Powder fuel injection structure, injection method and combustion chamber thereof

Abstract

The present application belongs to the field of engine, and particularly relates to a powder fuel injection structure, an injection method and a combustion chamber, wherein the powder fuel injection structure comprises a plurality of powder fuel injection pipes communicated with the combustion chamber, and a plurality of powder fuel jets from the powder fuel injection pipes collide with each other in the combustion chamber. The present application changes the powder fuel supply mode, so that two or more powder fuel jets collide in the combustion chamber, and the ignition efficiency and the combustion effect are improved from the three directions of destroying the oxidation layer of the outer wall of the powder fuel, generating heat energy of the powder fuel and improving the penetration depth and the spanwise diffusion range of the powder fuel.

Description

Technical Field

[0001] This invention belongs to the field of engines, specifically relating to a powder fuel injection structure, injection method and combustion chamber. Background Technology

[0002] The development of hypersonic vehicles has created an increasingly strong demand for higher-performance propulsion systems, especially high-specific-impulse systems with a wide range of adjustable flow rates. Powdered ramjet engines, using energetic particles (boron, metal particles and their alloys, coatings, etc.) as fuel, combine the advantages of solid-fuel ramjet engines (ease of maintenance and use) with those of liquid-fuel ramjet engines (ease of fuel flow adjustment and high specific impulse). Furthermore, as the incoming Mach number increases, the total incoming flow temperature rises, leading to increased dissociation of combustion products from traditional hydrocarbon fuels in high-temperature environments, resulting in incomplete heat release and reduced specific impulse. Energetic particles and their combustion products are less prone to dissociation in high-temperature environments, making them more advantageous as a propulsion system for wide-envelope vehicles. The basic operating process of a powdered ramjet engine is as follows: the supply unit generates fluidizing gas, which carries powdered fuel through the fuel injector into the combustion chamber to mix and burn with the incoming flow. The combustion products are then ejected through the nozzle to generate thrust. The fluidizing gas and powdered fuel at the fuel injector can reach the speed of sound.

[0003] However, at high flight speeds (Ma > 8), the supersonic air compressed through the engine intake still maintains a high velocity. Energetic particles have a short residence time in the engine combustion chamber, resulting in incomplete combustion and energy release. This leads to low combustion efficiency in powder fuel ramjet engines. Furthermore, energetic particles (such as boron particles) are highly reactive, with an oxide film on their surface, primarily composed of B2O3. Studies show that B2O3 has a melting point of 460℃ and a boiling point of 1860℃, exhibiting a low melting point and high boiling point. Therefore, during ignition and combustion, the oxide film on the surface of boron particles melts into a liquid, enveloping the particle surface and hindering the contact between elemental boron and oxygen, thus impeding further combustion. Currently, to address the difficulty of powder fuel blending, baffles and wedges are typically designed into the combustion chamber to create a low-speed zone and promote the blending and combustion of powder fuel. However, adding baffles and wedges to the combustion chamber increases internal resistance and reduces combustion chamber performance. To address the challenges of ignition and combustion of powdered fuels, methods such as mixing with reactive metals, coating particle surfaces, and alloying are generally employed to improve the fuel's combustion characteristics, thereby resolving the combustion organization difficulties in powdered fuel ramjet engines. However, these powdered fuel modification measures lead to both increased costs and reduced energy density. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a powder fuel injection structure, injection method and combustion chamber that utilizes the mutual collision of powder fuels to improve the mixing efficiency of powder fuels, remove oxide films and reuse energy.

[0005] The present invention provides a powder fuel injection structure, including a plurality of powder fuel injection pipes communicating with a combustion chamber, wherein multiple streams of powder fuel injected from the plurality of powder fuel injection pipes into the combustion chamber collide with each other in the combustion chamber.

[0006] Furthermore, the outlet directions of the plurality of powder fuel injection pipes intersect.

[0007] Furthermore, the outlets of the plurality of powder fuel injection pipes are arranged adjacent to each other.

[0008] Furthermore, the outlet directions of the plurality of powder fuel injection pipes are located on the same cross-section of the combustion chamber.

[0009] Furthermore, the powder fuel injection pipe has a tapered structure from the inlet to the outlet.

[0010] Furthermore, the powdered fuel ejected from the outlet of the powdered fuel injection pipe has a speed equal to the speed of sound.

[0011] Furthermore, the powder fuel injection pipe is located upstream of the concave cavity of the combustion chamber.

[0012] Furthermore, the powder fuel injection pipe is located upstream of the ignition device.

[0013] This invention also provides a powder fuel injection method using the above-described powder fuel injection structure, comprising the following steps: powder fuel injected into the combustion chamber by a plurality of powder fuel injection pipes collides with each other in the combustion chamber, and the oxide layer on the outside of the powder fuel is destroyed during the collision, exposing the powder fuel and increasing the reaction rate between the powder fuel and the oxidant; at the same time, the powder fuel gains internal energy during the collision, providing initial energy for the ignition of the powder fuel; and the powder fuel mixes and diffuses after the collision, improving the mixing effect between the powder fuel and the incoming airflow, as well as the penetration depth and spread diffusion range of the powder fuel in the combustion chamber.

[0014] The present invention also provides a combustion chamber including the above-described powder fuel injection structure.

[0015] The beneficial effects of this invention are that by changing the powder fuel supply method, the invention causes two or more streams of powder fuel to collide in the combustion chamber, which can improve ignition efficiency and combustion effect in three directions: destroying the oxide layer on the outer wall of the powder fuel, generating heat energy in the powder fuel, and increasing the penetration depth and spread of the powder fuel. Attached Figure Description

[0016] Appendix Figure 1 This is a schematic diagram of the combustion chamber of the present invention;

[0017] Appendix Figure 2 This is a cross-sectional view of the combustion chamber of the present invention;

[0018] Appendix Figure 3 This is a cross-sectional view of the combustion chamber of the present invention at the location of the powder fuel injection pipe;

[0019] Appendix Figure 4 This is a schematic diagram of the collision of powdered fuel in this invention (the thick black solid line in the figure represents the oxide layer of the energetic particles).

[0020] In the diagram, 1-Powdered fuel injection pipe; 2-Combustion chamber; 21-Cavity; 3-Ignition device; 4-Main air flow. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] 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 positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0023] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0026] As attached Figure 1 - Appendix Figure 4 As shown, the present invention provides a powder fuel injection structure, including a plurality of (at least two, for example two, three, etc.) powder fuel injection pipes 1 communicating with a combustion chamber 2, wherein multiple streams (at least two, for example two, three, etc.) of powder fuel injected from the plurality of powder fuel injection pipes 1 into the combustion chamber 2 collide with each other in the combustion chamber 2.

[0027] The powder fuel injection structure provided by the present invention allows multiple streams of powder fuel injected into the combustion chamber 2 by multiple powder fuel injection pipes 1 to collide with each other within the combustion chamber 2 during the powder fuel injection process.

[0028] At this point, please refer to the appendix. Figure 4 The oxide layer on the outside of the powdered fuel is destroyed during the collision process (powdered fuel is composed of several energetic particles. During this process, a single energetic particle collides with another or more energetic particles, causing the oxide layer on the energetic particle to be destroyed), exposing the fuel in the energetic particles, increasing the reaction rate between the powdered fuel and the oxidant, thereby improving the ignition efficiency of the powdered fuel and the complete combustion to release energy. When the collision intensity is sufficient, the powdered fuel will also deform or even break, increasing the contact area between the energetic particles and the oxidant, further accelerating the reaction rate between the energetic particles and the oxidant.

[0029] At the same time, the energetic particles of powdered fuel gain internal energy during mutual collisions, providing initial energy for the ignition of powdered fuel. Specifically, the collision process and the destruction of the oxide layer will result in the conversion of mechanical energy into internal energy, which will cause the energetic particles to generate heat to promote the ignition and combustion of powdered fuel.

[0030] Reference Appendix Figure 2 - Appendix Figure 4After the powdered fuel collides with each other, it mixes and diffuses, which improves the mixing effect between the powdered fuel and the incoming airflow, and also increases the penetration depth and spread of the powdered fuel in the combustion chamber 2. Specifically, the powdered fuel, as a gas-solid two-phase mixture, is fully mixed with the mainstream airflow 4. (Refer to Appendix) Figure 4 Meanwhile, during the collision of powdered fuels, the powdered fuels will diffuse in different directions and distances along their original trajectory depending on the collision angle, thereby increasing the penetration depth and spread of the powdered fuels in the combustion chamber 2, improving the mixing rate of the powdered fuels with the mainstream air 4, reducing the difficulty of ignition and combustion, and then using an energy-concentrating spark plug for ignition to achieve efficient combustion of the powdered fuels. In addition, under ideal conditions, that is, the speed of the energetic particles is fast enough and the internal energy generated by the collision is high enough to achieve the ignition energy of the energetic particles, the ignition device 3 can be omitted, thereby further simplifying the combustion chamber structure.

[0031] This invention improves ignition efficiency and combustion performance by altering the powder fuel supply method, causing two or more streams of powder fuel to collide within the combustion chamber 2. This interaction occurs in three directions: breaking down the oxide layer on the outer wall of the energetic particles, generating heat energy from the particles, and increasing the penetration depth and spanwise diffusion range of the powder fuel. This addresses current problems in powder fuel ramjet engines, including low powder fuel mixing efficiency, difficulty in removing the oxide layer from the energetic particle surface leading to ignition and combustion difficulties, and the short residence time of energetic particles in the combustion chamber 2 due to the high velocity of supersonic air compressed through the engine intake at high flight speeds (Ma>8), resulting in insufficient energy release. Furthermore, this powder fuel injection structure requires minimal structural modifications to the combustion chamber 2, eliminating the need for baffles, wedges, or other aerodynamic structures, and thus does not increase the internal resistance of the combustion chamber 2.

[0032] It should be noted that in this invention, one powder fuel injection pipe 1 injects one stream of powder fuel. When multiple streams (two or more streams) of powder fuel injected from multiple (two or more) powder fuel injection pipes 1 into the combustion chamber 2 collide with each other in the combustion chamber 2, each stream of powder fuel collides with another or more streams of powder fuel to improve the efficiency of ignition and combustion.

[0033] In one embodiment, the outlet directions of the plurality of powder fuel injection pipes 1 intersect, causing multiple jets to converge and collide at the intersection of their outlet directions. The combustion chamber 2 can be either a rectangular or circular combustion chamber. When using a rectangular combustion chamber, the plurality of powder fuel injection pipes 1 can be arranged on one side wall of the combustion chamber 2, forming an angle that allows multiple streams of powder fuel to collide. Alternatively, the plurality of powder fuel injection pipes 1 can be arranged on multiple (two to four) side walls of the combustion chamber 2, ensuring that one stream of powder fuel from each injection pipe 1 collides with one stream of powder fuel from at least another injection pipe 1. When using a circular combustion chamber, the plurality of powder fuel injection pipes 1 are disposed on the inner wall of the combustion chamber 2, ensuring that one stream of powder fuel from each injection pipe 1 collides with one stream of powder fuel from at least another injection pipe 1.

[0034] In one embodiment, the outlets of the plurality of powder fuel injection pipes 1 are arranged adjacent to each other. In this case, at least two streams of powder fuel can collide at a shallow penetration depth, thereby increasing the collision intensity of the at least two streams of powder fuel, improving the destructive effect on the oxide layer, and increasing the generated internal energy.

[0035] In one embodiment, the outlet directions of the plurality of powder fuel injection pipes 1 are located on the same cross-section of the combustion chamber 2, thereby ensuring that the multiple streams of powder fuel are at the same position in the combustion chamber 2, so that they can move synchronously and collide with each other as they are driven downstream of the combustion chamber 2 by the high-speed air mainstream 4, thus avoiding the multiple streams of powder fuel being unable to collide with each other due to the influence of the high-speed air mainstream 4 at different flow positions.

[0036] In one embodiment, the powder fuel injection pipe 1 has a tapered structure from the inlet to the outlet. This configuration can increase the ejection speed of the powder fuel at the outlet, thereby increasing the collision intensity and penetration depth of the multiple powder fuel streams.

[0037] In one embodiment, the powder fuel ejected from the outlet of the powder fuel injection pipe 1 has a velocity equal to the speed of sound, thereby ensuring the collision intensity and penetration depth of the powder fuel after it enters the combustion chamber 2.

[0038] In one embodiment, the powder fuel injection pipe 1 is located upstream of the cavity 21 of the combustion chamber 2. In this embodiment, the cavity 21 is a turbulence structure in the combustion chamber 2 of the powder scramjet engine, which can provide a recirculation zone, thereby increasing the residence time of the powder fuel in the combustion chamber 2 after the collision. At the same time, it allows the powder fuel to combine with the turbulence of the cavity 21 when it moves randomly after the collision, further improving the mixing of the powder fuel and the air mainstream 4.

[0039] In one embodiment, the powder fuel injection pipe 1 is located upstream of the ignition device 3, that is, the ignition device 3 is set between the powder fuel injection pipe 1 and the cavity 21, which can ensure the successful ignition of the powder fuel. The ignition device 3 can be a shaped spark plug, a solid igniter, or other reusable igniters.

[0040] In one embodiment, the energetic particles of the powdered fuel include, but are not limited to, boron, metal particles (aluminum, magnesium) and their alloys, coatings and modified powders.

[0041] The present invention also provides a powder fuel injection method using the above-mentioned powder fuel injection structure, comprising the following steps: powder fuel injected into the combustion chamber 2 by a plurality of the powder fuel injection pipes 1 collides with each other in the combustion chamber 2, the oxide layer on the outside of the powder fuel is destroyed during the collision, exposing the powder fuel and increasing the reaction rate between the powder fuel and the oxidant; at the same time, the powder fuel gains internal energy during the collision, providing initial energy for the ignition of the powder fuel; and the powder fuel mixes and diffuses after the collision, improving the mixing effect between the powder fuel and the incoming airflow, as well as the penetration depth and spread diffusion range of the powder fuel in the combustion chamber 2.

[0042] A combustion chamber 2 includes the above-described powder fuel injection structure.

[0043] The working process of this combustion chamber 2 is described as follows: Fluidizing gas carrying powdered fuel is accelerated to the speed of sound from the converging powdered fuel injection pipe 1 and enters the combustion chamber 2. Due to the design of multiple powdered fuel injection pipes 1, at least two streams of powdered fuel enter the combustion chamber 2 and collide. After high-speed collisions, the oxide film on the energetic particles containing the oxide film is destroyed, generating higher internal energy, providing energy for the ignition and combustion of the powdered fuel. The oxidant (generally air from the mainstream airflow) rapidly reacts with the fuel exposed on the surface of the energetic particles. Furthermore, depending on the collision angle, the powdered fuel diffuses in different directions and distances along its original trajectory, thereby increasing the penetration depth and spread of the powdered fuel in the combustion chamber 2, which is beneficial for the mixing of the powdered fuel with the mainstream airflow 4. After entering the combustion chamber 2 and colliding, the powdered fuel improves its mixing efficiency with the mainstream airflow 4, reduces the difficulty of ignition and combustion, and is then ignited using a shaped-electrode spark plug (ideally, this ignition device 3 can be omitted), achieving efficient combustion of the powdered fuel.

[0044] The above description is merely an embodiment and does not constitute any limitation on the present invention. Any person skilled in the art can make many possible variations, modifications, or alterations to the technical solutions of the present invention without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A powder fuel injection structure, characterized in that, It includes multiple powder fuel injection pipes (1) connected to the combustion chamber (2), and multiple streams of powder fuel injected from the multiple powder fuel injection pipes (1) into the combustion chamber (2) collide with each other in the combustion chamber (2).

2. The powder fuel injection structure as described in claim 1, characterized in that, The outlet directions of the plurality of powder fuel injection pipes (1) intersect.

3. The powder fuel injection structure as described in claim 2, characterized in that, The outlets of the plurality of powder fuel injection pipes (1) are arranged adjacent to each other.

4. The powder fuel injection structure as described in claim 3, characterized in that, The outlet directions of the plurality of powder fuel injection pipes (1) are located on the same cross section of the combustion chamber (2).

5. The powder fuel injection structure as described in claim 1, characterized in that, The powder fuel injection pipe (1) has a tapering structure from the inlet to the outlet.

6. The powder fuel injection structure as described in claim 5, characterized in that, The powder fuel ejected from the outlet of the powder fuel injection pipe (1) has a speed equal to the speed of sound.

7. The powder fuel injection structure as described in any one of claims 1-6, characterized in that, The powder fuel injection pipe (1) is located upstream of the cavity (21) of the combustion chamber (2).

8. The powder fuel injection structure as described in claim 7, characterized in that, The powder fuel injection pipe (1) is located upstream of the ignition device (3).

9. A method for injecting powdered fuel, characterized in that, Using the powder fuel injection structure as described in any one of claims 1-8, the following steps are included: the powder fuel injected into the combustion chamber (2) by the plurality of powder fuel injection pipes (1) collides with each other in the combustion chamber (2), the oxide layer outside the powder fuel is destroyed during the collision process, the fuel of the powder fuel is exposed, and the reaction rate of the powder fuel and the oxidant is increased; at the same time, the powder fuel gains internal energy during the collision process, providing initial energy for the ignition of the powder fuel; at the same time, the powder fuel will mix and diffuse after the collision, improving the mixing effect of the powder fuel and the air flow, as well as the penetration depth and spread diffusion range of the powder fuel in the combustion chamber (2).

10. A combustion chamber, characterized in that, Includes the powder fuel injection structure as described in any one of claims 1-8.

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