Thermal strain alloy support plate flame stabilizer applied to afterburner

Abstract

The invention discloses a thermal strain alloy support plate flame stabilizer applied to an afterburner, and belongs to the field of aero-engine afterburner design. The thermal strain alloy flame stabilizer is composed of two thin-wall performance adjusting plates, the adjusting plates generate thermal bending moment and deform when forming a temperature gradient in the thickness direction, and therefore the divergence angle of the tail edge of the supporting plate is changed in a self-adaptive mode. Flow channel blockage is weakened, and the total pressure loss is reduced; under the afterburning working condition, high-temperature fuel gas in a backflow area heats the inner side of the adjusting plate to promote the adjusting plate to expand outwards, a larger trailing edge divergence angle and the backflow area are formed, fuel evaporation and mixing are accelerated, and the penetration depth and the space uniformity are improved; meanwhile, the temperature difference is further increased through liquid drop impact and evaporation heat absorption, and deformation and combustion efficiency is enhanced. An additional executing mechanism is not needed, the structure is simple and reliable, and stress application efficient combustion and non-stress application low-resistance operation can be both considered.

Description

Technical Field

[0001] This invention belongs to the field of combustion organization in afterburners of aero-engines, and relates to a high-performance afterburner with a simple structure that combines high-efficiency combustion in afterburner mode with low flow resistance in non-afterburner mode. Background Technology

[0002] The afterburner is a key thrust-enhancing device used to improve the transient thrust level of an engine. It can significantly increase the engine's thrust output in a short period of time and is an important technological support for modern aircraft to achieve supersonic flight capabilities. Although the afterburner accounts for a relatively small proportion of the overall system weight, typically not exceeding one-fifth, its contribution to engine thrust performance is significant. For turbojet engines, thrust can be increased by about half after afterburner activation, while in turbofan engines, this thrust increase can even reach more than 70% of the original thrust. Therefore, afterburner technology has become an indispensable tool for fighter jets in typical mission phases such as takeoff, rapid climb, high-speed penetration, and maneuvering acceleration, and its performance level directly affects the aircraft's maneuverability and combat effectiveness. Therefore, continuously improving the combustion organization and efficiency of afterburners has significant engineering application value.

[0003] In traditional afterburners, fuel is typically injected into the main flow channel through injection rings positioned upstream of the flame stabilizer. The spatial arrangement of these injection rings improves the uniformity of fuel distribution in the high-speed incoming flow, thereby maintaining a stable flame. As aero-engines evolve towards higher temperatures, higher speeds, and lighter weights, components such as diffusers, fairings, flame stabilizers, fuel nozzles, and ignition devices are highly integrated, resulting in more compact afterburners with shorter axial dimensions. While this design effectively shortens the combustion chamber length and reduces system weight, it also shifts the combustion mode from premixed characteristics to primarily diffusion combustion. This makes precise control of fuel distribution in space difficult, negatively impacting combustion efficiency.

[0004] On the other hand, when the engine is not operating with afterburner, the backflow zone induced by the flame stabilizer and its downstream components still exists in the main flow channel, inevitably introducing additional flow blockage and total pressure loss, leading to a decrease in the engine's static thrust performance. Therefore, in the design of afterburners, how to reduce flow losses under non-afterburning conditions while achieving efficient and stable combustion organization under afterburning conditions has always been a core technical challenge that urgently needs to be solved. Summary of the Invention

[0005] This invention addresses the common problems of limited combustion efficiency and significant additional flow losses in afterburners by proposing a heat-strained alloy support plate flame stabilizer for use in afterburners. This solution utilizes the temperature response characteristics of heat-strained alloy materials to actively regulate the spatial distribution of fuel in the mainstream under afterburner conditions, without altering fuel injection parameters or injection methods. This effectively improves fuel penetration and enhances the fuel evaporation process from the perspective of flow and heat transfer mechanisms, thereby promoting thorough mixing of fuel and core combustion gases and improving combustion performance in the afterburner. Simultaneously, under non-afterburner conditions, this flame stabilizer can adaptively adjust its flow structure according to temperature changes, effectively reducing backflow-induced additional resistance and lowering overall flow losses.

[0006] This invention is implemented as follows:

[0007] A heat-strain alloy support plate flame stabilizer for use in an afterburner, the stabilizer consisting of an upstream rectifier support plate and a downstream heat-strain alloy flame stabilizer; the three-dimensional structure of the entire support plate is installed in the diffuser of the afterburner, connecting the afterburner center cone and the afterburner inner casing respectively; the space between the afterburner inner casing and the afterburner outer casing is filled with a lower temperature bypass gas; the lower temperature bypass gas flows into the center cone through the internal channel of the heat-strain alloy support plate flame stabilizer, and a portion of the gas flows out from the cooling slot at the trailing edge of the rectifier support plate.

[0008] The main features of the aforementioned heat-strained alloy support plate flame stabilizer are: a streamlined elliptical head structure at the leading edge of the rectifier support plate; a width of L0 and a length of L1 in the middle of the rectifier support plate; and a length of L2 and a width of L3 for the heat-strained alloy support plate flame stabilizer. L3 changes depending on the operating state of the afterburner. Considering nozzle installation, support plate strength, and combustion performance, the dimensions must satisfy the following relationships:

[0009] 40 mm > L0 (1)

[0010] L1 >> L2 (2)

[0011] 30 mm > L2 > 10 mm (3)

[0012] The aforementioned thermal strain alloy flame stabilizer is made of high-temperature alloy material and mainly consists of two thin-walled structures, named performance adjustment plates (the two performance adjustment plates have inner and outer sides, namely: the outer side and inner side of the first performance adjustment plate; the outer side and inner side of the second performance adjustment plate). As long as a stable and repeatable temperature asymmetry distribution is formed in the wall thickness direction or spanwise direction, a thermal bending moment will be generated, thereby causing macroscopic bending deformation. By directly changing the geometric configuration of the flame stabilizer's trailing edge under different operating conditions, the structural characteristics of the recirculation zone behind the flame stabilizer and the fuel penetration depth can be adjusted, achieving adaptive control of the flow resistance and combustion performance of the afterburner.

[0013] Furthermore, when the afterburner is not in operation, some of the bypass gas flows out from the cooling slits at the trailing edge of the rectifier support plate, forming low-temperature cooling gas inside the performance regulating plate. This continuous cooling causes the temperature inside the performance regulating plate to decrease. Meanwhile, the outer side of the performance regulating plate (outer side of the first performance regulating plate and outer side of the second performance regulating plate) contains high-temperature combustion gas, which is heated, resulting in a temperature distribution with a lower inner bottom and a higher outer top. This thermal stress pushes the performance regulating plates (outer side of the first performance regulating plate and inner side of the first performance regulating plate; outer side of the second performance regulating plate and inner side of the second performance regulating plate) to contract inward. The airflow passing over the support plate forms a small recirculation zone structure behind it, i.e., the recirculation zone in the non-afterburner state. This effectively reduces the obstruction effect of the combustion gas recirculation on the main flow channel, increasing the effective flow area between adjacent flame stabilizers and thus reducing flow losses in the afterburner in the non-afterburner state.

[0014] Furthermore, when the afterburner enters afterburner operation, the fuel injected by the injector rod flows along the fuel space trajectory behind the flame stabilizer and burns to form a high-temperature flame. The recirculation zone formed behind the rectifier support plate is the recirculation zone under afterburner conditions, leading to an increase in the temperature of the recirculation zone under afterburner conditions. The high-temperature combustion gas heats the inner side of the performance adjustment plate, causing the inner temperature to rise. Since the temperature of the afterburner recirculation zone is higher than the incoming flow temperature inside, the temperature of the inner side of the performance adjustment plate is also higher than that of the outer side. The resulting thermal stress causes the performance adjustment plates (outer side of the first performance adjustment plate, inner side of the first performance adjustment plate; outer side of the second performance adjustment plate, inner side of the second performance adjustment plate) to deform outward, forming a significant expansion angle structure at the trailing edge of the support plate.

[0015] At this time, due to the outward deformation of the performance adjustment plate under the afterburner condition, the airflow near the wall surface of the support plate tail edge expands circumferentially, transporting the gas / fuel mixture near the support plate to the area between adjacent support plates. This is equivalent to increasing the effective penetration depth of the fuel, thereby entraining more oxygen into the reaction zone, increasing the total amount of oxygen participating in combustion, and enhancing the overall combustion intensity of the afterburner.

[0016] Furthermore, a large recirculation zone structure is formed behind the performance adjustment plate where the airflow expands outward. The increase in the size of the recirculation zone significantly improves the evaporation rate of fuel in the high-temperature zone and shortens the fuel residence time, promoting rapid mixing of fuel and air and forming a more spatially uniform afterburning combustion field, thereby ensuring efficient and stable combustion in the afterburning combustion chamber under afterburning conditions.

[0017] At this point, after the two performance adjustment plates are spread out, the low-temperature fuel evaporation near the support plates will carry away the calorific value of the fuel gas inside the outer side of the performance adjustment plates (outer side of the first performance adjustment plate and outer side of the second performance adjustment plate), causing the local temperature to be lower than the internal temperature; at the same time, some large liquid droplets will directly collide with the outwardly expanding performance adjustment plates; further expanding the internal and external temperature gradient of the performance adjustment plates, resulting in a further increase in their deformation, and further enhancing the combustion efficiency of the afterburner.

[0018] Furthermore, the heat-strained alloy support plate flame stabilizer achieves adaptive adjustment of the recirculation zone structure, fuel penetration characteristics, and combustion process through passive response to temperature changes. Without introducing complex actuators and control systems, it simultaneously meets the dual performance requirements of low flow resistance operation in non-afterburning state and high-efficiency combustion in afterburning state.

[0019] The advantages of this invention over the prior art are as follows:

[0020] 1) This invention proposes a heat-strain alloy support plate flame stabilizer for use in afterburners. Utilizing the passive response characteristics of materials to temperature changes, it can automatically change the geometry of the trailing edge of the support plate and the size of the recirculation zone under afterburner and non-afterburner conditions. It does not require additional actuators and control systems, and achieves adaptive adjustment of combustion performance and flow resistance. It has a simple structure, high reliability, and is suitable for the high-temperature and high-speed environment of aero-engines.

[0021] 2) Under non-afterburning conditions, the thermal strain alloy support plate shrinks under the action of the outer bypass cooling gas, which reduces the volume of the trailing edge recirculation zone and reduces the degree of obstruction of the main flow channel by the recirculation. This significantly reduces the total pressure loss of the afterburner and improves the flow efficiency and economy of the engine under cruise and certain operating conditions.

[0022] 3) Under afterburner conditions, the performance adjustment plate expands outward under the heating of the high-temperature recirculated gas in the afterburner combustion zone, forming a large tail edge expansion angle, which significantly enhances the volume and strength of the recirculation zone behind the support plate and accelerates the fuel evaporation and mixing process. At the same time, after expanding outward, some fuel will directly impact the performance adjustment plate, and the evaporation heat absorption will further increase the temperature difference between the inside and outside of the adjustment plate, causing its deformation range to continue to increase.

[0023] 4) The outward-expanding performance adjustment plate delivers the fuel / fuel mixture near the flame stabilizer to the area between the support plates, which is equivalent to increasing the fuel penetration depth and spatial distribution uniformity, enhancing oxygen entrainment capacity, and avoiding local rich or poor fuel phenomena, thereby achieving stable and efficient combustion in the afterburner over a wide range of operating conditions. Attached Figure Description

[0024] Figure 1 This is a simplified structural diagram of an afterburner.

[0025] Figure 2 This is a cross-sectional view and a central cone structure diagram of a heat-strained alloy support plate flame stabilizer;

[0026] Figure 3 This is a schematic diagram of the thermal strain alloy flame stabilizer contracting when cooled under non-stressed conditions.

[0027] Figure 4 This is a schematic diagram of the thermal expansion of a heat-strained alloy flame stabilizer under applied force.

[0028] Among them, 101-afterburner inner inlet, 102-afterburner outer duct inlet, 2-hot strain alloy support plate flame stabilizer, 201-rectifier support plate, 202-hot strain alloy flame stabilizer, 202a-outer side of the first performance adjustment plate, 202d-outer side of the second performance adjustment plate, 202b-inner side of the first performance adjustment plate, 202c-inner side of the second performance adjustment plate, 3-center cone, 4-afterburner inner casing, 5-afterburner outer duct casing, 6-cooling seam, 7-fuel injector rod, 8-fuel space trajectory, 901-recirculation zone in non-afterburning state, 902-recirculation zone in afterburning state, 10-low temperature air inside the performance adjustment plate, 11-inner combustion gas outside the performance adjustment plate, 001-airflow direction of afterburner. Detailed Implementation

[0029] To make the objectives and effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0030] like Figure 1The diagram shows a simplified schematic of the afterburner structure at the tail of a turbofan aero-engine, showing only the 120° circumferential sector. The main internal combustion gas flows downstream along the inflow direction 001, passing sequentially through the afterburner internal inlet 101 and the heat-strain alloy support plate flame stabilizer 2 inside the diffuser. The inner boundary of the airflow is the afterburner center cone 3, and the outer boundary is the afterburner internal casing 4. The outer bypass cryogenic air flows along the afterburner airflow direction 001, passing sequentially through the afterburner outer bypass inlet 102 and splitting into two parts: one part flows away through the heat-strain alloy support plate flame stabilizer 2, and the majority of the air flows downstream into the outer bypass.

[0031] Figure 2 This is a cross-sectional view and a central cone structural diagram of a heat-strained alloy support plate flame stabilizer, combined with... Figure 1 It can be seen that the low-temperature air entering from the inside of the thermal strain alloy support plate flame stabilizer 2 is also divided into two parts: one part enters the central cone, and a small amount of air flows out from the inside of the support plate to form the cooling air 10 inside the performance adjustment plate.

[0032] The thermal strain alloy flame stabilizer 2 consists of an upstream rectifier support plate 201 and a downstream thermal strain alloy flame stabilizer 202; the thermal strain alloy flame stabilizer 202 consists of two performance adjustment plates. For ease of description, the inner and outer sides of the performance adjustment plates are named as the outer side of the first performance adjustment plate 202a and the inner side of the first performance adjustment plate 202b; the outer side of the second performance adjustment plate 202d and the inner side of the second performance adjustment plate 202c.

[0033] When the afterburner is not in operation, the entire thermal strain alloy support plate flame stabilizer is placed inside the inner chamber, with the inner chamber gas 11 located outside its performance adjustment plate. The overall structure is as follows: Figure 4 As shown, when the low-temperature air from the outer casing passes through the cooling seam 6, it cools the inner sides 202b and 202c of the first performance adjustment plate and the second performance adjustment plate of the thermal strain alloy flame stabilizer, lowering their temperature. Meanwhile, the outer sides 202a and 202d of the first and second performance adjustment plates contain high-temperature combustion gases. The temperature difference between the inside and outside creates a temperature gradient along the thickness of the performance adjustment plates, causing the performance adjustment plates of the thermal strain alloy flame stabilizer to contract inwards. This flow structure forms a small recirculation zone 901 behind the flame stabilizer, i.e., the recirculation zone 901 in the non-afterburning state. This increases the effective flow area in the non-afterburning state, effectively reducing the degree of blockage of the main flow channel by the gas recirculation. It significantly reduces the total pressure loss of the afterburner chamber in the non-afterburning state, thereby improving the engine's flow efficiency during cruise and certain operating conditions.

[0034] Under stressed operating conditions, the structure of the heat-strained alloy support plate flame stabilizer is as follows: Figure 4As shown, the fuel injected by the injector 7 flows and burns behind the flame stabilizer according to the fuel space trajectory 8, forming a high-temperature flame. The recirculation zone formed behind the rectifier support plate is the recirculation zone under afterburning conditions, which leads to an increase in the temperature of the recirculation zone under afterburning conditions. The high-temperature combustion gas heats the inner side of the performance adjustment plate, causing the inner temperature to rise. Since the temperature of the afterburning recirculation zone is higher than the incoming flow temperature inside, the temperature of the inner side of the performance adjustment plate is also higher than that of the outer side. The resulting thermal stress causes the performance adjustment plates (outer side of the first performance adjustment plate, inner side of the first performance adjustment plate; outer side of the second performance adjustment plate, inner side of the second performance adjustment plate) to deform and open outward, forming a significant expansion angle structure at the trailing edge of the support plate.

[0035] In the afterburning state, the recirculation zone 902 is filled with high-temperature combustion gases from the afterburner, which directly exchange heat with the heat-strained alloy flame stabilizer 202. The inner sides 202b and 202c of the first and second performance adjustment plates, directly opposite the recirculation zone, have combustion gases at temperatures significantly higher than those outside the original performance adjustment plates. Therefore, the performance adjustment plates expand outward, forming a larger trailing edge expansion angle. This not only increases the volume and intensity of the recirculation zone behind the support plates, accelerating fuel evaporation and mixing, but also, the outward expansion of the performance adjustment plates directs the fuel / gas mixture near the support plates towards the area between them, effectively increasing fuel penetration depth and uniform fuel spatial distribution, thus ensuring stable and efficient combustion in the afterburner.

[0036] Depend on Figure 4 It is known that when some larger diameter droplets impact the performance adjustment plate, the temperature of the outer side 202a of the first performance adjustment plate and the outer side 202d of the second performance adjustment plate will be further reduced, and the deformation of the performance adjustment plate will be further increased, thereby obtaining higher combustion efficiency.

[0037] This invention uses a heat-strained alloy as raw material, leveraging its passive response to temperature changes. Under afterburner conditions, the flame stabilizer regulating plate deforms and expands under high-temperature combustion gas heating, forming a circumferential expansion angle at the trailing edge of the support plate. This significantly increases the size and intensity of the recirculation zone, accelerating fuel evaporation and mixing. The expanded structure transports some fuel near the support plate to the area between adjacent support plates, increasing the effective penetration depth of the fuel. Simultaneously, large droplets impacting the regulating plate further evaporate and absorb heat, enhancing the temperature gradient inside and outside the regulating plate, causing its deformation amplitude to continuously increase, thereby strengthening afterburner combustion efficiency. Under non-afterburner conditions, the flame stabilizer contracts under the cooling effect of the bypass gas, reducing the volume of the recirculation zone at the trailing edge of the support plate, reducing the degree of flow channel blockage, and significantly reducing the total pressure loss of the afterburner. This invention requires no additional actuators or control systems, has a simple structure, high reliability, and can achieve adaptive optimization of combustion performance and flow loss in the afterburner over a wide range of operating conditions.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A heat-strained alloy support plate flame stabilizer for use in an afterburner, characterized in that, The heat strain alloy support plate flame stabilizer (2) consists of an upstream rectifier support plate (201) and a downstream heat strain alloy flame stabilizer (202); the tail edge of the rectifier support plate (201) is provided with a cooling slit (6). The leading edge structure of the rectifier support plate (201) is a streamlined elliptical head structure. The width of the middle of the rectifier support plate (201) is L0, and the length of the rectifier support plate (201) is L1. The length of the heat strain alloy support plate flame stabilizer (202) is L2, and the width is L3. L3 will change with the working state of the afterburner. Considering the nozzle installation, support plate strength, and combustion performance, the dimensions must meet the following relationship: 40 mm > L0 L1 >> L2 30 mm > L2 > 10 mm A single hot strain alloy flame stabilizer (202) consists of two performance adjustment plates made of hot strain alloy as raw material; When the performance adjustment plate is subjected to a large temperature gradient in its thickness direction, it will deform, directly changing the structure of the recirculation zone behind the flame stabilizer, the fuel penetration depth, and the flame stabilizer, adaptively adjusting the flow resistance and combustion performance of the afterburner.

2. The heat-strained alloy support plate flame stabilizer for use in an afterburner according to claim 1, characterized in that, The three-dimensional structure of the entire support plate is installed in the diffuser of the afterburner, and is connected to the afterburner center cone (3) and the external afterburner inner casing (4) respectively. The afterburner inner casing (4) and the afterburner outer casing (5) are filled with low-temperature outer bypass gas. The low-temperature outer bypass gas flows into the center cone (3) through the internal channel of the heat strain alloy support plate flame stabilizer (2), and a part of the gas flows out from the cooling slit (6) at the tail edge of the rectifier support plate (201).

3. A heat-strained alloy support plate flame stabilizer for use in an afterburner according to claim 1, characterized in that, The two performance adjustment plates have inner and outer sides, namely: the outer side of the first performance adjustment plate (202a) and the inner side of the first performance adjustment plate (202b); the outer side of the second performance adjustment plate (202d) and the inner side of the second performance adjustment plate (202c).

4. A heat-strained alloy support plate flame stabilizer for use in an afterburner according to claim 1, characterized in that, When the afterburner is not working, some of the low-temperature outer bypass gas flows out from the cooling slit (6) at the tail edge of the rectifier support plate (201) to cool the inside of the performance adjustment plate, while the outside of the performance adjustment plate contains the high-temperature gas. The temperature difference between the two sides causes the performance adjustment plate to contract inward, and the gas inside flows along the contraction support plate, forming a small recirculation zone behind the rectifier support plate (201), namely the recirculation zone (901) in the non-afterburner state, to avoid excessive flow loss in the non-afterburner state caused by gas recirculation and blockage of the flow channel by the recirculation zone.

5. A heat-strained alloy support plate flame stabilizer for use in an afterburner according to claim 1, characterized in that, When the afterburner is working, the recirculation zone formed behind the rectifier support plate (201) is the recirculation zone (902) in the afterburner state. The recirculation zone (902) in the afterburner state contains high-temperature combustion gases after combustion in the afterburner. These gases heat the inner side of the performance adjustment plate. The inner side of the performance adjustment plate contains relatively low-temperature internal combustion gases. The inner temperature is higher than the outer temperature, and the thermal stress will push the two performance adjustment plates apart. After the performance adjustment plates are pushed apart, an expansion angle will be formed at the trailing edge of the rectifier support plate (201), which will transport the air and fuel near the support plate to the area between the support plates. This is equivalent to increasing the penetration depth of the fuel and drawing more oxygen into the reaction zone. At the same time, a larger recirculation zone will be formed behind the outwardly expanding performance adjustment plate, which will increase the evaporation rate of the fuel and shorten the residence time of the fuel, thus ensuring the efficient combustion of the afterburner.

6. A heat-strained alloy support plate flame stabilizer for use in an afterburner according to claim 5, characterized in that, When the afterburner is in operation, after the performance adjustment plate is extended, the low-temperature fuel evaporation near the support plate will carry away the calorific value of the internal combustion gas on the outside of the performance adjustment plate (outside of the first performance adjustment plate (202a) and outside of the second performance adjustment plate (202d)), causing the local temperature to be lower than the internal temperature. At the same time, some large liquid droplets will directly collide with the outwardly expanding performance adjustment plate, further increasing the internal and external temperature gradient of the performance adjustment plate, resulting in a further increase in its deformation and further enhancing the combustion efficiency of the afterburner.

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