A secondary injection orifice structure for an oxygen nozzle

Abstract

This invention relates to the field of liquid rocket engine propellant injection technology, and provides a secondary injection hole structure for an oxygen nozzle, including a nozzle body and an inner bottom. The nozzle body has secondary injection holes directly machined through its sidewall. The inner bottom is fitted to the inner wall of the nozzle body, and the joint forms a circumferentially cylindrical brazing surface. The brazing surface is not directly connected to the secondary injection holes. There are multiple secondary injection holes, evenly distributed along the circumference of the nozzle body. In this invention, the secondary injection holes are directly machined on the nozzle body, the brazing surface is unrelated to the injection holes, and the brazing material will not enter the holes. Furthermore, in single-nozzle mode, liquid flow tests can be directly performed on the secondary injection holes to determine flow resistance characteristics, ensuring controllable oxygen path flow resistance in the final product and uniform flow rate in each injection hole, avoiding combustion instability caused by uneven flow.

Description

Technical Field

[0001] This utility model belongs to the field of liquid rocket engine propellant injection technology, and particularly relates to a secondary injection hole structure for an oxygen nozzle. Background Technology

[0002] In the pre-combustion chamber of an oxygen-rich, high-pressure staged combustion liquid rocket engine, the propellant mixing ratio deviates from the stoichiometric ratio, making combustion organization difficult and prone to problems such as unstable combustion, combustion oscillation, and flameout. The coaxial centrifugal nozzle and secondary injection orifice structure used in the existing technology have the following defects, and these defects directly affect the engine's operating performance: Secondary injection holes are easily blocked by brazing filler or have unstable flow resistance characteristics: Existing secondary injection holes are formed by brazing the nozzle and the inner bottom to form a rectangular groove. If the size of the rectangular groove is too small, the brazing filler will easily block the groove. Even if the size is appropriate, brazing filler will still remain at the connection between the groove and the inner bottom after brazing, which will change the actual flow cross section of the secondary injection hole, resulting in uncontrollable flow resistance characteristics. This will cause uneven flow in each injection hole, leading to uneven combustion, and in severe cases, unstable combustion. It is difficult to balance structural connection strength and liquid oxygen circumferential coverage: In the existing technology, if the spacing of the secondary injection holes in the rectangular groove is reduced to improve the liquid oxygen circumferential coverage, the brazing connection area between the nozzle and the inner bottom will be reduced, the connection strength will be reduced, and there is a risk of structural failure. If the spacing is increased to ensure the connection strength, the liquid oxygen circumferential coverage will decrease, which is not conducive to the mixing, atomization and evaporation of secondary injection liquid oxygen by the high-temperature gas in the center area of ​​the nozzle. At the same time, the temperature non-uniformity of the gas in the same cross section will increase. Poor cooling effect of injector surface between nozzles: The existing rectangular groove secondary injection hole spacing is large, and there is a gap in the circumferential coverage of liquid oxygen, which leads to an increase in the gas return zone between nozzles. The low temperature cooling effect of liquid oxygen cannot cover the gap area, resulting in excessively high local temperature of the injector surface, affecting the structural life and even causing thermal deformation, which leads to displacement of the injection hole position and further aggravates combustion instability. Therefore, a secondary injection hole structure for an oxygen nozzle is needed to solve the above problems. Utility Model Content

[0003] The purpose of this utility model embodiment is to provide a secondary injection hole structure for an oxygen nozzle to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution: A secondary injection hole structure for an oxygen nozzle includes a nozzle body and an inner bottom. The nozzle body has a secondary injection hole that penetrates its sidewall directly machined on it. The inner bottom is fitted to the inner wall of the nozzle body, and the fit between the two forms a brazing surface with a full circumference cylindrical surface. The brazing surface is not directly connected to the secondary injection hole. There are multiple secondary injection holes, which are evenly distributed along the circumference of the nozzle body. The secondary injection holes are machined directly on the nozzle body, allowing for machining and condition inspection before brazing, thus preventing brazing material from flowing into the holes during the brazing process. The brazing surface adopts a full-circumference cylindrical design, which significantly increases the connection area and improves the structural connection strength compared to the existing spline-shaped brazing surface. At the same time, since the brazing surface is not related to the secondary injection holes, the problem of brazing material clogging the injection holes or changing the flow resistance characteristics is completely solved.

[0005] A further technical solution is that the secondary injection hole has a waist-shaped hole structure, with semi-circular ends and a rectangular middle section. The length direction of the waist-shaped hole is consistent with the axial direction of the nozzle body, and the width direction of the waist-shaped hole is consistent with the radial direction of the nozzle body. The waist-shaped orifice design makes the corner space occupied much smaller than that of the existing rectangular groove. While ensuring that the flow area and pitch circle diameter are consistent with the existing technology, it can significantly reduce the circumferential spacing between adjacent secondary injection holes and improve the circumferential coverage of liquid oxygen. When liquid oxygen flows in from the inner wall end and flows out from the outer surface end of the secondary injection hole, the smooth structure of the waist-shaped orifice can also reduce flow resistance and further ensure the uniformity of flow.

[0006] A further technical solution is that the inner wall of the nozzle body is provided with a retraction chamber, the retraction chamber is located inside the secondary injection hole, and the retraction chamber is not connected to the secondary injection hole. The converging chamber provides a dedicated atomization and mixing space for a small amount of oxygen and fuel; it is radially spaced from the secondary injection orifice to avoid interference with the flow of liquid oxygen in the secondary injection orifice during the initial combustion process; at the same time, the annular structure of the converging chamber ensures that oxygen and fuel are uniformly mixed in the circumference, providing a stable mixture basis for subsequent initial combustion.

[0007] In a further technical solution, the height of the contact surface between the inner bottom and the inner wall of the nozzle body is not lower than the height of the secondary injection hole; The contact surfaces of the inner bottom and the inner wall of the nozzle body completely avoid the inner wall end orifice of the secondary injection hole in the axial direction, further preventing brazing material residue at the orifice. At the same time, the close contact of the contact surfaces can improve the sealing performance after brazing and prevent high-temperature gas from leaking from the gap between the inner wall and the inner bottom of the nozzle body.

[0008] In a further technical solution, the nozzle body is made of a high-temperature resistant alloy material, the inner bottom is made of an alloy material compatible with the nozzle body material, and the nozzle body and the inner bottom are connected by a vacuum brazing process, with the brazing material being a nickel-based brazing alloy that matches the base material. The high-temperature resistant alloy material of the nozzle body can withstand the high-temperature environment during engine operation, preventing oxidation or deformation of the inner wall and outer surface; the compatible alloy material of the inner bottom ensures brazing compatibility with the nozzle body and prevents cracks during welding; the vacuum brazing process can prevent oxidation of the brazing surface by air, and the high strength and high temperature resistance of the nickel-based brazing filler metal ensures that the brazing surface does not fail under long-term high temperature and high pressure environment, improving the overall reliability of the structure.

[0009] A further technical solution is that the inner wall of the retraction chamber is provided with a plurality of annular guide grooves, which are arranged along the circumference of the retraction chamber. The annular guide channel can guide the oxygen and fuel entering the converging chamber to flow along the channel body, forming a circumferential swirling flow; several annular guide channels can enhance the swirling flow intensity, improve the turbulent mixing effect of oxygen and fuel, and make the atomization of the two more uniform; several circumferential arrays with axes that coincide with the axis of the converging chamber ensure the symmetry of the swirling flow, avoid local uneven mixing, and further optimize the initial combustion efficiency.

[0010] Compared with the prior art, the beneficial effects of this utility model are: This invention solves the problem of unstable flow resistance in secondary injection holes and improves injection consistency: In the prior art, brazing material is easily left in the "brazing-formed hole", resulting in uncontrollable flow resistance; This structure directly processes the secondary injection hole on the nozzle body, the brazing surface is not related to the injection hole, the brazing material will not enter the hole, and the liquid flow test can be directly performed on the secondary injection hole in the single nozzle state to determine the flow resistance characteristics, ensuring that the oxygen path flow resistance of the final product is controllable, the flow rate of each injection hole is uniform, and avoiding combustion instability caused by uneven flow rate; This invention balances structural strength and liquid oxygen circumferential coverage to improve combustion efficiency: In the prior art, "spacing and strength" are contradictory; this structure improves the connection strength through the brazing of the entire cylindrical surface, while the waist-shaped secondary injection holes reduce the spacing and improve the circumferential coverage. This ensures that the brazing connection can withstand the high temperature and high pressure load during engine operation, and allows liquid oxygen to cover the nozzle circumference more evenly, fully contacting the high temperature gas, accelerating atomization and evaporation, and improving propellant combustion efficiency. This invention optimizes the cooling effect of the injector surface between nozzles, extending the structural lifespan: In the prior art, the spacing between the secondary injection holes is large, and there are gaps in the circumferential coverage of liquid oxygen, resulting in an increased gas return zone between nozzles and insufficient cooling of the injector surface; In this structure, the spacing between the secondary injection holes is reduced, and there are no gaps in the circumferential coverage of liquid oxygen. After the cryogenic liquid oxygen flows out from the secondary injection holes, it can fully cover the injector surface, especially the gas return zone between nozzles, reducing the local temperature of the injector surface, avoiding injection hole position displacement caused by thermal deformation, extending the service life of the nozzle structure, and reducing injection deviation caused by thermal deformation.

[0011] To more clearly illustrate the structural features and effects of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0012] Figure 1 This is a three-dimensional structural diagram of the present invention from the front view; Figure 2 This is a three-dimensional structural diagram of the present invention viewed from below; Figure 3 This is a top-view three-dimensional cross-sectional structural diagram of the present invention.

[0013] In the diagram: 1. Nozzle body; 2. Inner bottom; 3. Secondary injection hole; 4. Brazing surface; 5. Retraction chamber; 6. Annular guide groove. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0015] The specific implementation of this utility model will be described in detail below with reference to specific embodiments.

[0016] Example 1 like Figure 1 , Figure 2 and Figure 3 As shown, this utility model embodiment provides a secondary injection hole structure for an oxygen nozzle, including a nozzle body 1 and an inner bottom 2. First, a high-temperature resistant alloy material is selected, and through a series of processes such as forging and machining, the nozzle body 1 is formed into a cylindrical structure with open ends, ensuring that its inner wall and outer surface are both smooth cylindrical surfaces to meet the requirements of subsequent high-precision assembly and fluid flow. Next, using advanced CNC machining technology, secondary injection holes 3 penetrating from the inner wall to the outer surface are directly machined on the side wall of the nozzle body 1. These secondary injection holes 3 are waist-shaped holes and are evenly distributed along the circumference of the nozzle body 1. After machining, high-precision testing equipment is used to strictly test the dimensional accuracy, shape error, and penetration consistency of the secondary injection holes 3 to ensure that each hole meets the design standards. The inner bottom 2 is made of an alloy material compatible with the nozzle body 1 and is machined into a columnar structure. During assembly, the inner bottom 2 and the inner wall of the nozzle body 1 are precisely aligned so that they fit tightly together, forming a fitting area with a full circumference cylindrical surface, which is the brazing surface 4 used for subsequent brazing. During the fitting process, the tightness and coaxiality of the fitting are strictly controlled to ensure that the fitting area has no direct connection with the secondary injection hole 3, so as to avoid the brazing material affecting the secondary injection hole 3 during the subsequent brazing process. Subsequently, a vacuum brazing process is adopted, and a suitable nickel-based brazing filler metal is selected to weld the mating area. In a vacuum environment, the assembled components are placed in a brazing furnace and heated according to the precisely set temperature curve, holding time and other process parameters, so that the nickel-based brazing filler metal melts and evenly fills the mating area between the inner bottom 2 and the inner wall of the nozzle body 1. After cooling, a firm circumferential brazing surface 4 is formed, and the fixed connection between the nozzle body 1 and the inner bottom 2 is completed. In this embodiment, the secondary injection hole 3 is directly machined into the nozzle body 1 and extends through the inner wall to the outer surface. This design allows the flow resistance characteristics of the secondary injection hole 3 to be accurately determined through methods such as liquid flow testing before brazing, avoiding interference with the flow resistance of the injection hole during the subsequent brazing process. At the same time, since the brazing surface 4 is not related to the secondary injection hole 3, during the brazing process, the brazing material only fills the contact area between the inner bottom 2 and the inner wall of the nozzle body 1, and will not flow into the injection hole or remain at the orifice, effectively ensuring the integrity of the flow cross section of the secondary injection hole 3 and the stability of the flow resistance characteristics. The final assembled oxygen nozzle can achieve uniform liquid oxygen injection, providing a solid foundation for the stability of engine combustion. Moreover, the circumferentially contacting brazing surface 4 significantly improves the connection strength between the nozzle body 1 and the inner bottom 2, enabling it to withstand the vibration and pressure loads generated during engine operation.

[0017] Example 2 The difference between this embodiment and Embodiment 1 is that: for the secondary injection hole 3, the length of the waist-shaped hole is precisely set so that it is precisely matched with the axial range of the side wall of the nozzle body 1 to ensure a reasonable injection range of liquid oxygen in the axial direction; at the same time, according to the design requirements, the width of the waist-shaped hole is determined to ensure that the total flow area of ​​the secondary injection hole 3 is equal to that of the existing rectangular groove injection hole, so as to meet the engine's demand for liquid oxygen flow rate; in addition, the pitch circle diameter of the secondary injection hole 3 is set to be the same as that of the prior art, and the axis of the pitch circle is strictly coincident with the axis of the nozzle body 1, ensuring the symmetry and consistency of the secondary injection hole 3 in the circumferential distribution. The height of the contact surface between the inner bottom 2 and the inner wall of the nozzle body 1 is precisely calculated and designed to be no less than the height of the secondary injection hole 3 in the axial direction of the nozzle body 1, thereby ensuring that the brazing surface 4 of the contact area completely avoids the end hole of the inner wall of the secondary injection hole 3 in the axial direction. During the brazing process, the brazing process parameters are strictly controlled to ensure that the brazing material completely fills the contact area and forms a continuous and complete circumferential brazing surface.

[0018] In this embodiment, the unique shape design of the waist-shaped secondary injection hole 3 effectively reduces the circumferential spacing. While ensuring that the flow area and pitch circle diameter are consistent with the prior art, the circumferential coverage of liquid oxygen is significantly improved. After the liquid oxygen flows in from the inner wall end of the secondary injection hole 3, it can be evenly distributed along the circumference of the nozzle. When it flows out from the outer surface end, it fully contacts the high-temperature combustion gas, which accelerates the atomization and evaporation process of liquid oxygen and reduces the phenomenon of uneven combustion gas temperature. At the same time, the precise matching between the height of the mating surface and the axial height of the secondary injection hole 3 ensures that the brazing surface 4 completely avoids the injection hole, which not only avoids the influence of the brazing material on the injection hole, but also ensures the integrity and sealing of the brazing surface. The circumferential brazing surface structure greatly improves the connection strength and successfully solves the contradiction of "coverage and strength" that is difficult to balance in the prior art, ensuring that the structure operates stably and reliably in the harsh environment of engine high temperature and high pressure.

[0019] Example 3 Based on Example 2, this embodiment makes full use of the unique design of the concave chamber 5 and the annular guide groove 6. The inner wall of the nozzle body 1, located inside the secondary injection hole 3, is recessed through high-precision machining to carefully create the annular concave chamber 5. The size, shape, and relative position of the concave chamber 5 to the secondary injection hole 3 are strictly controlled according to the design requirements to ensure that it can provide an ideal dedicated space for the initial mixing of oxygen and fuel. Subsequently, 2-3 annular guide grooves 6 are machined on the inner wall of the converging chamber 5 using machining methods. The annular guide grooves 6 are evenly arranged along the circumference of the converging chamber 5, and their axes are strictly coincident with the axis of the converging chamber 5. The depth, width, and spacing between the grooves of the annular guide grooves 6 are precisely calculated and optimized to achieve efficient guidance of oxygen and fuel entering the converging chamber 5. After assembly, when the engine is running, a small amount of oxygen and fuel enters the converging chamber 5 through a specific inlet. Due to the guiding effect of the annular guide groove 6, the oxygen and fuel form a strong circumferential swirling flow in the converging chamber 5, which greatly enhances the turbulent mixing effect between the two, allowing the oxygen and fuel to come into more complete contact and mix, and the atomization to be more uniform. This uniformly mixed oxygen and fuel undergoes preliminary combustion in the converging chamber, and the high-temperature gas produced can diffuse evenly to the surroundings, avoiding the phenomenon of excessively high or low temperatures caused by uneven local combustion. Meanwhile, the cryogenic liquid oxygen flowing out of the secondary injection hole 3, on the basis of uniform circumferential coverage, can more effectively exchange heat with the high-temperature combustion gas, and provide comprehensive and uniform cooling to the injector surface. Especially in the area between the nozzles, due to the cryogenic cooling effect of the liquid oxygen, the temperature of the combustion gas return zone is effectively reduced, avoiding problems such as thermal deformation and ablation of the injector surface caused by excessively high local temperatures. This significantly extends the service life of the injector surface, while reducing injection deviation caused by thermal deformation, and further improving the overall performance and stability of the engine.

[0020] Working principle and usage process of this utility model: Liquid oxygen injection: Liquid oxygen enters the secondary injection hole structure of the oxygen nozzle through an external supply system. The secondary injection hole 3 is directly machined into the side wall of the nozzle body 1 and penetrates its inner wall and outer surface. Liquid oxygen flows in from the inner wall end of the secondary injection hole 3. Since the secondary injection hole 3 is a waist-shaped hole structure and is evenly distributed around the nozzle body 1, the liquid oxygen can spread evenly in the circumferential direction when it flows in. After flowing out from the outer surface end, it enters the combustion chamber in a uniform distribution state. The unique shape design of the waist-shaped hole reduces the circumferential spacing and improves the circumferential coverage of liquid oxygen compared with the traditional rectangular groove injection hole. This allows the liquid oxygen to come into more comprehensive contact with the high-temperature gas in the combustion chamber, providing sufficient oxidant for the subsequent combustion process. Oxygen and fuel initial mixing: A small amount of oxygen and fuel enters the converging chamber 5 on the inner wall of the nozzle body 1 through a specific inlet; the converging chamber 5 is located inside the secondary injection hole 3 and is not connected to the secondary injection hole 3, providing a dedicated space for the initial mixing of oxygen and fuel; on the inner wall of the converging chamber 5, there are 2-3 annular guide grooves 6. When oxygen and fuel enter the converging chamber 5, they form a circumferential swirling flow under the guidance of the annular guide grooves 6; this swirling motion greatly enhances the turbulent mixing effect between oxygen and fuel, allowing them to fully contact and mix, resulting in more uniform atomization, and providing a good mixed gas foundation for subsequent initial combustion in the converging chamber; Connection between the inner bottom and the nozzle body: The inner bottom 2 and the nozzle body 1 are connected by vacuum brazing. The inner bottom 2 and the inner wall of the nozzle body 1 are tightly fitted together, and the fitting area forms a full-circumferential cylindrical brazing surface 4. Before vacuum brazing, the inner bottom 2 and the nozzle body 1 are precisely assembled to ensure tight fitting and coaxiality. Then, the assembled parts are placed in a vacuum brazing furnace. In a vacuum environment, a nickel-based brazing filler metal that matches the base material is selected for welding. Under high temperature, the nickel-based brazing filler metal melts and fills the fitting area between the inner bottom 2 and the inner wall of the nozzle body 1. After cooling, a strong connection is formed, making the inner bottom 2 and the nozzle body 1 an integral structure that can withstand the high temperature and high pressure loads during engine operation. Relationship between brazing surface and secondary injection hole: There is no direct connection between brazing surface 4 and secondary injection hole 3. During the design and processing, by precisely controlling the dimensions of the inner bottom 2 and the nozzle body 1 as well as the position of the secondary injection hole 3, it is ensured that brazing surface 4 completely avoids the inner wall end opening of the secondary injection hole 3 in the axial direction. In this way, during the brazing process, the brazing material will not flow into the secondary injection hole 3 or remain at the opening, ensuring the stability of the flow resistance characteristics of the secondary injection hole 3, avoiding the problem of uneven liquid oxygen injection caused by the influence of brazing material, and ensuring the reliability and stability of the secondary injection hole structure of the oxygen nozzle. Improved combustion efficiency: The uniformly distributed liquid oxygen flowing out from the secondary injection hole 3 comes into full contact with the high-temperature gas diffused out after the initial combustion in the converging chamber 5; due to the high circumferential coverage of the liquid oxygen, the contact area with the gas is increased, making the combustion reaction more complete; at the same time, the oxygen and fuel that are uniformly mixed in the converging chamber 5 through the annular guide groove 6 can more effectively mix, atomize and evaporate with the liquid oxygen after the initial combustion, further improving the combustion efficiency, enabling the engine to make fuller use of the propellant energy and improve overall performance; Improved cooling effect: The cryogenic liquid oxygen flowing from the secondary injection hole 3 can comprehensively cool the injector surface while providing uniform circumferential coverage. Especially in the area between nozzles, the cryogenic effect of liquid oxygen can effectively reduce the temperature of the gas return zone. Compared with the existing technology where the large spacing of the secondary injection holes leads to gaps in the circumferential coverage of liquid oxygen and excessively high temperatures in the gas return zone between nozzles, the reduced spacing of the secondary injection holes 3 in this structure allows liquid oxygen to uniformly cover the injector surface, avoiding thermal deformation and ablation caused by excessively high local temperatures. This extends the service life of the injector surface and ensures the accuracy of the injection hole position, further improving the stability and reliability of the engine.

[0021] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A secondary injection orifice structure for an oxygen nozzle, comprising a nozzle body (1) and an inner bottom (2), characterized in that: The nozzle body (1) has a secondary injection hole (3) that penetrates its side wall directly. The inner bottom (2) is attached to the inner wall of the nozzle body (1). The two are attached to form a brazing surface (4) with a full circumference cylindrical surface. The brazing surface (4) is not directly connected to the secondary injection hole (3). There are multiple secondary injection holes (3), which are evenly distributed along the circumference of the nozzle body (1).

2. The secondary injection orifice structure of the oxygen nozzle according to claim 1, characterized in that: The secondary injection hole (3) is a waist-shaped hole structure. The two ends of the waist-shaped hole are semi-circular and the middle is rectangular. The length direction of the waist-shaped hole is consistent with the axial direction of the nozzle body (1), and the width direction of the waist-shaped hole is consistent with the radial direction of the nozzle body (1).

3. The secondary injection orifice structure of the oxygen nozzle according to claim 1, characterized in that: The inner wall of the nozzle body (1) is provided with a retraction chamber (5), which is located inside the secondary injection hole (3) and is not connected to the secondary injection hole (3).

4. The secondary injection hole structure of the oxygen nozzle according to claim 1, characterized in that: The height of the contact surface between the inner bottom (2) and the inner wall of the nozzle body (1) is not lower than the height of the secondary injection hole (3).

5. The secondary injection orifice structure of the oxygen nozzle according to claim 1, characterized in that: The nozzle body (1) is made of high temperature resistant alloy material, and the inner bottom (2) is made of alloy material compatible with the nozzle body (1). The nozzle body (1) and the inner bottom (2) are connected by vacuum brazing process, and the brazing material is a nickel-based brazing material that matches the base material.

6. The secondary injection orifice structure of the oxygen nozzle according to claim 3, characterized in that: The inner wall of the indentation chamber (5) is provided with a plurality of annular guide grooves (6), which are arranged along the circumference of the indentation chamber (5).

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