An integrated afterburner for supercritical kerosene supply, flame stabilization, and cooling

Abstract

This invention discloses an integrated afterburner based on supercritical kerosene, incorporating fuel supply, flame stabilization, and cooling. It comprises an afterburner, an outer bypass duct wall, fuel supply pipes, valves, relay nozzles, injection rods, a wall stabilizer, a center cone, multi-stage turbine blades, a rectifier support plate, injection orifices, a cavity vortex stabilizer, a regenerative cooling system, cooling oil pipes, cooling air pipes, film cooling orifices, a heat exchanger, and an electric nozzle. Fuel is supplied in sections via the injection rods to meet varying afterburner ratio requirements. Regenerative cooling lowers the wall temperature while raising the kerosene temperature to a supercritical state for external injection, reducing flow resistance losses and improving mixing and combustion efficiency. Fuel and air are mixed on both sides of the rectifier support plate's outer wall, with combustion taking place at the rear end. The cavity vortex stabilizer ensures stable and reliable flame during shifts. The rectifier support plate integrates fuel supply, flame stabilization, and cooling systems, improving space utilization and engine cruise economy.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to an integrated afterburner based on supercritical kerosene for fuel supply, flame stabilization, and cooling. Background Technology

[0002] An afterburner enables an aero engine to deliver maximum thrust in a short time, meeting the operational requirements of fighter jets for takeoff, climb, and pursuit, and enhancing aircraft maneuverability. The afterburner is typically located between the turbine and the exhaust nozzle and consists of components such as a mixture / diffuser, flame stabilizer, fuel supply system, and ignition system. Its working principle involves injecting fuel and burning it again after the turbine, significantly increasing the temperature and exhaust velocity of the combustion gases, thereby increasing the engine's specific thrust and total thrust. When a turbojet engine engages its afterburner, the total thrust can increase by 50%; for turbofan engines, it can increase by 70%, and even more than 150% under supersonic conditions.

[0003] Existing afterburner technology faces three main challenges. First, significant flow resistance loss. Since the afterburner operates only for a limited time, such as during takeoff and pursuit, it remains in a non-ignition state for most of the engine's operation. The internal fuel injectors and flame stabilizers contribute to substantial flow resistance loss, reducing fuel economy during cruise. Second, low combustion efficiency. This is due to the low total inlet pressure of the afterburner, sometimes below 0.1 MPa; high inlet air velocity, reaching 350–450 m / s; and an oxygen content in the intake air not exceeding 12%. These factors all negatively impact combustion, leading to a significant reduction in efficiency. Third, the combustion gas temperature increases further after afterburning, far exceeding the temperature that the combustion chamber materials can withstand. Therefore, an efficient cooling system must be designed for the afterburner.

[0004] Supercritical kerosene possesses both the high energy density of liquid aviation kerosene and a diffusion coefficient and viscosity close to that of gaseous fuels. Theoretically, supercritical kerosene has advantages such as easier ignition, faster mixing with air, and higher combustion efficiency. Currently, supercritical combustion of kerosene is widely used in rocket engines, but its application in aero engines is still in the laboratory stage. Moreover, current research on supercritical kerosene combustion in aero engines is limited to the main combustion chamber and does not include research on afterburners.

[0005] In summary, given the performance requirements of afterburners with wide speed range, high atmospheric range, and high heat load, there is an urgent need to develop an integrated afterburner design scheme that combines fuel supply, flame stabilization, and cooling, resulting in low flow resistance loss and high combustion efficiency. Summary of the Invention

[0006] This invention provides a design scheme for an integrated afterburner based on supercritical kerosene, which integrates fuel supply, flame stabilization and cooling, and meets the design requirements of a high total pressure recovery coefficient when the afterburner is closed and high combustion efficiency when it is open.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: an integrated afterburner based on supercritical kerosene for fuel supply, flame stabilization, and cooling. This integrated afterburner comprises an afterburner, an outer bypass wall, a fuel supply pipe, valves, a relay nozzle, an injection rod, a wall stabilizer, a center cone, multi-stage turbine blades, a rectifier support plate, injection holes, a concave cavity vortex stabilizer, a regenerative cooling system, cooling oil pipes, cooling air pipes, film gas holes, a heat exchanger, and an electric nozzle. The integrated afterburner based on supercritical kerosene for fuel supply, flame stabilization, and cooling is placed inside the outer bypass wall and fixed to ensure its correct orientation. The rectifier support plate integrates the fuel supply, flame stabilization, and cooling systems; the rectifier support plate must be streamlined to optimize the air and fuel flow paths. The fuel supply system consists of a fuel supply pipe, valves, a relay nozzle, an injection rod, and the rectifier support plate. Valves are installed in multiple fuel supply lines, which are vertically mounted at the front end of the inner wall of the outer bypass duct. The ends of the fuel supply lines are used as relay nozzles, distributed before, after, and between the multi-stage turbine blades. The valves are normally closed to ensure the relay nozzles operate under appropriate conditions. Multiple injection rods are obliquely arranged in the rectifier support plate behind the multi-stage turbine blades, extending to the vicinity of the vortex stabilizer in the concave cavity on the central cone. The injection rods employ an independent modular design, with independent fuel supply to each zone to meet the variable afterburner ratio requirements. Injection holes are evenly distributed on the injection rods. The wall stabilizer is fixed between the injection rods and the outer bypass duct wall. The cooling system consists of the rectifier support plate, regenerative cooling system, cooling oil pipes, cooling air pipes, film cooling holes, and a heat exchanger assembly. Two coiled regenerative cooling pipes are located within the rectifier support plate wall: the cooling oil pipe on the inner wall and the cooling air pipe on the outer wall. These, along with the film cooling holes and heat exchangers, form a film cooling and regenerative cooling system. Fuel injection holes on the injectors are evenly distributed on the outer wall of the rectifier support plate, while small-sized film cooling holes are evenly distributed on the remaining surfaces. The heat exchanger is fixed in the middle and rear sections of the rectifier support plate. Heat exchange tubes are coiled between the heat exchanger, fuel supply pipe, and cooling supply pipe to ensure sufficient heat exchange. The flame stabilization system consists of a wall-mounted stabilizer, a center cone, the rectifier support plate, and a cavity vortex stabilizer. A cavity, i.e., a cavity vortex stabilizer, is formed on the center cone in the same vertical direction as the injectors. Fuel is injected from the injectors, and a small amount of cooling air is ejected through the film cooling holes between the multiple injectors. An electric nozzle is fixed at the fuel injection and air junction for stable ignition. The wall-mounted stabilizer is fixed between the rectifier support plate and the outer bypass wall. Small-sized film cooling holes are evenly distributed on the outer wall of the wall-mounted stabilizer, and cooling air introduced from the outer bypass gas flows through the stabilizer into the interior of the rectifier support plate.

[0008] The fuel injectors are arranged inside the rectifier support plate, forming a recirculation zone on the rear wall of the streamlined rectifier support plate. Fuel and combustion gases are mixed on both sides of the outer wall of the rectifier support plate before combustion occurs at the rear. The radial stabilizer, wall stabilizer, and cavity vortex stabilizer are integrated and coupled. Multiple fuel injectors are arranged inside the rectifier support plate, and fuel is supplied through the side walls via the fuel injectors to meet the variable afterburner ratio requirements during afterburner operation. Kerosene heated by a heat exchanger is regenerated and cooled on the flame stabilizer wall, lowering the stabilizer wall temperature while further raising the kerosene temperature to a supercritical state before being injected outwards. This reduces flow resistance loss and improves mixing and combustion efficiency. The regenerated cooling oil pipe channel is located inside the cooling air pipe, avoiding direct contact between fuel and the hot wall, effectively inhibiting coking. Simultaneously, the introduced bypass air radially enters the rectifier support plate. Most of the air cools the fuel injector rods and then seeps out through the film cooling holes on the outer and rear end walls of the support plate, completing the cooling of the rectifier support plate. A small portion of the air enters the concave cavity vortex stabilizer, cooling the cavity structure while ensuring the stability and reliability of the on-duty flame. The wall-mounted stabilizer has openings in its inner wall, similarly introducing bypass air into the gaps in the outer wall of the wall-mounted stabilizer, which then seeps out through the film cooling holes on the inner wall to achieve a cooling effect. At lower flight speeds of Mach 3.5 and below, a combined cooling method, namely film cooling and regenerative cooling, is used; at higher flight speeds of Mach 5.0 and above, regenerative cooling of kerosene is mainly relied upon.

[0009] The rectifier support plate integrates the fuel supply, flame stabilization and cooling systems.

[0010] The valve is normally closed to ensure that the relay nozzle can ignite the relay hot jet under the condition of high-altitude flameout, thus ensuring stable and reliable ignition and flame.

[0011] Multiple fuel injectors are arranged inside the rectifier support plate. Fuel is supplied through the fuel injectors of the rectifier support plate via the side wall partitions to meet the variable afterburner ratio requirements when the afterburner is working.

[0012] The regenerated cooling kerosene is heated by a heat exchanger and then regenerated and cooled on the wall of the flame stabilizer. While reducing the temperature of the stabilizer wall, the temperature of the kerosene is further increased to a supercritical state before being sprayed outward, reducing flow resistance loss and improving the mixing effect and combustion efficiency.

[0013] The central cone has a recessed cavity structure, which cools the cavity structure while ensuring the stability and reliability of the flame during duty.

[0014] The cooling scheme is as follows: at lower flight speeds of less than or equal to 3.5 Ma, a combined cooling method is used, namely film cooling and regenerative cooling; at higher flight speeds of greater than or equal to 5.0 Ma, regenerative cooling of kerosene is the primary method.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] First, this invention innovatively adopts an integrated design that combines the fuel injector, fairing plate, and flame stabilizer into a single component, while also coupling the radial stabilizer, wall stabilizer, and concave cavity vortex stabilizer in a unified manner. This improves space utilization, reduces congestion, effectively minimizes flow resistance loss, increases the total pressure recovery coefficient, and enhances the engine's fuel economy during cruise.

[0017] Second, this invention innovatively utilizes regenerative cooling and a heat exchanger to heat kerosene to a supercritical state, making it easier to ignite and mix, thus improving combustion efficiency, reducing reliance on flame stabilizers, and consequently reducing the size of the stabilizer. This further reduces flow resistance losses while simultaneously reducing the weight of the aero-engine.

[0018] Third, addressing the thermal protection issues of integrated flame stabilizers, an innovative approach is adopted: based on film cooling, kerosene is used for regenerative cooling of the stabilizer wall. This reduces the stabilizer wall temperature while simultaneously preheating the kerosene to a supercritical state. This enhances kerosene combustion efficiency and stability, improves the combustion efficiency of the afterburner, and reduces the ignition and shutdown fuel-air ratios, thereby increasing the thermal efficiency and thrust-to-weight ratio of the aero-engine.

[0019] Fourth, by utilizing film cooling, regenerative cooling, and heat exchanger structure, coking is effectively suppressed. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a design scheme for an integrated afterburner based on supercritical kerosene, which combines fuel supply, flame stabilization, and cooling.

[0021] Figure 2 This is a schematic diagram of the integrated structure of fuel injection, flame stabilization and cooling in this invention.

[0022] Figure 3 This is a schematic diagram of the concave cavity flame stabilization structure in this invention.

[0023] Figure 4 This is a schematic diagram of the independent modular design of the fuel injector in this invention.

[0024] Figure 5 This is a schematic diagram of the rectifier support plate design in this invention.

[0025] Figure 6 This is a schematic diagram of the wall-mounted stabilizer design in this invention.

[0026] The components include: 1. Afterburner; 2. Outer bypass wall; 3. Fuel supply pipe; 4. Valve; 5. Relay nozzle; 6. Injection rod; 7. Wall stabilizer; 8. Center cone; 9. Multi-stage turbine blades; 10. Rectifier support plate; 11. Injection hole; 12. Cavity vortex stabilizer; 13. Regenerative cooling system; 14. Cooling oil pipe; 15. Cooling air pipe; 16. Film cooling hole; 17. Heat exchanger; 18. Electric nozzle. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] This invention relates to an integrated afterburner based on supercritical kerosene, which combines fuel supply, flame stabilization, and cooling. Figure 1 and Figure 2 As shown, it includes: an afterburner chamber 1, an outer bypass wall 2, a fuel supply pipe 3, a valve 4, a relay nozzle 5, an injection rod 6, a wall stabilizer 7, a center cone 8, multi-stage turbine blades 9, a rectifier support plate 10, an injection hole 11, a concave cavity vortex stabilizer 12, a regenerative cooling system 13, a cooling oil pipe 14, a cooling air pipe 15, a film gas hole 16, a heat exchanger 17, and an electric nozzle 18.

[0029] See Figure 1 This invention presents a schematic diagram of a supercritical kerosene-based integrated afterburner for fuel supply, flame stabilization, and cooling. The integrated afterburner 1 is placed inside the outer bypass wall 2 and fixed in place to ensure correct orientation. A streamlined support plate 10 integrates the fuel supply, flame stabilization, and cooling systems to optimize air and fuel flow paths. The fuel supply system consists of fuel supply pipes 3, valves 4, relay nozzles 5, injection rods 6, and the streamlined support plate 10. Valves 4 are installed in multiple fuel supply pipes 3, which are vertically installed at the front end of the inner wall of the outer bypass wall 2. The end of the fuel supply pipes 3 is the relay nozzle 5, which is distributed before, after, and between the multi-stage turbine blades 9. Valves 4 are normally closed to ensure that the relay nozzles 5 operate under appropriate conditions. Multiple fuel injector rods 6 are obliquely arranged in the rectifier support plate 10 behind the multi-stage turbine blades 9, extending to the vicinity of the concave vortex stabilizer 12 on the central cone 8. The fuel injector rods adopt an independent modular design, with independent fuel supply to each zone to meet the requirements of variable afterburner ratio. Fuel injection holes 11 are evenly distributed on the fuel injector rods. A wall-mounted stabilizer 7 is fixed between the fuel injector rods 6 and the outer bypass wall 2. See also Figure 2 , Figure 4 and Figure 5The cooling system consists of a rectifier support plate 10, a regenerative cooling system 13, cooling oil pipes 14, cooling air pipes 15, film cooling holes 16, and a heat exchanger 17. Two coiled regenerative cooling pipes, namely the cooling oil pipe 14 on the inner wall and the cooling air pipe 15 on the outer wall, form a film cooling and regenerative cooling system together with the film cooling holes 16 and the heat exchanger 17. Injection holes 11 on the injector rod 6 are evenly distributed on the outer wall of the rectifier support plate 10, and small-sized film cooling holes 16 are evenly distributed elsewhere. The heat exchanger 17 is fixed in the middle and rear sections of the rectifier support plate 10. Coiled heat exchange tubes between the heat exchanger 17, the fuel supply pipe 3, and the cooling oil supply pipe 14 ensure sufficient heat exchange. (See also...) Figure 3 and Figure 6 The flame stabilization system consists of a wall-mounted stabilizer 7, a central cone 8, a rectifier support plate 10, and a concave cavity vortex stabilizer 12. A concave cavity, i.e., the concave cavity vortex stabilizer 12, is formed on the central cone 8 in the same vertical direction as the fuel injector rods. Fuel is injected through the fuel injector rods 6, and a small amount of cooling air is ejected through film cooling holes 16 between the multiple fuel injector rods 6. An electric nozzle 18 is fixed at the fuel and air injection points for stable ignition. The wall-mounted stabilizer 7 is fixed between the rectifier support plate 10 and the outer bypass wall 2. The outer wall surface of the wall-mounted stabilizer 7 has uniformly sized small film cooling holes 16, through which cooling air introduced from the outer bypass gas into the rectifier support plate passes.

[0030] The fuel injector 6 is arranged inside the rectifier support plate 10, forming a recirculation zone on the rear end wall of the streamlined rectifier support plate 10. Fuel and combustion gases are mixed on both sides of the outer wall of the rectifier support plate 10 and then combusted at the rear end. The radial stabilizer, wall stabilizer 7, and cavity vortex stabilizer 12 are integrated and coupled. Multiple fuel injectors 6 are arranged inside the rectifier support plate 10. Fuel is supplied through the fuel injectors 6 of the rectifier support plate 10 via the side wall sections to meet the variable afterburner ratio requirements during afterburner operation. The kerosene heated by the heat exchanger 17 is regenerated and cooled on the flame stabilizer wall, which lowers the stabilizer wall temperature and further raises the kerosene temperature to a supercritical state before being sprayed outward, reducing flow resistance loss and improving mixing effect and combustion efficiency. The regenerated cooling oil pipe 14 is located inside the cooling air pipe 15 to avoid direct contact between fuel and the hot wall, effectively inhibiting coking. Simultaneously, the introduced bypass air radially enters the rectifier support plate 10. Most of the air cools the fuel injector 6 and then seeps out through the film cooling holes 16 on the outer and rear end walls of the support plate, completing the cooling of the rectifier support plate 10. A small portion of the air enters the concave cavity vortex stabilizer 12, cooling the cavity structure while ensuring the stability and reliability of the duty flame. The wall stabilizer 7 has openings on its inner wall, similarly introducing bypass air into the gaps in the outer wall of the wall stabilizer 7, which then seeps out through the film cooling holes 16 on the inner wall to achieve a cooling effect. At lower flight speeds of Mach 3.5 and below, a combined cooling method, namely film cooling and regenerative cooling, is used; at higher flight speeds of Mach 5.0 and above, regenerative cooling of kerosene is mainly relied upon.

[0031] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings and specific implementation processes. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various changes and optimizations to the above methods without departing from the principle of the present invention.

Claims

1. An integrated afterburner for supercritical kerosene, comprising an afterburner, an outer bypass wall, a fuel supply pipe, valves, a relay nozzle, an injection rod, a wall stabilizer, a center cone, multi-stage turbine blades, a flow straightener, injection orifices, a concave cavity vortex stabilizer, cooling oil pipes, cooling air pipes, film cooling orifices, a heat exchanger, and an electric nozzle; the afterburner is placed inside the outer bypass wall and fixed to ensure correct orientation; the flow straightener must be streamlined to optimize air and fuel flow paths. The fuel supply system consists of fuel supply pipes, valves, relay nozzles, injector rods, and a rectifier support plate. Valves are installed in multiple fuel supply pipes, which are vertically mounted at the front end of the inner wall of the outer bypass duct. Relay nozzles are located at the ends of the fuel supply pipes, distributed before and after the multi-stage turbine blades and between them. Multiple injector rods are arranged obliquely in the rectifier support plate behind the multi-stage turbine blades, extending to the vicinity of the vortex stabilizer in the concave cavity on the central cone. The injector rods adopt an independent modular design, with independent fuel supply to each zone to meet the requirements of variable afterburner ratio. The injector holes are evenly distributed on the top, and the wall-mounted stabilizer is fixed between the injector rod and the outer bypass wall. The cooling system consists of a rectifier branch plate, cooling oil pipes, cooling air pipes, film cooling holes, and a heat exchanger assembly. Two coiled regenerative cooling pipes, namely the cooling oil pipe on the inner wall and the cooling air pipe on the outer wall, form a film cooling and regenerative cooling system together with the film cooling holes and heat exchanger. Injector holes on the injector rod are evenly distributed on the outer wall of the rectifier branch plate, while smaller film cooling holes are evenly distributed elsewhere. The heat exchanger is fixed in the middle and rear sections of the rectifier branch plate. The flame stabilization system consists of a wall stabilizer, a center cone, a rectifier support plate, and a concave vortex stabilizer. A concave cavity, i.e., a concave vortex stabilizer, is opened on the center cone in the same vertical direction as the fuel injector rod. Fuel is injected from the fuel injector rod, and a small amount of cooling air is injected through the film gas holes between multiple fuel injector rods. An electric nozzle is fixed at the fuel injection and air junction for stable ignition. The wall stabilizer is fixed between the rectifier support plate and the outer bypass wall. The outer wall surface of the wall stabilizer has uniformly sized small film gas holes, and cooling air introduced from the outer bypass gas into the interior of the rectifier support plate passes through the wall stabilizer. The fuel injector is located inside the fairing plate, forming a recirculation zone on the rear wall of the streamlined fairing plate. Fuel and combustion gases are mixed on both sides of the outer wall of the fairing plate and then combusted at the rear. The fairing plate, wall-mounted stabilizer, and concave cavity vortex stabilizer are integrated and coupled. The cooling oil pipe channel is located inside the cooling air pipe, avoiding direct contact between the fuel and the hot wall and effectively suppressing coking. At the same time, the introduced bypass air enters the fairing plate radially. Most of the air cools the fuel injector and then seeps out from the film cooling holes on the outer and rear walls of the fairing plate, thus cooling the fairing plate. A small portion of the air enters the concave cavity vortex stabilizer. The wall-mounted stabilizer has openings on its inner wall, which also introduce bypass air into the gaps on the outer wall of the wall-mounted stabilizer, and then seeps out from the film cooling holes on the inner wall to achieve a cooling effect. At lower flight speeds of less than or equal to Mach 3.5, a combined cooling method, namely film cooling and regenerative cooling, is used. At higher flight speeds of greater than or equal to Mach 5.0, regenerative cooling of kerosene is the primary method.

2. The integrated supercritical kerosene-based afterburner for fuel supply, flame stabilization, and cooling as described in claim 1, characterized in that: The rectifier bracket integrates the fuel supply, flame stabilization and cooling systems, improving space utilization.

3. The integrated afterburner for fuel supply, flame stabilization, and cooling based on supercritical kerosene as described in claim 1, characterized in that: The valve is normally closed to ensure that the relay nozzle can ignite the relay hot jet under the condition of high-altitude flameout, thus ensuring stable and reliable ignition and flame.

4. The integrated afterburner for fuel supply, flame stabilization, and cooling based on supercritical kerosene as described in claim 1, characterized in that: Multiple fuel injectors are arranged inside the rectifier support plate. Fuel is supplied through the fuel injectors of the rectifier support plate and the side wall in sections to meet the variable afterburner ratio requirements when the afterburner is working.

5. The integrated afterburner for supercritical kerosene supply, flame stabilization, and cooling as described in claim 1, characterized in that: The kerosene heated by the heat exchanger is regenerated and cooled on the wall of the flame stabilizer. While reducing the temperature of the stabilizer wall, the temperature of the kerosene is further increased to the supercritical state, and then it is sprayed outward, reducing flow resistance loss and improving the mixing effect and combustion efficiency.

6. The integrated afterburner for fuel supply, flame stabilization, and cooling based on supercritical kerosene as described in claim 1, characterized in that: A concave cavity is opened on the center cone in the same vertical direction as the fuel injector rod, which is called a concave cavity vortex stabilizer. The concave cavity structure is cooled while ensuring the stable and reliable operation of the flame.

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