A swirler structure capable of reducing smoke in combustion chamber

Abstract

The present application belongs to the field of swirler design, and is a swirler structure that can reduce smoke in the combustion chamber, including a centrifugal fuel nozzle, a swirler outer ring, a swirler inner ring and swirler blades. There are multiple groups of swirler blades that are integrally connected between the swirler outer ring and the swirler inner ring. A deflection ring is provided at the trailing edge of the centrifugal fuel nozzle, and the deflection ring is provided corresponding to the position of the swirler blades. First, the purpose of effectively reducing smoke in the combustion chamber can be achieved without making major adjustments to the combustion chamber structure. The present invention is particularly advantageous when in-service combustion chambers or combustion chambers under development that have completed engineering design are required to take measures to reduce exhaust smoke. Second, the present invention can reduce smoke in the combustion chamber while also having the function of blowing away carbon deposits on the end of the centrifugal fuel nozzle. Third, the present invention is not only applicable to aircraft engines, but can also be applied to land / marine gas turbines that burn liquid fuels.

Description

Technical Field

[0001] The present application belongs to the field of swirler design, and in particular relates to a swirler structure capable of reducing smoke in a combustion chamber. Background Art

[0002] Combustion chamber smoke is the direct cause of aircraft engine exhaust smoke. While the smoke particles in exhaust smoke (containing approximately 96% carbon) are not inherently toxic, they can act as carriers of toxic substances and are small (0.01μm to 0.06μm), making them easily inhaled. Consequently, the International Civil Aviation Organization (ICAO) has established extremely strict regulations on the amount of smoke emitted by civil aircraft engines. In military aviation, the hot smoke particles in engine exhaust smoke increase the infrared signature of military aircraft, reducing their infrared stealth performance and ultimately their battlefield survivability. Furthermore, the black smoke trails from engines also negatively impact the aircraft's visual stealth. Statistics show that aircraft with high smoke production experience a tenfold increase in combat losses. Therefore, both military and civilian aircraft engines urgently require proactive and effective measures to reduce combustion chamber smoke.

[0003] The swirler is currently the primary flame tube head intake structure used in military / civilian aviation engine combustion chambers. The conventional axial flow blade swirler structure is shown in Figure 1-Figure 2 The main structure includes a swirler outer ring 3, an inner swirler ring 4, and swirler blades 5. While providing an appropriate amount of air to the liner head, the swirler also creates a recirculation zone to stabilize the flame, improve fuel atomization quality, and promote oil-air mixing. The liner head intake / atomization device, consisting of a swirler and a centrifugal fuel nozzle 1, has been widely used in military and civilian aircraft engines with a total compression ratio of less than 20. While this intake / atomization device boasts outstanding advantages such as a reliable structure and a wide stable operating range, it also has significant limitations.

[0004] As the overall compression ratio of aircraft engines increases, the airflow density within the combustion chamber liner increases, thereby increasing aerodynamic drag. This results in a decrease in the spray cone angle α of the centrifugal fuel nozzle 1 and a weakening of the penetration of the fuel spray 2, causing fuel to tend to accumulate in the center of the liner downstream of the centrifugal fuel nozzle 1. Simultaneously, fresh air flowing into the liner head through the swirler is swept away from the centrifugal fuel nozzle 1 by the intense swirl, resulting in a decrease in air flow in the downstream region of the centrifugal fuel nozzle 1. This situation is more severe when the swirler uses curved blades. The combined effect of these two factors creates a localized fuel-rich zone (with an equivalence ratio greater than 1.3) within the combustion zone near the liner head. Studies have shown that the presence of this localized fuel-rich zone within the combustion zone is the primary cause of smoke particle generation, leading to exhaust smoke in the combustion chamber. The liner head air intake / atomization device, consisting of a swirler and centrifugal fuel nozzle 1, is susceptible to exhaust smoke due to the combined effect of these factors. When exhaust smoke is observed in a combustion chamber using this type of intake / atomization device, significant structural adjustments are often required to reduce the smoke. This translates to substantial costly modifications to existing combustion chambers, and for combustion chambers currently under development, this can significantly increase development costs and lead times.

[0005] Therefore, how to effectively reduce the exhaust smoke phenomenon of the cyclone is a problem that needs to be solved. Summary of the Invention

[0006] The purpose of this application is to provide a swirler structure that can reduce smoke in the combustion chamber, so as to solve the problem that the existing swirler is difficult to solve the exhaust smoke phenomenon.

[0007] The technical solution of the present application is: a swirler structure capable of reducing smoke in a combustion chamber, comprising a centrifugal fuel nozzle, a swirler outer ring, a swirler inner ring and swirler blades; the centrifugal fuel nozzle is a cylindrical structure, the swirler outer ring and the swirler inner ring are coaxially arranged on the outside of the centrifugal fuel nozzle, and the swirler outer ring is arranged on the outside of the swirler inner ring, and there are multiple groups of swirler blades that are integrally connected between the swirler outer ring and the swirler inner ring; the center position of the centrifugal fuel nozzle sprays fuel spray; a deflector ring is provided at the trailing edge of the centrifugal fuel nozzle, the deflector ring is arranged corresponding to the position of the swirler blades, the end of the deflector ring is bent toward the center line of the centrifugal fuel nozzle, and the air flowing out of the swirler is divided into inner and outer streams by the deflector ring.

[0008] Preferably, the deflector ring includes a connecting piece and a guide ring; the guide ring has an L-shaped cross-section, an inner swirler channel for the inner air is formed between the guide ring and the outer wall of the centrifugal fuel nozzle, and the inner air is guided by the L-shaped structure, the outer wall of the guide ring and the external air form an outer swirler channel, and there are multiple groups of connecting pieces that are integrally connected between the guide ring and the outer wall of the centrifugal fuel nozzle.

[0009] Preferably, the end of the deflector ring is provided with expansion grooves uniformly distributed circumferentially.

[0010] Preferably, the deflector ring is designed to be integrated with the cyclone outer ring, the cyclone inner ring and the cyclone blades, and is manufactured by integral precision casting or additive manufacturing.

[0011] Preferably, the equivalence ratio of the inner air flow deflected by the deflection ring in the central area of ​​the flame tube downstream of the centrifugal fuel nozzle is not greater than 1.3; the flow coefficient of the outer swirler channel is 0.84-0.88, and the flow coefficient of the inner swirler channel is 0.58.

[0012] Preferably, the thickness t of the deflector ring is the same as the thickness of the swirler blade or 0.7 to 1.5 mm. When the spray cone angle α of the centrifugal fuel nozzle is 70° to 110° and the rotation direction of the fuel is the same as the rotation direction of the internal air, the turning angle β at the end of the deflector ring is usually 90°.

[0013] The swirler structure of this application, which can reduce combustion chamber smoke, can, firstly, effectively reduce combustion chamber smoke without making major adjustments to the combustion chamber structure. This invention is particularly advantageous when measures are required to reduce exhaust smoke in in-service combustion chambers or in combustion chambers under development that have completed engineering design. Secondly, while reducing combustion chamber smoke, this invention also removes carbon deposits on the ends of centrifugal fuel nozzles. Thirdly, this invention is applicable not only to aircraft engines but also to land and marine gas turbines that burn liquid fuels. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0015] Figure 1 It is a cross-sectional view of the overall structure in the background technology;

[0016] Figure 2 It is a schematic diagram of the end structure in the background technology;

[0017] Figure 3 This is a cross-sectional view of the overall structure of this application;

[0018] Figure 4This is a schematic diagram of the end structure of this application;

[0019] Figure 5 This is the axonometric drawing of the cross-section structure of this application.

[0020] 1. Centrifugal fuel nozzle; 2. Fuel spray; 3. Swirl outer ring; 4. Swirl inner ring; 5. Swirl blades; 6. Baffle ring; 7. Expansion groove; 8. Outer swirl channel; 9. Inner swirl channel; 10. Inner surface; 11. Outer surface; 12. Connecting piece; 13. Guide ring. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] A swirler structure that can reduce smoke in the combustion chamber, such as Figure 3-Figure 4 The centrifugal fuel nozzle 1 comprises a centrifugal fuel nozzle 1, a swirler outer ring 3, a swirler inner ring 4, and swirler vanes 5. The centrifugal fuel nozzle 1 is cylindrical in structure. The swirler outer ring 3 and the swirler inner ring 4 are coaxially arranged on the outside of the centrifugal fuel nozzle 1, with the swirler outer ring 3 being arranged outside the swirler inner ring 4. There are multiple sets of swirler vanes 5, which are integrally connected between the swirler outer ring 3 and the swirler inner ring 4. The fuel spray 2 is ejected from the center of the centrifugal fuel nozzle 1.

[0023] The trailing edge of the centrifugal fuel nozzle 1 is equipped with a deflector ring 6, positioned corresponding to the swirler blades 5. The end of the deflector ring 6 bends toward the centerline of the centrifugal fuel nozzle 1, dividing the air exiting the swirler into two streams: an inner stream and an outer stream. The outer stream, guided by the swirler blades 55, forms a strong swirl, and the swirl core structure undergoes a sudden change, resulting in a "vortex core destruction" phenomenon. This causes a sudden drop in the axial velocity of the air within the swirl core, ultimately creating a recirculation zone, thereby ensuring flame stability and efficient combustion in the combustion chamber. The inner stream, restricted by the deflector ring 6, is deflected toward the center of the downstream flame tube of the centrifugal fuel nozzle 1. This serves to enhance oil-gas mixing in this area and improve fuel atomization quality. This eliminates the localized oil-rich zone near the combustion zone near the flame tube head, removing the primary cause of smoke particle generation, thereby effectively reducing combustion chamber smoke. The inner stream also removes carbon deposits from the end face of the centrifugal fuel nozzle 1.

[0024] Preferably, the baffle ring 6 includes a connecting piece 12 and a guide ring 13. The guide ring 13 has an L-shaped cross-section. The guide ring 13 forms an inner swirler channel 9 for the inner air between the guide ring 13 and the outer wall of the centrifugal fuel nozzle 1. This L-shaped structure guides the inner air, while the outer wall of the guide ring 13 and the external air form an outer swirler channel 8. Multiple sets of connecting pieces 12 are integrally connected between the guide ring 13 and the outer wall of the centrifugal fuel nozzle 1 for secure connection. The connecting pieces 12 are tilted to provide a certain degree of guidance for the inner air.

[0025] Combine Figure 5 , the design principles of the baffle ring are as follows:

[0026] a) The diameter ΦD of the deflector ring is determined by the required deflected inner air flow rate, which should ensure that the equivalence ratio in the central area of ​​the flame tube downstream of the centrifugal fuel nozzle is not greater than 1.3.

[0027] b) The flow coefficient of the outer cyclone channel 8 corresponding to the outer air can be selected between 0.84 and 0.88.

[0028] c) The flow coefficient of the inner cyclone channel 9 corresponding to the inner air can be taken as about 0.58.

[0029] d) While ensuring structural strength, the blocking area of ​​the baffle ring should be minimized to reduce air flow resistance. To this end, the thickness t of the baffle ring 6 can be set to be the same as the thickness of the cyclone blades 5, or selected between 0.7 and 1.5 mm.

[0030] e) When the spray cone angle α of the centrifugal fuel nozzle 1 is 70° to 110° and the rotation direction of the fuel is the same as that of the inner air, the turning angle β at the end of the deflector ring 6 can usually be 90

[0031] °about.

[0032] f) The inner surface 10 at the end of the baffle ring 6 is relatively cool due to convection cooling from the air within the cyclone outlet. However, the outer surface 11 is relatively hot due to the intense radiation from the high-temperature combustion gases within the combustion zone. This creates a significant temperature difference between the inner and outer surfaces, leading to high thermal stress. To reduce thermal stress and prevent cracks and other failures, expansion slots 7 can be uniformly distributed circumferentially at the end of the baffle ring 6. These slots are typically 3 to 5 in number.

[0033] g) The baffle ring 6, the cyclone outer ring 3, the cyclone inner ring 4 and the cyclone blades 5 are designed to be an integrated structure and can be manufactured by integral precision casting or additive manufacturing.

[0034] In summary, the beneficial effects of the present application are as follows: 1. It effectively reduces combustion chamber smoke without making major adjustments to the combustion chamber structure. This invention is particularly advantageous when measures are required to reduce exhaust smoke in in-service combustion chambers or in combustion chambers under development that have completed engineering design. 2. The present invention not only reduces combustion chamber smoke but also removes carbon deposits on the ends of centrifugal fuel nozzles. 3. The present invention is applicable not only to aircraft engines but also to land and marine gas turbines that burn liquid fuels.

[0035] Finally, it should be noted that the drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention. Other structures can refer to common designs. In the absence of conflicts, the same embodiment and different embodiments of the present invention can be combined with each other.

[0036] Finally: 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, improvements, etc. 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 swirler structure capable of reducing smoke in a combustion chamber, characterized in that: The invention comprises a centrifugal fuel nozzle (1), a swirler outer ring (3), a swirler inner ring (4) and swirler blades (5); the centrifugal fuel nozzle (1) is a cylindrical structure, the swirler outer ring (3) and the swirler inner ring (4) are coaxially arranged on the outside of the centrifugal fuel nozzle (1), and the swirler outer ring (3) is arranged on the outside of the swirler inner ring (4); the swirler blades (5) are in a plurality of groups and are integrally connected between the swirler outer ring (3) and the swirler inner ring (4); the centrifugal fuel nozzle (1) sprays fuel spray (2) at the center position; a deflection ring (6) is provided at the trailing edge of the centrifugal fuel nozzle (1), the deflection ring (6) is arranged corresponding to the position of the swirler blades (5), and the end of the deflection ring (6) is bent toward the center line of the centrifugal fuel nozzle (1), so that the air flowing out of the swirler is divided into two streams, inner and outer, by the deflection ring (6); The baffle ring (6) includes a connecting piece (12) and a guide ring (13); the guide ring (13) has an L-shaped cross section, an inner swirler channel (9) for inner air is formed between the guide ring (13) and the outer wall of the centrifugal fuel nozzle (1), and the inner air is guided by the L-shaped structure; the outer wall of the guide ring (13) and the external air form an outer swirler channel (8); the connecting piece (12) is in a plurality of groups and is integrally connected between the guide ring (13) and the outer wall of the centrifugal fuel nozzle (1); The equivalence ratio of the inner air flow deflected by the deflection ring (6) in the central area of ​​the downstream flame tube of the centrifugal fuel nozzle (1) is not greater than 1.3; the flow coefficient of the outer swirler channel (8) is 0.84-0.88, and the flow coefficient of the inner swirler channel (9) is 0.

58.

2. The swirler structure for reducing combustion chamber smoke according to claim 1, characterized in that: The end of the baffle ring (6) is provided with expansion grooves (7) evenly distributed in the circumferential direction.

3. The swirler structure capable of reducing combustion chamber smoke according to claim 1, characterized in that: The baffle ring (6) is designed as an integrated whole with the cyclone outer ring (3), the cyclone inner ring (4) and the cyclone blades (5), and is manufactured by integral precision casting or additive manufacturing.

4. The swirler structure capable of reducing combustion chamber smoke according to claim 1, characterized in that: The thickness t of the deflector ring (6) is the same as the thickness of the swirler blade (5), or is selected between 0.7 and 1.5 mm; when the spray cone angle α of the centrifugal fuel nozzle (1) is 70° to 110° and the rotation direction of the fuel is the same as the rotation direction of the internal air, the turning angle β at the end of the deflector ring (6) is usually taken as 90°.

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