Ammonia fuel ignition enhancement device based on double-layer circulation, combustion chamber and ignition method

Abstract

The application relates to an ammonia fuel ignition enhancement device based on double-layer circulation, a combustion chamber and an ignition method, wherein the ammonia fuel ignition enhancement device comprises a plate-shaped main body; a cracking fuel channel and a non-cracking fuel channel are arranged in the plate-shaped main body in a thickness direction and the cracking fuel channel is adjacent to a high-temperature fuel gas heating side of the plate-shaped main body; an inner wall surface of the cracking fuel channel is provided with a cracking catalyst; liquid ammonia flowing through the cracking fuel channel is cracked to generate mixed gas containing hydrogen under the action of high temperature and the cracking catalyst; liquid ammonia flowing through the non-cracking fuel channel absorbs heat emitted by the cracking fuel channel to form main stream ammonia gas; based on time sequence control, mixed gas flame formed by igniting the mixed gas first ignites the main stream ammonia gas to form ammonia flame, and ignition enhancement of the ammonia fuel is realized. Through the mode of designing double-layer cooling channels, the generated mixed gas can reliably guarantee ignition enhancement and improvement of the success rate of ignition of the ammonia fuel.

Description

Technical Field

[0001] This invention relates to the aerospace field, and more particularly to an ammonia fuel ignition enhancement device, combustion chamber, and ignition method based on a dual-cycle ammonia fuel. Background Technology

[0002] In the field of aircraft propulsion, ramjet propulsion systems have become the ideal power source for modern aircraft due to their unique advantages. This system can capture oxygen from the air and react with it in the fuel, exhibiting significant characteristics such as high specific impulse and simple structure, thus attracting considerable attention in aerospace and other fields. In practical applications, ramjet propulsion systems often employ fuel regenerative cooling to achieve structural thermal protection, ensuring the system can withstand high-temperature environments during high-speed flight.

[0003] However, traditional hydrocarbon fuels suffer from a serious problem under high-temperature conditions: they are prone to coking. When traditional hydrocarbon fuels are used for regeneration cooling, coking causes carbon buildup to clog the regeneration cooling channels. As carbon deposits accumulate, the cooling effect of the channels gradually deteriorates, potentially leading to overheating damage to critical structures such as the engine. This problem has become a core bottleneck that urgently needs to be overcome in ramjet propulsion systems under high-speed, reusable conditions, severely limiting the improvement of ramjet propulsion system performance and the expansion of its application range.

[0004] Given the limitations of traditional hydrocarbon fuels, ammonia fuel, as a potential alternative fuel, is gradually gaining attention in research. Compared to traditional hydrocarbon fuels, ammonia fuel has many outstanding advantages, such as strong cooling capacity, which can more effectively absorb heat and provide better thermal protection for ramjet propulsion systems; and it does not produce coking during the pyrolysis process, avoiding the risk of cooling channel blockage.

[0005] However, ammonia fuel also faces some challenges in practical applications. Ammonia has an auto-ignition temperature as high as 650℃, and its residence time in the combustion chamber is extremely short, typically less than 1 ms. Under these conditions, traditional ignition methods often have a high failure rate, making it difficult to achieve stable ignition in ramjet propulsion systems, thus affecting the normal operation of the system. While the ignition problem of ammonia can be solved by using reactive fuels for ignition, such as using hydrogen to ignite ammonia to form a stable flame in traditional solutions, this method requires a high-pressure hydrogen tank, which not only increases the complexity of the system but also introduces higher safety risks. After all, if a high-pressure hydrogen tank leaks or other unexpected situations occur during storage and use, it could lead to serious safety accidents.

[0006] It is worth noting that ammonia, as a good carrier of hydrogen, can generate hydrogen under high-temperature or catalytic cracking conditions. Hydrogen possesses stable and reliable ignition and combustion capabilities, giving ammonia fuel the potential to achieve stable operation of the propulsion system at higher flight speeds. However, ammonia cracking faces two major challenges. Firstly, ammonia has a high cracking temperature, making it difficult to reach the required temperature under normal conditions, thus hindering its cracking. Secondly, ammonia has a strong endothermic vaporization capacity, further increasing the difficulty of reaching the cracking temperature. Using an external cracker to promote ammonia cracking requires additional energy supply, which undoubtedly increases the system's weight, negatively impacting the aircraft's performance.

[0007] It is evident that although ammonia fuel has certain application potential in ramjet propulsion systems, many problems such as ignition difficulties and pyrolysis challenges still need to be overcome before its practical application can be realized. Therefore, it is urgent to propose a more efficient, safe, and reliable ammonia fuel application technology, which is of great significance for promoting the development of ramjet propulsion systems. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an ammonia fuel ignition enhancement device based on a dual-layer cycle.

[0009] To achieve the above-mentioned objectives, the present invention provides an ammonia fuel ignition enhancement device based on a dual-layer cycle, comprising: a plate-shaped main body;

[0010] The plate-shaped main body is provided with pyrolysis fuel channels and non-pyrolysis fuel channels in layers along the thickness direction, and the pyrolysis fuel channels are adjacent to the high-temperature gas heating side of the plate-shaped main body.

[0011] The inner wall of the pyrolysis fuel channel is provided with a pyrolysis catalyst;

[0012] Liquid ammonia flowing through the cracking fuel channel is cracked under high temperature and the action of cracking catalyst to produce a hydrogen-containing mixture;

[0013] Liquid ammonia flowing through the non-cracking fuel channel absorbs the heat emitted by the cracking fuel channel to form mainstream ammonia gas;

[0014] Based on timing control, the mixed gas flame formed by igniting the mixed gas first ignites the mainstream ammonia gas to form an ammonia flame, thereby enhancing the ignition of ammonia fuel.

[0015] According to one aspect of the invention, the cross-section of the pyrolysis fuel channel is a regular shape with a length greater than its width, and the length direction of the cross-section is parallel to the high-temperature gas heating side of the plate-shaped body;

[0016] The cross-section of the non-pyrolysis fuel channel is a regular shape with a length greater than its width, and the length direction of the non-pyrolysis fuel channel is set at an angle to the high-temperature gas heating side of the plate-shaped body.

[0017] According to one aspect of the invention, the length direction of the non-pyrolysis fuel channel is perpendicular to the high-temperature gas heating side of the plate-shaped body.

[0018] According to one aspect of the invention, the cross-sectional shape of the pyrolysis fuel channel is consistent with that of the non-pyrolysis fuel channel.

[0019] According to one aspect of the present invention, along the planar direction of the high-temperature gas heating side of the plate-shaped body, a plurality of pyrolysis fuel channels are provided at equal intervals, and a plurality of non-pyrolysis fuel channels are provided at equal intervals.

[0020] According to one aspect of the invention, the pyrolysis catalyst has a temperature tolerance greater than 800°C and a pyrolysis activity decay rate of less than 3% / 100h.

[0021] According to one aspect of the invention, the plate-shaped body is an alloy plate, and the material composition of the alloy plate contains components that cause ammonia to crack.

[0022] To achieve the above-mentioned objectives, the present invention provides a combustion chamber employing the aforementioned dual-cycle ammonia fuel ignition enhancement device, comprising: a hollow combustion chamber body, a mixture nozzle, a mainstream ammonia nozzle, and a spark plug disposed on the combustion chamber body;

[0023] The combustion chamber body has at least a portion of its walls made of an ammonia fuel ignition enhancement device, and the high-temperature gas heating side of the plate-shaped body of the ammonia fuel ignition enhancement device is located on the inner side.

[0024] The cracked fuel channel of the ammonia fuel ignition enhancement device is connected to the mixed gas nozzle via a first control valve, and the non-cracking fuel channel is connected to the mainstream ammonia gas nozzle via a second control valve.

[0025] The combustion chamber body includes: a cylindrical part and a concave part;

[0026] The mixed gas nozzle, the mainstream ammonia nozzle, and the concave cavity are arranged on the same side of the cylinder.

[0027] Along the flow direction, both the mixed gas nozzle and the mainstream ammonia nozzle are located in front of the concave cavity, and the distance between the mixed gas nozzle and the leading edge of the concave cavity is greater than the distance between the mainstream ammonia nozzle and the leading edge of the concave cavity.

[0028] The spark plug is located at the bottom of the recessed portion.

[0029] According to one aspect of the invention, the distance between the mixed gas nozzle and the leading edge of the concave cavity is 1.5D, and the distance between the mainstream ammonia nozzle and the leading edge of the concave cavity is 0.5D, where D represents the depth of the concave cavity.

[0030] To achieve the above-mentioned objective, the present invention provides an ignition method for the aforementioned combustion chamber, comprising:

[0031] S1. Connect the cracked fuel channel and the non-cracking fuel channel of the ammonia fuel ignition enhancement device to the ammonia fuel source respectively, wherein liquid ammonia is input into the cracked fuel channel under the first preset condition and liquid ammonia is input into the non-cracking fuel channel under the second preset condition;

[0032] S2. The main body of the combustion chamber receives a supersonic inflow;

[0033] S3. The mixture formed in the cracked fuel channel is injected into the combustion chamber body as a transverse sonic jet based on the first control valve, and the mixture is ignited based on the spark plug;

[0034] S4. After the mixed gas flame continues to burn for a preset time, the mainstream ammonia gas formed in the non-cracking fuel channel is injected into the main body of the combustion chamber as a transverse sonic jet based on the second preset condition. The mainstream ammonia gas is ignited by the mixed gas flame to achieve enhanced ignition of ammonia fuel until the combustion flame extends to the entire concave cavity shear layer, thus completing the combustion chamber ignition.

[0035] According to one aspect of the present invention, by designing a double-layer cooling channel, the inner cracking fuel channel can significantly increase the cracking rate of ammonia fuel under the heating effect of high-temperature gas, thereby generating a stable hydrogen source. This effectively reduces the ignition delay time, which is more beneficial for enhancing the ignition of ammonia fuel and improving the ignition success rate.

[0036] According to one aspect of the present invention, this approach can directly utilize the waste heat of the combustion chamber wall to achieve efficient cracking of ammonia fuel without the need for an additional ammonia cracker or additional cracking energy consumption. This results in a significant weight reduction for the combustion chamber system using this approach, effectively reducing the overall complexity and giving the approach a better application prospect.

[0037] According to one aspect of the present invention, this approach eliminates the need for additional high-pressure hydrogen cylinders, significantly reducing the overall complexity of the system compared to traditional hydrogen ignition methods.

[0038] According to one aspect of the present invention, by designing a double-layer cooling channel, this approach not only achieves different processing capacities for ammonia fuel but also enables a double-layer heat insulation design. This results in a gradient reduction in wall temperature, significantly reducing the thermal stress on the combustion chamber walls and further enhancing the overall material and structural stability.

[0039] According to one aspect of the present invention, the inner layer of the cracked fuel channel can use ammonia fuel as the main functional structure for cracking and producing hydrogen. It can not only provide a mixture as an ignition source, but also make great use of the heat conducted during the generation of the mixture, thus greatly ensuring the stability and reliability of the wall structure. The outer layer of the non-cracking fuel channel can further supplement the wall heat dissipation, which can more effectively ensure the stability and reliability of the wall structure, while also making more effective use of the residual heat to form a large amount of mainstream ammonia gas. This is more beneficial for ensuring continuous and stable combustion after successful ignition, making the combustion chamber using this approach perform better.

[0040] According to one aspect of the present invention, this approach can achieve closed-loop energy utilization in the concave cavity based on the matching combustion effect of the mixed gas and the mainstream ammonia gas. The high-temperature injection of the mixed gas effectively reduces ignition energy consumption, improves flame stability, and enhances the ignition of the mainstream ammonia gas. Therefore, the matching of the flame core of the mixed gas flame with the injection timing of the mainstream ammonia gas makes the ignition process more reliable and the combustion efficiency higher.

[0041] According to one aspect of the present invention, this approach can achieve flexible and reliable control of the combustion flame distribution by controlling different proportions of the mixed gas and mainstream ammonia flow rates, which is of great significance for improving the performance control capability of the engine in actual operation.

[0042] According to one aspect of the present invention, the mixed gas is injected upstream of the concave cavity. Due to its high hydrogen content, it can spontaneously ignite to form a stable flame, providing a reliable guarantee for the initial energy field. Meanwhile, the mainstream ammonia gas is injected closer to the concave cavity, where it can be effectively ignited by the flame nucleus of the mixed gas flame. Therefore, this approach allows for stable ignition using the traditional transverse jet-assisted concave cavity ignition scheme, fully ensuring the development of the initial flame nucleus and the stability of the flame. Furthermore, based on the timing coordination of the mixed gas and mainstream gas injection processes, stable ignition and combustion in a pure ammonia ramjet engine are achieved.

[0043] According to one aspect of the present invention, this approach not only effectively improves the ignition reliability of the ammonia fuel ramjet propulsion system, but also makes full use of the heat generated during the combustion process, resulting in higher energy utilization efficiency.

[0044] According to one aspect of the present invention, this approach can fully utilize the heat distribution in different regions of the wall structure, thereby enabling the reliable operation of the ammonia fuel overpressure propulsion system and meeting the performance requirements of structural thermal protection and reliable ignition of the engine under high-speed conditions. Attached Figure Description

[0045] Figure 1 This is a structural diagram of the ammonia fuel ignition enhancement device based on a dual-layer cycle according to the present invention;

[0046] Figure 2 This is a structural diagram of the combustion chamber of the present invention;

[0047] Figure 3 This is a flame distribution diagram of the process of igniting mainstream ammonia gas with a mixed gas in Embodiment 1 of the present invention, wherein, Figure 3 (a) shows the autoignition diagram of the air-fuel mixture at the distal end of the combustion chamber downstream of the concave cavity. Figure 3 (b) shows the flame developing and expanding in situ at the far end of the combustion chamber. Figure 3 (c) shows the propagation diagram of the flame moving upstream along the combustion chamber. Figure 3 (d) shows the propagation diagram of the flame entering the flame stabilization zone of the concave cavity along the rear edge of the concave cavity. Figure 3 (e) shows a flame diagram in which a temperature-controlled flame base is formed within the concave portion, igniting the mainstream ammonia gas. Figure 3 (f) shows the state diagram of the co-combustion of the gas mixture and the mainstream ammonia, with a stable flame near the front end of the concave cavity. Figure 3 (g) represents the state diagram where the mixed gas and mainstream ammonia gas are co-burning, and the stable flame is located near the front end of the concave cavity. Figure 3 (h) represents the state diagram where the mixed gas and mainstream ammonia gas burn together, and the stable flame extends to the entire concave cavity. Figure 3 (i) represents a state diagram showing the co-combustion of the mixed gas and the mainstream ammonia gas, with a stable flame extending to the entire concave cavity and extending downstream of the concave cavity;

[0048] Figure 4 The image shows the flame time-averaged values ​​of the mixed gas and mainstream ammonia at different flow rates in Example 2 of the present invention. Figure 4 (a) shows the flame time-averaged plot at a flow ratio of 1.5:1. Figure 4 (b) shows the flame time-averaged diagram with a flow rate ratio of 1:1. Figure 4 (c) shows the flame time-averaged plot at a flow ratio of 0.61:1. Figure 4 (d) shows the flame time-averaged plot at a flow ratio of 0.28:1;

[0049] In the figure, 11-plate-shaped main body, 111-cracking fuel channel, 112-non-cracking fuel channel, 2-combustion chamber main body, 3-mixed gas nozzle, 4-mainstream ammonia nozzle, 5-spark plug, 1-ammonia fuel ignition enhancement device, 21-cylinder section, 22-cavity section. Detailed Implementation

[0050] In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present 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, the above terms should not be construed as limitations on the present invention.

[0051] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0052] like Figure 1 As shown, according to one embodiment of the present invention, the ammonia fuel ignition enhancement device based on a double-layer circulation includes: a plate-shaped main body 11; wherein, the plate-shaped main body 11 can realize heat exchange of liquid ammonia fuel, so as to realize the vaporization of ammonia fuel and the cooling of the entire plate-shaped main body 11, so as to achieve the stability and reliability of the overall structure. For this purpose, a cracked fuel channel 111 and a non-cracking fuel channel 112 are arranged in layers along the thickness direction within the plate-shaped main body 11, and the cracked fuel channel 111 is adjacent to the high-temperature gas heating side of the plate-shaped main body 11; correspondingly, the non-cracking fuel channel 112 is adjacent to the cooling side of the plate-shaped main body 11 away from the high-temperature gas. Thus, a temperature difference can be generated between the two layers of channels to achieve the layered cooling of the plate-shaped main body 11, and to achieve different heating effects on the liquid ammonia fuel. In this embodiment, a cracking catalyst is provided on the inner wall of the cracked fuel channel 111. Therefore, based on the dual-sided channel, the functions of fuel cracking, wall cooling, and ignition enhancement can be integrated within the plate-shaped main body 11. This allows the solution to achieve complex multi-functionality with a simple structure, resulting in superior ignition enhancement and more reliable service life and stability. Specifically, liquid ammonia flowing through the cracked fuel channel 111 cracks under high temperature and the action of the cracking catalyst to produce a hydrogen-containing mixture. Liquid ammonia flowing through the non-cracking fuel channel 112 absorbs the heat emitted by the cracked fuel channel 111 to form mainstream ammonia. Given the different gases formed in different channels, based on timing control, the flame formed by igniting the mixed gas first ignites the mainstream ammonia to form an ammonia flame, thus achieving enhanced ignition of the ammonia fuel.

[0053] In this embodiment, in the cracking fuel channel 111, liquid ammonia is first evaporated and vaporized into ammonia gas at a high temperature. Then, based on the surrounding cracking catalyst and high temperature conditions, the ammonia gas undergoes a cracking reaction (NH3→ 1.5H2+ 0.5N2) as the heat absorption increases. As a result, a mixed gas containing hydrogen is formed, wherein the formed mixed gas is a hydrogen-rich gas.

[0054] In this embodiment, the hydrogen content in the mixture is greater than 35%, so that the mixture formed by this scheme has the effect of igniting the mixture based on hydrogen self-ignition to form a stable mixture flame, so as to fully and reliably realize the stable self-sustaining ability of the mixture after ignition, thereby achieving a stable enhancement effect on ignition.

[0055] like Figure 1 As shown, according to one embodiment of the present invention, the cross-section of the pyrolysis fuel channel 111 is a regular shape with a length greater than its width, and the length direction of the cross-section is parallel to the high-temperature gas heating side of the plate-shaped body 11. In this embodiment, the cross-section of the pyrolysis fuel channel 111 can be set as rectangular, and its long side is parallel to the high-temperature gas heating side of the plate-shaped body 11. This can sufficiently increase the heat exchange area between the pyrolysis fuel channel 111 and the high-temperature gas heating side, thereby providing the pyrolysis fuel channel 111 with a more adequate high-temperature environment, which is more beneficial for maintaining a continuous and stable output of the mixture. Of course, in other configurations, the cross-section of the pyrolysis fuel channel 111 can also be set as an oblong shape. In this case, the arc-shaped edge at the end position can effectively increase the area of ​​the inner wall of the entire pyrolysis fuel channel 111, which is more beneficial for increasing the area of ​​the pyrolysis catalyst, thereby more effectively maintaining the amount of mixture generated. Furthermore, the elongated oval shape allows for a partial reduction in the wall thickness between adjacent pyrolysis fuel channels 111, thus narrowing and limiting the heat conduction path. This facilitates greater heat absorption within the pyrolysis fuel channels 111, which is beneficial for maintaining a high-temperature environment within them. In other embodiments, the long side of the pyrolysis fuel channel 111 cross-section can be further wavy. This effectively maintains the overall structural strength while increasing the wall area to accommodate the amount of pyrolysis catalyst. The partially thinned wall further enhances heat absorption capacity.

[0056] Furthermore, the cross-section of the non-pyrolysis fuel channel 112 is a regular shape with a length greater than its width, and the length direction of the non-pyrolysis fuel channel 112 is set at an angle to the high-temperature gas heating side of the plate-shaped main body 11. In this embodiment, the inclined setting of the non-pyrolysis fuel channel 112 relative to the high-temperature gas heating side effectively reduces the contact area between the non-pyrolysis fuel channel 112 and the pyrolysis fuel channel 111. As a result, the non-pyrolysis fuel channel 112 mainly plays the role of heat absorption and cooling. Under the condition that the liquid ammonia inside is evaporated and vaporized, pyrolysis basically does not occur. Moreover, the small contact area with the pyrolysis fuel channel 111 effectively avoids the heat loss in the pyrolysis fuel channel 111, which is beneficial to ensuring the stability of the high-temperature environment in the pyrolysis fuel channel 111.

[0057] Furthermore, based on the inclined non-pyrolysis fuel channel 112, more rib-shaped structures are formed in the partition wall between adjacent non-pyrolysis fuel channels 112, so as to reduce the heat absorption while increasing the load-bearing capacity of the engine wall structure, making the structural reliability of the plate-shaped main body 11 more excellent.

[0058] In this embodiment, the cross-section of the non-pyrolysis fuel channel 112 can be set to one of rectangle, oblong, or ellipse, thereby effectively reducing the contact area between it and the pyrolysis fuel channel 111 when it is arranged at an angle.

[0059] like Figure 1 As shown, according to one embodiment of the present invention, the length direction of the non-pyrolysis fuel channel 112 is perpendicular to the high-temperature gas heating side of the plate-shaped body 11. In this embodiment, the length direction of the non-pyrolysis fuel channel 112 is perpendicular to the length direction of the pyrolysis fuel channel 111, thereby making the heat transfer area between the non-pyrolysis fuel channel 112 and the pyrolysis fuel channel 111 smaller, and making its processing more convenient.

[0060] like Figure 1 As shown, according to one embodiment of the present invention, the cross-sectional shapes of the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 are identical. In this embodiment, the cross-sections of the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 are preferably set to rectangles with the same dimensions, so that when they are arranged perpendicularly to each other, the input of liquid ammonia in their channels can be more easily and precisely matched and controlled. This allows the layered channels to achieve their respective functional effects under different input conditions. For example, in the pyrolysis fuel channel 111, liquid ammonia flows at a low speed and the evaporation, vaporization and pyrolysis processes are fully realized under high temperature and low pressure, while in the non-pyrolysis fuel channel 112, it flows at a high mass flow rate and high speed, thereby generating a large amount of mainstream ammonia gas to achieve stable support of the mainstream ammonia flame after ignition.

[0061] In this embodiment, the cross-sectional length of the pyrolysis fuel channel 111 can be set to 5 mm and the width can be set to 1 mm; the cross-sectional length of the non-pyrolysis fuel channel 112 can be set to 5 mm and the width can be set to 1 mm.

[0062] like Figure 1 As shown, according to one embodiment of the present invention, the pyrolysis fuel channel 111 can be configured as one of a linear channel, a wave-shaped channel, a spiral channel, or a detour channel. Correspondingly, the non-pyrolysis fuel channel 112 can be configured as one of a linear channel, a wave-shaped channel, a spiral channel, or a detour channel. The configuration can be selected according to actual needs, and will not be elaborated here.

[0063] like Figure 1 As shown, according to one embodiment of the present invention, along the planar direction of the high-temperature gas heating side of the plate-shaped main body 11, a plurality of pyrolysis fuel channels 111 and a plurality of non-pyrolysis fuel channels 112 are equally spaced. The interval between the pyrolysis fuel channels 111 is greater than or equal to 1 mm, i.e., the wall thickness between adjacent pyrolysis fuel channels 111; the interval between the non-pyrolysis fuel channels 112 is greater than or equal to 1 mm, i.e., the wall thickness between adjacent non-pyrolysis fuel channels 112; furthermore, the interval between the pyrolysis fuel channels 111 and the non-pyrolysis fuel channels 112 is greater than or equal to 1 mm, i.e., the wall thickness between adjacent non-pyrolysis fuel channels 112 and pyrolysis fuel channels 111. In this embodiment, the pyrolysis fuel channels 111 and the non-pyrolysis fuel channels 112 are preferably configured as linear channels or corrugated channels, so that they can cover the corresponding areas based on the equally spaced arrangement, thereby achieving sufficient heat exchange capacity. In this embodiment, the extending directions of the pyrolysis fuel channels 111 and the non-pyrolysis fuel channels 112 can be parallel or angled to each other, thereby meeting different heat exchange requirements.

[0064] According to another embodiment of the present invention, along the planar direction of the high-temperature gas heating side of the plate-shaped body 11, both the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 can be configured as one. In this case, it is preferred that the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 be configured as a spiral channel or a meandering channel, so that the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 can fully cover the corresponding area, so that they have sufficient heat exchange capacity.

[0065] like Figure 1As shown, according to one embodiment of the present invention, the cracking catalyst has a temperature tolerance greater than 800°C and a cracking activity decay rate of less than 3% / 100h. This fully ensures the applicability of the combustion chamber of the ramjet propulsion system using this cracking catalyst, and also allows for repeated use in a short period. In this embodiment, the cracking catalyst can be a ruthenium-based catalyst (Ru / SS-316L), which is deposited onto the inner wall of the cracking fuel channel 111 by plating to form a corresponding cracking catalyst layer. In this embodiment, based on the cracking catalyst, ammonia can achieve endothermic reaction during the cracking process (66 kJ / mol), thereby reducing the wall temperature of the plate-shaped main body 11 by 200-250°C. With excellent ammonia cracking efficiency, the superior endothermic cooling performance makes this solution more reliable in high-temperature environments.

[0066] In this embodiment, the coating thickness of the cracking catalyst should not be too thick. Preferably, the flow resistance loss of the flow channel caused by the cracking catalyst should not exceed 5%. This can effectively ensure that the cracking fuel channel 111 of this solution has excellent mixture generation efficiency, and can also fully ensure the smooth flow of fluid therein, which is especially beneficial for ensuring the stable and high-speed injection of the mixture into the combustion chamber.

[0067] like Figure 1 As shown, according to one embodiment of the present invention, the plate-shaped main body 11 is an alloy plate, and the material composition of the alloy plate contains components that cause ammonia to crack. Since the non-cracking fuel channel 112 is the channel for forming mainstream ammonia, no catalyst layer is provided inside it. Instead, based on the partial components contained in the material of the plate-shaped main body 11 itself, a small amount of ammonia in the mainstream ammonia that is in contact with the wall surface undergoes low-degree cracking at a lower temperature (not higher than 400°C). On the one hand, it can further promote the rapid cooling of the wall surface based on the heat absorption of liquid ammonia evaporation and vaporization and the heat absorption of low-degree cracking at the boundary position. On the other hand, it can also mix a small amount of hydrogen in the mainstream ammonia, which is more beneficial for improving the ignition success rate of the mainstream ammonia and the stable self-sustaining after ignition enhancement.

[0068] In this embodiment, the plate-shaped main body 11 may be made of stainless steel plate containing nickel-based components.

[0069] Combination Figure 1 and Figure 2As shown, according to one embodiment of the present invention, this solution provides a combustion chamber employing the aforementioned ammonia fuel ignition enhancement device based on a double-layer circulation, comprising: a hollow combustion chamber body 2, a mixed gas nozzle 3, a mainstream ammonia nozzle 4, and a spark plug 5 disposed on the combustion chamber body 2; in this embodiment, at least a portion of the wall surface of the combustion chamber body 2 is made of the ammonia fuel ignition enhancement device 1, and the high-temperature gas heating side of the plate-shaped body 11 of the ammonia fuel ignition enhancement device 1 is located on the inner side to achieve direct contact with the high-temperature gas, thereby providing a high-temperature environment for the cracked fuel channel 111. Further, the cracked fuel channel 111 of the ammonia fuel ignition enhancement device 1 is connected to the mixed gas nozzle 3 via a first control valve, and the non-cracking fuel channel 112 is connected to the mainstream ammonia nozzle 4 via a second control valve.

[0070] In this embodiment, the combustion chamber body 2 includes a cylindrical portion 21 and a recessed portion 22; wherein, the mixed gas nozzle 3, the mainstream ammonia nozzle 4, and the recessed portion 22 are arranged on the same side of the cylindrical portion 21; thus, along the incoming flow direction, the mixed gas nozzle 3 and the mainstream ammonia nozzle 4 are both located in front of the recessed portion 22, and the distance between the mixed gas nozzle 3 and the leading edge of the recessed portion 22 is greater than the distance between the mainstream ammonia nozzle 4 and the leading edge of the recessed portion 22.

[0071] In this embodiment, the spark plug 5 is disposed at the bottom of the recessed portion 22. The spark plug 5 is used to achieve the ignition function. Specifically, the spark plug 5 can be arranged at the center of the bottom of the recessed portion 22.

[0072] like Figure 2 As shown, according to one embodiment of the present invention, both the mixed gas nozzle 3 and the mainstream ammonia nozzle 4 are sonic straight nozzles.

[0073] like Figure 2 As shown, according to one embodiment of the present invention, the rear wall surface of the cavity portion 22 is an inclined wall surface, and its inclination angle can be set to 45°.

[0074] like Figure 2As shown, according to one embodiment of the present invention, the distance between the mixed gas nozzle 3 and the leading edge of the concave cavity portion 22 is 1.5D, and the distance between the mainstream ammonia nozzle 4 and the leading edge of the concave cavity portion 22 is 0.5D, where D represents the depth of the concave cavity portion 22. With the above arrangement, based on the arrangement position of the mixed gas nozzle 3, a transverse sonic jet can be injected from the leading edge of the concave cavity portion 22 at a distance of 1.5D, where transverse refers to the direction perpendicular to the incoming vertical flow. For the formation of the sonic jet, it is only necessary to control the injection pressure to exceed a preset value to form a sonic jet after it exits the nozzle. Thus, a jet wake is formed in the supersonic airflow, and part of the mixed gas is drawn into the concave cavity 22 by the concave cavity portion 22. As a result, based on the hydrogen content of more than 35% in the mixed gas, the ignition delay of the mixed gas is controlled within the range of less than 0.08 ms. Compared with the ignition requirement of more than 2 ms for pure ammonia, it has extremely high ignition timeliness and ignition efficiency. Therefore, based on the self-ignition of the rich hydrogen, a stable mixed gas flame can be formed, achieving the effect of enhanced ignition.

[0075] Furthermore, based on the arrangement of the mainstream ammonia nozzle 4, the mainstream ammonia gas can be injected into the combustion chamber as a transverse sonic jet from the leading edge of the cavity at 0.5D. Under the action of a stable gas-mixed flame, the mainstream ammonia gas can be effectively ignited, allowing the flame to extend to the entire cavity shear layer of the cavity portion 22, thus achieving the formation of a stable ammonia flame under ignition enhancement. Here, transverse refers to the direction perpendicular to the incoming flow. For the formation of the sonic jet, it is only necessary to control the injection pressure to exceed a preset value to form a sonic jet after it is ejected from the nozzle.

[0076] Combination Figure 1 and Figure 2 As shown, according to one embodiment of the present invention, when only a portion of the wall surface of the combustion chamber body 2 is made of the ammonia fuel ignition enhancement device 1, the ammonia fuel ignition enhancement device 1 can be arranged in the high-temperature region of the combustion chamber body 2 (such as a portion of the cylindrical portion 21 and / or a portion of the cavity portion 22) to achieve the corresponding heat exchange effect and the corresponding ammonia cracking effect. The ammonia fuel ignition enhancement device 1 can be installed on the combustion chamber body 2 in a fitted manner, so that the high-temperature gas heating side of the plate-shaped body 11 of the ammonia fuel ignition enhancement device 1 forms a portion of the inner wall surface of the combustion chamber body 2, thereby achieving sufficient contact with the high-temperature gas. Alternatively, the side wall of a predetermined area of ​​the combustion chamber body 2 can be used as the plate-shaped body 11 of the ammonia fuel ignition enhancement device 1. The ammonia fuel ignition enhancement device 1 can be formed by directly machining the corresponding cracked fuel channel 111 and non-cracking fuel channel 112 in the corresponding predetermined area (such as a portion of the cylindrical portion 21 and / or a portion of the cavity portion 22). The machining method can be achieved by 3D printing, machining, etc., which will not be elaborated here.

[0077] In this embodiment, since the formed mixed gas and mainstream ammonia need to be sent to the mixed gas nozzle 3 and mainstream ammonia nozzle 4 respectively, external pipeline connection or corresponding connection passage can be directly processed on the combustion chamber body 2 for connection. As long as the stable and reliable delivery of the mixed gas and mainstream ammonia can be achieved, it will not be elaborated here.

[0078] Combination Figure 1 and Figure 2 As shown, according to another embodiment of the present invention, when the entire wall surface of the combustion chamber body 2 is made of the ammonia fuel ignition enhancement device 1, the ammonia fuel ignition enhancement device 1 is integral with the combustion chamber body 2, that is, the entire wall surface of the combustion chamber body 2 is directly used as the plate-shaped body 11. Thus, it is possible to distribute the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 in layers on the entire wall surface of the combustion chamber body 2. That is, the distribution range of the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 covers the entire area of ​​the wall surface of the cylinder part 21 and the cavity part 22. In this arrangement, the extension path of the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 is designed to achieve connection with the corresponding nozzle.

[0079] Combination Figure 1 and Figure 2 As shown, according to one embodiment of the present invention, the inlets of the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 on the combustion chamber body 2 can be set according to actual needs. For example, they can be set at the end of the combustion chamber body 2 in the incoming flow direction, or they can be set on the outer wall of the combustion chamber body 2, as long as they can meet the need for convenient connection with the external ammonia fuel source. The outlets of the pyrolysis fuel channel 111 and the non-pyrolysis fuel channel 112 are connected to the corresponding nozzles based on the set external pipeline or internal channel path. The specific setting method is only required to meet the need for reliable and stable connection, and will not be described in detail here.

[0080] According to one embodiment of the present invention, this solution provides an ignition method for the aforementioned combustion chamber, comprising:

[0081] S1. Connect the cracked fuel channel 111 and the non-cracking fuel channel 112 of the ammonia fuel ignition enhancement device 1 to the ammonia fuel source respectively, wherein liquid ammonia is input into the cracked fuel channel 111 under the first preset condition and liquid ammonia is input into the non-cracking fuel channel 112 under the second preset condition.

[0082] S2. The combustion chamber body 2 receives a supersonic inflow;

[0083] S3. Based on the first control valve, the mixture formed in the cracked fuel passage 111 is injected into the combustion chamber body 2 as a transverse sonic jet, and the mixture is ignited by the spark plug 5;

[0084] S4. After the mixed gas flame continues to burn for a preset time, the mainstream ammonia gas formed in the non-pyrolysis fuel channel 112 is controlled to be injected into the combustion chamber body 2 in a transverse sonic jet based on the second preset condition. The mainstream ammonia gas is ignited by the mixed gas flame to achieve enhanced ignition of ammonia fuel until the combustion flame extends to the entire concave cavity shear layer, thus completing the combustion chamber ignition.

[0085] According to one embodiment of the present invention, in step S1, the step of inputting liquid ammonia into the pyrolysis fuel channel 111 under the first preset conditions includes: the flow rate of liquid ammonia and the pressure of liquid ammonia, thereby realizing the gasification and pyrolysis of liquid ammonia in the pyrolysis fuel channel 111 under low flow rate and low pressure.

[0086] Furthermore, in the step of inputting liquid ammonia into the non-cracking fuel channel 112 under the second preset conditions, the second preset conditions include: the flow rate of liquid ammonia and the pressure of liquid ammonia, thereby achieving the vaporization of liquid ammonia at a high flow rate in the non-cracking fuel channel 112 and forming a large flow of mainstream ammonia gas.

[0087] According to one embodiment of the present invention, in step S2, the step of inputting a supersonic flow into the combustion chamber body 2, the supersonic flow is a supersonic airflow.

[0088] According to one embodiment of the present invention, in step S3, after the mixture flame continues to burn for a preset time, the preset time is greater than or equal to 500ms.

[0089] According to one embodiment of the present invention, in step S3, where the mainstream ammonia gas formed in the non-pyrolysis fuel channel 112 is controlled to be injected into the combustion chamber body 2 as a transverse sonic jet based on the second preset conditions, the mixed gas and the mainstream ammonia gas are input at a fixed flow rate ratio, and the fixed flow rate ratio of the mixed gas and the mainstream ammonia gas is greater than or equal to 0.28:1. Therefore, the combustion process can be flexibly controlled based on different flow rate ratios, effectively ensuring the working stability of this solution and improving its working performance.

[0090] To further illustrate this plan, further examples will be provided.

[0091] Example 1

[0092] Based on the aforementioned setup, a corresponding combustion chamber is constructed, and the cracked fuel channel 111 and non-cracking fuel channel 112 of the ammonia fuel ignition enhancement device 1 are respectively connected to the ammonia fuel source, and the combustion chamber body 2 is input with a supersonic flow.

[0093] A fixed flow rate of air-fuel mixture is preferentially introduced into the combustion chamber, and the mixture is ignited by spark plug 5 to form a stable air-fuel flame.

[0094] The combustion flow field was stabilized at intervals of more than 500 ms, and the mixed gas and mainstream ammonia were input at a flow ratio of 0.28:1. The propagation process of the mixed gas flame and the ignited mainstream ammonia flame was as follows: Figure 3 As shown. By Figure 3 It can be seen that ammonia gas, which cannot be ignited by conventional methods, achieves synchronous combustion of mainstream ammonia gas under the ignition enhancement effect of the mixed gas, which fully proves the effectiveness of this scheme.

[0095] Example 2

[0096] Based on Example 1, ignition enhancement experiments were conducted under different ratios of the mixed gas and mainstream ammonia by adjusting the flow rate ratio of the mixed gas and mainstream ammonia. Figure 4 As shown. By Figure 4 It can be seen that reliable ignition and stable mainstream ammonia combustion flames were obtained under different flow ratios, and different flame distribution areas were obtained, which further fully verified the effectiveness of the scheme and its control effect on mainstream ammonia combustion.

[0097] The above description is merely an example of a specific solution of the present invention. For any devices and structures not described in detail herein, it should be understood that they are implemented using common devices and methods already available in the art.

[0098] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Those skilled in the art will recognize that the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ammonia fuel ignition enhancement device based on two-layer circulation, characterized by, The device comprises: a plate-shaped body (11); a pyrolysis fuel passage (111) and a non-pyrolysis fuel passage (112) are arranged in the plate-shaped body (11) in the thickness direction, and the pyrolysis fuel passage (111) is adjacent to the high-temperature gas heating side of the plate-shaped body (11); an inner wall surface of the pyrolysis fuel passage (111) is provided with a pyrolysis catalyst; liquid ammonia flowing through the pyrolysis fuel passage (111) is pyrolyzed to produce mixed gas containing hydrogen under the action of high temperature and the pyrolysis catalyst; liquid ammonia flowing through the non-pyrolysis fuel passage (112) absorbs heat emitted by the pyrolysis fuel passage (111) to form main ammonia gas; based on time sequence control, the mixed gas flame formed by igniting the mixed gas first ignites the main ammonia gas to form an ammonia flame, thereby realizing ignition enhancement of ammonia fuel; a cross section of the pyrolysis fuel passage (111) is a regular shape with a length greater than a width, and the length direction of the cross section is parallel to the high-temperature gas heating side of the plate-shaped body (11); a cross section of the non-pyrolysis fuel passage (112) is a regular shape with a length greater than a width, and the length direction of the non-pyrolysis fuel passage (112) is arranged at an angle with the high-temperature gas heating side of the plate-shaped body (11).

2. The dual-layer cycle based ammonia fuel ignition enhancement device of claim 1, wherein, The length direction of the non-pyrolysis fuel passage (112) is arranged perpendicularly to the high-temperature gas heating side of the plate-shaped body (11).

3. The dual-layer cycle based ammonia fuel ignition enhancement device of claim 2, wherein, The cross section shapes of the pyrolysis fuel passage (111) and the non-pyrolysis fuel passage (112) are consistent.

4. The dual-layer cycle based ammonia fuel ignition enhancement device of claim 3, wherein, A plurality of pyrolysis fuel passages (111) are arranged at equal intervals along the planar direction of the high-temperature gas heating side of the plate-shaped body (11), and a plurality of non-pyrolysis fuel passages (112) are arranged at equal intervals.

5. The dual cycle based ammonia fuel ignition enhancement device according to any one of claims 1 to 4, characterized in that, The pyrolysis catalyst has a tolerance temperature greater than 800℃ and a pyrolysis activity decay rate less than 3% / 100h.

6. The dual cycle based ammonia fuel ignition enhancement device according to any one of claims 1 to 4, characterized in that, The plate-shaped body (11) is an alloy plate body, and the material composition of the alloy plate body contains a component that causes ammonia to be pyrolyzed.

7. A combustion chamber employing the dual-layer cycle based ammonia fuel ignition enhancement device according to any one of claims 1 to 6, characterized in that, The device comprises: a hollow combustion chamber body (2), a mixed gas nozzle (3), a main ammonia gas nozzle (4) and a spark plug (5) arranged on the combustion chamber body (2); at least part of the wall surface of the combustion chamber body (2) is made of the ammonia fuel ignition enhancement device (1), and the high-temperature gas heating side of the plate-shaped body (11) of the ammonia fuel ignition enhancement device (1) is located on the inner side; the pyrolysis fuel passage (111) of the ammonia fuel ignition enhancement device (1) is connected to the mixed gas nozzle (3) based on a first control valve, and the non-pyrolysis fuel passage (112) is connected to the main ammonia gas nozzle (4) based on a second control valve; the combustion chamber body (2) comprises: a cylinder portion (21) and a concave cavity portion (22); the mixed gas nozzle (3), the main ammonia gas nozzle (4) and the concave cavity portion (22) are arranged on the same side of the cylinder portion (21); in the direction of the incoming flow, the mixed gas nozzle (3) and the main ammonia gas nozzle (4) are both arranged in front of the concave cavity portion (22), and the interval between the mixed gas nozzle (3) and the front edge of the concave cavity portion (22) is greater than the interval between the main ammonia gas nozzle (4) and the front edge of the concave cavity portion (22); the spark plug (5) is arranged at the bottom of the concave cavity portion (22).

8. The combustion chamber of claim 7, wherein The mixed gas nozzle (3) is spaced apart from the front edge of the cavity portion (22) by 1.5D, and the main stream ammonia gas nozzle (4) is spaced apart from the front edge of the cavity portion (22) by 0.5D, wherein D represents the depth of the cavity portion (22).

9. A method of igniting a combustion chamber as claimed in any one of claims 7 or 8, characterised in that, Comprise: S1. The cracking fuel channel (111) and the non-cracking fuel channel (112) of the ammonia fuel ignition enhancement device (1) are respectively connected to an ammonia fuel source, wherein liquid ammonia is input into the cracking fuel channel (111) under a first preset condition, and liquid ammonia is input into the non-cracking fuel channel (112) under a second preset condition; S2. The combustion chamber body (2) inputs supersonic incoming flow; S3. Based on the first control valve, the mixed gas formed in the cracking fuel channel (111) is injected into the combustion chamber body (2) in the form of a transverse sonic jet, and the mixed gas is ignited based on the spark plug (5); S4. After the mixed gas flame continues to burn for a preset time, the main stream ammonia gas formed in the non-cracking fuel channel (112) is injected into the combustion chamber body (2) in the form of a transverse sonic jet based on the second preset condition, and the main stream ammonia gas is ignited based on the mixed gas flame, thereby achieving ignition enhancement of the ammonia fuel, until the combustion flame expands to the entire cavity shear layer, and the ignition of the combustion chamber is completed.

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