Sloped detonation engine and its initiation method

Abstract

The application discloses a slanting detonation engine and a detonation method thereof, and belongs to the field of aero-engine technology.The slanting detonation engine comprises a fairing, a refractory fuel injector, a flammable fuel injector, an air inlet, a combustion chamber and a tail nozzle; the air inlet comprises a first wedge surface and a second wedge surface; the refractory fuel injector is arranged on an upper wall surface close to an air inlet outlet; the combustion chamber is connected with the air inlet; a tail wedge surface is arranged at the end of the combustion chamber; the wedge angle of the tail wedge surface is 20 degrees; the tail nozzle is connected with the combustion chamber; the flammable fuel injector is arranged at the front end of the fairing; a double-layer fuel auxiliary detonation method is adopted; the flammable fuel is used to assist the detonation of the refractory fuel, so that the length of the refractory fuel induction zone is reduced, there is no dynamic structure response and no additional energy injection, which is beneficial to the application of an engineering prototype, and thrust gain is obtained to the maximum extent; due to the characteristics that the refractory gas is not easy to detonate, the slanting detonation wave can be inhibited from detaching, and the lower limit of the flight Mach number of the slanting detonation engine can be greatly widened.

Description

Technical Field

[0001] This invention relates to the field of air-breathing hypersonic propulsion technology, and more specifically, to a slant detonation engine and its detonation method. Background Technology

[0002] Hypersonic propulsion technology is one of the key technologies of interest in 21st-century aerospace. Currently, the performance development of traditional aero-engines has gradually reached its limits, unable to continue meeting the thrust demands for higher supersonic speeds. Existing aero-engines are based on isobaric combustion, and this combustion organization is one of the reasons why engine performance is difficult to further improve. Therefore, researchers hope to utilize near-constant-volume detonation combustion to meet higher thrust requirements and have proposed the following three technical solutions: pulse detonation engine (PDE), rotating detonation engine (RDE), and oblique detonation engine (ODE). Among them, the oblique detonation engine (ODE), which utilizes oblique detonation waves (ODW) for combustion organization, has received increasing attention in recent years due to its advantages such as simple structure, small combustion chamber size, and high specific impulse.

[0003] Since the concept of oblique detonation propulsion was proposed, researchers have conducted extensive studies on oblique detonation waves in high-speed incoming flows, focusing on the initiation and stationary characteristics of oblique detonation waves within the oblique detonation combustion chamber, as well as the composition of the wave system structure. The research primarily involves the wave system structure of the oblique detonation zone and the combustion organization of the oblique detonation wave surface. One key aspect of the research on the initiation zone wave system structure is the length of the induction zone. Using hydrogen as fuel, numerical simulations of the oblique detonation wave structure under different flight conditions revealed that the length of the detonation wave induction zone increases significantly with increasing flight altitude and decreasing Mach number. However, an excessively long induction zone prevents the detonation wave from initiating within a finite length, thus failing to generate thrust. Therefore, there is an urgent need to propose an oblique detonation engine and its initiation method to reduce the length of the detonation wave induction zone.

[0004] Patent Document 1 (Publication No.: CN114109649B) provides a high-speed ramjet engine. The engine body includes an intake duct, a mixing section, a combustion chamber, and a tail nozzle connected in sequence. A first wedge surface unit is provided on the intake duct, a second wedge surface unit is provided on the mixing section, a combustion chamber wedge surface is provided on the combustion chamber for inducing the generation of stationary oblique detonation waves, and a tail nozzle wedge surface is provided on the tail nozzle. A nozzle orifice unit for spraying propellant spray is provided on the second wedge surface unit. The edge of the intake duct and the edge of the mixing section are non-horizontal straight lines. Patent Document 1 solves common problems such as high fuel injector resistance, limited fuel injection height, low fuel mixing efficiency, poor combustion stability, and severe detonation wave / boundary layer interference by improving the engine structure. However, this structure still cannot reduce the length of the detonation wave induction zone, and the detonation wave cannot be ignited within a limited length, thus failing to generate thrust.

[0005] Patent document 2 (publication number: CN116291880A) provides a method for accelerating the initiation of a slant detonation engine by disturbing the initiation zone. By adding external interference to the lower wall of the combustion chamber of the slant detonation engine, the incoming gas is affected by the external disturbance to generate a bow-shaped shock wave in the slant detonation wave initiation zone. The bow-shaped shock wave generated by the disturbance in the initiation zone interacts with the oblique shock wave generated at the front end of the lower wall of the engine combustion chamber to generate an oblique detonation wave. However, this method still cannot reduce the length of the detonation wave induction zone, and the detonation wave cannot be initiated within a limited length, thus failing to generate thrust. Summary of the Invention

[0006] In view of this, the present invention provides a detonation engine and its initiation method to reduce the length of the detonation wave induction zone.

[0007] In a first aspect, this application provides a slant detonation engine, including a cowling, a non-flammable fuel injector, a flammable fuel injector, an air intake, a combustion chamber, and a tail nozzle;

[0008] The air intake includes a first wedge and a second wedge, and the hypersonic flow passes through the first wedge and the second wedge to compress and generate a slanted shock wave.

[0009] The flame-retardant fuel injector is disposed on the upper wall near the outlet of the air intake, and is used to inject flame-retardant fuel when the hypersonic flow enters the air intake; the flame-retardant fuel injector is a transverse array cantilever injector.

[0010] The combustion chamber is connected to the air intake, and the mixture of fuel and the hypersonic inflow is fully combusted through the combustion chamber. The end of the combustion chamber is provided with a tail wedge surface with a wedge angle of 20°.

[0011] The tail nozzle is connected to the combustion chamber and is used to discharge the combustion products of the combustion chamber to generate thrust.

[0012] The flammable fuel injector is disposed at the front end of the fairing and is used to inject flammable fuel when the hypersonic flow enters the air intake; the flammable fuel injector is a transverse array cantilever injector.

[0013] Secondly, this application also provides a method for initiating a slant-detonation engine, the method being used for initiating the aforementioned slant-detonation engine, comprising:

[0014] The hypersonic flow enters the intake and is compressed at the first and second wedge surfaces. At the same time, the non-flammable fuel injector injects non-flammable fuel, and the flammable fuel injector injects flammable fuel.

[0015] The compressed hypersonic stream is mixed with the flammable fuel injected by the flammable fuel injector and the flammable fuel injected by the flammable fuel injector to obtain a mixed stream;

[0016] The mixed inlet flow configuration includes a well-mixed upper sub-inlet flow and a lower sub-inlet flow. The upper sub-inlet flow is a mixture of non-flammable fuel and upper gas located above the combustion chamber inlet, wherein the upper gas is air. The lower sub-inlet flow is a mixture of flammable fuel and lower gas located below the combustion chamber inlet, wherein the lower gas is air.

[0017] The upper and lower sub-streams are compressed at the tail wedge surface, causing them to burn in a detonation manner.

[0018] Optionally, the fire-retardant fuel includes hydrocarbon fuels.

[0019] Optionally, the hydrocarbon fuel includes one or a combination of ethylene, methane, and kerosene.

[0020] Optionally, the flammable fuel is hydrogen.

[0021] Compared with the prior art, the oblique detonation engine and its initiation method provided by the present invention achieve at least the following beneficial effects:

[0022] The oblique detonation engine and its initiation method provided by this invention involve injecting fuel into the hypersonic inlet when it enters the air intake. The hypersonic inlet is compressed in the air intake and mixed with the fuel to form a mixed inlet. The mixed inlet is configured to include an upper sub-inlet and a lower sub-inlet, which are compressed at the tail wedge surface, causing them to burn in a detonation manner. The dual-layer fuel-assisted initiation method utilizes flammable fuel to assist the detonation of non-flammable fuel, thereby reducing the length of the non-flammable fuel induction zone. There is no dynamic structural response or additional energy injection, which is beneficial for engineering prototype applications and maximizes thrust gain. Due to the characteristic that non-flammable gases are not easily detonated, oblique detonation wave detachment can be suppressed, and the lower limit of the Mach number for oblique detonation engine flight can be significantly widened.

[0023] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0024] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0026] Figure 1 This is a structural schematic diagram of the oblique detonation engine provided in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the fuel supply system provided in an embodiment of the present invention;

[0028] Figure 3 This is a flowchart of the detonation method for a slant detonation engine provided in an embodiment of the present invention;

[0029] Figure 4(a) is a schematic diagram of the hydrogen / air oblique detonation wave structure provided in the embodiment of the present invention;

[0030] Figure 4(b) is a schematic diagram of the oblique detonation wave structure of methane / air provided in the embodiment of the present invention;

[0031] Figure 4(c) is a schematic diagram of the oblique detonation wave structure of hydrogen / air and methane / air provided in the embodiments of the present invention;

[0032] Figure 5 This is a schematic diagram of the structure of double-layer fuel stratified detonation in the combustion chamber calculation domain provided in an embodiment of the present invention;

[0033] Figure 6 This is a microscopic wave diagram of the action of the double-layer fuel provided in an embodiment of the present invention. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0035] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0036] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0037] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0038] An exemplary embodiment is as follows: typical flight conditions of the oblique detonation engine: flight altitude 20km, flight Mach number 9, the difficult-to-burn fuel is methane, the flammable fuel is hydrogen, the equivalence ratio of methane to air is 1, the injection pressure is 131894.4Pa, the temperature is 666.6K, and the speed is 2489.5m / s; the equivalence ratio of hydrogen to air is 1, the injection pressure is 131894.4Pa, the temperature is 666.6K, and the speed is 2489.5m / s.

[0039] See Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of the oblique detonation engine provided in an embodiment of the present invention; this embodiment provides an oblique detonation engine, including a cowling 1, a non-flammable fuel injector 2, a flammable fuel injector 3, an air intake 4, a combustion chamber 5, and a tail nozzle 6;

[0040] The air intake 4 includes a first wedge surface 41 and a second wedge surface 42. Hypersonic air flows through the first wedge surface 41 and the second wedge surface 42 and compresses to generate oblique shock waves.

[0041] The flame-retardant fuel injector 2 is located on the upper wall near the outlet of the intake duct 4 and is used to inject flame-retardant fuel when the hypersonic flow enters the intake duct 4; the flame-retardant fuel injector 2 is a transverse array cantilever injector.

[0042] Combustion chamber 5 is connected to intake duct 4. The mixture of fuel and hypersonic flow is fully combusted through combustion chamber 5. A tail wedge surface 51 is provided at the end of combustion chamber 5, and the wedge angle θ of tail wedge surface 51 is 20°.

[0043] The tail nozzle 6 is connected to the combustion chamber 5 and is used to discharge the combustion products of the combustion chamber 5 to generate thrust.

[0044] The flammable fuel injector 3 is configured at the front end of the fairing 1 and is used to inject flammable fuel when the hypersonic flow enters the intake 4; the flammable fuel injector 3 is a transverse array cantilever injector.

[0045] For details, please refer to [link / reference]. Figure 1 As shown, the oblique detonation engine provided in this embodiment includes: a cowling 1, a non-flammable fuel injector 2, a flammable fuel injector 3, an air intake 4, a combustion chamber 5, and a tail nozzle 6; optionally, the oblique detonation engine can be located at the bottom of the fuselage, adopting an integrated design of the fuselage and the engine; the tail nozzle 6 can be a gradually expanding tail nozzle.

[0046] The air intake 4 includes a first wedge surface 41 and a second wedge surface 42. Hypersonic flow passes through the first wedge surface 41 and the second wedge surface 42 and is compressed to generate oblique shock waves. Specifically, the air intake 4 includes an upper wall and a side wall. The upper wall includes the first wedge surface 41 and the second wedge surface 42. The slope of the second wedge surface 42 is greater than the slope of the first wedge surface 41. The side wall of the air intake adopts an inward-curving design to connect the air intake and the combustion chamber. The side wall of the air intake is connected to the first wedge surface 41 of the upper wall of the air intake, the second wedge surface 42 of the upper wall of the air intake, and the bottom fairing 1 by an arc transition.

[0047] The flame-retardant fuel injector 2 is located on the upper wall near the outlet of the intake duct 4 and is used to inject flame-retardant fuel when the hypersonic flow enters the intake duct 4; the flame-retardant fuel injector 2 can be a transverse array cantilever injector.

[0048] Combustion chamber 5 is connected to intake duct 4. The mixture of fuel and hypersonic incoming flow is fully combusted through combustion chamber 5. A tail wedge surface 51 is provided at the end of combustion chamber 5. The wedge surface angle θ of tail wedge surface 51 can be 20°.

[0049] The tail nozzle 6 is connected to the combustion chamber 5 and is used to discharge the combustion products of the combustion chamber 5 to generate thrust.

[0050] The fairing 1 is located at the bottom of the air intake 4, combustion chamber 5 and tail nozzle 6, and is connected to the side wall of the air intake 4 by an arc transition. This bottom fairing 1 is used to reduce the drag encountered by the aircraft during flight.

[0051] The flammable fuel injector 3 is configured at the front end of the fairing 1 and is used to inject flammable fuel when the hypersonic flow enters the intake 4; the flammable fuel injector 3 can be a transverse array cantilever injector.

[0052] The flammable fuel injector 2 injects flammable fuel, and the flammable fuel injector 3 injects flammable fuel. After mixing with the hypersonic incoming flow, they form upper and lower sub-flows, respectively. Then, in the combustion chamber, the flammable fuel in the lower sub-flow assists the flammable fuel in the upper sub-flow to detonate, thereby reducing the length of the flammable fuel induction zone. There is no dynamic structural response or additional energy injection, which is beneficial for the application of engineering prototypes and maximizes the thrust gain. Due to the characteristic that flammable gases are not easy to detonate, the detonation wave can be suppressed, which can significantly widen the lower limit of the flight Mach number of the detonation engine.

[0053] It should be noted that both the flammable fuel injector 2 and the flammable fuel injector 3 can be selected as transverse array cantilever injectors. This type of fuel injector does not use a nozzle design because, compared with nozzles, the transverse array cantilever injector can increase the penetration depth of the injected fuel, improve the mixing effect of fuel and air, and the air cushion formed between the wall and the fuel can effectively prevent the fuel from penetrating the boundary layer. It can also generate axial vortices downstream to enhance the mixing efficiency of fuel and air.

[0054] High-speed incoming air is compressed through the first wedge surface 41 and the second wedge surface 42 of the intake duct 4 to generate oblique shock waves. At the same time, at the outlet of the intake duct 4, the recalcitrant fuel injector 2 injects hydrocarbon fuel (recalcitrant fuel), and the flammable fuel injector 3 injects hydrogen (flammable fuel). After being compressed, the air reaches the two fuel injectors and mixes with the injected fuel. Through mixing over a certain distance, the fuel and air are uniformly mixed. Then, the air enters the combustion chamber 5 and is compressed, burned, and released heat through the oblique wedge of the combustion chamber 5 (the oblique wedge is located in the combustion chamber 5, and the surface of the oblique wedge is the tail wedge surface 51). Finally, the combustion products are discharged through the tail nozzle 6, generating thrust.

[0055] See Figure 2 As shown, Figure 2 This is a schematic diagram of the fuel supply system provided in an embodiment of the present invention; the oblique detonation engine provided in this embodiment also includes a flammable fuel supply system 8 and a non-flammable fuel supply system 7; combined with Figure 1 As shown, the flammable fuel supply system 8 is used to supply flammable fuel to the flammable fuel injector 3; the non-flammable fuel supply system 7 is used to supply non-flammable fuel to the non-flammable fuel injector 2.

[0056] The flammable fuel supply system 8 includes a flammable fuel tank 81. The outlet of the flammable fuel tank 81 is connected in sequence to a head flammable fuel switch 82, a tail flammable fuel switch 83, and a flammable fuel pump 84 via pipes. The outlet of the flammable fuel pump 84 is connected to a flammable fuel injector 3 via a pipe. The flammable fuel tank 81 can hold hydrogen gas, which is transported to the flammable fuel injector 3 and sprayed to the outside via pipes. The head flammable fuel switch 82 is used to control the fuel injection, and the tail flammable fuel switch 83 can be a throttle valve, which is used to precisely control the flow rate and volume of the fuel injection.

[0057] The flammable fuel supply system 7 includes a flammable fuel tank 71. The outlet of the flammable fuel tank 71 is connected in sequence to a head flammable fuel switch 72, a tail flammable fuel switch 73, and a flammable fuel pump 74 via pipes. The outlet of the flammable fuel pump 74 is connected to the flammable fuel injector 2 via pipes. The flammable fuel tank 71 can hold methane, which is transported to the flammable fuel injector 2 via pipes and sprayed to the outside. The head flammable fuel switch 72 is used to control the fuel injection, and the tail flammable fuel switch 73 can be a throttle valve, which is used to precisely control the flow rate and volume of the fuel injection.

[0058] As can be seen from the above embodiments, the oblique detonation engine provided in this embodiment achieves at least the following beneficial effects:

[0059] This embodiment provides a tilt-detonation engine, which is equipped with two fuel injectors. A non-flammable fuel injector 2 is located on the upper wall near the outlet of the intake duct 4, and a flammable fuel injector 3 is located at the front end of the fairing 1. When the hypersonic flow enters the intake duct, the non-flammable fuel injector 2 injects non-flammable fuel, and the flammable fuel injector 3 injects flammable fuel. The hypersonic flow is compressed in the intake duct and mixed with the fuel to obtain a mixed flow. The mixed flow is configured to include an upper sub-flow and a lower sub-flow. The combustion chamber 5 is connected to the intake duct 4. The end of the engine is provided with a tail wedge surface 51, which compresses the upper and lower sub-sub flows, causing them to burn in the form of detonation. The flammable fuel injected by the flammable fuel injector assists the flammable fuel injected by the flammable fuel injector in detonating, thereby reducing the length of the flammable fuel induction zone. There is no dynamic structural response or additional energy injection, which is beneficial for the application of engineering prototypes and maximizes the thrust gain. Due to the characteristic that flammable gases are not easy to detonate, the detonation wave can be suppressed, which can significantly widen the lower limit of the Mach number of the detonation engine.

[0060] See Figure 3 As shown, Figure 3 This is a flowchart of the detonation method for a slant-detonation engine provided in this embodiment of the invention; this embodiment also provides a detonation method for a slant-detonation engine, which is used for detonating the slant-detonation engine in the above embodiment, including:

[0061] Step S1, Combining Figure 1 As shown, the hypersonic flow enters the intake duct 4 and is compressed at the first and second wedge surfaces. At the same time, the non-flammable fuel injector 2 injects non-flammable fuel and the flammable fuel injector 3 injects flammable fuel.

[0062] Step S2: The compressed hypersonic flow is mixed with the flammable fuel injected by the flammable fuel injector 2 and the flammable fuel injected by the flammable fuel injector 3 to obtain a mixed flow.

[0063] The mixed inlet flow configuration includes a well-mixed upper sub-inlet flow and a lower sub-inlet flow. The upper sub-inlet flow is a mixture of non-flammable fuel and upper gas located above the inlet of combustion chamber 5, and the upper gas is air. The lower sub-inlet flow is a mixture of flammable fuel and lower gas located below the inlet of combustion chamber 5, and the lower gas is air.

[0064] Step S3: The upper and lower sub-sub flows are compressed at the tail wedge surface 51, so that the upper and lower sub-sub flows finally burn in the form of detonation.

[0065] Specifically, in combination Figure 1 and Figure 3 As shown, this embodiment also provides a method for initiating a slant detonation engine. This method is used for initiating the slant detonation engine in the above embodiment and includes:

[0066] Step S1: The hypersonic flow enters the intake duct 4 and is compressed at the first wedge surface 41 and the second wedge surface 42. At the same time, the non-flammable fuel injector 2 injects non-flammable fuel and the flammable fuel injector 3 injects flammable fuel. Through step S1, the oblique detonation engine is simultaneously equipped with hypersonic flow, non-flammable fuel and flammable fuel.

[0067] Step S2: The compressed hypersonic stream mixes with the flammable fuel injected by the flammable fuel injector 2 and the flammable fuel injected by the flammable fuel injector 3 to obtain a mixed stream; after step S2, the hypersonic stream is fully mixed with the flammable fuel and the flammable fuel to obtain a mixed stream.

[0068] The mixed inlet flow configuration includes a well-mixed upper sub-inlet flow and a lower sub-inlet flow. The upper sub-inlet flow is a mixture of non-flammable fuel and upper gas located above the inlet of combustion chamber 5, and the upper gas is air. The lower sub-inlet flow is a mixture of flammable fuel and lower gas located below the inlet of combustion chamber 5, and the lower gas is air.

[0069] Step S3: The upper and lower sub-sub streams are compressed at the tail wedge surface 51, causing them to burn in the form of detonation. The dual-layer fuel-assisted detonation method uses the flammable fuel of the lower sub-sub stream to assist the detonation of the non-flammable fuel of the upper sub-sub stream, thereby reducing the length of the non-flammable fuel induction zone. There is no dynamic structural response or additional energy injection, which is beneficial for engineering prototype applications and maximizes thrust gain. Due to the characteristic that non-flammable gases are not easy to detonate, the detonation wave can be suppressed, and the lower limit of the Mach number of the detonation engine can be significantly widened.

[0070] The tail wedge surface 51 is a solid wall with a certain angle, mainly used to compress and capture the high-speed incoming flow from the intake. The upper sub-flow is located on the side of the lower sub-flow away from the tail wedge surface 51. The upper and lower sub-flows are injected in the same direction. They are initiated by using flammable fuel to assist non-flammable fuel, thereby reducing the length of the non-flammable fuel induction zone. There is no dynamic structural response or additional energy injection, which is beneficial for engineering prototype applications and maximizes thrust gain. Both the upper and lower sub-flows are obtained through sonic injection, and both ensure an injection equivalence ratio of 1 and an injection volume of... It is not a key parameter for characterization, and the difference in injection volume is due to its sound speed and chemical combustion characteristics; the upper and lower quantum flows are compressed at the tail wedge 51, so that the upper and lower quantum flows burn in the form of detonation; due to the characteristic that the difficult-to-ignite fuel ODW is not easy to detonate, the ODW separation can be suppressed, thereby greatly widening the lower limit of the flight Mach number of the oblique detonation engine; the upper and lower quantum flows enter the combustion chamber for complete combustion, and the final combustion products are discharged through the tail nozzle to generate thrust, thereby realizing the complete start-up process of the oblique detonation engine.

[0071] As can be seen from the above embodiments, the oblique detonation engine initiation method provided in this embodiment achieves at least the following beneficial effects:

[0072] The oblique detonation engine initiation method provided in this embodiment involves injecting fuel from a fuel injector when the hypersonic flow enters the air intake. The hypersonic flow is compressed in the air intake and mixed with the fuel to form a mixed flow. The mixed flow is configured to include an upper sub-flow and a lower sub-flow, which are compressed at the tail wedge surface, causing them to burn in a detonation manner. The dual-layer fuel-assisted initiation method utilizes flammable fuel to assist the detonation of non-flammable fuel, thereby reducing the length of the non-flammable fuel induction zone. There is no dynamic structural response or additional energy injection, which is beneficial for engineering prototype applications and maximizes thrust gain. Due to the characteristic that non-flammable gases are not easily detonated, oblique detonation wave detachment can be suppressed, and the lower limit of the Mach number for oblique detonation engine flight can be significantly widened.

[0073] In some alternative embodiments, see also [link to previous document]. Figure 3 As shown, difficult-to-burn fuels include hydrocarbon fuels; flammable fuels are hydrogen.

[0074] For details, please refer to [link / reference]. Figure 3As shown, in this embodiment, the difficult-to-burn fuel includes hydrocarbon fuel; the flammable fuel is hydrogen; the hydrocarbon fuel includes any one or a combination of several of ethylene, methane and kerosene, and this embodiment does not specifically limit this; it can be understood that in this embodiment, the upper layer influent can use only a mixture of methane and air, or only a mixture of ethylene and air, or only a mixture of kerosene and air, or any mixture of ethylene, methane, kerosene and air; preferably, the hydrocarbon fuel can be methane.

[0075] Optionally, the fire-retardant fuel includes hydrocarbon fuels and filling gas; the filling gas is generally air, specifically oxygen and nitrogen; the proportion of hydrocarbon fuel in the fire-retardant fuel depends on the type of hydrocarbon fuel; generally, the combustion effect is best when the mixture ratio of hydrocarbon fuel and air is a stoichiometric ratio, such as CH4 + 2O2 = CO2 + 2H2O; when the hydrocarbon fuel is CH4, the mixture ratio of hydrocarbon fuel and air is: CH4:O2:N2 = 1:2:7.52; if CH4:O2:N2 is less than 1:2:7.52, it will lead to incomplete combustion of the oblique detonation wave in the combustion chamber, resulting in detonation failure; if CH4:O2:N2 is greater than 1:2:7.52, it will lead to a large detonation wave angle and unstable combustion.

[0076] It should be noted that, currently, the main fuels available for aero engines are hydrogen and hydrocarbon fuels. For oblique detonation engines, the experiments and numerical simulations conducted on their basic flow field characteristics have primarily focused on hydrogen. Through theoretical analysis and numerical simulation, the propagation speeds of detonation waves from hydrogen and hydrocarbon fuels have been calculated and compared. Compared to the detonation structure of hydrogen in the combustion chamber of an oblique detonation engine, the induction zone of hydrocarbon fuel is too long, making it difficult to ignite and thus a difficult-to-burn gas. However, it has also been found that engines using hydrocarbon fuels are easier to stabilize, and hydrocarbon fuels are easier to store and have a higher volumetric impulse than hydrogen, thus better meeting the needs of weaponry.

[0077] In this embodiment, the upper sub-flow includes hydrocarbon fuel and air; the hydrocarbon fuel can specifically be methane; the main reason why oblique detonation engines are difficult to apply at low Mach numbers is that the angle difference between the oblique detonation wave and the oblique shock wave generated by hydrogen fuel is large under low Mach number conditions, resulting in a large subsonic region after the oblique detonation wave, thus causing the phenomenon of separation and forward propagation. However, methane ODW (ODW is oblique detonation wave, which is generated by the high-speed incoming flow passing through the wedge surface and generating an oblique shock wave. After the shock wave is compressed, the pressure and temperature increase to form the oblique detonation wave) has a slower reaction rate and stronger stability, which can suppress ODW separation to a certain extent, thus potentially greatly widening the lower limit of the flight Mach number of the oblique detonation engine. Methane can better adapt to the low Mach environment; the equivalence ratio of methane to upper gas can be 1.

[0078] In this embodiment, the lower sub-flow includes hydrogen and air; the hypersonic flow is compressed in the intake duct 2 and mixed with fuel to obtain a mixed flow; this mixed flow includes a mixture of hydrocarbon fuel and air and a mixture of hydrogen and air; in the actual detonation process, hydrocarbon fuel may have the problem of excessively long detonation zone length. To avoid this problem, this embodiment uses easily detonable hydrogen to assist the difficult-to-burn hydrocarbon fuel in detonation, reducing the length of the hydrocarbon fuel detonation zone, thereby achieving the purpose of hydrocarbon fuel detonation; specifically, the equivalence ratio of hydrogen to lower sub-gas can be injected in a 1:1 ratio. Referring to Figures 4(a), 4(b), and 4(c), Figure 4(a) is a schematic diagram of the oblique detonation wave structure of hydrogen / air provided in an embodiment of the present invention; Figure 4(b) is a schematic diagram of the oblique detonation wave structure of methane / air provided in an embodiment of the present invention; Figure 4(c) is a schematic diagram of the oblique detonation wave structure of hydrogen / air and methane / air provided in an embodiment of the present invention; wherein, the horizontal axis x represents the length of the combustion chamber calculation domain, the vertical axis y represents the height of the combustion chamber calculation domain, T represents the temperature, and its color bar is used to represent the temperature value; macroscopically, the necessary condition for flammable fuel to assist non-flammable fuel in detonation and form a stable detonation wave is that the angle of the oblique detonation wave generated by hydrogen is greater than the angle of the oblique detonation wave generated by methane.

[0079] See Figure 5 As shown, Figure 5 This is a schematic diagram of the structure of double-layer fuel stratified detonation in the combustion chamber calculation domain provided by the embodiment of the present invention. The wedge angle θ refers to the angle between the incoming flow direction and the wedge surface. In this embodiment, the wedge angle θ of the tail wedge surface 51 can be 20°, so that the incoming flow of the lower layer can successfully ignite the incoming flow of the upper layer, which can ensure that the injected fuel can successfully trigger the detonation wave within a limited length, thereby generating reliable thrust. At the same time, this design also effectively avoids the phenomenon of oblique detonation wave detachment, ensures the stable propagation of the detonation wave, and enables it to be stationed at the required position, while also preventing thermal blockage in the combustion chamber.

[0080] It should be noted that this embodiment uses the typical flight conditions of a slant detonation engine as an example. The typical flight conditions for a slant detonation engine are: flight altitude 20km, Mach number 9, methane as the non-flammable fuel, hydrogen as the flammable fuel, a methane to air equivalence ratio of 1, injection pressure of 131894.4 Pa, temperature of 666.6 K, and velocity of 2489.5 m / s; or a hydrogen to air equivalence ratio of 1, injection pressure of 131894.4 Pa, temperature of 666.6 K, and velocity of 2489.5 m / s. Of course, these values ​​can be adjusted appropriately according to actual conditions. This embodiment specifies the wedge angle and gas equivalence... The specific values ​​of the gas equivalence ratio, flight altitude, flight Mach number, incoming flow pressure, temperature, and velocity are not limited. First, the flight altitude and flight Mach number determine the incoming flow pressure, temperature, and velocity. Under the same flight altitude and flight Mach number conditions, changes in the gas equivalence ratio will affect the detonation and combustion, but the range and values ​​of how this affects different flight conditions cannot be determined. Second, under the condition that the flight altitude, flight Mach number, and equivalence ratio are all determined, the wedge angle determines whether the gas can be detonated. Therefore, under the condition that other values ​​remain unchanged, the wedge angle can be 20°. If the wedge angle exceeds 20°, the lower layer incoming flow cannot successfully ignite the upper layer incoming flow.

[0081] It should be noted that the "dual-fuel assisted detonation method" is unique compared to the method of using hydrogen or methane alone in that it combines two different fuels to achieve detonation, thus providing a more reliable and stable detonation effect in certain situations. The dual-fuel assisted detonation method has the following advantages:

[0082] 1. Complex combustion characteristics: Hydrogen and methane are two different fuels with different combustion characteristics, ignition capabilities and explosion limits. Combining them in a reasonable way to achieve controlled detonation is a complex engineering problem that requires full consideration of the interaction between the two fuels and the combustion process.

[0083] 2. Complexity of reaction kinetics: Hydrogen and methane have different combustion rates and kinetic behaviors under different conditions. Combining the two may require consideration of different temperatures, pressures and mixing ratios to achieve a stable and predictable detonation effect.

[0084] 3. Optimized combustion process: The dual-fuel assisted detonation method may need to be optimized under different operating conditions to obtain the best combustion efficiency and detonation performance. This may involve the adjustment of multiple parameters, which increases the complexity of the method.

[0085] 4. Innovative thinking: Combining two different fuels into a dual-fuel assisted detonation method requires innovative thinking, because such a combination may not be thought of naturally. It requires crossing the boundaries of traditional thinking and integrating different elements together.

[0086] Therefore, adopting a dual-fuel assisted detonation method requires not only in-depth knowledge of combustion and chemistry, but also a combination of creative thinking and engineering practice to achieve a reliable, efficient and safe detonation process, which is not something that those skilled in the art would easily come up with.

[0087] The following description uses methane / air and hydrogen / air as examples to verify the effectiveness of the detonation method of the inclined detonation engine provided in this embodiment. Methane / air and hydrogen / air are mixed in stoichiometric ratios of methane:2 oxygen:7.52 nitrogen and 2 hydrogen:oxygen:3.76 nitrogen. Double-layer fuel (i.e., upper and lower inlet streams, the upper inlet stream being methane and air, and the lower inlet stream being hydrogen and air) is injected before the combustion chamber inlet, and the hydrogen-air detonation wave is used to induce the detonation of the difficult-to-burn gas. The fuel injected near the tail wedge 51 is hydrogen, and the fuel injected away from the tail wedge 51 is methane. The fuel injection direction maintains a certain angle with the wedge, and the injection angles of hydrogen and methane are consistent.

[0088] Hydrogen gas is compressed by the tail wedge 51 (i.e., the supersonic hydrogen gas flow hits the tail wedge 51 and generates an attached oblique shock wave, and the gas pressure jumps after the shock wave), and an oblique shock wave is generated. The region behind this shock wave surface corresponds to the hydrogen-air reaction zone. Methane is also compressed by the shock wave (i.e., methane passes through a wedge and generates an oblique shock wave, and the gas pressure jumps after the shock wave), and an oblique shock wave is generated. The region behind this shock wave surface corresponds to the methane-air reaction zone.

[0089] See Figure 6 As shown, Figure 6 This is a microscopic wave diagram of the dual-fuel interaction provided in this embodiment of the invention; hydrogen and methane burn, and the fuel ignites and diffuses outward to generate a flame surface. Between the shock surface and the flame surface of the two gaseous fuels, there exists a compression wave (i.e., after the gas flow is compressed by the tail wedge 51, an oblique shock wave is generated; the density and pressure increase after the shock wave, thus generating a compression wave). This compression wave is the main reason why hydrogen can successfully ignite methane; through the analysis of… Figure 6Microscopic wave system analysis of double-layer fuel detonation proposes a theoretical criterion for hydrogen-initiated methane: compression wave (hydrogen) > compression wave (methane), macroscopically manifested as α(hydrogen) > α(methane); under the same incoming flow conditions, when the detonation wave angle induced by the same wedge angle is α(hydrogen) > α(methane), it is called the detonable zone; when α(hydrogen) < α(methane), it is called the non-detonable zone. In other words, for successful hydrogen-initiated methane, compression wave (hydrogen) > compression wave (methane) is always manifested macroscopically as α(hydrogen) > α(methane).

[0090] As can be seen from the above embodiments, the oblique detonation engine and its initiation method provided by the present invention achieve at least the following beneficial effects:

[0091] The oblique detonation engine and its initiation method provided by this invention involve injecting fuel into the hypersonic inlet when it enters the air intake. The hypersonic inlet is compressed in the air intake and mixed with the fuel to form a mixed inlet. The mixed inlet is configured to include an upper sub-inlet and a lower sub-inlet, which are compressed at the tail wedge surface, causing them to burn in a detonation manner. The dual-layer fuel-assisted initiation method utilizes flammable fuel to assist the detonation of non-flammable fuel, thereby reducing the length of the non-flammable fuel induction zone. There is no dynamic structural response or additional energy injection, which is beneficial for engineering prototype applications and maximizes thrust gain. Due to the characteristic that non-flammable gases are not easily detonated, oblique detonation wave detachment can be suppressed, and the lower limit of the Mach number for oblique detonation engine flight can be significantly widened.

[0092] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A slant detonation engine, characterized in that, It includes the fairing, the non-flammable fuel injector, the flammable fuel injector, the air intake, the combustion chamber, and the tail nozzle; The air intake includes a first wedge and a second wedge, and the hypersonic flow passes through the first wedge and the second wedge to compress and generate a slanted shock wave. The flame-retardant fuel injector is disposed on the upper wall near the outlet of the air intake, and is used to inject flame-retardant fuel when the hypersonic flow enters the air intake; the flame-retardant fuel injector is a transverse array cantilever injector. The combustion chamber is connected to the air intake, and the mixture of fuel and the hypersonic inflow is fully combusted through the combustion chamber. The end of the combustion chamber is provided with a tail wedge surface with a wedge angle of 20°. The tail nozzle is connected to the combustion chamber and is used to discharge the combustion products of the combustion chamber to generate thrust. The flammable fuel injector is disposed at the front end of the fairing and is used to inject flammable fuel when the hypersonic flow enters the air intake; the flammable fuel injector is a transverse array cantilever injector.

2. A method for initiating a slant-detonation engine, the method being used for initiating the slant-detonation engine as described in claim 1, characterized in that, include: The hypersonic flow enters the intake and is compressed at the first and second wedge surfaces. At the same time, the non-flammable fuel injector injects non-flammable fuel, and the flammable fuel injector injects flammable fuel. The compressed hypersonic stream is mixed with the flammable fuel injected by the flammable fuel injector and the flammable fuel injected by the flammable fuel injector to obtain a mixed stream; The mixed inlet flow configuration includes a well-mixed upper sub-inlet flow and a lower sub-inlet flow. The upper sub-inlet flow is a mixture of non-flammable fuel and upper gas located above the combustion chamber inlet, wherein the upper gas is air. The lower sub-inlet flow is a mixture of flammable fuel and lower gas located below the combustion chamber inlet, wherein the lower gas is air. The upper and lower sub-streams are compressed at the tail wedge surface, causing them to burn in a detonation manner.

3. The detonation method for the oblique detonation engine according to claim 2, characterized in that, The fire-retardant fuels include hydrocarbon fuels.

4. The detonation method for the oblique detonation engine according to claim 3, characterized in that, The hydrocarbon fuels include any one or a combination of several of ethylene, methane, and kerosene.

5. The detonation method for the oblique detonation engine according to claim 2, characterized in that, The flammable fuel is hydrogen.

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