A compound nozzle for an aeroengine combustion chamber

Abstract

This invention discloses a composite nozzle for an aero-engine combustion chamber, belonging to the field of aero-engine technology. The nozzle comprises, from the inside out, a lotus-shaped central blunt body, a swirler blade assembly, and a liquid film generator, arranged coaxially. An oil collecting ring is formed within the peripheral wall of the liquid film generator; the input end of the oil collecting ring is connected to the oil inlet pipe, and the output end is connected to the combustion chamber through a narrow slit in the liquid film. Multiple atomizing air holes are circumferentially formed on the peripheral wall at the outlet end of the liquid film generator. The swirler blade assembly consists of multiple axially swirling blades. The lotus-shaped central blunt body is cylindrical, with several cooling holes formed axially within it. Its outlet end has an expanding structure, forming a converging outlet with the inner wall of the liquid film generator outlet. Swirling air entering the liquid film generator through the swirler blade assembly flows into the combustion chamber through the converging outlet and the atomizing air holes. Air passing through the lotus-shaped central blunt body enters the combustion chamber through the cooling holes. This invention solves the problem of poor atomization in existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine technology, specifically relating to a composite nozzle for aero-engine combustion chambers. Background Technology

[0002] With the development of aero-engine technology, higher requirements have been placed on engine performance, such as better ignition performance, adaptability and stability under a wider range of operating conditions, and lower fuel consumption. The combustion chamber, as one of the core components of an aero-engine, is a crucial location for energy supply. Fuel is injected into the combustion chamber through nozzles and atomized under the action of high-speed airflow, forming a large number of fuel droplets. These droplets then rapidly mix with air, evaporate, and burn. Good atomization and mixing are the cornerstones of efficient combustion.

[0003] The most important performance indicators for aero-engine combustors are ignition performance, idle shut-off performance, and combustion efficiency. Ignition performance requires a wide ignition boundary to allow the engine to adapt to harsher environments. A greater number and smaller size of atomized droplets near the igniter facilitates ignition. Idle shut-off performance requires the combustor to remain lit during rapid throttle reduction. Smaller atomized droplet sizes result in a larger recirculation zone, and the presence of a localized rich-fuel zone acting as an ignition source makes shut-off more difficult under lean-fuel conditions at idle. Higher combustion efficiency leads to lower fuel consumption, resulting in longer flight distances. Finer atomized droplet sizes lead to faster evaporation and longer combustion duration, further enhancing combustion efficiency. Combustion chamber design also considers issues affecting combustor lifespan, such as nozzle coking and head carbon buildup. Closer flame proximity to the nozzle and inadequate cooling of the head injection unit can both contribute to nozzle coking and carbon buildup.

[0004] As the above analysis shows, the flow field, spray field, and combustion are three inseparable parts. Therefore, previous researchers proposed the concept of a composite nozzle, which designs the entire head unit as a composite nozzle, taking into account both the flow field and the spray field. The composite nozzle can generate the flow field pattern required for combustion, and also atomize the injected fuel using the incoming air as atomizing air. A classic design uses a centrifugal nozzle at the center, for example, by setting axial or radial swirlers around the nozzle. The fuel is sprayed from the nozzle in the form of a liquid cone, broken and atomized under the action of the swirling flow. The atomized droplets evaporate in the combustion chamber and mix with air along with the swirling flow. There are also multi-point injection schemes, which set multiple injection points at the head to ensure more uniform mixing.

[0005] However, as the design conditions of aero-engine combustors become increasingly demanding and performance requirements become more stringent, the aforementioned injection units are no longer suitable. Specifically, for the scheme using centrifugal nozzles at the center, under lower operating conditions, the reduced injection pressure and smaller cone angle result in a "pencil-shaped" appearance, failing to achieve good atomization. Secondly, installing centrifugal nozzles at the center of the injection unit, with a smaller cone angle, results in shallower radial penetration, leading to insufficient droplet quantity near the igniter, and the droplet size also fails to meet requirements, making it difficult to achieve satisfactory ignition performance. Furthermore, for multi-point injection systems, since there are multiple injection points on the nozzle, using centrifugal nozzles for all of them would require very complex anti-coking measures. Centrifugal nozzles are also very sensitive to injection pressure. Once the throttle lever is pulled down quickly, the injection pressure drops, atomization immediately deteriorates, and the problem of engine stalling due to lean fuel at low speeds becomes more serious. Therefore, most multi-point injection systems use direct-injection nozzles. However, due to the large penetration depth and poor atomization effect of direct-injection nozzles, under high operating conditions, the direct-injection liquid column may be sprayed onto the flame tube wall, causing fuel droplets to collide with the flame tube wall over a large area, resulting in carbon buildup at high temperatures, which leads to poor flame tube cooling and reduced combustion chamber life. Summary of the Invention

[0006] The technical problem to be solved:

[0007] To avoid the shortcomings of existing technologies, this invention provides a composite nozzle for the combustion chamber of an aero-engine, in which fuel is injected into the combustion chamber in the form of a large-scale annular rotating liquid film, which is more conducive to the atomization of the incoming high-speed air. Combined with the structure of the liquid film generator, air is ejected from different paths, forming two atomizations, which solves the problem of poor atomization effect in existing technologies.

[0008] The technical solution of the present invention is: a composite nozzle for the combustion chamber of an aero-engine, which is coaxially arranged from the inside to the outside with a lotus-shaped central blunt body, a swirler blade group and a liquid film generator, the two ends of the lotus-shaped central blunt body being flush with the two ends of the liquid film generator, and the swirler blade group being located at the air inlet end of the liquid film generator;

[0009] An oil collecting ring is formed inside the peripheral wall of the liquid film generator. The input end of the oil collecting ring is connected to the oil inlet pipe, and the output end is connected to the combustion chamber through a narrow liquid film slit located inside the peripheral wall of the liquid film generator outlet end. Multiple atomizing air holes are formed circumferentially on the peripheral wall of the liquid film generator outlet end.

[0010] The hydrocyclone blade assembly consists of multiple axial swirling blades, whose inner and outer peripheral surfaces are respectively connected to the inner wall surface of the liquid film generator and the outer peripheral surface of the lotus-shaped central blunt body.

[0011] The lotus-shaped central blunt body is cylindrical, with several cooling holes opened along the axial direction inside. The end located at the nozzle outlet has an expanding structure, forming a converging outlet between it and the inner wall of the liquid film generator outlet.

[0012] Swirling air enters the liquid film generator through the cyclone separator blade assembly and is then introduced into the combustion chamber through the convergent outlet and the atomizing air hole; air passing through the lotus-shaped central blunt body enters the combustion chamber through the cooling hole.

[0013] A further technical solution of the present invention is: the liquid film generator is a ring structure, the inner wall of its outlet end converges inward, and an annular liquid film slit is opened in the converging end to connect the oil collecting ring with the combustion chamber; a liquid film swirl baffle is provided in the liquid film slit, the liquid film swirl baffle is composed of multiple liquid film swirl baffles evenly distributed along the circumference, and a swirl channel is formed between adjacent liquid film swirl baffles, so that fuel is injected into the combustion chamber in the form of a rotating liquid film.

[0014] A further technical solution of the present invention is: an annular oil collecting ring is formed between the inner wall and the outer wall of the liquid film generator; the oil collecting ring is sealed to the annular end face of the inlet end of the liquid film generator by an annular front baffle, and to the annular end face of the outlet end of the liquid film generator by an annular rear baffle; an annular through groove, i.e., a liquid film slit, is opened in the circumferential direction inside the rear baffle, and the center surface of the liquid film slit is an inwardly converging conical surface.

[0015] A further technical solution of the present invention is: the upper and lower walls of the plurality of liquid film swirling baffles are respectively attached to the upper and lower walls of the liquid film narrow slit; both circumferential end walls are flat, and a swirling channel is formed between two adjacent liquid film swirling baffles.

[0016] A further technical solution of the present invention is: the expansion structure of the lotus-shaped central blunt body is a frustum-shaped blunt body head, the small diameter end of the frustum is connected to the cylindrical body of the lotus-shaped central blunt body and has the same diameter, and the large diameter end faces outward and is flush with the outlet end of the liquid film generator; a number of cooling holes are opened along the axial direction inside the lotus-shaped central blunt body, wherein the cooling holes penetrating the cylindrical body and the frustum-shaped blunt body head are divided into central cooling holes and peripheral cooling holes, wherein the cooling holes penetrating the outer edge of the frustum-shaped blunt body head are blunt body cooling holes.

[0017] A further technical solution of the present invention is as follows: the central cooling hole, the peripheral cooling hole, and the blunt body cooling hole of the lotus-shaped central blunt body are all straight holes of equal diameter, and the center line of the hole is consistent with the mainstream direction; the diameter of the central cooling hole is larger than the diameter of the peripheral cooling hole by 50% to 100%; the diameter of the peripheral cooling hole is larger than the diameter of the blunt body cooling hole by 10% to 20%.

[0018] A further technical solution of the present invention is: the central surface of the converging outlet formed between the inner wall of the liquid film generator outlet and the expansion section of the lotus-shaped central blunt body is an outwardly expanding cone surface with an expansion angle greater than 15°; the convergence angle of the liquid film slit is greater than 10°; the convergence angle of the liquid film slit and the expansion angle of the converging outlet are opposite in direction, and the convergence angle of the liquid film slit is 2-5° smaller than the expansion angle of the converging outlet.

[0019] A further technical solution of the present invention is that the angle between the centerline of the atomizing air hole and the centerline of the lotus-shaped central blunt body is equal to the expansion angle of the converging outlet; the angle between the line connecting the outlet center point of adjacent atomizing air holes and the array center of all atomizing air holes is 10~15°.

[0020] A further technical solution of the present invention is that: the effective flow area of ​​the oil inlet pipe is more than 1.5 times the effective flow area of ​​the swirl channel in the liquid film swirling baffle ring; the radial height of the oil collecting ring is 3 times the thickness of the liquid film slit.

[0021] A further technical solution of the present invention is that the swirl angle of the swirling channel is opposite in direction and equal in magnitude to the swirl angle of the axial swirling blade; the number of swirling channels is the same as the number of axial swirling blades, and they are evenly distributed along the circumference.

[0022] Beneficial effects

[0023] The beneficial effects of this invention are as follows:

[0024] 1. According to the composite nozzle structure for an aero-engine combustion chamber provided by the present invention, fuel is injected into the combustion chamber through a swirling channel 42 and a liquid film slit 351 in the form of a large-scale annular rotating liquid film (the diameter of the liquid film exceeds the outer diameter of the axial swirling blade 11), increasing the contact area with air and facilitating atomization with the high-speed incoming air. Furthermore, the incoming air is divided into two parts for two stages of atomization, ensuring efficient atomization under low injection pressure. Specifically, one part of the incoming air enters the atomization air hole 331 and undergoes the first atomization at the liquid film outlet, forcing radial shear deformation at local locations on the liquid film surface, resulting in perforation or cracks. The other part of the air forms a high-speed expanding swirling airflow through the converging outlet 5, performing a second atomization on the liquid film. The broken liquid film is subjected to tensile forces in the circumferential and axial directions, causing the perforations or cracks on the liquid film surface to further expand, ultimately leading to breakage and the generation of a large number of droplets. Because the injection point is close to the high-speed swirling air at the outlet, the broken droplets will quickly follow the high-speed swirling air and diffuse in the combustion chamber. Therefore, the influence of high-speed airflow dominates both fuel atomization and fuel-air mixing, and the distribution of the spray field is not sensitive to the injection pressure.

[0025] Based on this feature, even under low injection pressure, the atomized particle size can still meet the ignition requirements under idle conditions. Furthermore, the fuel is injected at the periphery of the compound nozzle, closer to the igniter. Combined with the optimized convergent outlet center cone expansion angle, the high-speed airflow direction at the outlet points directly to the igniter, which increases the number of fuel droplets near the igniter. This helps to expand the idle ignition boundary and further improve the idle ignition performance of the combustion chamber.

[0026] 2. According to the composite nozzle structure for an aero-engine combustion chamber provided by the present invention, since the converging outlet 5 is an expanding channel with an expansion angle greater than 10°, the swirling air, after passing through the outer wall of the lotus-shaped central blunt body 2 and the converging outlet 5, will form a recirculation zone with a large radial dimension in the combustion chamber. Furthermore, fuel is sprayed towards the front end of the recirculation zone in the form of an annular liquid film, and its corresponding position is located outside the recirculation zone where the axial velocity is comparable to the flame propagation speed, thus providing conditions for stable combustion. Therefore, once the fuel droplets are atomized, they can continuously supply fuel for combustion in this area.

[0027] Based on the above characteristics, when the throttle is reduced rapidly, the spray pattern distribution in the combustion chamber does not change significantly, and the atomization effect can still be guaranteed. In addition, the fuel droplets are rapidly supplied to the combustion area, ensuring stable operation of the combustion chamber, expanding the idle stall boundary, and effectively reducing the risk of idle lean stall in the combustion chamber.

[0028] Furthermore, under cruise conditions, compared to direct-fire nozzles, annular liquid films have poor penetration capabilities and are sprayed towards the combustion chamber axis, preventing them from directly impacting the flame tube wall and thus effectively preventing carbon buildup in the flame tube. Secondly, under the same operating conditions, the atomized liquid film produces finer droplets, and because it is directly injected into the stable combustion zone, the evaporation and combustion rates of the atomized droplets are increased, which is beneficial for improving combustion efficiency.

[0029] 3. According to the composite nozzle structure for the combustion chamber of an aero-engine provided by the present invention, the incoming air is ejected from the rear end face of the lotus-shaped central blunt body 2 in the form of a jet through the central cooling hole 211, multiple outer cooling holes 212 and blunt body cooling holes 221. On the one hand, it can cool the end face of the blunt body, and on the other hand, it pushes the recirculation zone in the combustion chamber away from the head by a small distance, which is conducive to the formation of a detached flame.

[0030] Based on the above characteristics, under any operating condition, the temperature of the central bluff body is reduced by convective heat transfer within the cooling holes, forming a detached flame that reduces the amount of radiation received by the entire composite nozzle. This keeps the entire combustion chamber head at a lower temperature, making it difficult for the fuel to reach the coking temperature when it passes through the head to the injection point. Therefore, it can effectively prevent coking of the combustion chamber nozzle and improve the combustion chamber life. Attached Figure Description

[0031] Figure 1 This is an exploded view of the composite nozzle according to an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of the hydrocyclone blade assembly according to an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of the structure of the lotus seedpod-shaped central blunt body in an embodiment of the present invention.

[0034] Figure 4 This is a front view of the liquid film generator according to an embodiment of the present invention.

[0035] Figure 5 for Figure 4 AA sectional view.

[0036] Figure 6 This is a schematic diagram of the liquid film swirling baffle structure in an embodiment of the present invention.

[0037] Figure 7 This is a front view of the structural assembly of the composite nozzle according to an embodiment of the present invention.

[0038] Figure 8 for Figure 7 AA sectional view.

[0039] Figure 9 for Figure 8 A schematic diagram of the center plane structure of the convergent exit.

[0040] Figure 10 This is a partial cross-sectional view of the structural assembly of the composite nozzle according to an embodiment of the present invention.

[0041] Figure 11 This is a schematic diagram illustrating the working process of the composite nozzle structure according to an embodiment of the present invention.

[0042] Explanation of reference numerals in the attached drawings: 1. Hydrocyclone blade assembly; 11. Axial swirling blade; 12. Hydrocyclone inner wall; 13. Hydrocyclone outer wall; 14. Hydrocyclone inlet wall; 2. Lotus-shaped central blunt body; 21. Rod core; 211. Central cooling hole; 212. Peripheral cooling hole; 22. Blunt body head; 221. Blunt body cooling hole; 3. Liquid film generator; 31. Oil inlet pipe; 32. Liquid film generator outer wall; 33. Liquid film generator inner wall; 331. Atomizing air hole; 332. Front inner wall; 34. Front baffle; 35. Rear baffle 351. Liquid film slit; 352. Front wall of rear baffle; 36. Oil collecting ring; 4. Liquid film swirl baffle ring; 41. Liquid film swirl baffle; 411. Upper wall of swirl baffle; 412. Lower wall of swirl baffle; 413. Circumferential front wall; 414. Circumferential rear wall; 415. Axial front wall of swirl baffle; 42. Swirl channel; 5. Converging outlet; 51. Center surface; 6. Combustion chamber; 7. High-speed swirling air; 71. Airflow around the recirculation zone; 72. Airflow in the center of the recirculation zone; 8. Annular liquid film; 9. Droplet cluster; 10. Igniter. Detailed Implementation

[0043] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0044] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0045] To address the poor atomization effect of existing aero-engine combustion chamber nozzle designs, this invention provides a composite nozzle. From the inside out, it coaxially comprises a lotus-shaped central blunt body, a swirler blade assembly, and a liquid film generator. The two ends of the lotus-shaped central blunt body are flush with the two ends of the liquid film generator. The swirler blade assembly is located at the air inlet end of the liquid film generator. An oil collecting ring is formed within the peripheral wall of the liquid film generator. The input end of the oil collecting ring is connected to the oil inlet pipe, and the output end is connected to the combustion chamber through a narrow liquid film slit located within the peripheral wall of the liquid film generator's outlet end. Furthermore, at the outlet end of the liquid film generator… Multiple atomizing air holes are circumferentially opened on the peripheral wall; the cyclone separator blade assembly consists of multiple axially swirling blades, whose inner and outer circumferential surfaces are respectively connected to the inner wall surface of the liquid film generator and the outer circumferential surface of the lotus-shaped central blunt body; the lotus-shaped central blunt body is cylindrical, with several cooling holes axially opened inside, and its end at the nozzle outlet is an expanding structure, forming a converging outlet between it and the inner wall of the liquid film generator outlet; the swirling air entering the liquid film generator through the cyclone separator blade assembly is introduced into the combustion chamber through the converging outlet and the atomizing air holes; the air passing through the lotus-shaped central blunt body enters the combustion chamber through the cooling holes.

[0046] The fuel of this invention is injected into the combustion chamber in the form of a large-scale annular rotating liquid film, which is more conducive to the atomization of the incoming high-speed air. Combined with the liquid film generator mechanism, the air is sprayed out from different paths, forming two atomizations, which solves the problem of poor atomization effect in the prior art.

[0047] The above technical solution will be further explained below with reference to the accompanying drawings:

[0048] Reference Figure 1 As shown, this embodiment presents a composite nozzle structure for an aero-engine combustion chamber, comprising a swirler blade assembly 1, a lotus-shaped central blunt body 2, a liquid film generator 3, and a liquid film swirling baffle ring 4.

[0049] Reference Figure 2-6As shown, the hydrocyclone blade assembly 1 consists of multiple axial swirling blades 11. The inner wall surface 12 and the outer wall surface 13 of the hydrocyclone are both part of a cylindrical surface, and the inlet wall surface 14 of the hydrocyclone is part of a plane. The lotus-shaped central blunt body 2 consists of a rod core 21 and a blunt body head 22. The rod core 21 is a cylinder, and the blunt body head 22 is a hollow frustum. The rod core 21 has a central cooling hole 211 located at the center of the cylinder and several rings of peripheral cooling holes 212. The blunt body head 22 has several rings of blunt body cooling holes 221. The liquid film generator 3 consists of an oil inlet pipe 31, an outer wall surface 32 of the liquid film generator, an inner wall surface 33 of the liquid film generator, a front baffle 34, and a rear baffle 35. The outer wall surface 32 of the liquid film generator, the inner wall surface 33 of the liquid film generator, and the front baffle 35 are also present. An oil collecting ring 36 is formed between the rear baffle 35 and the oil inlet pipe 31. The oil inlet pipe 31 is inserted into the outer wall surface 32 of the liquid film generator and connected to the oil collecting ring 36. An annular liquid film slit 351 is opened in the rear baffle 35. The liquid film slit 351 penetrates the rear baffle 35 and is connected to the oil collecting ring. A ring of multiple atomizing air holes 331 is opened downstream of the inner wall surface 33 of the liquid film generator. The atomizing air holes 331 penetrate the inner wall surface 33 of the liquid film generator. The liquid film swirl baffle ring 4 is composed of multiple liquid film swirl baffles 41. The upper wall surface 411 and the lower wall surface 412 of the swirl baffle 41 can respectively fit the upper and lower walls of the liquid film slit 351. A swirl channel 42 is formed between the circumferential front wall surface 413 and the circumferential rear wall surface 414 of the liquid film swirl baffle 41.

[0050] Reference Figure 7-9 As shown, the hydrocyclone blade assembly 1 is fixedly sleeved on the rod core 21 of the lotus-shaped central blunt body 2. The outer wall surface 13 of the hydrocyclone is fixedly connected to the inner wall surface of the liquid film generator 3. The inlet wall surface 14 of the hydrocyclone, the front wall surface of the rod core 21 and the front wall surface of the front baffle 34 of the liquid film generator are flush. The liquid film swirling baffle ring 4 is embedded in the liquid film slit 351. The axial front wall surface 415 of the swirling baffle is flush with the front wall surface 352 of the rear baffle 35. The inner wall surface 33 of the liquid film generator and the blunt head 22 of the lotus-shaped central blunt body 2 form a converging outlet 5. The central plane of the converging outlet 5 is an expanding cone surface.

[0051] Specifically, the central cooling hole 211, the peripheral cooling hole 212, and the blunt body cooling hole 221 of the lotus-shaped central blunt body 2 are all straight holes, with the center line of the hole aligned with the mainstream direction. The diameter of the central cooling hole 211 of the lotus-shaped central blunt body 2 is larger than that of the peripheral cooling hole by 50% to 100%, and the diameter of the peripheral cooling hole 212 is larger than that of the blunt body cooling hole 221 by 10% to 20%. This is because the oxygen content of the gas flowing back to the head is lower and the temperature is higher closer to the center, and the larger the cooling hole closer to the center, the better the afterburning effect and the better the cooling effect on the central area.

[0052] Specifically, the angle between the generatrix of the center plane of the liquid film slit and the center line of the lotus-shaped central blunt body 2 should be greater than 10°. This angle is also called the convergence angle of the liquid film slit. The angle between the generatrix of the center plane 51 of the converging outlet 5 and the center line of the lotus-shaped central blunt body 2 should be greater than 15°. This angle is also called the expansion angle of the converging outlet 5. It should be noted that the convergence angle of the liquid film slit and the expansion angle of the converging outlet 5 are opposite in direction. The purpose is to make the outflowing liquid film directly impact the surface of the high-speed airflow at the outlet, thereby increasing the aerodynamic shearing effect of liquid film breakup. The convergence angle of the liquid film slit is 2~5° smaller than the expansion angle of the converging outlet 5. This is because the airflow will undergo a sudden expansion process after entering the combustion chamber from the narrow head space, and the angle of the airflow will be larger. In order to adapt to this change in angle, it is necessary to reduce the convergence angle of the liquid film slit.

[0053] Specifically, the angle between the centerline of the atomizing air hole 331 and the centerline of the lotus-shaped blunt body 2 is equal to the expansion angle of the converging outlet 5. This is to prevent the atomizing air from being immediately carried away by the high-speed swirling air at the outlet, and also to enhance the breaking of the liquid film ejected from the narrow slit of the liquid film.

[0054] Specifically, the angle between the outlet center point of two adjacent atomizing air holes 331 and the line connecting the array center of all atomizing air holes 331 is 10~15°. The reason for this design is that too large an angle will cause the liquid film to break up unevenly, resulting in uneven circumferential distribution of fuel in the combustion chamber, which will affect the outlet temperature distribution; while too small an angle will cause insufficient strength of the inner wall surface 33 of the liquid film generator near the atomizing air holes 331.

[0055] Specifically, the effective flow area of ​​the oil inlet pipe 31 is more than 1.5 times the effective flow area of ​​the swirl channel 42 in the liquid film swirl baffle ring 4, and the height of the oil collecting ring 36 is more than 3 times the thickness of the liquid film slit 351. This is to allow the fuel to become congested when entering the liquid film slit, thereby filling the entire oil collecting ring.

[0056] Specifically, the swirl angle of the swirl channel 42 in the liquid film swirl baffle ring 4 is opposite in direction and equal in size to the swirl angle of the axial swirl blade 11. The purpose is to increase the circumferential relative velocity between the annular liquid film 8 and the outlet high-speed airflow, thereby increasing the local Weber number, enhancing the aerodynamic shear force, and making the liquid film easier to atomize.

[0057] Working principle:

[0058] The working principle of the composite nozzle structure provided in this embodiment is as follows: Figure 10-11 As shown, the composite nozzle of this embodiment is installed on the front flange of the combustion chamber, the front flange of the combustion chamber is connected to the flame tube, and an igniter 10 is installed on the flame tube.

[0059] The incoming air first enters the blade channel in the cyclone blade assembly 1, the central cooling hole 211 and the peripheral cooling hole 212 of the lotus-shaped central blunt body 2. Most of the airflow flowing through the blade channel in the cyclone blade assembly 1 flows into the combustion chamber from the converging outlet 5. A portion flows into the combustion chamber through the atomizing air hole 331 of the liquid film generator 3 and the blunt body cooling hole 221 of the lotus-shaped central blunt body 2. The airflow passing through the central cooling hole 211 and the peripheral cooling hole 212 of the lotus-shaped central blunt body 2 directly enters the combustion chamber. The fuel enters the oil collecting ring 36 through the fuel inlet pipe 31, and then enters the liquid film narrow slit 351 through multiple swirl channels 42 on the liquid film swirl baffle ring 4. Finally, it is injected into the combustion chamber 6 in the form of an annular liquid film 8.

[0060] The incoming high-speed airflow flows out through the converging outlet 5 to form a high-speed swirling airflow 7. After the annular liquid film 8 is ejected from the narrow slit 351, it is subjected to the action of the outflowing air in the atomizing air hole 331 and undergoes the first breakage at the liquid film outlet. This forces radial shear deformation to occur in a localized area on the surface of the liquid film 8, resulting in perforation or cracks on the surface of the annular liquid film 8. Then, under the action of the high-speed swirling airflow 7, the liquid film is further broken up. The liquid film is subjected to circumferential and axial tensile forces, causing the perforations or cracks on the surface of the liquid film to expand further, and finally atomization is completed, producing a group of droplets 9.

[0061] Because the injection point is not the center of the conventional combustion chamber, it is closer to the edge of the recirculation zone. The broken droplet group 9 will spread rapidly in the combustion chamber 6 with the central airflow 72 of the recirculation zone. Since the airflow speed at the periphery of the recirculation zone is low, it meets the conditions for flame stability, and the flame often stays there. Therefore, the droplet group 9 will evaporate and burn faster. This phenomenon is like "adding fuel to the fire": once the fuel droplets are atomized, they continuously supply fuel to the airflow in this area for combustion, which is beneficial to improving combustion efficiency and flame stability. In addition, unlike the conventional combustion chamber, the central surface 51 of the converging outlet 5 is an expanding cone. Therefore, the high-speed swirling air 7 will obtain a higher radial velocity after exiting, and the recirculation zone is wider. The droplet group 9 can be easily carried to the igniter position, which is beneficial to improving ignition performance.

[0062] As can be seen from the above, whether it is fuel atomization, fuel-air mixing, fuel evaporation or diffusion, the influence of high-speed airflow is dominant, so the distribution of the spray field is not sensitive to the injection pressure.

[0063] According to the composite nozzle structure provided in the embodiment of the present invention, the incoming air is directly injected into the combustion chamber through the central cooling hole 211, the peripheral cooling hole 212 and the blunt body cooling hole 221. On the one hand, it can be used to cool the blunt body head 22 and remove the heat inside the lotus-shaped central blunt body 2. On the other hand, the outflowing air from these cooling holes directly rushes towards the head of the recirculation zone, which can push the recirculation zone downstream, so that a gap is formed between the recirculation zone and the head, which is conducive to the formation of a detached flame and can effectively prevent fuel coking. In addition, for the liquid film generator 3, since the fuel fills the entire oil collecting ring 36 and the liquid film slit 351, the fuel can be used as a cold source to cool the liquid film generator 3. On the other hand, the fuel is heated and injected into the combustion chamber 6, which is also conducive to the rapid evaporation and combustion of fuel in the combustion chamber 6.

[0064] Example:

[0065] The specific dimensions of the gas turbine combustion chamber head injection unit structure in this embodiment are as follows:

[0066] Based on the parameters provided by the overall department, the outer diameter of the composite nozzle is determined to be 50mm and the total length is 30mm.

[0067] The swirl angle of the axial swirling blades is 35°, the diameter of the outer wall of the axial swirling blade assembly is 36 mm, the axial length of the axial swirling blades is 14.32 mm, the thickness is 1.56 mm, and the number of swirling blades is 12.

[0068] The core 21 of the lotus-shaped central blunt body 2 has a diameter of 14mm and a length of 30mm. The blunt head 22 has a cone angle of 134° and a length of 4.4mm. The blunt head 22 can be fitted and fixed to the surface of the core. Its interior is a hollow cylindrical surface with a diameter of 14mm. The central cooling hole 211 inside the lotus-shaped central blunt body 2 has a diameter of 1mm. There are three rings of outer cooling holes 212. The number of holes in each ring from the inside out in the core 21 are 8, 16, and 32, respectively, and they are evenly distributed in each ring. The radial spacing between each ring is 1.7 mm, and the diameter of the outer cooling holes 212 is 0.6 mm. There are two rings of blunt body cooling holes 221, each ring containing 36 holes, evenly distributed circumferentially. The radial spacing between the two rings is 1.6 mm, and the diameter of each hole is 0.5 mm. The radial spacing between the first layer of outer cooling holes 212 and the center cooling hole 211 from the inside out is 2 mm, and the radial spacing between the first layer of blunt body cooling holes 221 and the third layer of outer cooling holes 212 from the inside out is 2.2 mm.

[0069] The front baffle 34 of the liquid film generator 3 has an axial length of 3 mm, the rear baffle 35 has an axial length of 7 mm, the oil inlet pipe 31 has an outer diameter of 5 mm, an inner diameter of 3 mm, and an effective flow area of ​​7.07 mm². 2The outer wall diameter of the oil collecting ring 36 is 45mm, the inner wall diameter is 41mm, the length of the oil collecting ring 36 is 20mm, the thickness of the liquid film slit 351 is 0.5mm, the height of the oil collecting ring 36 is 4 times the thickness of the liquid film slit 351, the upper wall diameter of the upstream end face of the liquid film slit 351 is 43.5mm, the angle between the generatrix of the center face of the liquid film slit and the center line of the lotus-shaped central blunt body 2 is 30°, the angle between the center line of the atomizing air hole 331 and the center line of the liquid film generator 3 is 35°, the diameter of the atomizing air hole 331 is 0.5mm, the axial distance between the starting position center and the downstream end face of the liquid film generator 3 is 3.4mm, there are 36 atomizing air holes in a circle, and the angle between the line connecting the outlet center point of two adjacent atomizing air holes 331 and the array center of all atomizing air holes 331 is 10°.

[0070] The liquid film swirl baffle 4 consists of 12 liquid film swirl baffles 41. The upper wall surface 411 and lower wall surface 412 of each baffle 41 can be fitted against the upper and lower walls of the liquid film slit 351. The axial length of each baffle 41 is 1.5 mm. A swirl channel 42 is formed between the circumferential front wall surface 413 and circumferential rear wall surface 414 of each baffle 41. The height of the swirl channel 42 is 1.3 mm, the swirl angle is 35°, and the direction is opposite to the swirl angle direction of the hydrocyclone blades. The effective flow area of ​​the swirl channel 42 is 4.47 mm². 2 The effective flow area of ​​the oil inlet pipe 31 is 1.58 times that of the swirl channel 42.

[0071] The expansion angle of the converging outlet 5 and the angle between the centerline of the atomizing air hole 331 and the centerline of the liquid film generator 3 are equal, both being 35°.

[0072] Based on the above, an embodiment of the present invention can be determined. It is worth noting that this embodiment adopts all the preferred parameter schemes of the present invention.

[0073] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A composite nozzle for an aircraft engine combustion chamber, characterized in that: From the inside out, a lotus-shaped central blunt body, a cyclone separator blade assembly, and a liquid film generator are coaxially arranged. The two ends of the lotus-shaped central blunt body are flush with the two ends of the liquid film generator, and the cyclone separator blade assembly is located at the air inlet end of the liquid film generator. The liquid film generator has an oil collecting ring inside its peripheral wall. The input end of the oil collecting ring is connected to the oil inlet pipe, and the output end is connected to the combustion chamber through a narrow liquid film slit located inside the peripheral wall of the liquid film generator's outlet end. Multiple atomizing air holes are opened circumferentially on the peripheral wall at the outlet end of the liquid film generator; The hydrocyclone blade assembly consists of multiple axial swirling blades, whose inner and outer peripheral surfaces are respectively connected to the inner wall surface of the liquid film generator and the outer peripheral surface of the lotus-shaped central blunt body. The lotus-shaped central blunt body is cylindrical, with several cooling holes opened along the axial direction inside. The end located at the nozzle outlet has an expanding structure, forming a converging outlet between it and the inner wall of the liquid film generator outlet. Swirling air enters the liquid film generator through the cyclone separator blade assembly and is then introduced into the combustion chamber through the convergent outlet and the atomizing air hole. Air passing through the lotus-shaped central blunt body enters the combustion chamber through cooling holes.

2. The composite nozzle for an aero-engine combustion chamber according to claim 1, characterized in that: The liquid film generator has a circular structure with its inner wall at the outlet end converging inward. An annular liquid film slit is opened in the converging end to connect the oil collecting ring with the combustion chamber. A liquid film swirl baffle is provided in the liquid film slit. The liquid film swirl baffle is composed of multiple liquid film swirl baffles evenly distributed along the circumference. Swirl channels are formed between adjacent liquid film swirl baffles, so that fuel is injected into the combustion chamber in the form of a rotating liquid film.

3. A composite nozzle for an aircraft engine combustion chamber according to claim 2, characterized in that: The inner and outer walls of the liquid film generator are connected by an annular oil collecting ring. The oil collecting ring is sealed to the annular end face of the liquid film generator inlet by an annular front baffle and to the annular end face of the liquid film generator outlet by an annular rear baffle. The rear baffle has an annular through groove, i.e., a liquid film slit, circumferentially opened in the inner side. The center surface of the liquid film slit is an inwardly converging conical surface.

4. A composite nozzle for an aero-engine combustion chamber according to claim 3, characterized in that: The upper and lower walls of multiple liquid film swirl baffles are respectively attached to the upper and lower walls of the liquid film narrow slit; Both of its circumferential end walls are flat, and a swirling channel is formed between two adjacent liquid film swirling baffles.

5. A composite nozzle for an aero-engine combustion chamber according to claim 2, characterized in that: The effective flow area of ​​the oil inlet pipe is more than 1.5 times the effective flow area of ​​the swirl channel in the liquid film swirling baffle ring; the radial height of the oil collecting ring is 3 times the thickness of the liquid film slit.

6. A composite nozzle for an aircraft engine combustion chamber according to claim 1, characterized in that: The expanded structure of the lotus-shaped central blunt body is a frustum-shaped blunt body head. The small-diameter end of the frustum is connected to the cylindrical body of the lotus-shaped central blunt body and has the same diameter. The large-diameter end faces outward and is flush with the outlet end of the liquid film generator. Several cooling holes are opened along the axial direction inside the lotus-shaped central blunt body. The cooling holes that penetrate the cylindrical body and the frustum-shaped blunt body head are divided into central cooling holes and peripheral cooling holes. The cooling holes that penetrate the outer edge of the frustum-shaped blunt body head are blunt body cooling holes.

7. A composite nozzle for an aero-engine combustion chamber according to claim 6, characterized in that: The central cooling hole, peripheral cooling hole, and blunt body cooling hole of the lotus-shaped central blunt body are all straight holes of equal diameter, and the center line of the hole is consistent with the mainstream direction; the diameter of the central cooling hole is larger than the diameter of the peripheral cooling hole by 50% to 100%; the diameter of the peripheral cooling hole is larger than the diameter of the blunt body cooling hole by 10% to 20%.

8. A composite nozzle for an aero-engine combustion chamber according to claim 1, characterized in that: The central surface of the converging outlet formed between the inner wall of the liquid film generator outlet and the expanding section of the lotus-shaped central blunt body is an outwardly expanding cone with an expansion angle greater than 15°; the convergence angle of the liquid film slit is greater than 10°; the convergence angle of the liquid film slit and the expansion angle of the converging outlet are opposite in direction, and the convergence angle of the liquid film slit is 2-5° smaller than the expansion angle of the converging outlet.

9. A composite nozzle for an aircraft engine combustion chamber according to claim 1, characterized in that: The angle between the centerline of the atomizing air hole and the centerline of the lotus-shaped central blunt body is equal to the expansion angle of the converging outlet; the angle between the line connecting the outlet center point of an adjacent atomizing air hole and the array center of all atomizing air holes is 10~15°.

10. A composite nozzle for an aircraft engine combustion chamber according to claim 4, characterized in that: The swirl angle of the swirling channel is opposite in direction and equal in magnitude to that of the axial swirling blade; the number of swirling channels is the same as the number of axial swirling blades, and they are evenly distributed circumferentially.

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