Injection unit structure and injector adapted to gas-liquid dual mode injection

Abstract

The application belongs to the technical field of aerospace propulsion, and particularly relates to a structure of a injection unit suitable for gas-liquid dual-mode injection and an injector, which comprises a propellant total collection cavity, a first secondary collection cavity, a second secondary collection cavity, a first branch, a second branch and a combustion chamber; the propellant total collection cavity is communicated with the two secondary collection cavities, the two secondary collection cavities are communicated with the combustion chamber through the first branch and the second branch respectively, and the first branch is provided with a converging-diverging nozzle and the second branch is a straight channel. The application further discloses the injector using the structure of the injection unit, which is manufactured through diffusion welding technology. The application utilizes the differential flow characteristics of the converging-diverging nozzle for gas-liquid propellants, realizes self-adaptive injection of liquid-phase self-impact mixing and gas-phase cyclone mixing, has no moving parts and simple structure, improves the mixing efficiency and reliability of the engine under non-expected working conditions, is suitable for a reusable small-sized low-temperature liquid rocket engine, has high manufacturing precision, low cost and is easy to expand into an injection unit array.

Description

Technical Field

[0001] This invention belongs to the field of aerospace propulsion technology, specifically relating to an injection unit structure and injector adapted to gas-liquid dual-mode injection. Background Technology

[0002] The injector is a core component of a liquid rocket engine. Propellant is ejected, atomized, mixed, and then burned from it. The quality of atomization and mixing directly affects the engine's combustion efficiency, and consequently, its specific impulse. Furthermore, for non-self-igniting propellants requiring ignition, the mixing quality also affects the engine's starting characteristics. Poorly mixed propellant is difficult to ignite, leading to anything from delayed or failed ignition to, in severe cases, combustion chamber explosions. Therefore, the design of the injector has a crucial impact on the rocket engine's performance and reliability.

[0003] Traditional injector designs are mostly designed for liquid propellants, which aligns with the actual operating conditions of most engines. However, for small liquid rocket engines using cryogenic propellants such as liquid oxygen and methane, the propellant flow rate is small and the system pressure is below the critical pressure. When the propulsion system is poorly cooled or malfunctions, the incoming flow may sometimes be gaseous. The density of saturated gas and liquid of the same working fluid differs by tens to hundreds of times, resulting in a huge difference in injection pressure drop. Injectors designed with liquid propellant parameters often cannot adapt to gaseous incoming flows. In this case, the injector operates under non-design conditions, which can easily lead to poor mixing.

[0004] Patent document CN 110805926 A discloses a dual-channel propeller injector adapted to gas-liquid two-phase injection. This injector includes a main channel and an auxiliary channel. The main channel includes a row of main injection holes and a main inlet fuel supply pipe. The auxiliary channel includes a row of auxiliary injection holes and an auxiliary inlet fuel supply pipe, with an auxiliary inlet diaphragm valve installed on the auxiliary inlet fuel supply pipe. This invention employs dual propellant channels, allowing propellants of different phases to be injected through both channels separately, ensuring the fuel supply to the propeller under moderate system pressure, and adapting to a wide range of changes in temperature, density, pressure, and phase of the fuel at the outlet of the actively cooled combustion chamber. However, this invention requires a diaphragm valve to control the flow of different propellant phases, contains numerous moving parts, has high manufacturing costs, a bulky structure, and low overall reliability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a spray unit structure and sprayer that can adapt to both gaseous and liquid spraying.

[0006] According to the present invention, an injection unit structure adapted to gas-liquid dual-mode injection includes a propellant collection chamber, a first-stage collection chamber, a second-stage collection chamber, a first branch, a second branch, and a combustion chamber.

[0007] The propellant collection chamber is connected to the first-stage collection chamber and the second-stage collection chamber, respectively. The first-stage collection chamber is connected to one end of the first branch, and the second-stage collection chamber is connected to one end of the second branch. The other ends of the first branch and the second branch are both connected to the combustion chamber.

[0008] The first branch has an integrated converging and expanding nozzle, while the second branch is a straight channel without a throttling structure. The axis of the first branch intersects the axis of the second branch and the angle between their ray vectors is an obtuse angle, and the axes of both the first and second branches are tangent to the inner wall of the combustion chamber. The propellant collection chamber is located on a different plane from the first branch and the second branch.

[0009] Preferably, the connection between the first-stage collection cavity and the first branch, and the connection between the second-stage collection cavity and the second branch, both adopt a rounded transition structure.

[0010] Preferably, the connection between the first branch and the combustion chamber, and the connection between the second branch and the combustion chamber, are both sharp-edged structures.

[0011] Preferably, the propellant collection cavity is located within the rhomboid space formed by the coplanar projections of the first branch and the second branch, and the projections of the first-stage collection cavity, the second-stage collection cavity, the first branch, and the second branch.

[0012] The present invention also provides an injector that adopts the above-described injector unit structure adapted to gas-liquid dual-mode injection, and the injector is manufactured using diffusion welding technology.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention utilizes the differentiated flow characteristics of gaseous and liquid propellants in a fixed-structure converging-expanding nozzle, enabling the injection unit to operate stably in two different modes: when the inlet propellant is in liquid or gaseous state. This effectively solves the problem of reduced mixing efficiency of traditional injectors under unexpected inflow conditions, significantly reduces the risk of ignition delay, ablation, and explosion, and improves the engine's performance and operational reliability.

[0014] 2. This invention achieves gas-liquid dual-mode adaptation through a fixed-structure dual-branch collaborative design. It has a compact and lightweight structure, eliminates the risk of wear and failure of moving parts, and improves the structural reliability and service life of the injector.

[0015] 3. This invention employs a chemical etching + diffusion welding manufacturing process, which can achieve structural precision on the order of 5μm, meeting the manufacturing requirements of precision structures such as expansion and contraction nozzles and microchannels. Furthermore, chemical etching can form a large number of injection unit channel patterns in one step, and diffusion welding can achieve reliable welding of thin metal plates, resulting in low manufacturing cost and high processing efficiency. At the same time, the injection unit structure has good reproducibility and can be easily expanded into large injectors through array arrangement, adapting to liquid rocket engines with different thrust. Attached Figure Description

[0016] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the flow within the channel of the injection unit structure of the present invention when the propellant is in liquid state; Figure 3 This is a schematic diagram of the flow within the channel of the injection unit structure of the present invention when the propellant is in a gaseous state. Figure 4 This is a schematic diagram of the manufacturing process of the injector of the present invention.

[0017] The following are the labeling elements in the figure: 1. Propellant main chamber; 11. First stage chamber; 12. Second stage chamber; 21. First branch; 211. Converging nozzle; 22. Second branch; 3. Combustion chamber. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0019] Example 1 like Figure 1 As shown, this embodiment provides an injection unit structure adapted to gas-liquid dual-mode injection, including a propellant main chamber 1, a first-stage chamber 11, a second-stage chamber 12, a first branch 21, a second branch 22, and a combustion chamber 3. The propellant adapted in this embodiment is a cryogenic non-self-igniting propellant.

[0020] The propellant collection chamber 1 is connected to the first stage collection chamber 11 and the second stage collection chamber 12 through the flow channel. The first stage collection chamber 11 is connected to the combustion chamber 3 through the first branch 21, and the second stage collection chamber 12 is connected to the combustion chamber 3 through the second branch 22.

[0021] In this embodiment, the first branch 21 is a channel integrating a contraction-expansion nozzle 211, which is designed according to the design specifications of a sonic nozzle with a gaseous inflow. The second branch 22 is a straight channel. The axis of the first branch 21 intersects the axis of the second branch 22, and the angle between the ray vectors of the two axes is 140°. The axes of both branches are tangential to the inner wall of the combustion chamber 3. The propellant collection chamber 1 belongs to a different plane from the first branch 21 and the second branch 22. The propellant collection chamber 1 is located in the rhomboid space enclosed by the projections of the first stage collection chamber 11, the second stage collection chamber 12, the first branch 21, and the second branch 22, which helps to reduce the space occupied by the injection unit.

[0022] The connection between the first stage collector 11 and the first branch 21, and the connection between the second stage collector 12 and the second branch 22, both adopt a rounded transition structure, which helps to reduce the flow resistance from the collector to the branch. The connection between the first branch 21 and the combustion chamber 3, and the connection between the second branch 22 and the combustion chamber 3, both adopt a sharp edge structure, which helps to guide the fluid at the branch outlet. The channel width of the first branch 21 and the second branch 22 is 0.5 mm, and the length-to-diameter ratio is 25.

[0023] Working principle In this embodiment, when the injection unit is working, the propellant enters from the propellant main collection chamber 1 and is divided into two paths, flowing into the first stage collection chamber 11 and the second stage collection chamber 12 through channels respectively. The propellant in the first stage collection chamber 11 enters the combustion chamber 3 through the first branch 21, and the propellant in the second stage collection chamber 12 enters the combustion chamber 3 through the second branch 22.

[0024] like Figure 2 As shown, when the incoming flow is liquid, the injection unit operates in liquid phase injection mode. The expansion nozzle 211 is designed for a gaseous incoming flow, so the throat diameter of the expansion nozzle 211 is larger than that of the liquid flow. The expansion nozzle generates only a small amount of flow resistance for the liquid propellant, and no cavitation occurs. Therefore, the flow rates and velocities of the two liquid propellants in the first branch 21 and the second branch 22 are close. After the two liquids are injected into the combustion chamber 3, they undergo self-impact mixing. The direction of the combined momentum after the impact is parallel to the bisector of the obtuse angle between the two branches. The injection unit achieves the same high-efficiency mixing effect as a conventional dual-strand self-impact unit.

[0025] like Figure 3As shown, when the incoming flow is gaseous, the injection unit operates in gas phase injection mode. The converging nozzle 211 plays a throttling role. The converging nozzle 211 uses the congestion effect of the gas to limit the flow rate of the gaseous propellant in the first branch 21, while the second branch 22 is a straight channel with no throttling effect, and the flow rate of the gaseous propellant is larger. After the two gas streams converge in the combustion chamber 3, the direction of the combined momentum is close to the flow direction of the second branch 22, and they will flow along the inner wall of the combustion chamber 3 to form a swirling flow. The injection unit realizes centrifugal injection unit.

[0026] Example 2 like Figure 4 As shown, this embodiment provides an injector that adopts the injector unit structure adapted to gas-liquid dual-mode injection as described in Embodiment 1, including three thin metal plates.

[0027] All three thin metal plates are made of SUS304 stainless steel. The three thin metal plates include an upper thin metal plate, a middle thin metal plate, and a lower thin metal plate. All three thin metal plates are etched using a chemical etching process. The upper and lower thin metal plates are etched with patterns of the propellant main chamber 1, the flow channels on both sides of the propellant main chamber 1, the cavity connecting the first stage chamber 11 and the flow channel, and the cavity connecting the second stage chamber 12 and the flow channel. The middle thin metal plate is etched with patterns of the first branch 21, the diverging nozzle 211, the second branch 22, the cavity connecting the first stage chamber 11 and the first branch 21, and the cavity connecting the second stage chamber 12 and the second branch 22. The etching precision is controlled at the 5μm level to ensure the precision structure of the diverging nozzle 211.

[0028] After the upper, middle, and lower thin metal plates are etched, they are precisely stacked according to the design requirements to ensure the coaxiality and connectivity of the channel patterns in each layer. The stacked thin metal plates are then placed in a diffusion welding device for welding, so that the thin metal plates form an integrated three-dimensional injection unit structure.

[0029] The injector prepared in this embodiment has no moving parts, has a compact structure, and is lightweight. The injector can achieve efficient mixing of propellants under both liquid and gaseous propellant conditions, with high mixing efficiency, meeting the requirements for use in small cryogenic liquid rocket engines. It is also suitable for reusability and its reliability is significantly improved.

[0030] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0031] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A jetting unit structure adapted to gas-liquid dual-mode injection, characterized in that, It includes a propellant main chamber (1), a first-stage chamber (11), a second-stage chamber (12), a first branch (21), a second branch (22), and a combustion chamber (3); The propellant collection chamber (1) is connected to the first stage collection chamber (11) and the second stage collection chamber (12) respectively. The first stage collection chamber (11) is connected to one end of the first branch (21), and the second stage collection chamber (12) is connected to one end of the second branch (22). The other end of the first branch (21) and the other end of the second branch (22) are both connected to the combustion chamber (3).

2. The injection unit structure adapted to gas-liquid dual-mode injection according to claim 1, characterized in that, The first branch (21) has an integrated expansion nozzle (211) on its channel, and the second branch (22) is a straight channel without a throttling structure.

3. The injection unit structure adapted to gas-liquid dual-mode injection according to claim 1, characterized in that, The axis of the first branch (21) intersects the axis of the second branch (22) and the angle between their ray vectors is an obtuse angle.

4. The injection unit structure adapted to gas-liquid dual-mode injection according to claim 1, characterized in that, The axes of the first branch (21) and the second branch (22) are both tangential to the inner wall of the combustion chamber (3).

5. The injection unit structure adapted to gas-liquid dual-mode injection according to claim 1, characterized in that, The propellant collection chamber (1) belongs to a different plane from the first branch (21) and the second branch (22).

6. An injection device, characterized in that, The injector is manufactured using diffusion welding technology and employs the injector unit structure adapted to gas-liquid dual-mode injection as described in any one of claims 1 to 5.

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