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

Abstract

The invention relates to an ammonia fuel ignition enhancing device based on double-layer circulation, a combustion chamber and an ignition method. A cracking fuel channel and a non-cracking fuel channel are arranged in the plate-shaped main body in a layered mode in the thickness direction, and the cracking fuel channel is adjacent to the high-temperature fuel gas heating side of the plate-shaped main body. A cracking catalyst is arranged on the inner wall surface of the cracking fuel channel; the liquid ammonia flowing through the cracking fuel channel is cracked under the action of high temperature and a cracking catalyst to generate hydrogen-containing mixed gas; the liquid ammonia flowing through the non-cracking fuel channel absorbs heat emitted by the cracking fuel channel to form mainstream ammonia gas; on the basis of time sequence control, mixed gas flames formed by igniting mixed gas firstly ignite mainstream ammonia gas to form ammonia flames, and ignition enhancement of ammonia fuel is achieved. According to the scheme, by designing the double-layer cooling channel, reliable guarantee can be provided for ignition enhancement of ammonia fuel and improvement of the success rate of ignition on the basis of the generated mixed gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerospace, and in particular to an ammonia fuel ignition enhancement device based on double-layer circulation, a combustion chamber and an ignition method. BACKGROUND

[0002] In the field of aircraft power, ramjet propulsion system has become an ideal power device for current aircraft due to its unique advantages. This system can capture oxygen in the air to react with fuel, has high specific impulse, simple structure and other significant characteristics, and therefore is highly concerned in the fields of aerospace, etc. In practical applications, the ramjet propulsion system often uses fuel regenerative cooling to achieve structural thermal protection, so as to ensure that the system can withstand high temperature environment during high-speed flight.

[0003] However, there is a serious problem with traditional hydrocarbon fuels under high temperature conditions, i.e. coking. When traditional hydrocarbon fuels are used for regenerative cooling, coking will cause carbon deposition in the regenerative cooling channel. With the continuous accumulation of carbon deposition, the cooling effect of the channel gradually deteriorates, and eventually the key structure such as engine may be damaged due to overheating. This problem has become a core bottleneck that needs to be broken through for the ramjet propulsion system under high-speed and reusable conditions, and seriously limits the performance improvement and application range expansion of the ramjet propulsion system.

[0004] In view of the limitations of traditional hydrocarbon fuels, ammonia fuel, as a potential alternative fuel, has gradually entered the research field. Compared with 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 the ramjet propulsion system; and no coking phenomenon occurs during cracking, avoiding the risk of cooling channel blockage.

[0005] However, ammonia fuel also faces some challenges in practical applications. The self-ignition temperature of ammonia is as high as 650℃, and the residence time in the combustion chamber is extremely short, usually less than 1ms. Under this condition, the traditional ignition method often has a high failure rate, and it is difficult to achieve stable ignition of the ramjet propulsion system, thereby affecting the normal operation of the system. Although active fuel ignition can be used to solve the ammonia ignition problem, such as using hydrogen to ignite ammonia to form a stable flame in the traditional scheme. However, this method requires carrying a high-pressure hydrogen tank, which not only increases the complexity of the system, but also brings high safety risks. After all, high-pressure hydrogen tanks may cause serious safety accidents during storage and use, such as leakage or other accidents.

[0006] It is worth noting that ammonia as a good carrier of hydrogen can generate hydrogen under the condition of high temperature or catalytic cracking, and hydrogen has stable and reliable ignition combustion ability, which makes ammonia fuel have the potential to realize stable operation of the power device at a higher flight speed. However, ammonia cracking faces two big problems. On the one hand, the cracking temperature of ammonia is high, and it is difficult to reach the required temperature for cracking under normal circumstances, resulting in difficulty in cracking of ammonia. On the other hand, ammonia has strong gasification endothermic capacity, which further increases the difficulty of reaching the cracking temperature. If an external cracker is used to promote the cracking of ammonia, additional energy supply is required, which undoubtedly increases the weight of the system, and the increase in weight will adversely affect the performance of the aircraft.

[0007] Therefore, although ammonia fuel has certain application potential in ramjet propulsion systems, many problems such as ignition difficulty and cracking difficulty need to be overcome to realize its actual application. Therefore, it is urgent to propose a more efficient, safe and reliable ammonia fuel application technology, which has important significance for promoting the development of ramjet propulsion systems. SUMMARY

[0008] The technical problem to be solved by the present application is to provide an ammonia fuel ignition enhancement device based on double-layer circulation.

[0009] To achieve the above-mentioned application purposes, the present application provides an ammonia fuel ignition enhancement device based on double-layer circulation, comprising: a plate-shaped main body; A cracking fuel channel and a non-cracking fuel channel are arranged in the plate-shaped main body in the thickness direction, and the cracking fuel channel is adjacent to the high-temperature gas heating side of the plate-shaped main body; The inner wall surface of the cracking fuel channel is provided with a cracking catalyst; The liquid ammonia flowing through the cracking fuel channel is cracked to generate a mixed gas containing hydrogen under the action of high temperature and the cracking catalyst; The liquid ammonia flowing through the non-cracking fuel channel absorbs the heat emitted by the cracking fuel channel to form a main stream of ammonia gas; Based on time sequence control, the mixed gas flame formed by igniting the mixed gas first ignites the main stream of ammonia gas to form an ammonia flame, thereby realizing the ignition enhancement of ammonia fuel.

[0010] According to one aspect of the present application, the cross section of the cracking fuel channel 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 main body; The cross section of the non-cracking fuel channel is a regular shape with a length greater than a width, and the length direction of the non-cracking fuel channel is arranged at an angle with the high-temperature gas heating side of the plate-shaped main body.

[0011] According to one aspect of the present application, the length direction of the non-cracking fuel channel is arranged vertically to the high-temperature gas heating side of the plate-shaped main body.

[0012] According to an aspect of the present application, the cross-sectional shape of the pyrolysis fuel passage and the non-pyrolysis fuel passage is uniform.

[0013] According to an aspect of the present application, a plurality of pyrolysis fuel passages are arranged at equal intervals along the plane direction of the high-temperature gas heating side of the plate-shaped body, and a plurality of non-pyrolysis fuel passages are arranged at equal intervals.

[0014] According to an aspect of the present application, the pyrolysis catalyst has a tolerance temperature greater than 800°C and a pyrolysis activity decay rate less than 3% / 100h.

[0015] According to an aspect of the present application, the plate-shaped body is an alloy plate body, and the material composition of the alloy plate body contains a component that causes ammonia to be pyrolyzed.

[0016] To achieve the above-mentioned object, the present application provides a combustion chamber using the aforementioned ammonia fuel ignition enhancement device based on double-layer circulation, comprising: a hollow combustion chamber body, a mixed gas nozzle, a main stream ammonia gas nozzle and a spark plug arranged on the combustion chamber body; At least part of the wall surface of the combustion chamber body is made of the 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; The pyrolysis fuel passage of the ammonia fuel ignition enhancement device is connected to the mixed gas nozzle based on a first control valve, and the non-pyrolysis fuel passage is connected to the main stream ammonia gas nozzle based on a second control valve; The combustion chamber body comprises: a cylinder portion and a concave cavity portion; The mixed gas nozzle, the main stream ammonia gas nozzle and the concave cavity portion are arranged on the same side of the cylinder portion; Along the incoming flow direction, the mixed gas nozzle and the main stream ammonia gas nozzle are both arranged in front of the concave cavity portion, and the interval between the mixed gas nozzle and the front edge of the concave cavity portion is greater than the interval between the main stream ammonia gas nozzle and the front edge of the concave cavity portion; The spark plug is arranged at the bottom of the concave cavity portion.

[0017] According to an aspect of the present application, the interval between the mixed gas nozzle and the front edge of the concave cavity portion is 1.5D, and the interval between the main stream ammonia gas nozzle and the front edge of the concave cavity portion is 0.5D, wherein D represents the depth of the concave cavity portion.

[0018] To achieve the above-mentioned object, the present application provides an ignition method for the aforementioned combustion chamber, comprising: S1. The pyrolysis fuel passage and the non-pyrolysis fuel passage of the ammonia fuel ignition enhancement device are connected to the ammonia fuel source respectively, wherein liquid ammonia is input to the pyrolysis fuel passage under a first preset condition, and liquid ammonia is input to the non-pyrolysis fuel passage under a second preset condition; S2. The combustion chamber body inputs supersonic incoming flow; S3. Control the mixed gas formed in the cracking fuel channel to be injected into the combustion chamber body in a transverse sonic speed jet flow based on the first control valve, and ignite the mixed gas based on the spark plug; S4. After the mixed gas flame continues to burn for a preset time, control the main stream ammonia gas formed in the non-cracking fuel channel to be injected into the combustion chamber body in a transverse sonic speed jet flow based on a second preset condition, ignite the main stream ammonia gas based on the mixed gas flame, achieve ignition enhancement of the ammonia fuel, and expand the combustion flame to the entire recessed cavity shear layer to complete the ignition of the combustion chamber.

[0019] According to one scheme of the present application, the inner cracking fuel channel can greatly increase the ammonia fuel cracking rate under the heating action of high-temperature gas, and can generate a stable hydrogen source, thereby effectively reducing the ignition delay time, which is more beneficial to achieve ignition enhancement of ammonia fuel and improve the success rate of ignition.

[0020] According to one scheme of the present application, the present scheme can directly utilize the waste heat of the combustion chamber wall surface to achieve efficient cracking of ammonia fuel, without the need to set up an additional ammonia cracker, and also without additional cracking energy consumption, so that the combustion chamber system adopting the present scheme can be greatly reduced in weight and effectively reduce the overall complexity, so that the present scheme has a more optimal application prospect.

[0021] According to one scheme of the present application, the present scheme does not need to carry an additional high-pressure hydrogen cylinder, and compared with the traditional hydrogen ignition method, the overall complexity of the system is greatly reduced.

[0022] According to one scheme of the present application, the present scheme can achieve double-layer heat insulation design based on the double-layer cooling channel under the condition of realizing different processing capabilities of ammonia fuel, so that the wall surface temperature presents a gradient reduction effect, greatly reducing the wall surface thermal stress of the combustion chamber adopting the present scheme, and more beneficial to ensure the stability of the overall material and structure.

[0023] According to one scheme of the present application, the inner cracking fuel channel of the present scheme can use ammonia fuel as the main functional structure for hydrogen production, which not only can provide mixed gas as an ignition source, but also can greatly utilize the heat conducted in the process of generating mixed gas, thereby greatly ensuring the stability and reliability of the wall surface structure; and the outer non-cracking fuel channel can further serve as a supplement for wall surface heat dissipation, more effectively ensuring the stability and reliability of the wall surface structure, and can further effectively utilize the residual heat to form a large amount of main stream ammonia gas, which is more beneficial to ensure the continuous and stable combustion after successful ignition, so that the combustion chamber adopting the present scheme has more excellent working performance.

[0024] According to one scheme of the present application, the scheme can realize the closed loop of the cavity energy based on the matching of the combustion effect of the mixed gas and the main flow gas, wherein the high-temperature injection of the mixed gas effectively reduces the ignition energy consumption, improves the stability of the flame and the ignition enhancement of the main flow ammonia gas. Thus, based on the matching of the ignition process of the mixed gas flame and the main flow ammonia gas injection timing, the ignition process is more reliable, and the combustion efficiency is higher.

[0025] According to one scheme of the present application, the scheme can realize the flexible and reliable regulation and control of the combustion flame distribution by controlling the different deployment ratios of the mixed gas and the main flow ammonia gas flow, which has important significance for improving the performance regulation and control ability of the engine in actual work.

[0026] According to one scheme of the present application, the mixed gas in the scheme is injected upstream of the cavity, and since it contains a large amount of hydrogen, it can self-ignite to form a stable flame, which provides reliable guarantee for providing an initial energy field. The main flow ammonia gas is injected in the near field closer to the cavity, which can be effectively ignited by the kernel of the mixed gas flame. Therefore, the scheme can still use the traditional transverse jet flow to cooperate with the cavity ignition scheme to realize stable ignition, which fully guarantees the development of the initial kernel and the stability of the flame. Thus, based on the timing cooperation of the injection process of the mixed gas and the main flow gas, stable ignition and combustion of the pure ammonia ramjet engine are realized.

[0027] According to one scheme of the present application, the scheme not only effectively improves the ignition reliability of the ammonia fuel ramjet propulsion system, but also fully utilizes the heat generated in the combustion process, so that the energy utilization rate of the scheme is higher.

[0028] According to one scheme of the present application, the scheme can fully utilize the heat distribution of different regions of the wall surface structure to realize the reliable work of the ammonia fuel overpressure propulsion system, and meet the performance needs of structural thermal protection and reliable ignition of the engine under high-speed conditions. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a structure diagram of the ammonia fuel ignition enhancement device based on the double-layer cycle of the present application; Figure 2 It is a structure diagram of the combustion chamber of the present application; Figure 3 It is a flame distribution diagram of the process of the mixed gas igniting the main flow ammonia gas in Example 1 of the present application, wherein, Figure 3 (a) indicates the self-ignition diagram of the mixed gas at the far end of the combustion chamber downstream of the cavity part, Figure 3 (b) indicates the development and growth diagram of the flame at the far end of the combustion chamber, Figure 3 (c) indicates the propagation diagram of the flame along the combustion chamber upstream, Figure 3 (d) indicates the propagation diagram of the flame along the cavity part rear along into the cavity part flame stabilization zone, 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; 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; 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

[0030] 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.

[0031] 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.

[0032] like Figure 1As shown, according to an embodiment of the present application, the double-layer circulation based ammonia fuel ignition enhancement device of the present application comprises: a plate-shaped body 11; wherein the plate-shaped body 11 can realize heat exchange of liquid ammonia fuel, so as to realize gasification of the ammonia fuel while realizing cooling of the whole plate-shaped body 11, so as to achieve stable and reliable overall structure. To this end, the plate-shaped body 11 is layered in the thickness direction and is provided with a cracking fuel channel 111 and a non-cracking fuel channel 112, and the cracking fuel channel 111 is adjacent to the high-temperature fuel gas heating side of the plate-shaped body 11; correspondingly, the non-cracking fuel channel 112 is adjacent to the cooling side of the plate-shaped body 11 away from the high-temperature fuel gas, so that a temperature difference between the double-layer channels can be generated to realize layered cooling of the plate-shaped body 11 and different heating effects of the liquid ammonia fuel. In this embodiment, the inner wall surface of the cracking fuel channel 111 is provided with a cracking catalyst; thus, based on the double-sided channel, the functions of fuel cracking, wall cooling and ignition enhancement can be integrated in the plate-shaped body 11, so that the present scheme can realize complex functions based on a simple structure, so as to have more excellent ignition enhancement effect and more reliable service life and stability; specifically, the liquid ammonia flowing through the cracking fuel channel 111 is cracked to produce hydrogen-containing mixed gas under the action of high temperature and the cracking catalyst; the liquid ammonia flowing through the non-cracking fuel channel 112 absorbs the heat emitted by the cracking fuel channel 111 to form main ammonia gas; under the condition of different gases formed in different channels, based on time sequence control, the mixed gas flame formed by the mixed gas is ignited first to ignite the main ammonia gas to form ammonia flame, so as to realize ignition enhancement of the ammonia fuel.

[0033] In this embodiment, in the cracking fuel channel 111, the liquid ammonia is first evaporated and gasified into ammonia gas under high temperature, and then based on the surrounding cracking catalyst and high temperature condition, the ammonia gas produces a cracking reaction (NH3→ 1.5H2+ 0.5N2) as the heat absorption increases, so that the mixed gas containing hydrogen gas is formed, wherein the formed mixed gas is hydrogen-rich gas.

[0034] In this embodiment, the content of hydrogen gas in the mixed gas is greater than 35%, so that the mixed gas formed by the present scheme has the effect of igniting the stable mixed gas flame based on the hydrogen gas self-ignition, so as to sufficiently and reliably realize the stable self-sustaining ability of the mixed gas after ignition, thereby realizing stable ignition enhancement effect.

[0035] As shown in the above embodiment, the present application can realize the functions of fuel cracking, wall cooling and ignition enhancement in one device, and can realize stable ignition enhancement of the ammonia fuel based on a simple structure, so as to have more excellent ignition enhancement effect and more reliable service life and stability. Figure 1As shown, according to an embodiment of the present application, the cross section of the cracking 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; in this embodiment, the cross section of the cracking fuel passage 111 can be set as a rectangle, and the long side thereof is parallel to the high-temperature gas heating side of the plate-shaped body 11, which can sufficiently increase the heat exchange area between the cracking fuel passage 111 and the high-temperature gas heating side, so that the cracking fuel passage 111 has a more sufficient high-temperature environment, which is more beneficial to maintaining the continuous and stable output of the mixed gas. Of course, in other setting modes, the cross section of the cracking fuel passage 111 can also be set as an oblong circle, so that the arc-shaped side at the end position can effectively increase the area of the inner side wall surface of the entire cracking fuel passage 111, which is more beneficial to increasing the setting area of the cracking catalyst, and thus is more effective to maintaining the generation amount of the mixed gas. In addition, the setting mode based on the oblong circle can also effectively reduce the wall thickness between the adjacent cracking fuel passages 111 at some positions, so that the heat conduction path is limited and reduced, which is more beneficial to making more heat be absorbed by the cracking fuel passage 111, and thus is more beneficial to guaranteeing the high-temperature environment in the cracking fuel passage 111. In addition, in other embodiments, the long side of the cross section of the cracking fuel passage 111 can be further set as a wavy surface, so that the overall structural strength can be effectively guaranteed, and the wall surface area can be increased to realize the setting amount of the cracking catalyst, and the heat absorption capacity can be improved based on the thinning of some wall surfaces.

[0036] Further, the cross section of the non-cracking fuel passage 112 is a regular shape with a length greater than a width, and the length direction of the non-cracking fuel passage 112 has an angle with the high-temperature gas heating side of the plate-shaped body 11; in this embodiment, the inclined setting mode of the non-cracking fuel passage 112 relative to the high-temperature gas heating side effectively reduces the contact area between the non-cracking fuel passage 112 and the cracking fuel passage 111, so that the non-cracking fuel passage 112 mainly plays a role of heat absorption and cooling, and the internal liquid ammonia is basically not cracked in the case of being evaporated and gasified, and the heat in the cracking fuel passage 111 is effectively prevented from escaping based on the small contact area with the cracking fuel passage 111, which is beneficial to guaranteeing the stability of the high-temperature environment in the cracking fuel passage 111.

[0037] In addition, the inclined setting of the non-cracking fuel passage 112 makes the interval wall between the adjacent non-cracking fuel passages 112 form more rib-shaped structures, so as to reduce the absorption of heat and increase the bearing capacity of the engine wall structure, so that the structural reliability of the plate-shaped body 11 is more excellent.

[0038] In the present embodiment, the cross section of the non-cracking fuel passage 112 can be set to one of a rectangle, an oblong, and an ellipse, so that the contact area between the non-cracking fuel passage 112 and the cracking fuel passage 111 is effectively reduced when arranged obliquely.

[0039] As shown in FIG. 1, according to an embodiment of the present application, the length direction of the non-cracking fuel passage 112 is arranged perpendicularly to the high-temperature gas heating side of the plate-shaped body 11. In the present embodiment, the length direction of the non-cracking fuel passage 112 is arranged perpendicularly to the length direction of the cracking fuel passage 111, so that the heat transfer area between the non-cracking fuel passage 112 and the cracking fuel passage 111 is smaller, and the processing is more convenient. Figure 1 As shown in FIG. 1, according to an embodiment of the present application, the cross section shape of the cracking fuel passage 111 and the non-cracking fuel passage 112 is consistent; in the present embodiment, the cross section of the cracking fuel passage 111 and the non-cracking fuel passage 112 is preferably set to a rectangle with the same size, so that when arranged perpendicularly to each other, the input of liquid ammonia in the passages can be more easily and accurately controlled, so that the layered passages realize their respective functional effects under different input conditions, for example, in the cracking fuel passage 111, the liquid ammonia flows at a low speed, and the evaporation and cracking processes are fully realized under high temperature and low pressure, while in the non-cracking fuel passage 112, the liquid ammonia flows at a high speed with a large mass flow, so that a large amount of main stream ammonia gas can be produced to stably support the main stream ammonia gas flame after ignition is completed.

[0040] Figure 1 In the present embodiment, the cross section length of the cracking fuel passage 111 can be set to 5 mm, and the width can be set to 1 mm; the cross section length of the non-cracking fuel passage 112 can be set to 5 mm, and the width can be set to 1 mm.

[0041] As shown in FIG. 1, according to an embodiment of the present application, the cracking fuel passage 111 can be set to one of a linear passage, a wave-shaped passage, a spiral-shaped passage, and a circuitous passage, and correspondingly, the non-cracking fuel passage 112 can be set to one of a linear passage, a wave-shaped passage, a spiral-shaped passage, and a circuitous passage, and the arrangement can be selected according to actual needs, which will not be described here.

[0042] As shown in FIG. 1, according to an embodiment of the present application, the cracking fuel passage 111 can be set to one of a linear passage, a wave-shaped passage, a spiral-shaped passage, and a circuitous passage, and correspondingly, the non-cracking fuel passage 112 can be set to one of a linear passage, a wave-shaped passage, a spiral-shaped passage, and a circuitous passage, and the arrangement can be selected according to actual needs, which will not be described here. Figure 1 As shown in FIG. 1, according to an embodiment of the present application, the cracking fuel passage 111 can be set to one of a linear passage, a wave-shaped passage, a spiral-shaped passage, and a circuitous passage, and correspondingly, the non-cracking fuel passage 112 can be set to one of a linear passage, a wave-shaped passage, a spiral-shaped passage, and a circuitous passage, and the arrangement can be selected according to actual needs, which will not be described here.

[0043] 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.

[0044] 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.

[0045] like Figure 1 As 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.

[0046] In the present embodiment, the plating thickness of the cracking catalyst should not be too thick, preferably, the flow passage modulus loss caused by the cracking catalyst should not exceed 5%, thereby, in the case of effectively ensuring the excellent mixed gas generation efficiency of the cracking fuel passage 111 of the present scheme, the smooth flow of the fluid therein can also be sufficiently ensured, which is more beneficial to ensure the stable high-speed injection of the mixed gas to the combustion chamber.

[0047] As shown in Figure 1 According to an embodiment of the present application, the plate-shaped body 11 is an alloy plate body, and the material composition of the alloy plate body contains a component that causes cracking of ammonia; wherein, since the non-cracking fuel passage 112 is a passage for forming the main flow of ammonia, no catalyst layer is arranged therein, but based on the partial component contained in the material of the plate-shaped body 11, a small amount of ammonia in the main flow of ammonia that contacts the wall surface is cracked at a low temperature (not higher than 400°C), on the one hand, the rapid cooling of the wall surface can be further promoted based on the heat absorption of the evaporation and gasification of liquid ammonia and the low degree of cracking heat absorption at the boundary position, on the other hand, a small amount of hydrogen can also be mixed in the main flow of ammonia, thereby, it is more beneficial to improve the ignition success rate of the main flow of ammonia and the stable self-sustaining after the ignition enhancement.

[0048] In the present embodiment, the plate-shaped body 11 can adopt a stainless steel plate body containing a nickel-based component.

[0049] As shown in Figure 1 and Figure 2 According to an embodiment of the present application, the present scheme provides a combustion chamber using the aforementioned ammonia fuel ignition enhancement device based on double-layer circulation, comprising: a hollow combustion chamber body 2, a mixed gas nozzle 3, a main flow of ammonia nozzle 4 and a spark plug 5 arranged on the combustion chamber body 2; in the present embodiment, 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 to realize direct contact with the high-temperature gas, thereby providing a high-temperature environment for the cracking fuel passage 111. Further, the cracking fuel passage 111 of the ammonia fuel ignition enhancement device 1 is connected to the mixed gas nozzle 3 based on the first control valve, and the non-cracking fuel passage 112 is connected to the main flow of ammonia nozzle 4 based on the second control valve.

[0050] In the present embodiment, the combustion chamber body 2 comprises: a cylinder portion 21 and a concave portion 22; wherein, the mixed gas nozzle 3, the main flow of ammonia nozzle 4 and the concave portion 22 are arranged on the same side of the cylinder portion 21; thereby, along the incoming flow direction, the mixed gas nozzle 3 and the main flow of ammonia nozzle 4 are both arranged in front of the concave portion 22, and the interval between the mixed gas nozzle 3 and the leading edge of the concave portion 22 is greater than the interval between the main flow of ammonia nozzle 4 and the leading edge of the concave portion 22.

[0051] In the embodiment, the spark plug 5 is arranged at the bottom of the cavity portion 22, and the spark plug 5 is arranged at the center of the bottom of the cavity portion 22 for realizing the ignition function.

[0052] As shown in Figure 2 the embodiment of the present application, the mixed gas nozzle 3 and the main flow ammonia gas nozzle 4 are both acoustic velocity straight nozzles.

[0053] As shown in Figure 2 the embodiment of the present application, the rear wall surface of the cavity portion 22 is an inclined wall surface, and the inclination angle thereof is set to 45°.

[0054] As shown in Figure 2 the embodiment of the present application, the interval between the mixed gas nozzle 3 and the front edge of the cavity portion 22 is 1.5D, and the interval between the main flow ammonia gas nozzle 4 and the front edge of the cavity portion 22 is 0.5D, wherein D represents the depth of the cavity portion 22. Through the above arrangement, based on the arrangement position of the mixed gas nozzle 3, the mixed gas can be injected from the front edge of the cavity portion 22 at 1.5D as a transverse acoustic velocity jet, wherein the transverse direction is perpendicular to the height flow. For the formation of the acoustic velocity jet, only the injection pressure needs to be controlled to be greater than a preset value, and the acoustic velocity jet can be formed after the nozzle is injected. Thus, the jet wake is formed in the supersonic airflow, and part of the mixed gas is entrained into the cavity backflow area of the cavity portion 22, thereby controlling the ignition delay of the mixed gas to be less than 0.08 ms based on the hydrogen content of more than 35% in the mixed gas, which has extremely high ignition timeliness and ignition efficiency compared with the ignition requirement of more than 2 ms of pure ammonia, and thus the entire mixed gas can be ignited by the hydrogen-rich spontaneous combustion, so as to form a stable mixed gas flame and achieve the effect of ignition enhancement.

[0055] Further, based on the arrangement position of the main flow ammonia gas nozzle 4, the main flow ammonia gas can be injected into the combustion chamber as a transverse acoustic velocity jet from the front edge of the cavity at 0.5D, and the main flow ammonia gas can be effectively ignited under the action of the stable mixed gas flame, so that the flame can be expanded to the entire cavity shear layer of the cavity portion 22, thereby realizing the stable ammonia flame formed under the ignition enhancement effect; wherein the transverse direction is perpendicular to the height flow. For the formation of the acoustic velocity jet, only the injection pressure needs to be controlled to be greater than a preset value, and the acoustic velocity jet can be formed after the nozzle is injected.

[0056] In combination with Figure 1 and Figure 2As shown, according to one embodiment of the present application, in the case that only part 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 area of the combustion chamber body 2 (such as part of the position of the barrel portion 21 and / or part of the position of the recessed cavity portion 22) to achieve the corresponding heat exchange effect and the corresponding ammonia cracking effect; wherein the ammonia fuel ignition enhancement device 1 can be installed on the combustion chamber body 2 in a fitting manner, so that the high-temperature gas heating side of the plate-shaped body 11 of the ammonia fuel ignition enhancement device 1 forms part of the inner wall surface of the combustion chamber body 2 to achieve sufficient contact with the high-temperature gas; of course, the side wall of the pre-set area of the combustion chamber body 2 can also be used as the plate-shaped body 11 of the ammonia fuel ignition enhancement device 1, and by directly processing the corresponding cracking fuel channel 111 and non-cracking fuel channel 112 in the corresponding pre-set area (such as part of the position of the barrel portion 21 and / or part of the position of the recessed cavity portion 22), the formation of the ammonia fuel ignition enhancement device 1 can be achieved, wherein the processing method can be realized by 3D printing, machining, etc., which will not be described here.

[0057] In the present embodiment, since the formed mixed gas and the main stream ammonia gas need to be sent to the mixed gas nozzle 3 and the main stream ammonia gas nozzle 4 respectively, for this purpose, the connection can be realized by using external pipeline connection or directly processing corresponding connection passages on the combustion chamber body 2, as long as the stable and reliable delivery of the mixed gas and the main stream ammonia gas can be realized, which will not be described here.

[0058] Combining Figure 1 and Figure 2 As shown, according to another embodiment of the present application, in the case that all the wall surfaces of the combustion chamber body 2 are made of the ammonia fuel ignition enhancement device 1, the ammonia fuel ignition enhancement device 1 is integrated with the combustion chamber body 2, i.e. directly using all the wall surfaces of the combustion chamber body 2 as the plate-shaped body 11, thereby the cracking fuel channel 111 and the non-cracking fuel channel 112 can be distributed on all the wall surfaces of the combustion chamber body 2, i.e. the distribution range of the cracking fuel channel 111 and the non-cracking fuel channel 112 covers all the areas of the wall surfaces of the barrel portion 21 and the recessed cavity portion 22, in this arrangement, the extension path of the cracking fuel channel 111 and the non-cracking fuel channel 112 can be designed to realize the connection with the corresponding nozzle.

[0059] Combining Figure 1 and Figure 2As shown, according to an embodiment of the present application, the inlet of the cracking fuel channel 111 and the non-cracking fuel channel 112 on the combustion chamber body 2 can be arranged according to actual needs, for example, can be arranged at the end of the incoming flow direction of the combustion chamber body 2, or can be arranged on the outer side wall surface of the combustion chamber body 2, as long as it can meet the needs of convenient connection with the external ammonia fuel source, and the outlet of the cracking fuel channel 111 and the non-cracking fuel channel 112 is connected to the corresponding nozzle based on the arranged external pipeline or internal channel path, and the specific arrangement mode can meet the reliable and stable connection, which will not be described here.

[0060] According to an embodiment of the present application, the present application provides an ignition method for the aforementioned combustion chamber, comprising: S1. The cracking fuel channel 111 and the non-cracking fuel channel 112 of the ammonia fuel ignition enhancement device 1 are connected to the 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. The mixed gas formed in the cracking fuel channel 111 is injected into the combustion chamber body 2 in a transverse sonic jet based on the first control valve, and the mixed gas is ignited based on the spark plug 5; S4. After the mixed gas flame burns 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 a transverse sonic jet based on the second preset condition, and the main stream ammonia gas is ignited based on the mixed gas flame, achieving ignition enhancement of the ammonia fuel, until the combustion flame expands to the entire cavity shear layer, completing the ignition of the combustion chamber.

[0061] According to an embodiment of the present application, in the step of inputting liquid ammonia into the cracking fuel channel 111 under a first preset condition in step S1, the first preset condition includes the flow rate of liquid ammonia and the pressure of liquid ammonia, so as to realize the gasification and cracking of liquid ammonia in the cracking fuel channel 111 under low flow rate and low pressure.

[0062] Further, in the step of inputting liquid ammonia into the non-cracking fuel channel 112 under a second preset condition, the second preset condition includes the flow rate of liquid ammonia and the pressure of liquid ammonia, so as to realize the gasification of liquid ammonia in the non-cracking fuel channel 112 under high flow rate and form a large flow rate of main stream ammonia gas.

[0063] According to an embodiment of the present application, in the step of inputting supersonic incoming flow into the combustion chamber body 2 in step S2, the supersonic incoming flow is a supersonic air flow.

[0064] According to an embodiment of the present application, in the step after the mixed gas flame burns for a preset time in step S3, the preset time is greater than or equal to 500 ms.

[0065] According to an embodiment of the present application, in step S3, the step of controlling the main flow of ammonia gas formed in the non-cracking fuel channel 112 to be injected into the combustion chamber body 2 in a transverse sonic jet based on the second preset condition, the mixed gas and the main flow of ammonia gas are input at a fixed ratio of flow rate, and the fixed ratio of the flow rate of the mixed gas and the main flow of ammonia gas is greater than or equal to 0.28:1. Thus, flexible regulation of the combustion process can be achieved based on different flow ratios, effectively ensuring the working stability of the present scheme and improving the working performance of the present scheme.

[0066] To further illustrate the present scheme, it is further exemplified.

[0067] Example 1 Based on the foregoing settings, a corresponding combustion chamber is constructed, and the cracking fuel channel 111 and the non-cracking fuel channel 112 of the ammonia fuel ignition enhancement device 1 are connected to the ammonia fuel source, respectively, and the combustion chamber body 2 inputs supersonic incoming flow.

[0068] The mixed gas is preferentially input into the combustion chamber at a fixed flow rate, and the mixed gas is ignited based on the spark plug 5 to form a stable mixed gas flame.

[0069] The combustion flow field is stabilized at intervals of 500 ms or more, and the mixed gas and the main flow of ammonia gas are input at a flow rate input ratio of 0.28:1, and the propagation process of the mixed gas flame and the ignited main flow of ammonia gas is as shown in Figure 3 It can be seen that the ammonia gas, which cannot be ignited by conventional means, is ignited synchronously by the mixed gas under the ignition enhancement of the mixed gas, fully proving the effectiveness of the present scheme. Figure 3

[0070] Example 2 On the basis of Example 1, by adjusting the flow ratio of the mixed gas and the main flow of ammonia gas, ignition enhancement experiments of different ratios of mixed gas and main flow of ammonia gas are carried out, and as shown in Figure 4 It can be seen that reliable ignition and stable main flow of ammonia gas combustion flame are obtained under different flow ratios, and different flame distribution regions are obtained, further fully verifying the effectiveness of the present scheme and the regulation effect on the main flow of ammonia gas combustion. Figure 4 The above content is only an example of the specific scheme of the present application, and for the devices and structures not described in detail, it should be understood that the general devices and general methods in the art are used to implement them.

[0071] The above content is only an example of the specific scheme of the present application, and for the devices and structures not described in detail, it should be understood that the general devices and general methods in the art are used to implement them.

[0072] ​The above merely describes one of the embodiments of the present application and is not used to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An ammonia fuel ignition enhancement device based on two-layer circulation, characterized by, include: Plate-shaped body (11); Within the plate-shaped main body (11), a pyrolysis fuel channel (111) and a non-pyrolysis fuel channel (112) are arranged in layers along the thickness direction, and the pyrolysis fuel channel (111) is adjacent to the high-temperature gas heating side of the plate-shaped main body (11). The inner wall of the pyrolysis fuel channel (111) is provided with a pyrolysis catalyst; Liquid ammonia flowing through the cracking fuel channel (111) is cracked 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 from the cracking fuel channel (111) to form mainstream ammonia gas; 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.

2. The dual-layer cycle based ammonia fuel ignition enhancement device of claim 1, wherein, 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). 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 body (11).

3. The dual-layer cycle based ammonia fuel ignition enhancement device of claim 2, wherein, 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).

4. The dual-layer cycle based ammonia fuel ignition enhancement device of claim 3, wherein, The cross-sectional shape of the pyrolysis fuel channel (111) is the same as that of the non-pyrolysis fuel channel (112).

5. The dual-layer cycle based ammonia fuel ignition enhancement device of claim 4, wherein, Along the plane direction of the high-temperature gas heating side of the plate-shaped main body (11), there are multiple pyrolysis fuel channels (111) and multiple non-pyrolysis fuel channels (112) at equal intervals.

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

7. The dual cycle based ammonia fuel ignition enhancement device according to any one of claims 1 to 5, characterized in that, 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.

8. A combustion chamber employing the dual-layer cycle based ammonia fuel ignition enhancement device according to any one of claims 1 to 7, characterized in that, include: A hollow combustion chamber body (2), a mixture nozzle (3), a mainstream ammonia nozzle (4) and a spark plug (5) are provided on the combustion chamber body (2); The combustion chamber body (2) has at least a portion of its walls made of an 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 cracked fuel channel (111) of the ammonia fuel ignition enhancement device (1) is connected to the mixed gas nozzle (3) based on the first control valve, and the non-cracking fuel channel (112) is connected to the mainstream ammonia gas nozzle (4) based on the second control valve. The combustion chamber body (2) includes: a cylindrical part (21) and a cavity part (22); The mixed gas nozzle (3), the mainstream ammonia nozzle (4), and the concave cavity portion (22) are arranged on the same side of the cylinder portion (21); Along the flow direction, the mixed gas nozzle (3) and the mainstream ammonia nozzle (4) are both located in front of the concave cavity (22), and the distance between the mixed gas nozzle (3) and the leading edge of the concave cavity (22) is greater than the distance between the mainstream ammonia nozzle (4) and the leading edge of the concave cavity (22). The spark plug (5) is located at the bottom of the recessed portion (22).

9. The combustion chamber of claim 8, 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).

10. A method of igniting a combustion chamber as claimed in any one of claims 8 or 9, 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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