arranged on the axial side wall of the first base, and the plurality of first blades are evenly arranged in a circumferential direction with the center of the first base as the center of the circle; An annular pipeline is arranged in the first base, and the annular pipeline is used for the main combustion stage fuel to enter. A fuel cavity is arranged in the first blade, and a first fuel inlet is arranged on the surface of the first blade facing the first base, and the first fuel inlet communicates the annular pipeline with the fuel cavity; A first fuel outlet is provided on a circumferential side wall of the first blade, a first air flow channel is provided between the first blades and between the first base and the venturi tube, and the first fuel outlet is communicated with the first air flow channel; The pre-combustion stage swirler comprises a second base, a second blade and a pre-combustion stage nozzle; The second base is sleeved on the pre-combustion stage nozzle, and the second blade is axially arranged in the second base; A plurality of the second blades are provided, a second air flow channel is provided between every two of the second blades, and the second air flow channel axially penetrates the base; The base is connected to the venturi tube, and one end of the pre-combustion stage nozzle passes through the base and extends into the venturi tube; One end of the pre-combustion stage nozzle extending into the venturi tube is provided with a second fuel outlet, and the other end is provided with a second fuel inlet; The outlet flame stabilizer comprises a plurality of petals, the plurality of petals are fixedly connected to each other, the plurality of petals are evenly arranged along the circumference of the first base, and there is a gap between every two petals; The petals are arranged tilted, and the tilting direction of the petals is tilted from the center of the first base to the surroundings; The inner wall of the venturi tube is provided with protrusions, the protrusions are arranged along the circumference of the venturi tube, and the diameter of the protrusions gradually increases from the center of the venturi tube to both ends; A third air flow channel is provided at the maximum diameter of the protrusion, the third air flow channel radially penetrates the venturi tube and the protrusion, and the third air flow channel is communicated with the first air flow channel.

2. A swirler suitable for a reflow combustion chamber according to claim 1, characterized in that: The first blades are arranged in an arc shape, and the bending angles and directions of the plurality of first blades are consistent.

3. A swirler suitable for a reflow combustion chamber according to claim 1, characterized in that: The second blade is arranged to be inclined along the circumference of the second base from one end close to the venturi tube to the other end.

4. A swirler suitable for a reflow combustion chamber according to claim 1, characterized in that: The pre-combustion stage nozzle comprises a straight tube section and a contraction tube section, wherein the straight tube section is fixedly connected to the contraction tube section, and the diameter of the contraction tube section gradually decreases from one end close to the straight tube section to the other end; The maximum diameter of the contraction tube section is equal to the diameter of the straight tube section; The second fuel outlet is arranged at an end of the contraction tube section away from the straight tube section.

5. The swirler suitable for a reflow combustion chamber according to claim 1, characterized in that: The edge of the petal is arranged in an arc shape.

6. The swirler suitable for a reflow combustion chamber according to claim 1, characterized in that: The second fuel outlet is disposed close to the third air flow passage.

7. The swirler suitable for a reflow combustion chamber according to claim 1, characterized in that: A main combustion stage nozzle is arranged at one end of the first base away from the pre-combustion stage swirler. The main combustion stage nozzle is connected to the annular pipeline and is used to provide main combustion stage fuel.

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