Powder fuel injection structure, powder fuel injection method and combustion chamber of powder fuel injection structure

Abstract

The invention belongs to the field of engines, and particularly relates to a powder fuel injection structure, an injection method and a combustion chamber of the powder fuel injection structure, the powder fuel injection structure comprises a plurality of powder fuel injection pipes communicated with the combustion chamber, and multiple strands of powder fuel injected into the combustion chamber from the powder fuel injection pipes collide with one another in the combustion chamber. By changing the supply mode of the powder fuel, two or more strands of powder fuel collide in the combustion chamber, and the ignition efficiency and the combustion effect can be improved through interaction of three directions of destroying an oxide layer on the outer wall of the powder fuel, enabling the powder fuel to generate heat energy and improving the penetration depth and the spanwise diffusion range of the powder fuel.

Description

Technical Field

[0001] The invention belongs to the field of engines, and in particular relates to a powder fuel injection structure, an injection method and a combustion chamber thereof. Background Art

[0002] The development of hypersonic vehicles has an increasingly strong demand for higher performance power systems, especially high specific impulse power systems with flow rates that can be adjusted over a wide range. Powder fuel ramjet engines that use energetic particles (boron, metal particles and their alloys, coatings, etc.) as fuel have the advantages of easy maintenance and use of solid fuel ramjet engines and easy adjustment of fuel flow and high specific impulse of liquid fuel ramjet engines. In addition, as the Mach number of the incoming flow increases, the total temperature of the incoming flow increases, and the degree of dissociation of the combustion products of traditional hydrocarbon fuels in high temperature environments intensifies, resulting in insufficient heat release and reduced specific impulse. Energetic particles and combustion products are not easy to dissociate in high temperature environments. This feature makes energetic particles more advantageous as a propulsion system for wide envelope aircraft. The basic working process of a powder fuel ramjet engine is that the supply device generates fluidizing gas, carries powdered fuel through the fuel injection port into the combustion chamber for mixing and combustion with the incoming flow, and its combustion products are ejected through the nozzle to generate thrust. Among them, the fluidizing gas and powdered fuel speeds at the fuel injection port can reach the speed of sound.

[0003] However, when the flight speed of the aircraft is high (Ma>8), the supersonic air compressed by the engine inlet still has a high speed, and the energetic particles have a short residence time in the engine combustion chamber, and cannot be fully burned and release energy in the combustion chamber, which makes the combustion efficiency of the powder fuel ramjet engine low, and the residence time in the combustion chamber is short, and it cannot be completely burned and release energy. In addition, energetic particles (boron particles as an example) are relatively active, and there will be an oxide film on their surface, the main component of which is B2O3. Studies have shown that the melting point of B2O3 is 460℃ and the boiling point is 1860℃, showing the characteristics of low melting point and high boiling point. Therefore, during the ignition and combustion process of boron particles, the surface oxide film will melt into liquid and wrap around the surface of the particles, hindering the contact between elemental boron and oxygen and hindering its further combustion reaction. At present, in order to solve the problem of difficult powder fuel mixing, turbulent structures such as support plates and oblique splits are generally designed in the combustion chamber to create a low-speed zone and promote the mixing and combustion of powder fuel. However, adding support plates and oblique splits in the combustion chamber will increase the internal resistance of the combustion chamber and reduce the working performance of the combustion chamber. In order to solve the problem of powder fuel ignition and combustion difficulties, methods such as mixing active metals, particle surface coating and alloying are generally used to improve the combustion characteristics of the fuel itself, thereby solving the problem of powder fuel ramjet combustion organization difficulties. Such powder fuel modification measures will, on the one hand, increase the cost of powder fuel, and on the other hand, reduce the energy density of the powder fuel itself. 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 which utilize the mutual collision of powder fuels to improve the powder fuel mixing efficiency, remove the oxide film and recycle the energy.

[0005] The invention provides a powder fuel injection structure, comprising a plurality of powder fuel injection pipes connected with a combustion chamber, wherein a plurality of powder fuels injected from the plurality of powder fuel injection pipes into the combustion chamber collide with each other in the combustion chamber.

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

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

[0008] Furthermore, 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 speed of the powdered fuel sprayed from the outlet of the powdered fuel injection pipe is equal to the speed of sound.

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

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

[0013] The present invention also provides a powder fuel injection method, which uses the above-mentioned powder fuel injection structure and includes the following steps: the powder fuels sprayed into the combustion chamber by multiple powder fuel injection pipes collide with each other in the combustion chamber, and the oxidation layer outside the powder fuel is destroyed during the mutual collision process, so that the fuel of the powder fuel is exposed, thereby increasing the reaction rate of the powder fuel and the oxidant; at the same time, the powder fuel obtains internal energy during the mutual collision process, providing initial energy for the ignition of the powder fuel; at the same time, the powder fuels will mix and diffuse after colliding with each other, thereby improving the mixing effect of the powder fuel and the air flow, as well as the penetration depth and spanwise diffusion range of the powder fuel in the combustion chamber.

[0014] The present invention also provides a combustion chamber, comprising the powder fuel injection structure.

[0015] The beneficial effect of the present invention is that, by changing the powder fuel supply mode, the present invention causes two or more powder fuels to collide in the combustion chamber, which can interact to improve the ignition efficiency and combustion effect from three directions: destroying the oxide layer of the outer wall of the powder fuel, causing the powder fuel to generate heat energy, and increasing the penetration depth and spanwise diffusion range of the powder fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attached Figure 1 It is a structural schematic diagram of the combustion chamber of the present invention; Attached Figure 2 It is a schematic cross-sectional view of a combustion chamber of the present invention; Attached Figure 3 A cross-sectional view of the combustion chamber of the present invention at the location of the powder fuel injection pipe; Attached Figure 4 Schematic diagram of the collision of powdered fuel in the present invention (the thick black solid line in the figure is the oxidation layer of the energetic particles).

[0017] In the figure, 1-powder fuel injection pipe; 2-combustion chamber; 21-recessed cavity; 3-ignition device; 4-main air flow. DETAILED DESCRIPTION

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] As attached Figure 1 -Attached Figure 4 As shown, the present invention provides a powder fuel injection structure, comprising a plurality of (at least two, such as two, three, etc.) powder fuel injection pipes 1 connected to a combustion chamber 2, wherein a plurality of (at least two, such as two, three, etc.) powder fuels sprayed from the plurality of powder fuel injection pipes 1 into the combustion chamber 2 collide with each other in the combustion chamber 2.

[0024] In the powder fuel injection structure provided by the present invention, during the powder fuel injection process, multiple streams of powder fuel injected into the combustion chamber 2 by the multiple powder fuel injection pipes 1 collide with each other in the combustion chamber 2 .

[0025] At this time, refer to the attached Figure 4 The oxidation layer outside the powder fuel is destroyed during the mutual collision process (the powder fuel is composed of a number of energetic particles. During this process, a single energetic particle collides with another or more energetic particles, so that the oxidation layer on the energetic particles is destroyed), exposing the fuel of the energetic particles, increasing the reaction rate of the powder fuel and the oxidant, and thus improving the ignition efficiency of the powder fuel and the full combustion and energy release. When the collision intensity is sufficient, the powder fuel will also deform or even break, increasing the contact area between the particles and the oxidant, and further accelerating the reaction rate of the energetic particles and the oxidant. At the same time, the energetic particles of the powder fuel obtain internal energy during the mutual collision process, providing initial energy for the ignition of the powder fuel. Specifically, the collision process and the destruction of the oxide layer will result in the conversion of mechanical energy into internal energy, so that the energetic particles generate heat to promote the ignition and combustion of the powder fuel. Reference Figure 2 -Attached Figure 4 After the powder fuel collides with each other, it will mix and diffuse, which will improve the mixing effect of the powder fuel and the air flow on the one hand, and on the other hand, it will improve the penetration depth and spanwise diffusion range of the powder fuel in the combustion chamber 2. Specifically, the powder fuel is fully mixed with the main air stream 4 as a gas-solid two-phase mixture. Figure 4At the same time, in the process of mutual collision of powdered fuels, the powdered fuel will diffuse in different directions and distances on the original motion trajectory according to the different collision angles, thereby increasing the penetration depth and spanwise diffusion range of the powdered fuel in the combustion chamber 2, improving the mixing rate of the powdered fuel and the mainstream air 4, reducing the difficulty of ignition and combustion, and then using a focused spark plug for ignition to achieve efficient combustion of the powdered fuel. 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 reach the ignition energy of the energetic particles, the ignition device 3 can be omitted, thereby further simplifying the combustion chamber structure.

[0026] That is, the present invention changes the powder fuel supply mode to make two or more powder fuels collide in the combustion chamber 2, which can improve the ignition efficiency and combustion effect from three directions: destroying the oxide layer of the outer wall of the energetic particles, making the energetic particles generate heat energy, and increasing the penetration depth and span-wise diffusion range of the powder fuel, and solve the problems existing in the current powder fuel ramjet engine, including low powder fuel blending efficiency, difficult ignition and combustion process caused by the difficulty in removing the oxide layer on the surface of the energetic particles, and when the flight speed of the aircraft is high (Ma>8), the supersonic air compressed through the engine intake duct still has a high speed, the energetic particles have a short residence time in the engine combustion chamber 2, and cannot be fully burned and released in the combustion chamber 2. In addition, the powder fuel injection structure has minimal structural improvements in the combustion chamber 2, and there is no need to design spoiler structures such as support plates and oblique splits, and the internal resistance of the combustion chamber 2 will not be increased.

[0027] It should be noted that in the present invention, one powder fuel injection pipe 1 injects a 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 stream or multiple streams of powder fuel to obtain the effect of improving the efficiency of ignition and combustion.

[0028] In one embodiment, the outlet directions of the plurality of powder fuel injection pipes 1 intersect, so that the plurality of jets will converge and collide at the intersection of their outlet directions. The combustion chamber 2 may be a rectangular combustion chamber or a circular combustion chamber. When a rectangular combustion chamber is adopted, the plurality of powder fuel injection pipes 1 may be arranged on a single side wall of the combustion chamber 2, and the plurality of powder fuel injection pipes 1 have an angle, so that the plurality of powder fuels collide with each other; the plurality of powder fuel injection pipes 1 may be arranged on a plurality of (two to four) side walls of the combustion chamber 2, and at this time, it is only necessary to ensure that a stream of powder fuel ejected from each powder fuel injection pipe 1 collides with a stream of powder fuel ejected from at least another powder fuel injection pipe 1. When a circular combustion chamber is adopted, the plurality of powder fuel injection pipes 1 are arranged on the inner wall of the combustion chamber 2, and it is sufficient to ensure that a stream of powder fuel ejected from each powder fuel injection pipe 1 collides with a stream of powder fuel ejected from at least another powder fuel injection pipe 1.

[0029] In one embodiment, outlets of a plurality of the powder fuel injection pipes 1 are arranged adjacent to each other. At this time, at least two streams of powder fuel can collide at a shallow penetration depth, thereby increasing the collision strength of at least two streams of powder fuel, increasing the destructive effect on the oxide layer, and increasing the generated internal energy.

[0030] In one of the embodiments, 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 plurality of powder fuels are at the same flow position in the combustion chamber 2, so that they can move synchronously and collide with each other while being driven by the high-speed air mainstream 4 to move downstream of the combustion chamber 2, thereby preventing the plurality of powder fuels from colliding with each other at different flow positions due to the influence of the high-speed air mainstream 4.

[0031] In one embodiment, the powder fuel injection pipe 1 has a tapered structure from the inlet to the outlet. This arrangement can increase the spraying speed of the powder fuel at the outlet, thereby increasing the collision strength and penetration depth of multiple powder fuel streams.

[0032] In one of the embodiments, the speed of the powder fuel sprayed out from the outlet of the powder fuel injection pipe 1 is equal to the speed of sound, thereby ensuring the collision strength and penetration depth of the powder fuel after entering the combustion chamber 2.

[0033] In one of the embodiments, the powder fuel injection pipe 1 is arranged upstream of the concave cavity 21 of the combustion chamber 2. In this embodiment, the concave cavity 21 is a turbulent structure in the combustion chamber 2 of the powder scramjet engine, which can provide a reflow zone, thereby increasing the residence time of the powder fuel in the combustion chamber 2 after the collision, and at the same time, the powder fuel is combined with the turbulent flow of the concave cavity 21 during random movement after the collision, thereby further improving the mixing of the powder fuel and the air mainstream 4.

[0034] In one embodiment, the powder fuel injection pipe 1 is located upstream of the ignition device 3, that is, the ignition device 3 is arranged between the powder fuel injection pipe 1 and the concave cavity 21, which can ensure the successful ignition of the powder fuel. The ignition device 3 can use a concentrated spark plug, or a solid igniter or other reusable igniter.

[0035] 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.

[0036] The present invention also provides a powder fuel injection method, which uses the above-mentioned powder fuel injection structure and includes the following steps: the powder fuels sprayed into the combustion chamber 2 by the multiple powder fuel injection pipes 1 collide with each other in the combustion chamber 2, and the oxidation layer outside the powder fuel is destroyed during the mutual collision process, so that the fuel of the powder fuel is exposed, thereby increasing the reaction rate of the powder fuel and the oxidant; at the same time, the powder fuel obtains internal energy during the mutual collision process, providing initial energy for the ignition of the powder fuel; at the same time, the powder fuels will mix and diffuse after colliding with each other, thereby improving the mixing effect of the powder fuel and the air flow, as well as the penetration depth and spanwise diffusion range of the powder fuel in the combustion chamber 2.

[0037] A combustion chamber 2 comprises the above-mentioned powder fuel injection structure.

[0038] The working process of the combustion chamber 2 is described as follows: the fluidizing gas carries the powder fuel and accelerates it to the speed of sound from the powder fuel injection pipe 1 of the tapered structure and then enters the combustion chamber 2; due to the design of the multiple powder fuel injection pipes 1, at least two streams of powder fuel can collide after entering the combustion chamber 2. After the energetic particles containing the oxide film collide at high speed, the oxide film is destroyed and a higher internal energy is generated, providing energy for the ignition and combustion of the powder fuel. The oxidant (generally the air in the air mainstream) reacts quickly with the fuel exposed on the surface of the energetic particles. In addition, the powder fuel will diffuse in different directions and distances on the original motion trajectory according to the different collision angles, thereby increasing the penetration depth and spanwise diffusion range of the powder fuel in the combustion chamber 2, which is conducive to the mixing of the powder fuel with the air mainstream 4. After the powder fuel enters the combustion chamber 2 and collides, the mixing efficiency with the air mainstream 4 is improved, and the difficulty of ignition and combustion is reduced. Then, the energy-gathering spark plug is used for ignition (the ignition device 3 can be omitted under ideal conditions) to achieve efficient combustion of the powder fuel.

[0039] 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. A powder fuel injection structure, characterized in that: The invention comprises a plurality of powder fuel injection pipes (1) connected to a combustion chamber (2), wherein a plurality of powder fuels injected from the plurality of 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 according to claim 1, characterized in that: The outlet directions of the plurality of powder fuel injection pipes (1) intersect.

3. The powder fuel injection structure according to 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 according to 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 according to claim 1, characterized in that: The powder fuel injection pipe (1) has a tapered structure from the inlet to the outlet.

6. The powder fuel injection structure according to claim 5, characterized in that: The speed of the powdered fuel sprayed out from the outlet of the powdered fuel injection pipe (1) is equal to the speed of sound.

7. The powder fuel injection structure according to any one of claims 1 to 6, characterized in that: The powder fuel injection pipe (1) is arranged upstream of the concave cavity (21) of the combustion chamber (2).

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

9. A powder fuel injection method, characterized in that: The use of the powder fuel injection structure as described in any one of claims 1 to 8 comprises the following steps: the powder fuel sprayed into the combustion chamber (2) by the plurality of powder fuel injection pipes (1) collides with each other in the combustion chamber (2), and the oxidation layer outside the powder fuel is destroyed during the mutual collision process, so that the fuel of the powder fuel is exposed, thereby increasing the reaction rate of the powder fuel and the oxidant; at the same time, the powder fuel obtains internal energy during the mutual collision process, providing initial energy for the ignition of the powder fuel; at the same time, the powder fuel will mix and diffuse after colliding with each other, thereby increasing the mixing effect of the powder fuel and the air flow, as well as the penetration depth and spanwise diffusion range of the powder fuel in the combustion chamber (2).

10. A combustion chamber, characterized in that: The invention comprises a powder fuel injection structure as claimed in any one of claims 1 to 8.

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