Ammonia-hydrogen power wide-speed-range scramjet engine and combustion method thereof

Abstract

The invention belongs to the field of scramjet engines, and particularly relates to an ammonia-hydrogen power wide-speed-range scramjet engine and a combustion method thereof. The ammonia-hydrogen power wide-speed-range scramjet engine comprises a combustion chamber, a liquid ammonia storage device and a hydrogen storage device; a concave cavity is formed in the combustion chamber, a fuel injection section upstream injection hole is formed in a fuel injection section of the concave cavity, the concave cavity is located at the downstream of the fuel injection section, a fuel injection section upstream micro-jet injection hole is formed in the upstream of the fuel injection section upstream injection hole, and a concave cavity inner micro-jet injection hole is formed in the concave cavity; the liquid ammonia storage device is connected with an upstream injection hole of the fuel injection section through a cooling structure; and the hydrogen storage device is connected with the upstream micro-jet injection hole of the fuel injection section and the micro-jet injection hole in the concave cavity. According to the invention, liquid ammonia and hydrogen are introduced as fuels to realize wide-range combustion organization, so that wide-range efficient combustion is realized, the fuel heat absorption requirement of high-Mach-number active cooling thermal protection is met, and zero carbon emission can be realized in the whole process.

Description

Technical Field

[0001] The present invention belongs to the field of scramjet engines, and in particular relates to an ammonia-hydrogen powered wide-speed range scramjet engine and a combustion method thereof. Background Art

[0002] In the field of aerospace engines, wide-speed range scramjet engine technology has become the focus and hot direction of current research at home and abroad. When the Mach number exceeds 8, the total temperature of the inflow in the combustion chamber is as high as 2200K or more. The high flow rate and high total temperature cause the endothermic hydrocarbon fuel commonly used in wide-range scramjet engines to begin to dissociate and absorb heat and cannot effectively release heat to do work. At this time, the scramjet engine will face severe thrust defects and thermal protection problems, and even coking and clogging of pipelines. This requires that the fuel working fluid must have both high calorific value and excellent heat absorption capacity.

[0003] At present, scramjet engines usually use endothermic hydrocarbon fuels. After complete combustion, the combustion products include carbon dioxide. After incomplete combustion, carbon monoxide and kerosene cracking products will also be generated, polluting the atmospheric environment. In addition, existing scramjet engines do not consider the issue of carbon emission management and are not suitable for future civil flights.

[0004] In addition, the current wide-speed range scramjet engine technology still has the following problems: (1) Existing hydrocarbon fuel scramjet engines have problems with low fuel calorific value and insufficient heat absorption capacity under a wide range of flight conditions, especially under high Mach number 8+ flight conditions. This leads to low specific thrust, difficulty in thermal protection, and even easy cracking and coking, which have a significant impact on the overall performance and safety of the engine. The engine can only operate below Mach 7.

[0005] (2) At present, the carbon-containing exhaust gas emitted by scramjet engines and their combined power engines will cause pollution, and the issue of zero carbon emissions has not yet been considered. They cannot be applied to future work scenarios such as civil hypersonic aircraft and aerospace planes.

[0006] (3) The existing pure ammonia scramjet engine has poor ammonia activity and low calorific value, making it difficult to ignite and burn, and it is impossible to achieve supersonic robust combustion; the existing pure hydrogen scramjet engine, although hydrogen has high activity and high calorific value, has low energy density and small volume specific impulse, and cannot be used in practical applications. At present, there is no wide-speed range combustion method based on ammonia-hydrogen hybrid power and its scramjet engine. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide an ammonia-hydrogen powered wide-speed range scramjet engine and a combustion method thereof, so as to solve the technical problems of insufficient thrust performance and severe coking exposed by existing hydrocarbon fuel scramjet engines under wide range flight conditions, especially high Mach number flight conditions, and achieve the goal of zero carbon emissions from the engine.

[0008] The present invention provides an ammonia-hydrogen powered wide speed range scramjet engine, comprising a combustion chamber, a liquid ammonia storage device and a hydrogen storage device; The combustion chamber is provided with at least one concave cavity, the fuel injection section of the concave cavity is provided with a fuel injection section upstream injection hole, the concave cavity is located downstream of the fuel injection section, an upstream micro-jet injection hole of the fuel injection section is provided upstream of the upstream injection hole of the fuel injection section, and an intra-concave micro-jet injection hole is provided in the concave cavity; The liquid ammonia storage device is connected to the upstream injection hole of the fuel injection section through a cooling structure, and the cooling structure is a cooling pipe attached to the wall of the combustion chamber, or a cooling channel arranged in the wall of the combustion chamber; The hydrogen storage device is connected to the upstream micro-jet injection hole of the fuel injection section and the micro-jet injection hole in the concave cavity through a pipeline.

[0009] Furthermore, the ammonia-hydrogen powered wide-speed range scramjet engine also includes a nickel-based catalyst supply device arranged at the end of the cooling structure, and the nickel-based catalyst supply device is used to provide nickel-based catalyst to the liquid ammonia after absorbing heat through the cooling structure, so as to promote its cracking to produce hydrogen and nitrogen.

[0010] Furthermore, the ammonia-hydrogen powered wide speed range scramjet engine further includes a nitrogen storage device; The nitrogen storage device is connected to the ends of the liquid ammonia storage device and the hydrogen storage device to provide transportation power to the liquid ammonia storage device and the hydrogen storage device.

[0011] Furthermore, the combustion chamber and the concave cavity are rectangular or circular in cross section; When the combustion chamber and the concave cavity are rectangular cross-sections, the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity are distributed in a multi-point spanwise manner; When the combustion chamber and the concave cavity are circular cross-sections, the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity are evenly distributed in the circumferential direction.

[0012] Furthermore, the upstream injection hole of the fuel injection section, the upstream micro-jet injection hole of the fuel injection section and the micro-jet injection hole in the concave cavity are all provided with sonic nozzles, and the sonic nozzles are arranged perpendicular to the wall surface.

[0013] The present invention also provides an ammonia-hydrogen powered wide-speed range scramjet engine combustion method, using the ammonia-hydrogen powered wide-speed range scramjet engine, comprising the following steps: After passing through the cooling structure, liquid ammonia absorbs heat from the combustion chamber wall, and then cracks into hydrogen and nitrogen. The liquid ammonia enters the combustion chamber through the upstream injection holes of the fuel injection section for combustion. When the pressure or flame distribution in the combustion chamber becomes unstable, hydrogen is injected from the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity to regulate the combustion.

[0014] Furthermore, the combustion chamber is provided with two concave cavities, namely a primary concave cavity and a secondary concave cavity; The upstream injection hole of the fuel injection section located at the first-stage concave cavity is the upstream injection hole of the fuel injection section of the first-stage concave cavity. F- Jet1 The upstream injection hole of the fuel injection section located at the secondary cavity is the upstream injection hole of the fuel injection section of the secondary cavity. F- Jet2 ; The upstream micro-jet injection hole of the fuel injection section located at the first-stage concave cavity is the upstream micro-jet injection hole of the fuel injection section of the first-stage concave cavity. M-Jet1 The upstream micro-jet injection hole of the fuel injection section located at the secondary cavity is the upstream micro-jet injection hole of the fuel injection section of the secondary cavity. M-Jet3 ; The micro jet injection hole in the first-stage concave cavity is the micro jet injection hole in the first-stage concave cavity. M-Jet2 The micro jet injection hole in the concave cavity located in the secondary concave cavity is the micro jet injection hole in the secondary concave cavity. M-Jet4 .

[0015] Furthermore, the upstream micro jet injection hole of the first-stage concave fuel injection section M-Jet1 To the upstream injection hole of the first-stage cavity fuel injection section F-Jet1 distance lm w The flow distance between the upstream injection hole of the first-stage concave fuel injection section and the leading edge of the first-stage concave FJ The ratio should satisfy 0.5≤ lm w / FJ ≤1.5; the sum of the two satisfies lm w + FJ ≤ l21 , where l21 is the length of the fuel injection section of the first-stage cavity; Micro jet injection hole in the first-stage cavity M-Jet2 Distance from the front edge of the primary cavity lmJ Should meet ( l22-d25 ) / 2≤ lm w ≤ l22-d25 , where l22 is the length of the primary cavity; d25 is the height of the front wall of the first-level cavity; The upstream microjet injection holes of the secondary cavity fuel injection section M-Jet3 To the upstream injection holes of the secondary cavity fuel injection section F-Jet2 Distance lm w The ratio to the flow direction distance of the injection hole of the secondary cavity fuel injection section from the leading edge of the secondary cavity satisfies 0.5 ≤ FWf / lm w / FWf ≤ 1.5; The sum of the two should satisfy lm w + FWf ≤ l23 , where l23 Is the length of the secondary cavity fuel injection section; The microjet injection holes in the secondary cavity M-Jet4 The distance from the leading edge of the secondary cavity lm w Satisfies ([[]] l24-d26 ) / 2 ≤ lmJ ≤ l24-d26 , where l24 Is the length of the secondary cavity; d26 Is the height of the front wall of the secondary cavity.

[0016] Furthermore, the height of the transverse flow channel F-Jet1 At the upstream injection hole of the primary cavity fuel injection section dJ1 Is determined according to the thermal throat of Ma = 6 - 10 in the cruise state; The height of the transverse flow channel F-Jet2 At the upstream injection hole of the secondary cavity fuel injection section dJ2 Is mainly determined according to the thermal throat of Ma = 4 - 6 in the cruise state.

[0017] The present invention also provides a combustion method for an ammonia-hydrogen powered wide-speed-range scramjet engine, using the above ammonia-hydrogen powered wide-speed-range scramjet engine, including the following steps: In the engine ignition and start-up stage (<Ma 4), liquid ammonia cannot be completely cracked after passing through the cooling structure. At this time, hydrogen is guided to assist in ignition. The pre-injection pressure is kept consistent when all the upstream injection holes of the fuel injection section inject. The pre-injection pressure is kept consistent when all the upstream microjet injection holes and the microjet injection holes in the cavity of the fuel injection section inject. The ratio of the global equivalence ratio of the hydrogen guided to the main fuel of ammonia satisfies 1 / 4 ≤ Ф H2 / Ф NH3 ≤ 1 / 2; S11, Inject the hydrogen for guidance through the microjet injection holes in the secondary cavity M-Jet4 ; S12, The pressure sensor detects the microjet injection holes in the secondary cavity M-Jet4When the pressure before spraying is stable, which is recorded as time t0, the ignition device in the secondary cavity is activated, with an ignition frequency of 50 Hz and an ignition time of 200 ms. S13, at t0+50ms, the upstream injection hole of the first-stage concave fuel injection section F-Jet1 Begin injecting the main fuel through the cooling structure; S14, at t0+200ms, the micro-jet injection hole in the secondary cavity M-Jet4 Stop injection and the ignition device stops working; During the engine low-speed cruise stage (Ma 4-Ma 6), liquid ammonia is endothermally cracked into a hydrogen-containing mixture by the cooling structure. The pre-injection pressure of all upstream injection holes of the fuel injection section is kept consistent during injection. The pre-injection pressure of all upstream micro-jet injection holes of the fuel injection section and the micro-jet injection holes in the cavity are kept consistent during injection. The global equivalent ratio of hydrogen micro-jet to ammonia main fuel satisfies 1 / 7≤ Ф H2 / Ф NH3 ≤1 / 3; S21, the main fuel passes through the upstream injection hole of the secondary cavity fuel injection section F-Jet2 Enter the combustion chamber and burn; S22, after detecting the instability of the pressure or flame distribution in the combustion chamber, the micro-jet injection hole upstream of the secondary cavity fuel injection section M-Jet3 Micro jet injection hole in the secondary cavity M-Jet4 Inject hydrogen to control combustion. The hydrogen injection time should be 50ms≤ t H2 ≤100ms; During the high-speed cruise stage of the engine (Ma 6-Ma 10), the liquid ammonia can be fully absorbed by the cooling structure and then catalytically cracked into hydrogen and nitrogen; the pre-injection pressure of all upstream injection holes of the fuel injection section is kept consistent when injecting, and the pre-injection pressure of all upstream micro-jet injection holes of the fuel injection section and the micro-jet injection holes in the cavity are kept consistent when injecting, and the global equivalent ratio of hydrogen micro-jet to ammonia main fuel should meet 1 / 7≤ Ф H2 / Ф NH3 ≤1 / 3; S31, cracked hydrogen and nitrogen pass through the upstream injection hole of the first-stage concave fuel injection section F-Jet1 Enter the combustion chamber and burn; S32, after detecting that the pressure or flame distribution in the combustion chamber is unstable, the micro-jet injection hole upstream of the first-stage concave cavity fuel injection section M-Jet1 Micro jet injection hole in the first-stage cavity M-Jet2 Inject hydrogen to control combustion. The hydrogen injection time should be 50ms≤ t H2≤100ms.

[0018] The beneficial effect of the present invention is that the ammonia-hydrogen powered wide-speed range scramjet engine provided by the present invention, on the basis of the existing scramjet engine technical solution, realizes a wide range of combustion organization by introducing liquid ammonia and hydrogen as fuel, thereby achieving wide-range efficient combustion while meeting the fuel heat absorption requirements of high Mach number active cooling thermal protection, and can achieve zero carbon emissions throughout the process, and is expected to provide a realistic and feasible power option for future civil hypersonic aircraft or aerospace planes.

[0019] Compared with the scramjet engine using endothermic hydrocarbon fuel, the present invention introduces liquid ammonia as the engine fuel. Without losing the active cooling effect, it can avoid the problems of cracking and coking of hydrocarbon fuel under high Mach number conditions and insufficient specific thrust, while achieving zero carbon emissions of the engine.

[0020] Compared with the scramjet engine using liquid ammonia fuel, which has a low ammonia activity and low calorific value and cannot effectively achieve ignition and flame stabilization in supersonic airflow, the ammonia-hydrogen powered wide-speed range scramjet engine can effectively achieve ignition and flame stabilization in supersonic airflow.

[0021] Compared with the scramjet engine using hydrogen, although hydrogen has high activity and calorific value, it has low energy density and small volume specific impulse, so it cannot be used in practical applications. In addition, the liquid hydrogen storage technology is not mature at this stage and cannot be put into practical use. This ammonia hydrogen powered wide speed range scramjet engine has been tested and verified to be feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 It is a schematic diagram of the three-dimensional structure of the ammonia-hydrogen powered wide-speed range scramjet engine of the present invention; Attached Figure 2 It is a schematic diagram of the structure of the combustion chamber in the ammonia-hydrogen powered wide speed range scramjet engine of the present invention; Attached Figure 3 It is a schematic diagram of the dimensions of the combustion chamber in the ammonia-hydrogen powered wide speed range scramjet engine of the present invention; Attached Figure 4 It is a schematic diagram of the structure of the ammonia-hydrogen powered wide-speed range scramjet engine of the present invention; Attached Figure 5 This is a visible light image of the ammonia-hydrogen powered wide-range combustion method applied in the combustion chamber of the ammonia-hydrogen powered wide-speed range scramjet engine of the present invention under simulated flight Ma6 conditions.

[0023] In the figure: 1 - isolation section, 2 - cavity section, 3 - tail nozzle, 4 - liquid ammonia storage tank, 5 - hydrogen storage tank, 6 - cooling structure, 7 - nitrogen storage device; 2-1——first-stage concave cavity fuel injection section, 2-2——first-stage concave cavity, 2-3——second-stage concave cavity fuel injection section, 2-4——second-stage concave cavity; l0 ——Scramjet combustion chamber length, l1 ——Isolation section length, l2 —— length of the concave cavity section, l21 ——First-stage cavity fuel injection section length, l22 ——First-level cavity length, l23 ——The length of the fuel injection section of the secondary cavity, l24 ——Secondary cavity length, d11 ——Inlet flow channel height of isolation section, d12 ——Isolation section outlet flow channel height, d21 ——Height of the flow channel at the leading edge of the first-stage cavity, d22 ——Height of the flow channel at the trailing edge of the first-stage concave cavity, d23 ——Height of the flow channel at the leading edge of the secondary cavity, d24 ——height of the flow channel at the rear edge of the secondary cavity, d25 ——The height of the front wall of the first-stage cavity, d26 ——Height of the front wall of the secondary cavity, d3 ——Height of outlet flow channel of concave cavity section, α1 ——The inclination angle of the rear wall of the first-stage cavity, α2 ——The inclination angle of the rear wall of the secondary cavity; F-Jet1 ——Upstream injection hole of the first-stage concave fuel injection section, F-Jet2 ——Upstream injection hole of the secondary cavity fuel injection section, M-Jet1 ——Micro jet injection hole upstream of the first-stage concave fuel injection section, M-Jet2 ——Micro jet injection hole in the first-stage cavity, M-Jet3 ——Micro jet injection hole upstream of the secondary cavity fuel injection section, M-Jet4 ——Micro jet injection hole in the secondary cavity, dJ1 ——Upstream injection hole of the first-stage cavity fuel injection section F-Jet1 Height of transverse flow channel, dJ2 ——Upstream injection hole of the secondary cavity fuel injection section F-Jet2 —Height of transverse flow channel, FJ ——Upstream injection hole of the first-stage cavity fuel injection section F-Jet1 Flow distance from the leading edge of the first-stage cavity, FWf ——Upstream injection hole of the secondary cavity fuel injection section F- Jet2 Flow distance from the front edge of the secondary cavity, lm w ——Micro jet injection hole upstream of the first-stage cavity fuel injection section M-Jet1 The distance from the upstream injection hole of the first-stage cavity fuel injection section F-Jet1Flow distance, lmJ ——Micro jet injection hole in the first-stage cavity M- Jet2 Flow distance from the leading edge of the first-stage cavity, lm w ——Micro jet injection hole upstream of the secondary cavity fuel injection section M-Jet3 The distance from the upstream injection hole of the secondary cavity fuel injection section F-Jet2 Flow distance, lm w ——Micro jet injection hole in the secondary cavity M- Jet4 Streamwise distance from the leading edge of the secondary cavity. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0026] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] The reference profile described in the invention is the combustion chamber profile of an ammonia-hydrogen scramjet engine determined according to mission requirements, such as the profile with the highest performance at the cruise point, the profile suitable for wide-range operation, etc. The structure of the ammonia-hydrogen scramjet engine described in the present invention is as Figure 1 and Figure 2 shown, and the specific dimensions of the combustion chamber are as Figure 3 shown. The configuration can be a rectangular cross-section or an axisymmetric circular cross-section. In the combustion chamber of a two-dimensional rectangular cross-section engine, the cavity is symmetrically arranged on the upper and lower walls. In the combustion chamber of an axisymmetric circular cross-section engine, the cavity is an annular structure.

[0030] As shown in the attached Figure 1 - attached Figure 4 shown, the present invention provides an ammonia-hydrogen powered wide-speed range scramjet engine, including a combustion chamber, a liquid ammonia storage device 4 and a hydrogen storage device 5, wherein the liquid ammonia storage device 4 preferably uses a liquid ammonia storage tank, and the hydrogen storage device 5 preferably uses a hydrogen storage tank; At least one cavity is provided on the combustion chamber. The fuel injection section of the cavity is provided with upstream injection holes of the fuel injection section. The cavity is located downstream of the fuel injection section. Upstream of the upstream injection holes of the fuel injection section, there are upstream microjet injection holes of the fuel injection section. Microjet injection holes inside the cavity are provided inside the cavity; The liquid ammonia storage device 4 is connected to the upstream injection holes of the fuel injection section through a cooling structure 6. The cooling structure 6 is a cooling pipe attached to the combustion chamber wall or a cooling channel provided inside the combustion chamber wall. Before the liquid nitrogen enters the upstream injection holes of the fuel injection section, it first passes through the cooling structure 6. On the one hand, it absorbs heat from the combustion chamber wall, reduces the temperature of the combustion chamber wall, and improves its thermal protection performance. On the other hand, it can absorb heat through high-temperature cracking to improve its combustion effect; The hydrogen storage device 5 is connected to the upstream microjet injection holes of the fuel injection section and the microjet injection holes inside the cavity through pipelines. By setting hydrogen, and the upstream microjet injection holes of the fuel injection section and the microjet injection holes inside the cavity are respectively located upstream and downstream of the upstream injection holes of the fuel injection section, it can be used for auxiliary ignition when the aircraft is in the engine ignition startup stage (<Ma 4), and for combustion regulation when the aircraft is in the low-speed cruise stage (Ma 4 - Ma 6) and the engine high-speed cruise stage (Ma 6 - Ma10).

[0031] The ammonia-hydrogen powered wide-speed range scramjet engine provided by the present invention, based on the existing scramjet engine technical solutions, realizes a wide range of combustion organization by introducing liquid ammonia and hydrogen as fuels, thereby achieving wide-range efficient combustion while meeting the fuel heat absorption requirements of high Mach number active cooling thermal protection, and can achieve zero carbon emissions throughout the process, and is expected to provide a realistic and feasible power option for future civil hypersonic aircraft or aerospace planes.

[0032] Compared with the scramjet engine using endothermic hydrocarbon fuel, the present invention introduces liquid ammonia as the engine fuel. Without losing the active cooling effect, it can avoid the problems of cracking and coking of hydrocarbon fuel under high Mach number conditions and insufficient specific thrust, while achieving zero carbon emissions of the engine.

[0033] Compared with the scramjet engine using liquid ammonia fuel, which has a low ammonia activity and low calorific value and cannot effectively achieve ignition and flame stabilization in supersonic airflow, the ammonia-hydrogen powered wide-speed range scramjet engine can effectively achieve ignition and flame stabilization in supersonic airflow.

[0034] Compared with scramjet engines that use hydrogen, although hydrogen has high activity and calorific value, it has low energy density and small volume specific impulse, so it cannot be used in practical applications. In addition, liquid hydrogen storage technology is not mature at this stage and cannot be used in practical applications. This ammonia-hydrogen powered wide-speed range scramjet engine has been verified to be feasible through experiments.

[0035] In one embodiment, the ammonia-hydrogen powered wide-speed range scramjet engine further includes a nickel-based catalyst supply device disposed at the end of the cooling structure 6, and the nickel-based catalyst supply device is used to provide a nickel-based catalyst to the liquid ammonia after absorbing heat through the cooling structure 6, and promote the decomposition of the liquid ammonia after absorbing heat through the cooling structure 6 to produce hydrogen and nitrogen. Specifically, the liquid ammonia after absorbing heat is rapidly decomposed under the action of the nickel-based catalyst to produce 75% hydrogen and 25% nitrogen, further promoting combustion and achieving zero carbon emissions throughout the process.

[0036] In one of the embodiments, the ammonia-hydrogen powered wide speed range scramjet engine further includes a nitrogen storage device 7; The nitrogen storage device 7 is connected to the ends of the liquid ammonia storage device 4 and the hydrogen storage device 5 to provide transportation power to the liquid ammonia storage device 4 and the hydrogen storage device 5. Preferably, a control valve is also provided between the nitrogen storage device 7 and the liquid ammonia storage device 4 and the hydrogen storage device 5.

[0037] In one embodiment, the combustion chamber and the concave cavity are rectangular or circular in cross section; When the combustion chamber and the concave cavity are rectangular cross-sections, the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity are distributed in multiple points in a spanwise direction, thereby improving the uniformity of hydrogen injection.

[0038] When the combustion chamber and the concave cavity are circular in cross section, the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity are evenly distributed circumferentially, thereby improving the injection uniformity of hydrogen.

[0039] In one of the embodiments, the upstream injection hole of the fuel injection section, the upstream micro-jet injection hole of the fuel injection section and the micro-jet injection hole in the concave cavity are all provided with sonic nozzles, and the sonic nozzles are arranged perpendicular to the wall at 90 degrees.

[0040] The present invention also provides an ammonia-hydrogen powered wide-speed range scramjet engine combustion method, using the ammonia-hydrogen powered wide-speed range scramjet engine, comprising the following steps: After passing through the cooling structure 6, the liquid ammonia absorbs heat from the combustion chamber wall, and then cracks into hydrogen and nitrogen. The ammonia enters the combustion chamber through the upstream injection hole of the fuel injection section and burns. When the pressure or flame distribution in the combustion chamber becomes unstable, hydrogen is injected from the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity to regulate the combustion.

[0041] The present invention is not limited to a dual-cavity combustion chamber configuration, but may be applied to a single-cavity or multi-cavity combustion chamber configuration.

[0042] In a specific embodiment, the combustion chamber is provided with two concave cavities, namely a primary concave cavity 2-2 and a secondary concave cavity 2-4; The upstream injection hole of the fuel injection section located at the first-stage concave cavity is the upstream injection hole of the fuel injection section of the first-stage concave cavity. F- Jet1 The upstream injection hole of the fuel injection section located at the secondary cavity is the upstream injection hole of the fuel injection section of the secondary cavity. F- Jet2 ; The upstream micro-jet injection hole of the fuel injection section located at the first-stage concave cavity is the upstream micro-jet injection hole of the fuel injection section of the first-stage concave cavity. M-Jet1 The upstream micro-jet injection hole of the fuel injection section located at the secondary cavity is the upstream micro-jet injection hole of the fuel injection section of the secondary cavity. M-Jet3 ; The micro jet injection hole in the first-stage concave cavity is the micro jet injection hole in the first-stage concave cavity. M-Jet2 The micro jet injection hole in the concave cavity located in the secondary concave cavity is the micro jet injection hole in the secondary concave cavity. M-Jet4 .

[0043] Preferably, the upstream micro jet injection hole of the first-stage concave cavity fuel injection section M-Jet1 To the upstream injection hole of the first-stage cavity fuel injection section F-Jet1 distance lm w The flow distance between the upstream injection hole of the first-stage concave fuel injection section and the leading edge of the first-stage concave FJ The ratio should satisfy 0.5≤ lm w / FJ ≤1.5, to ensure that the hydrogen micro jet will not affect the normal injection of the main fuel due to being too close, nor will it lose the combustion control effect due to being too far away; the sum of the two meets lm w + FJ ≤ l21 , where l21 is the length of the fuel injection section of the first-stage cavity; Micro jet injection hole in the first-stage cavity M-Jet2 Distance from the front edge of the primary cavity lmJ Should meet ( l22-d25 ) / 2≤ lmJ ≤ l22-d25 This size constraint is the optimization result obtained in the actual test process, which can achieve the ideal control effect; where, l22 is the length of the primary cavity; d25 is the height of the front wall of the first-level concave cavity; Micro jet injection hole upstream of the secondary cavity fuel injection section M-Jet3 To the upstream injection hole of the secondary cavity fuel injection section F-Jet2 distance lm w The distance between the injection hole of the secondary cavity fuel injection section and the front edge of the secondary cavity in the flow direction FWf The ratio satisfies 0.5≤ lm w / FWf ≤1.5; the sum of the two should satisfy lm w + FWf ≤ l23 , where l23 is the length of the fuel injection section of the secondary cavity; Micro jet injection hole in the secondary cavity M-Jet4 Distance from the front edge of the secondary cavity lm w satisfy( l24-d26 ) / 2≤ lm w ≤ l24-d26 , where l24 is the length of the secondary cavity; d26 is the height of the front wall of the secondary cavity.

[0044] Preferably, the upstream injection hole of the first-stage concave cavity fuel injection section F-Jet1 Height of transverse flow channel dJ1 Determined by the thermal throat of the cruise state Ma=6~10; Upstream injection hole of the secondary cavity fuel injection section F-Jet2 Height of transverse flow channel dJ2 It is mainly determined by the thermal throat in the cruise state Ma=4~6. The specific relationship between the thermal throat and the flow channel area is as follows:

[0045] In the formula is the static pressure, is the specific heat ratio, is the Mach number, is the flow channel area, is the total temperature. The flow channel height dJ1 and dJ2 can be inversely calculated through the flow channel area.

[0046] In this embodiment, the first-stage cavity 2-2 is mainly used for scramjet combustion organization at high incoming flow Mach numbers (Ma6~10), and the second-stage cavity 2-4 is mainly used for scramjet combustion organization at low incoming flow Mach numbers (Ma4~6). Correspondingly, the fuel injection section 2-1 of the first-stage cavity is responsible for fuel injection into the first-stage cavity 2-2, and the fuel injection section 2-3 of the second-stage cavity is responsible for fuel injection into the second-stage cavity 2-4.

[0047] The长深比range of the first-stage cavity 2-2 of the present invention is 6 < l22 / d25 < 8, preferably 7, and the长深比range of the second-stage cavity is 4 < l24 / d26 < 6, preferably 5. The trailing edge inclination angles of the first-stage cavity 2-2 and the second-stage cavity 2-4 are both 45°.

[0048] Under the high Mach number cruise state of the present invention, the ratio of the trailing edge flow channel height of the second-stage cavity to the inlet height of the inlet should satisfy 1.25 ≤ d24 / d11 ≤ 1.50, preferably 1.4; under the cruise state required for low Mach number and high equivalence ratio operation, the ratio of the trailing edge flow channel height of the first-stage cavity to the inlet height of the inlet should satisfy 1.15 ≤ d22 / d11 ≤ 1.25, preferably 1.2.

[0049] The expansion angle range of the inclined wall surface of the present invention is between 1.5° and 3.5°, preferably 2°. The flow direction distance of each injection hole in the fuel injection section of the first-stage cavity from the leading edge of the first-stage cavity FJ and the flow direction distance of each injection hole in the fuel injection section of the second-stage cavity from the leading edge of the second-stage cavity FWf are inversely calculated according to the expansion angle and are not strictly restricted. This calculation method is a prior art and will not be elaborated here.

[0050] The present invention also provides a combustion method for an ammonia-hydrogen powered wide-speed-range scramjet engine, using the above ammonia-hydrogen powered wide-speed-range scramjet engine, including the following steps: During the engine ignition and start-up stage (<Ma 4), the liquid ammonia cannot be completely cracked after passing through the cooling structure 6. At this time, hydrogen is guided to assist in ignition. The pre-injection pressures of all the upstream injection holes in all the fuel injection sections are kept consistent, and the pre-injection pressures of all the upstream micro-jet injection holes and the micro-jet injection holes in the cavity during injection are kept consistent. The ratio of the guiding hydrogen to the global equivalence ratio of the ammonia main fuel satisfies 1 / 4 ≤ Ф H2 / ФNH3 ≤1 / 2, preferably 1 / 3; S11, micro jet injection hole in the secondary cavity M-Jet4 Injection of guided hydrogen; S12, the pressure sensor detects the micro-jet injection hole in the secondary cavity M-Jet4 When the pressure before spraying is stable, which is recorded as time t0, the ignition device in the secondary cavity 2-4 is activated, the ignition frequency is 50Hz, and the ignition time lasts for 200ms; S13, at t0+50ms, the upstream injection hole of the first-stage concave fuel injection section F-Jet1 Start injecting the main fuel through the cooling structure 6; S14, at t0+200ms, the micro-jet injection hole in the secondary cavity M-Jet4 Stop injection and the ignition device stops working; During the engine low-speed cruising stage (Ma 4-Ma 6), liquid ammonia is endothermally cracked into a hydrogen-containing mixture by the cooling structure 6. The pre-injection pressure of all upstream injection holes of the fuel injection section is kept consistent during injection. The pre-injection pressure of all upstream micro-jet injection holes of the fuel injection section and the micro-jet injection holes in the cavity are kept consistent during injection. The global equivalent ratio of hydrogen micro-jet to ammonia main fuel satisfies 1 / 7≤ Ф H2 / Ф NH3 ≤1 / 3, preferably 1 / 5; S21, the main fuel passes through the upstream injection hole of the secondary cavity fuel injection section F-Jet2 Enter the combustion chamber and burn; S22, after detecting the instability of the pressure or flame distribution in the combustion chamber, the micro-jet injection hole upstream of the secondary cavity fuel injection section M-Jet3 Micro jet injection hole in the secondary cavity M-Jet4 Inject hydrogen to control combustion. The hydrogen injection time should be 50ms≤ t H2 ≤100ms, preferably 75ms; During the high-speed cruising stage of the engine (Ma 6-Ma 10), the liquid ammonia can be fully absorbed by the cooling structure 6 to be cracked into hydrogen and nitrogen; the pre-injection pressure of all upstream injection holes of the fuel injection section is kept consistent during injection, the pre-injection pressure of all upstream micro-jet injection holes of the fuel injection section and the micro-jet injection holes in the cavity are kept consistent during injection, and the global equivalent ratio of the hydrogen micro-jet to the ammonia main fuel should meet the requirement of 1 / 7≤ Ф H2 / Ф NH3 ≤1 / 3, preferably 1 / 5; S31, cracked hydrogen and nitrogen pass through the upstream injection hole of the first-stage concave fuel injection section F-Jet1 Enter the combustion chamber and burn; S32, after detecting that the pressure or flame distribution in the combustion chamber is unstable, the micro-jet injection hole upstream of the first-stage concave cavity fuel injection section M-Jet1 Micro jet injection hole in the first-stage cavity M-Jet2 Inject hydrogen to control combustion. The hydrogen injection time should be 50ms≤ t H2 ≤100ms as combustion, preferably 75ms.

[0051] Reference Figure 5 , attached Figure 5 This is a visible light image of the ammonia-hydrogen powered wide-range combustion method applied in the combustion chamber under simulated flight Ma6 conditions. From the attached figure, it can be seen that the use of guided hydrogen control means can successfully ignite the ammonia jet in the supersonic combustion chamber, thereby allowing the engine to ignite and start normally.

[0052] In addition, the present invention has been verified through ground tests and can achieve efficient and reliable combustion and thermal protection in the range of Ma4~10.

[0053] The above is only an embodiment and does not limit the present invention in any way. Any person skilled in the art can use the above disclosed technical contents to make many possible changes, modifications or modifications to the technical solutions of the present invention into equivalent embodiments of equivalent changes without departing from the scope of the technical solutions of the present invention. Therefore, any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. An ammonia-hydrogen powered wide speed range scramjet engine, characterized in that: It comprises a combustion chamber, a liquid ammonia storage device (4) and a hydrogen storage device (5); The combustion chamber is provided with at least one concave cavity, the fuel injection section of the concave cavity is provided with a fuel injection section upstream injection hole, the concave cavity is located downstream of the fuel injection section, an upstream micro-jet injection hole of the fuel injection section is provided upstream of the upstream injection hole of the fuel injection section, and an intra-concave micro-jet injection hole is provided in the concave cavity; The liquid ammonia storage device (4) is connected to the upstream injection hole of the fuel injection section via a cooling structure (6), and the cooling structure (6) is a cooling pipe attached to the wall surface of the combustion chamber, or a cooling channel arranged in the wall surface of the combustion chamber; The hydrogen storage device (5) is connected to the upstream micro-jet injection hole of the fuel injection section and the micro-jet injection hole in the concave cavity through a pipeline.

2. The ammonia-hydrogen powered wide speed range scramjet engine according to claim 1, characterized in that: It also includes a nickel-based catalyst supply device arranged at the end of the cooling structure (6), and the nickel-based catalyst supply device is used to provide a nickel-based catalyst to the liquid ammonia after absorbing heat through the cooling structure (6), so as to promote its cracking to produce hydrogen and nitrogen.

3. The ammonia-hydrogen powered wide speed range scramjet engine according to claim 1, characterized in that: Also included is a nitrogen storage device (7); The nitrogen storage device (7) is connected to the ends of the liquid ammonia storage device (4) and the hydrogen storage device (5) to provide transport power to the liquid ammonia storage device (4) and the hydrogen storage device (5).

4. The ammonia-hydrogen powered wide speed range scramjet engine according to claim 1, characterized in that: The combustion chamber and the concave cavity are rectangular or circular in cross section; When the combustion chamber and the concave cavity are rectangular cross-sections, the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity are distributed in a multi-point spanwise manner; When the combustion chamber and the concave cavity are circular cross-sections, the micro-jet injection holes upstream of the fuel injection section and the micro-jet injection holes in the concave cavity are evenly distributed in the circumferential direction.

5. The ammonia-hydrogen powered wide speed range scramjet engine according to claim 1, characterized in that: The upstream injection hole of the fuel injection section, the upstream micro-jet injection hole of the fuel injection section and the micro-jet injection hole in the concave cavity are all provided with sonic nozzles, and the sonic nozzles are arranged perpendicular to the wall surface.

6. The ammonia-hydrogen powered wide speed range scramjet engine according to any one of claims 1 to 5, characterized in that: The combustion chamber is provided with two concave cavities, namely a primary concave cavity (2-2) and a secondary concave cavity (2-4); The upstream injection hole of the fuel injection section located at the first-stage concave cavity is the upstream injection hole of the fuel injection section of the first-stage concave cavity. F-Jet1 The upstream injection hole of the fuel injection section located at the secondary cavity is the upstream injection hole of the fuel injection section of the secondary cavity. F-Jet2 ; The upstream micro-jet injection hole of the fuel injection section located at the first-stage concave cavity is the upstream micro-jet injection hole of the fuel injection section of the first-stage concave cavity. M-Jet1 The upstream micro-jet injection hole of the fuel injection section located at the secondary cavity is the upstream micro-jet injection hole of the fuel injection section of the secondary cavity. M-Jet3 ; The micro jet injection hole in the first-stage concave cavity is the micro jet injection hole in the first-stage concave cavity. M-Jet2 The micro jet injection hole in the concave cavity located in the secondary concave cavity is the micro jet injection hole in the secondary concave cavity. M-Jet4 .

7. The ammonia-hydrogen powered wide speed range scramjet engine according to claim 6, characterized in that: Micro jet injection hole upstream of the first-stage cavity fuel injection section M-Jet1 To the upstream injection hole of the first-stage cavity fuel injection section F-Jet1 distance lm w The flow distance between the upstream injection hole of the first-stage concave fuel injection section and the leading edge of the first-stage concave FJ The ratio should satisfy 0.5≤ lm w / FJ ≤1.5; the sum of the two satisfies lm w + FJ ≤ l21 , where l21 is the length of the fuel injection section of the first-stage cavity; Micro jet injection hole in the first-stage cavity M-Jet2 Distance from the front edge of the primary cavity lmJ Should meet ( l22-d25 ) / 2≤ lmJ ≤ l22-d25 , where l22 is the length of the primary cavity; d25 is the height of the front wall of the first-level concave cavity; Micro jet injection hole upstream of the secondary cavity fuel injection section M-Jet3 To the upstream injection hole of the secondary cavity fuel injection section F- Jet2 distance lm w The distance between the injection hole of the secondary cavity fuel injection section and the front edge of the secondary cavity in the flow direction FWf The ratio satisfies 0.5≤ lm w / FWf ≤1.5; the sum of the two should satisfy lm w + FWf ≤ l23 , where l23 is the length of the fuel injection section of the secondary cavity; Micro jet injection hole in the secondary cavity M-Jet4 Distance from the front edge of the secondary cavity lm w satisfy( l24-d26 ) / 2≤ lmJ ≤ l24-d26 , where l24 is the length of the secondary cavity; d26 is the height of the front wall of the secondary cavity.

8. The ammonia-hydrogen powered wide speed range scramjet engine according to claim 7, characterized in that: The upstream injection hole of the first-stage concave cavity fuel injection section F-Jet1 Height of transverse flow channel dJ1 Determined according to the thermal throat of the cruise state Ma=6~10; Upstream injection hole of the secondary cavity fuel injection section F-Jet2 Height of transverse flow channel dJ2 It is mainly determined by the thermal throat in the cruising state Ma=4~6.

9. An ammonia-hydrogen powered wide speed range scramjet engine combustion method, characterized in that: Using the ammonia-hydrogen powered wide speed range scramjet engine according to any one of claims 1 to 5 comprises the following steps: After passing through the cooling structure (6), the liquid ammonia absorbs heat from the combustion chamber wall, and after absorbing heat, it is catalytically cracked into hydrogen and nitrogen, and enters the combustion chamber through the upstream injection hole of the fuel injection section for combustion. When the pressure in the combustion chamber or the flame distribution becomes unstable, hydrogen is injected from the micro-jet injection hole upstream of the fuel injection section and the micro-jet injection hole in the concave cavity to regulate the combustion.

10. An ammonia-hydrogen powered wide speed range scramjet engine combustion method, characterized in that: Using the ammonia-hydrogen powered wide speed range scramjet engine according to any one of claims 6 to 8 comprises the following steps: During the engine ignition start-up phase, liquid ammonia cannot be completely cracked after passing through the cooling structure (6). At this time, hydrogen is guided to assist in ignition. The pre-injection pressure of all upstream injection holes of the fuel injection section is kept consistent during injection. The pre-injection pressure of all upstream micro-jet injection holes of the fuel injection section and the micro-jet injection holes in the cavity are kept consistent during injection. The global equivalence ratio of the guided hydrogen to the ammonia main fuel satisfies 1 / 4≤ Ф H2 / Ф NH3 ≤1 / 2; S11, micro jet injection hole in the secondary cavity M-Jet4 Injection of guided hydrogen; S12, the pressure sensor detects the micro-jet injection hole in the secondary cavity M-Jet4 When the pressure before spraying is stable, which is recorded as time t0, the ignition device in the secondary cavity (2-4) is activated, the ignition frequency is 50 Hz, and the ignition time lasts for 200 ms; S13, at t0+50ms, the upstream injection hole of the first-stage concave fuel injection section F-Jet1 Starting to inject the main fuel through the cooling structure (6); S14, at t0+200ms, the micro-jet injection hole in the secondary cavity M-Jet4 Stop injection and the ignition device stops working; During the engine low-speed cruising stage, liquid ammonia is endothermally cracked into a hydrogen-containing mixture by the cooling structure (6). The pre-injection pressure of all the upstream injection holes of the fuel injection section is kept consistent during injection. The pre-injection pressure of all the upstream micro-jet injection holes of the fuel injection section and the micro-jet injection holes in the cavity are kept consistent during injection. The global equivalent ratio of the hydrogen micro-jet to the ammonia main fuel satisfies 1 / 7≤ Ф H2 / Ф NH3 ≤1 / 3; S21, the main fuel passes through the upstream injection hole of the secondary cavity fuel injection section F-Jet2 Enter the combustion chamber and burn; S22, after detecting the instability of the pressure or flame distribution in the combustion chamber, the micro-jet injection hole upstream of the secondary cavity fuel injection section M-Jet3 Micro jet injection hole in the secondary cavity M-Jet4 Inject hydrogen to control combustion. The hydrogen injection time should be 50ms≤ t H2 ≤100ms; During the high-speed cruising stage of the engine, the liquid ammonia can be fully absorbed by the cooling structure (6) and then catalytically cracked into hydrogen and nitrogen; the pre-injection pressure of all the upstream injection holes of the fuel injection section is kept consistent during injection, the pre-injection pressure of all the upstream micro-jet injection holes of the fuel injection section and the micro-jet injection holes in the cavity are kept consistent during injection, and the global equivalent ratio of the hydrogen micro-jet to the ammonia main fuel should satisfy 1 / 7≤ F H2 / F NH3 ≤1 / 3; S31, cracked hydrogen and nitrogen pass through the upstream injection hole of the first-stage concave fuel injection section F-Jet1 Enter the combustion chamber and burn; S32, after detecting that the pressure or flame distribution in the combustion chamber is unstable, the micro-jet injection hole upstream of the first-stage concave cavity fuel injection section M-Jet1 Micro jet injection hole in the first-stage cavity M-Jet2 Inject hydrogen to control combustion. The hydrogen injection time should be 50ms≤ t H2 ≤100ms.

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