A center-swirl dual-shear gas-liquid nozzle adapted to large mixing ratio working conditions

Abstract

A central swirling dual-shear gas-liquid nozzle adapted to high mixture ratio conditions is disclosed, applicable to bicomponent gas-liquid engines using gaseous nitrous oxide as oxidizer and liquid high-energy kerosene as fuel, relating to the field of rocket engine propulsion technology. This nozzle employs a unique three-layer concentric annular flow channel design: a central gas path, annular liquid path, and outer gas path, integrating an axial swirler within the central gas path. This structure causes the central gas to rotate at high speed, forming a dual shear mechanism with the liquid film in the annular liquid path and the outer direct-flow airflow, effectively solving the problem of large and unevenly distributed atomized droplets caused by excessively high gas-phase ratios under high mixture ratio conditions. Through numerical simulation and experimental verification, this invention can improve the Sottle average diameter of atomized particles by approximately 30% compared to ordinary dual-shear nozzles, and the droplet distribution is more dispersed, significantly improving the gas-liquid mixing quality and combustion efficiency.

Description

Technical Field

[0001] This invention relates to a central swirling dual-shear gas-liquid nozzle adapted to high mixture ratio conditions, used to improve the atomization and mixing performance of gas-liquid propellant combined engines when the oxygen-fuel mixture ratio is high, and relates to the field of liquid rocket engine propulsion technology. Background Technology

[0002] The novel gas-liquid combined cycle engine is a new type of non-toxic power unit that uses gaseous nitrous oxide as the oxidant and liquid high-energy kerosene as fuel. To achieve efficient combustion, the injector needs to effectively atomize and mix the fuel and oxidant. However, in this type of engine, the oxidant-to-fuel ratio is relatively high (approximately 7:1), which poses a significant challenge to achieving effective atomization.

[0003] First, the atomization quality is poor. In gas-liquid two-phase flow, the atomization process mainly relies on the shearing effect of the gas on the liquid. Traditional dual-shear nozzles utilize the gas-liquid velocity difference for atomization. However, under high mixing ratio conditions, the gas phase flow rate is much greater than the liquid phase flow rate. At this time, the traditional single direct current or external swirling flow method of the nozzle is insufficient in shearing disturbance of the liquid film, resulting in incomplete liquid film breakup, which in turn leads to larger and unevenly distributed droplets after atomization. Studies have shown that shearing and impact forces are the main causes of atomization. Therefore, under high gas phase ratios, effectively organizing the flow field to enhance the shearing effect on the liquid film becomes the key to improving atomization performance.

[0004] Secondly, the mixing effect is limited. The ultimate goal of atomization is to promote gas-liquid mixing. In a conventional structure with a central liquid flow and an outer airflow, the liquid jet is easily dispersed by the high-speed airflow. In this case, although the liquid film can be atomized, the mixing uniformity is poor, which is not conducive to stable combustion. Studies have shown that the presence or absence of a swirler in the structure has a significant impact on the gas-liquid flow pattern and mixing effect within the injector.

[0005] Therefore, there is an urgent need for a new type of nozzle structure that can enhance the dynamic interaction between the gas phase and the liquid phase under high gas phase ratio conditions, promote liquid film breakup, and obtain a finer and more uniform atomization field to improve combustion efficiency. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and solve the problem of large droplet size and uneven distribution caused by excessively high gas phase ratio under the condition of large mixing ratio (about 7:1).

[0007] The objective of this invention is achieved through the following technical solutions: A central swirling dual-shear gas-liquid nozzle adapted to high mixing ratio conditions employs a three-layer concentric annular flow channel design from the inside out, comprising a liquid inlet connector, an outer nozzle, a central nozzle, an inner nozzle, a swirler, and a gas inlet connector. All components are integrally formed using 3D printing. The outer nozzle, central nozzle, inner nozzle, and swirler are coaxially arranged from the outside in. The swirler is a solid cylindrical structure with swirling threaded flow channels on its outer wall, fixedly installed within the central cavity of the hollow cylindrical inner nozzle. The bottom of the inner nozzle has a constricted nozzle structure to generate rotational motion in the central gas flowing through it, ultimately resulting in a swirling ejection from the constricted nozzle. The central nozzle is a hollow, stepped cylinder with a constricted nozzle structure at the bottom, sandwiched between the outer and inner nozzles. An opening at the top of the central nozzle connects to the upper opening of the outer nozzle and the central opening of the liquid inlet connector, connecting the liquid path. The liquid flows through the opening into the central nozzle and the inner nozzle. After passing through the cavity between the outer and inner nozzles, a constricted annular nozzle, consisting of a central nozzle and an inner nozzle, ejects the liquid. The outer nozzle is a hollow cylinder with a constricted nozzle structure at the bottom, fitted around the outside of the central nozzle and connected to the central hole of the side air inlet connector. After the air flows into the cavity between the outer and central nozzles, it is ejected from the constricted annular nozzle. The central nozzle has several air passage connecting holes on its side, used to connect the air passage cavities of the outer and inner nozzles. The gas utilizes the speed difference between the rotating airflow ejected from the inner nozzle and the direct current airflow ejected from the outer nozzle, as well as the collision of the airflows, to create a double shearing effect on the annular thin liquid film ejected from the central nozzle, achieving efficient liquid fragmentation and atomization.

[0008] The above applies to the center-swirling double-shear gas-liquid nozzle, wherein the swirler is an axial swirler, and its blade structure can be straight blades, helical blades or oblique groove structure, with a blade installation angle of 30°~60°.

[0009] The above applies to the central swirling dual-shear gas-liquid nozzle, where the nozzle outlet cross-section formed by the annular central nozzle and the inner nozzle is a converging and then straight cylindrical annular slit with a slit width of 0.1mm~0.5mm, used to form an initial liquid film of uniform and stable thickness.

[0010] The above applies to the central swirling double-shear gas-liquid nozzle, where the nozzle outlet cross-section formed by the outer nozzle and the central nozzle is a converging and then straight cylindrical annular slit, with its airflow direction parallel to the nozzle axis, used to perform secondary shearing on the initially broken droplets and constrain the spray cone angle.

[0011] The above-mentioned flow channels of the liquid inlet connector, outer nozzle, central nozzle, inner nozzle, cyclone separator and gas inlet connector are all integrally manufactured by metal 3D printing technology to ensure the coaxiality and structural integrity of each flow channel.

[0012] The above applies to the central swirling double shear gas-liquid nozzle, wherein the overall structural material of the nozzle is titanium alloy or high-temperature nickel-based alloy to ensure good mechanical properties in high-temperature environments.

[0013] The above applies to the center-swirling double-shear gas-liquid nozzle, which is used in a gas-liquid combined engine that uses gaseous nitrous oxide as an oxidant and liquid high-energy kerosene as fuel, with a design working condition oxygen-fuel mixture ratio of (6~8):1.

[0014] Compared with the prior art, the present invention has the following advantages: (1) The central swirling dual-shear gas-liquid nozzle proposed in this invention significantly improves atomization quality. Through the central swirling structure, a dual-enhanced shearing of the liquid film is innovatively achieved. The central swirling not only increases the relative velocity of the gas and liquid, but its rotational component also introduces additional centrifugal instability, making the liquid film easier to break into fine droplets. Experiments show that the atomized SMD is reduced by about 30%, and the distribution is more uniform.

[0015] (2) The central swirling dual-shear gas-liquid nozzle proposed in this invention provides better mixing. The presence of the swirling flow creates a stronger turbulent mixing zone between the gas and liquid phases downstream of the nozzle outlet, effectively improving the uniformity of fuel and oxidant mixing. This lays the foundation for rapid and stable combustion within the engine.

[0016] (3) The central swirling dual-shear gas-liquid nozzle proposed in this invention has a compact structure, strong adaptability, and can be integrated with the engine head design. It can achieve integrated manufacturing of complex flow channels through 3D printing technology, and has good process feasibility. This design is particularly suitable for large mixture ratio conditions with oxygen-fuel mixture ratios between 6:1 and 8:1.

[0017] (4) The central swirling dual-shear gas-liquid nozzle proposed in this invention has reliable performance and broad application prospects. It can effectively improve the combustion efficiency of gas-liquid propellant combined engines and plays an important role in promoting the development of non-toxic propulsion technology for spacecraft. Its design concept can also provide a reference for other fields that require high-precision gas-liquid mixing. Attached Figure Description

[0018] Figure 1 This is a front view of the structure of the central swirling dual-shear gas-liquid nozzle according to an embodiment of the present invention.

[0019] Figure 2 This is a side view of the central swirling dual-shear gas-liquid nozzle with a gas passage connection hole structure, according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the gas-liquid path of the central swirling dual-shear gas-liquid nozzle according to an embodiment of the present invention.

[0021] Figure 4 This is a simulation diagram of the atomization effect compared to a regular nozzle.

[0022] Figure 5 This is a simulation diagram of the atomization effect of the central swirling dual-shear gas-liquid nozzle in an embodiment of the present invention.

[0023] Figure 6 This is a high-speed photographic comparison of the actual atomization effects of the central swirling dual-shear gas-liquid nozzle (right side of the figure) and a conventional nozzle (left side of the figure) in an embodiment of the present invention.

[0024] The attached diagrams are labeled as follows: liquid inlet connector-1, outer nozzle-2, center nozzle-3, inner nozzle-4, cyclone separator-5, and gas inlet connector-6. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0026] A central swirling dual-shear gas-liquid nozzle adapted to high mixing ratio conditions, the nozzle comprising a liquid inlet connector 1, an outer nozzle 2, a central nozzle 3, an inner nozzle 4, a swirler 5, and a gas inlet connector 6, as shown below. Figure 1 As shown. All parts are integrally formed using 3D printing, with the outer nozzle 2, center nozzle 3, inner nozzle 4, and cyclone separator coaxially arranged from the outside in, as shown. Figure 2 As shown; wherein, the cyclone separator 5 is a solid cylindrical structure with swirling threaded flow channels on its outer wall, and is fixedly installed in the middle cavity of the inner nozzle 4 of the hollow cylindrical structure; the bottom of the inner nozzle 4 is a constricted nozzle structure, which is used to generate a rotating motion of the central gas flowing through it, and finally spray it out from the constricted nozzle; the central nozzle 3 is a hollow, stepped cylinder with a constricted nozzle structure at the bottom, and is sandwiched between the outer nozzle 2 and the inner nozzle 4, with an opening at the upper end of the central nozzle 3 connecting to the upper end hole of the outer nozzle 2 and the liquid inlet connector. The central hole of nozzle 1 is connected to the liquid path. The liquid flows into the cavity between the central nozzle 3 and the inner nozzle 4 through the hole and is ejected from the constricted annular nozzle formed by the combination of the central nozzle 3 and the inner nozzle 4. The outer nozzle 2 is a hollow cylinder with a constricted nozzle structure at the bottom. It is fitted on the outside of the central nozzle 3 and is connected to the central hole of the gas inlet connector 6 on the side. The gas flows into the cavity between the outer nozzle 2 and the central nozzle 3 and is ejected from the constricted annular nozzle formed by the combination of the outer nozzle 2 and the central nozzle 3.

[0027] The central nozzle 3 has several air passage connecting holes on its side, which are used to connect the air passage cavities of the outer nozzle 2 and the inner nozzle 4. The gas utilizes the speed difference between the rotating airflow ejected from the inner nozzle 4 and the direct airflow ejected from the outer nozzle 2, as well as the collision of the airflows, to form a double shearing effect on the annular thin liquid film ejected from the central nozzle 3, thereby achieving efficient liquid breaking and atomization.

[0028] Due to the complex internal flow channel structure, it is preferable to use metal 3D printing technology (such as SLM) for one-piece molding to ensure the accuracy of the flow channels and the overall structural strength. TC4 titanium alloy or Inconel 718 high-temperature alloy can be selected as the printing material to withstand the propellant environment and potential high combustion temperatures.

[0029] like Figure 3 As shown, the outermost layer is the outer ring gas path, flowing in from the gas path inlet connector. Its outlet is a converging then straight cylindrical annular slit, with the airflow direction parallel to the nozzle axis. The middle layer is an annular liquid path, with its flow channel outlet machined into a converging annular slit, which helps to form a stable and uniformly thick initial liquid film, which is ejected between the two gas paths. The innermost layer is the central gas path, connected to the outer ring gas path through a gas path connecting hole, where a cyclone separator 5 is fixedly installed. This cyclone separator has a structure with a series of inclined blades or channels, which allows the central gas to generate a high-speed central rotating airflow after flowing through it. The large-flow airflow and small-flow liquid flow ejected by the three sets of nozzles can achieve sufficient gas-liquid mixing under high mixture ratio conditions, thereby improving combustion efficiency.

[0030] like Figure 4 , Figure 5 Simulation results and Figure 6 The high-speed photography results show that the spray cone angle of a conventional dual-shear nozzle is unstable, and large droplets peel off at the edges. In contrast, the spray cone angle of the nozzle of this invention remains stable at approximately 59°, with clear spray boundaries, uniform liquid mist distribution, and no obvious liquid jet or droplet aggregation, proving the effectiveness of the dual-shear mechanism.

[0031] A central swirling dual-shear gas-liquid nozzle adapted to high mixture ratio conditions is disclosed, suitable for gas-liquid propellant combined engines using gaseous nitrous oxide as the oxidant and liquid high-energy kerosene as fuel. This nozzle employs a unique three-layer concentric annular flow channel design: a central gas path, annular liquid path, and outer gas path, integrating an axial swirler within the central gas path. This structure causes the central gas to rotate at high speed, forming a dual shear mechanism with the liquid film in the annular liquid path and the outer direct-flow airflow. This effectively solves the problem of large and unevenly distributed atomized droplets caused by the excessively high gas-phase ratio under high mixture ratio (approximately 7:1) conditions. Through numerical simulation and experimental verification, this invention improves the Sottle mean diameter (SMD) of atomized particles by approximately 30% compared to ordinary dual-shear nozzles, and also results in a more dispersed droplet distribution, significantly improving gas-liquid mixing quality and combustion efficiency.

[0032] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0033] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and 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 content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A center-swirling dual-shear gas-liquid nozzle suitable for high mixing ratio conditions, characterized in that, Includes liquid inlet connector (1), outer nozzle (2), center nozzle (3), inner nozzle (4), cyclone separator (5), and gas inlet connector (6). The center cyclone double shear gas-liquid nozzle is integrally formed by 3D printing. An outer nozzle (2), a central nozzle (3), an inner nozzle (4), and a cyclone separator (5) are arranged coaxially from the outside to the inside. The cyclone separator (5) is a solid cylindrical structure with a swirling threaded flow channel on the outer wall. It is fixedly installed in the middle cavity of the hollow cylindrical inner nozzle (4). The bottom of the inner nozzle (4) is a constricted nozzle structure. The cyclone separator (5) is used to make the central gas flowing through it rotate and finally spray out from the bottom of the inner nozzle (4). The central nozzle (3) is a hollow cylinder with a step and a constricted nozzle structure at the bottom. The inner nozzle (4) is located in the middle cavity of the central nozzle (3) and is stuck at the step. The opening on the central nozzle (3) is connected to the central hole of the liquid inlet connector (1) through the upper hole of the outer nozzle (2) to connect the liquid path. After the liquid path flows into the cavity between the central nozzle (3) and the inner nozzle (4) through the hole, it is sprayed out from the central nozzle. The nozzle (3) and the inner nozzle (4) are combined to form a constricted annular nozzle. The outer nozzle (2) is a hollow cylinder with a constricted nozzle structure at the bottom. It is fitted on the outside of the central nozzle (3) and connected to the central hole of the air inlet connector (6) on the side. After the air flows into the cavity formed between the outer nozzle (2) and the central nozzle (3), it is ejected from the constricted annular nozzle formed by the combination of the outer nozzle (2) and the central nozzle (3). The central nozzle (3) has several air passage connecting holes on the side near the liquid inlet connector (1) to connect the inner cavity of the outer nozzle (2) and the inner cavity of the inner nozzle (4). There is a speed difference between the rotating airflow ejected by the inner nozzle (4) and the direct airflow ejected by the outer nozzle (2). By utilizing the speed difference of the airflow and the collision of the airflow, a double shearing effect is formed on the annular thin liquid film ejected by the central nozzle (3), so as to achieve efficient breaking and atomization of the liquid.

2. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The cyclone (5) is an axial cyclone, and the blade structure adopts a straight blade, a spiral blade, or a slanted groove structure, with a blade installation angle of 30°~60°.

3. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The nozzle outlet section formed by the central nozzle (3) and the inner nozzle (4) is a converging cylindrical annular slit with a slit width ranging from 0.1 mm to 0.5 mm, which is used to form an initial liquid film with uniform and stable thickness.

4. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The nozzle outlet section formed by the outer nozzle (2) and the center nozzle (3) is a converging and then straight cylindrical annular slit. The airflow direction is parallel to the nozzle axis, which is used to perform secondary shearing on the initially broken droplets and constrain the spray cone angle.

5. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The flow channels of the liquid inlet connector (1), outer nozzle (2), center nozzle (3), inner nozzle (4), cyclone separator (5), and gas inlet connector (6) are all manufactured in one piece using metal 3D printing technology to ensure the coaxiality and structural integrity of each flow channel.

6. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The central swirling double-shear gas-liquid nozzle is made of titanium alloy or high-temperature nickel-based alloy material.

7. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The central swirl-type dual-shear gas-liquid nozzle is used in a gas-liquid combined engine that uses gaseous nitrous oxide as an oxidant and liquid high-energy kerosene as fuel, with a design oxygen-fuel mixture ratio of (6~8):

1.

8. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The printing material for the central swirling dual-shear gas-liquid nozzle is either TC4 titanium alloy or Inconel 718 high-temperature alloy.

9. The central swirling dual-shear gas-liquid nozzle according to claim 1, characterized in that, The central swirling double shear gas-liquid nozzle adopts a three-layer concentric annular flow channel design: central gas path, annular liquid path, and outer gas path. The outermost layer is the outer ring gas path, which flows in from the gas path inlet connector (6). Its outlet is a converging and then straight cylindrical annular slit, and the airflow ejection direction is parallel to the nozzle axis. The middle layer is the annular liquid path, and its flow channel outlet is processed into a converging annular slit, which is sandwiched between the two layers of gas path and ejected. The innermost layer is the central gas path, which is connected to the outer ring gas path through the gas path connecting hole.

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