Attitude and orbit control two-component liquid rocket engine and unified type establishing method thereof

Abstract

The invention provides an attitude and orbit control two-component liquid rocket engine and a unified type establishing method thereof. The attitude and orbit control two-component liquid rocket engine comprises targeted design of an electromagnetic valve, an injector, a combustion chamber section and a spray pipe extension section. The electromagnetic valve is a pneumatic electromagnetic valve and works in a double-voltage driving mode, and an electrical interface is a double-point double-wire interface; the head cavity of the injector is small in volume and is provided with a goblet, a V-shaped groove and a heating sheet mounting groove structure; the characteristic length of the combustion chamber section is small; the area ratio of the combustion chamber section is iteratively designed according to an airflow separation theory; the spray pipe extending section is combined with the combustion chamber section in a welding or screwing mode, different area ratios of the spray pipe extending section are obtained, and engines with different thrust, specific impulse and sizes are designed. According to the method, the working characteristics and requirements of the attitude and orbit control engine are extracted, the performance which must be met is designed in a targeted mode, and the purpose of sharing components of the engine is achieved, so that the product complexity is reduced, the research and development, test, manufacturing and management cost is reduced, and the reliability and maintainability of the product are improved.

Description

Technical Field

[0001] The present invention relates to the field of spacecraft propulsion technology, and in particular to a method and system for establishing a unified model of an attitude and orbit control bipropellant liquid rocket engine. Background Art

[0002] Based on their mission, bipropellant liquid rocket engines used in space propulsion systems can be divided into attitude control engines and orbit control engines. Attitude control engines adjust the vehicle's pitch, yaw, and roll attitude through short-duration pulses, while orbit control engines use long-term steady-state operation to shift or maintain the vehicle's orbit. A bipropellant liquid rocket engine in space primarily consists of solenoid valves, injectors, and nozzles. The solenoid valves control the supply of oxidizer and fuel. The injectors inject the oxidizer and fuel into the combustion chamber, atomizing and mixing them. The nozzle converts the thermal energy of the combustion gas into kinetic energy, providing thrust.

[0003] To meet the requirements of different mission profiles during flight, space propulsion liquid propulsion systems typically require a single orbital control engine and multiple attitude control engines. Due to the varying engine performance requirements required by propulsion system designs, common designs often incorporate different components, such as solenoid valves, injectors, and nozzles. This complicates propulsion system technology and management, hindering system cost reduction and product maintenance.

[0004] Although attitude control engines and orbit control engines perform different tasks, by balancing their functional requirements, performance indicators, and system compatibility, unified design of attitude and orbit control engines can be achieved, achieving the goal of sharing key engine components, ultimately optimizing costs and improving product reliability and maintainability. This implementation involves the unified design of the following key engine components: 1) Solenoid valves, designed to meet millisecond-level high-frequency pulse response speeds and minute-level long-term power-on requirements, while also minimizing flow resistance losses; 2) Injectors, designed to minimize head cavity volume and provide excellent thermal insulation and heat protection, while also meeting both normal ground temperature and vacuum low-temperature operation requirements; and 3) Nozzles, designed to provide excellent dynamic response, long combustion chamber life, and a reasonable and adjustable area ratio.

[0005] Patent document CN113107710A discloses a low-thrust bipropellant attitude control engine, comprising: a solenoid valve mounting support, wherein a first solenoid valve and a second solenoid valve are respectively provided on both sides of the upper end of the solenoid valve mounting support, and a cavity is opened in the lower part of the solenoid valve mounting support; a Laval nozzle, wherein the Laval nozzle is connected to the lower end of the solenoid valve mounting support; and a bipropellant nozzle, wherein the bipropellant nozzle is arranged in the cavity in the lower part of the solenoid valve mounting support; and two blind holes are opened in the bipropellant nozzle, and injection holes are opened on the blind holes.

[0006] However, patent document CN113107710A only provides a design method for an attitude control engine, without considering the design of common engine components, that is, it fails to achieve a unified design of attitude control engines and orbit control engines. Summary of the Invention

[0007] In view of the defects in the prior art, the purpose of the present invention is to provide an attitude and orbit control bipropellant liquid rocket engine and a method for establishing the same.

[0008] According to the present invention, a bipropellant liquid rocket engine for attitude and orbit control is provided, comprising: a solenoid valve 1, an injector 2, a combustion chamber section 3, and a nozzle extension section 4;

[0009] The solenoid valve 1, injector 2, combustion chamber section 3, and nozzle extension section 4 are connected in sequence. The upper end of the injector 2 is installed using a high-footed cup structure 5, and a V-shaped groove structure 6 is processed on the screw support. A heating plate mounting groove 7 is fixedly provided on the lower surface of the injector 2.

[0010] Preferably, the combustion chamber section 3 and the nozzle extension section 4 are combined through a bolt connection structure 8 or an electron beam welding structure 9 to obtain different nozzle extension section area ratios and set up engines with different thrust, specific impulse and size.

[0011] Preferably, the solenoid valve 1 is a pneumatic solenoid valve;

[0012] The moving parts of the pneumatic solenoid valve include an air circuit drive assembly, an air circuit valve core, a liquid circuit push rod and a liquid circuit valve core;

[0013] The solenoid valve 1 supplies propellant by opening the valve core of the liquid path through helium, and the valve core stroke is 1 / 4 of the diameter.

[0014] Preferably, the solenoid valve 1 operates in a dual-voltage driving mode, and the corresponding air circuit driving component uses a dual-point dual-wire electrical interface redundant design.

[0015] Preferably, the injector 2 is located between the solenoid valve 1 and the nozzle, and its head cavity volume is 2150mm 3 ~2415mm 3 , the head cavity filling time is 7.1ms~8.2ms.

[0016] Preferably, the diameter of the lower cylinder of the goblet structure 5 is 10 mm, and the diameter of the upper cylinder is 20 mm;

[0017] The V-groove structure 6 has a total of five V-grooves, all of which are symmetrically distributed with respect to the central plane;

[0018] There are four heating plate installation slots 7 in total, which are evenly arranged along the circumference.

[0019] Preferably, the combustion chamber section 3 is the area where the propellant is broken, atomized, evaporated, mixed, and burned; the nozzle extension section 4 is the area where the gas expands and accelerates;

[0020] The characteristic length of the combustion chamber section 3 is 200 to 500 mm, where the characteristic length refers to the ratio of the combustion chamber volume to the throat area;

[0021] The area ratio of the combustion chamber section 3 is iteratively set according to the airflow separation theory, and the area ratio refers to the ratio of the outlet area to the throat area.

[0022] Preferably, the combustion chamber section 3 includes a base material and a surface coating, the base material is niobium tungsten alloy, and the surface coating is molybdenum silicide.

[0023] According to the present invention, a method for establishing a unified model of an attitude and orbit control bipropellant liquid rocket engine is provided, comprising:

[0024] Step S1: Performing targeted settings on the solenoid valve, injector, and combustion chamber section of the attitude and orbit control bipropellant liquid rocket engine;

[0025] Step S2: iteratively calculating the area ratio of the combustion chamber segment according to the set solenoid valve, injector, and combustion chamber segment;

[0026] Step S3: Based on the calculated combustion chamber section area ratio, the nozzle extension section of the attitude and orbit control bipropellant liquid rocket engine is combined through a bolt connection structure or an electron beam welding structure to obtain different nozzle extension section area ratios to simultaneously meet the working requirements of the attitude and orbit control engine. The two engines can be used as the attitude control engine and orbit control engine of the same power system respectively.

[0027] Preferably, step S2 includes:

[0028] Step S2.1: Preliminary selection of area ratio ε e ';

[0029] Step S2.2: The combustion chamber pressure p is known c , mixing ratio γ m and area ratio ε e ', calculate the outlet gas pressure p according to the thermodynamic formula e ;

[0030] Step S2.3: Calculate the ultimate pressure ratio δ using the following formula:

[0031]

[0032] Among them, k represents the outlet gas adiabatic index, M e represents the outlet gas Mach number, and β represents the expansion half angle of the nozzle;

[0033] Step S2.4: Calculate the separation surface pressure p according to the limit pressure ratio δ s , the formula is as follows:

[0034]

[0035] Among them, p a Indicates outlet air pressure;

[0036] Step S2.5: Compare the separation surface pressure p s and the outlet gas pressure p e The size of p s >p e , then return to step S2.1 and select a smaller area ratio ε e 'Re-iterate the calculation; if p s <p e , then the current area ratio ε e 'Output and store in the area ratio list, return to step S2.1 and select the larger area ratio ε e 'Perform iterative calculation again;

[0037] Step S2.6: Finally, select the area ratio list, p s Close to but less than p e The area ratio ε e ' as the area ratio of the combustion chamber section.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The present invention identifies the differences and connections between attitude control engines and orbit control engines, analyzes the power system mission indicators, refines the operating characteristics and requirements of attitude and orbit control engines, balances the contradictions and conflicts in their use requirements, and conducts targeted design for the performance that must be met. This achieves the goal of sharing engine components, thereby improving the production efficiency of components and reducing R&D, testing, and manufacturing costs.

[0040] 2. The present invention reduces product complexity, shortens product development time, reduces product management costs, and improves product reliability and maintainability by integrating the types of engine components, which is conducive to the mass production of space propulsion liquid power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0042] Figure 1 Schematic diagram of the overall structure of the engine;

[0043] Figure 2 This is a schematic diagram of the heat insulation and low temperature working structure of the injector;

[0044] Figure 3 Schematic diagram of the nozzle connection structure.

[0045] The figure shows:

[0046] DETAILED DESCRIPTION

[0047] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, without departing from the scope of the present invention, a number of variations and improvements may be made by those skilled in the art. These all fall within the scope of protection of the present invention.

[0048] This invention refines the operating characteristics and requirements of attitude and orbit control engines, specifically designing the necessary performance features to achieve the goal of shared engine components. This reduces product complexity, lowers R&D, testing, manufacturing, and management costs, and improves product reliability and maintainability. Specifically, this invention achieves this goal of shared components by specifically designing the solenoid valves, injectors, combustion chamber sections, and nozzle extensions in liquid rocket engines.

[0049] According to the present invention, a bipropellant liquid rocket engine for attitude and orbit control is provided. Figure 1 As shown, the system comprises: a solenoid valve 1, an injector 2, a combustion chamber section 3, and a nozzle extension section 4. These are connected in sequence. The injector 2 is mounted on its upper end using a goblet structure 5, with a V-groove structure 6 machined into the screw support. A heater plate mounting groove 7 is fixedly provided on the lower surface of the injector 2. The combustion chamber section 3 and the nozzle extension section 4 are connected via a bolt connection structure 8 or an electron beam welding structure 9 to achieve different nozzle extension section area ratios, enabling the creation of engines with varying thrust, specific impulse, and dimensions to simultaneously meet the operational requirements of attitude and orbit control engines. These engines can serve as both attitude and orbit control engines within the same power system. 511 is the professional code for electron beam welding.

[0050] The solenoid valve 1 is a pneumatic solenoid valve that uses helium to push open the liquid valve core to supply propellant. The valve core travels 1 / 4 of the valve diameter. The solenoid valve 1 uses a dual-voltage drive mode, that is, after high voltage starts, it switches to low voltage for maintenance. The electrical interface is a two-point, two-wire design. In other words, the air circuit drive component of the solenoid valve 1 uses a redundant two-point, two-wire electrical interface design.

[0051] Specifically, the present invention utilizes a pneumatic solenoid valve for the solenoid valve 1. This utilizes the advantages of gas viscosity being lower than liquid and the valve core being lightweight and having low inertia to enable rapid valve operation, thereby achieving a rapid response. The main moving parts of the pneumatic solenoid valve include an air circuit drive assembly, an air circuit valve core, a liquid circuit push rod, and a liquid circuit valve core. The operating sequence is as follows: the air circuit drive assembly is energized and turned on, the air circuit valve core is lifted, and control gas enters the valve cavity and acts on the liquid circuit push rod, which lifts the liquid circuit valve core, allowing propellant to flow into the engine. Furthermore, the solenoid valve 1 operates using a dual-voltage drive mode, i.e., it switches from a high voltage start to a low voltage for maintenance, thereby reducing power consumption and heat generation. The air circuit drive assembly utilizes a dual-point, dual-wire electrical interface redundancy design to ensure the reliability of the coil when powered for extended periods. Furthermore, the stroke of the solenoid valve 1 is 1 / 4 of its diameter, preventing excessive flow resistance loss during high-flow operation.

[0052] The injector 2 is located between the solenoid valve 1 and the nozzle, and its head cavity volume is small, which is 2150mm 3 ~2415mm 3 The head cavity filling time is 7.1ms to 8.2ms. A goblet structure 5 and a V-groove structure 6 are provided on the injector 2, and a heater plate mounting groove 7 is provided below the injector 2. The cylinder below the goblet structure 5 has a diameter of 10mm, and the cylinder above it has a diameter of 20mm. The V-groove structure 6 has five V-grooves, all symmetrically distributed about the center plane. There are four heater plate mounting grooves 7, evenly arranged along the circumference.

[0053] The injector head cavity volume affects the pulse performance of the attitude control engine and the aftereffect impulse of the trajectory control engine. Therefore, the head cavity volume should be minimized while ensuring reasonable flow distribution. This can be achieved by shortening the pipeline from the solenoid valve to the injection orifice, reducing the injection area, reducing the number of turns of the direct current injection pair, and integrating the flow channel space. During engine operation, heat from the nozzle flows through the injector and then the solenoid valve via heat conduction. Therefore, the injector should be insulated and heat-protected to reduce heat transfer to the solenoid valve. This prevents abnormal phenomena such as valve core swelling and propellant vaporization caused by heat backflow after long-term operation, thereby improving the reliability of the solenoid valve. From a structural design perspective, the present invention adopts a "goblet" mounting structure for the injector, increasing thermal resistance by reducing the cross-sectional area. In addition, a "V-shaped groove" is machined into the screw support to reduce the contact area between the solenoid valve and the injector, thereby reducing heat transfer. In addition, a heating plate mounting groove is provided on the lower surface of the injector, and the heating plate is fixed to the injector by screws, so as to maintain the structural temperature of the engine within the normal temperature range before ignition in a high-altitude and low-temperature environment, thereby preventing abnormal combustion phenomena such as deflagration during high-altitude and low-temperature pulse operation of the attitude control engine or multiple steady-state starts of the orbit control engine.

[0054] The nozzle consists of a combustion chamber section 3 and a nozzle extension section 4. The combustion chamber section 3 is where the propellant breaks up, atomizes, evaporates, mixes, and burns, affecting engine performance parameters such as combustion efficiency and response time. The nozzle extension section 4 is where the combustion gas expands and accelerates, affecting the engine's thrust.

[0055] The characteristic length of the combustion chamber section 3 (the ratio of the combustion chamber volume to the throat area) is small, ranging from 200 to 500 mm. If the response time requirement is higher, the characteristic length should be smaller. Since the combustion chamber section 3 is subjected to high temperature and high pressure of the fuel gas, the life of the engine mainly depends on the life of the combustion chamber section. The combustion chamber section 3 includes a base material and a surface coating. The base material is niobium tungsten alloy, and the surface coating is molybdenum silicide. The area ratio of the combustion chamber section 3 (the ratio of the outlet area to the throat area) is iteratively set according to the airflow separation theory. The size of the area ratio determines the outlet pressure p of the fuel gas. e , when the outlet air pressure p a The outlet pressure of the gas p e When the ratio is greater than the limit pressure ratio δ, a shock wave will be generated, causing the airflow to separate in the nozzle. The vibration caused by the airflow separation may cause damage to the nozzle. Therefore, when setting the combustion chamber section, the design requirements of the area ratio should be met to prevent the occurrence of airflow separation.

[0056] The purpose of the unified setting of the present invention is to achieve component sharing of the solenoid valve 1, the injector 2 and the combustion chamber section 3, that is, the set related components can simultaneously meet the working requirements of the attitude control engine and the track control engine.

[0057] A method for establishing a unified model of an attitude and orbit control bipropellant liquid rocket engine provided by the present invention includes:

[0058] Step S1: Perform targeted settings on the solenoid valve, injector, and combustion chamber section of the attitude and orbit control bipropellant liquid rocket engine.

[0059] Step S2: Iteratively calculating the area ratio of the combustion chamber segment based on the set solenoid valve, injector, and combustion chamber segment. Step S2 includes:

[0060] Step S2.1: Preliminary selection of area ratio ε e '.

[0061] Step S2.2: The combustion chamber pressure p is known c , mixing ratio γ m and area ratio ε e ', calculate the outlet gas pressure p according to the thermodynamic formula e .

[0062] Step S2.3: Calculate the ultimate pressure ratio δ using the following formula:

[0063]

[0064] Among them, k represents the outlet gas adiabatic index, M e represents the outlet gas Mach number, and β represents the expansion half angle of the nozzle.

[0065] Step S2.4: Calculate the separation surface pressure p according to the limit pressure ratio δ s , the formula is as follows:

[0066]

[0067] Among them, p a Indicates outlet air pressure.

[0068] Step S2.5: Compare the separation surface pressure p s and the outlet gas pressure p e The size of p s >p e , then return to step S2.1 and select a smaller area ratio ε e 'Re-iterate the calculation; if p s <p e , then the current area ratio ε e 'Output and store in the area ratio list, return to step S2.1 and select the larger area ratio ε e 'Perform iterative calculation again.

[0069] Step S2.6: Finally, select the area ratio list, p s Close to but less than p e The area ratio ε e ' as the area ratio of the combustion chamber section.

[0070] Step S3: Based on the calculated combustion chamber section area ratio, the nozzle extension section of the attitude and orbit control bipropellant liquid rocket engine is combined through a bolt connection structure or an electron beam welding structure to obtain different nozzle extension section area ratios to simultaneously meet the working requirements of the attitude and orbit control engine. The two engines can be used as the attitude control engine and orbit control engine of the same power system respectively.

[0071] Furthermore, the performance of the attitude and orbit control bipropellant liquid rocket engine of the present invention was verified in combination with actual tests, as described in detail below:

[0072] Solenoid valve 1 allows 3.5MPa helium to enter its inner chamber, driving the hydraulic valve core, achieving rapid response. The solenoid valve's no-load on / off response speed is less than 15ms, and its loaded on / off response speed is less than 10ms. It starts with a high voltage of 28V, which automatically switches to a low voltage of 22V after 10 seconds for maintenance. The coil also utilizes a dual-point, dual-wire electrical interface redundancy design. This targeted design ensures reliable operation for a single 1100s power-up. With a diameter of 8mm and a stroke of 2mm, the solenoid valve maintains a flow resistance of no more than 0.40MPa at a flow rate of 350g / s.

[0073] Injector 2 is a direct current injector with an O-type head cavity volume of 2150mm 3 The filling time of the O-type head cavity is 7.1ms, and the volume of the F-type head cavity is 2415mm 3 , the F-way filling time is 8.2ms. The injector 2 is provided with a goblet structure 5, the lower cylindrical diameter of the goblet structure 5 is 10mm, and the upper cylindrical diameter is 20mm. The injector 2 is provided with a V-groove structure 6 on the screw pillar, and the V-groove structure 6 has a total of 5 V-grooves, which are symmetrically distributed with respect to the center plane. The angle of the V-groove is 60°, the depth is 0.5mm, and the spacing between each other is 2mm. A heating plate mounting groove 7 is provided below the injector 2, and there are four heating plate mounting grooves 7 in total, which are evenly arranged along the circumference. The heating plate mounting groove 7 is fixed to the heating plate by an M5 screw, and the heating plate mounting groove has a depth of 1mm, an inner diameter of 45mm, an outer diameter of 60mm, a circumferential angle of 35°, and an internal chamfer of 2mm.

[0074] The characteristic length of combustion chamber segment 3 is 300 mm. The engine startup acceleration time is 23 to 28 ms, and the shutdown deceleration time is 17 to 30 ms. The metal material of combustion chamber segment 3 is niobium tungsten alloy, and the surface coating material is molybdenum silicide. The area ratio of combustion chamber segment 3 is calculated as follows:

[0075] First, the area ratio ε is preliminarily selected e ' is 6.5.

[0076] Then, calculate the outlet gas pressure p e , engine combustion chamber pressure p c Take 1.8MPa, mixing ratio γ m Take 1.65, the combined area ratio ε e ' is 6.5, calculate the outlet gas pressure p according to the thermodynamic formula e It is 38126Pa.

[0077] Next, the ultimate pressure ratio δ is calculated. According to the thermodynamic formula, the outlet gas adiabatic index k is calculated to be 1.247, and the outlet gas Mach number M is calculated to be e is 2.995, and the nozzle expansion half angle β is 0.6077rad;

[0078]

[0079] Next, calculate the separation surface pressure p s , The outlet air pressure p a Select atmospheric pressure 101325Pa.

[0080] Finally, compare the separation surface pressure p s and outlet gas pressure p e The size of p s =37081Pa<p e =38126Pa, that is, p s Close to but less than p e , ε e 'Selecting 6.5 is reasonable. The combustion chamber section 3 has an area ratio ε e 'The engine vacuum thrust at 6.5 is 1800N, and the engine vacuum specific impulse is The total engine height is 212mm, which can be used as an attitude control engine.

[0081] In order to improve the specific impulse and thrust of the engine, the nozzle extension section 4 with different area ratios is welded or screwed to the combustion chamber section 3. For example, the nozzle extension section area ratio ε e Select 80, the engine vacuum thrust increases to 2050N, the engine vacuum specific impulse The total engine height is 480mm, which can be used for track control engines.

[0082] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0083] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A bipropellant liquid rocket engine for attitude and orbit control, characterized in that: include: Solenoid valve (1), injector (2), combustion chamber section (3), nozzle extension section (4); The solenoid valve (1), the injector (2), the combustion chamber section (3), and the nozzle extension section (4) are connected in sequence. The upper end of the injector (2) is installed using a high-footed cup structure (5), and a V-shaped groove structure (6) is processed on the screw support. The lower surface of the injector (2) is fixedly provided with a heating plate installation groove (7).

2. The attitude and orbit control bipropellant liquid rocket engine according to claim 1, characterized in that: The combustion chamber section (3) and the nozzle extension section (4) are combined via a bolt connection structure (8) or an electron beam welding structure (9) to obtain different nozzle extension section area ratios, thereby setting engines with different thrusts, specific impulses and sizes.

3. The attitude and orbit control bipropellant liquid rocket engine according to claim 1, characterized in that: The solenoid valve (1) is a pneumatic solenoid valve; The moving parts of the pneumatic solenoid valve include an air circuit drive assembly, an air circuit valve core, a liquid circuit push rod and a liquid circuit valve core; The solenoid valve (1) supplies propellant by opening the valve core of the liquid path through helium, and the valve core stroke is 1 / 4 of the diameter.

4. The attitude and orbit control bipropellant liquid rocket engine according to claim 1, characterized in that: The solenoid valve (1) operates in a dual-voltage driving mode, and the corresponding air circuit driving component uses a dual-point dual-line electrical interface redundancy design.

5. The attitude and orbit control bipropellant liquid rocket engine according to claim 1, characterized in that: The injector (2) is located between the solenoid valve (1) and the nozzle, and its head cavity volume is 2150mm 3 ~2415mm 3 , the head cavity filling time is 7.1ms~8.2ms.

6. The attitude and orbit control bipropellant liquid rocket engine according to claim 1, characterized in that: The diameter of the lower cylinder of the goblet structure (5) is 10 mm, and the diameter of the upper cylinder is 20 mm; The V-shaped groove structure (6) has a total of five V-shaped grooves, all of which are symmetrically distributed with respect to the central plane; There are four heating plate installation grooves (7) in total, which are evenly arranged along the circumference.

7. The attitude and orbit control bipropellant liquid rocket engine according to claim 1, characterized in that: The combustion chamber section (3) is the area where the propellant is broken, atomized, evaporated, mixed, and burned; the nozzle extension section (4) is the area where the gas expands and accelerates; The characteristic length of the combustion chamber section (3) is 200 to 500 mm, and the characteristic length refers to the ratio of the combustion chamber volume to the throat area; The area ratio of the combustion chamber section (3) is iteratively set according to the airflow separation theory, and the area ratio refers to the ratio of the outlet area to the throat area.

8. The attitude and orbit control bipropellant liquid rocket engine according to claim 1, characterized in that: The combustion chamber section (3) comprises a base material and a surface coating, the base material is a niobium-tungsten alloy, and the surface coating is molybdenum silicide.

9. A method for establishing a unified model of an attitude and orbit control bipropellant liquid rocket engine according to any one of claims 1 to 8, characterized in that: include: Step S1: Performing targeted settings on the solenoid valve, injector, and combustion chamber section of the attitude and orbit control bipropellant liquid rocket engine; Step S2: iteratively calculating the area ratio of the combustion chamber segment according to the set solenoid valve, injector, and combustion chamber segment; Step S3: Based on the calculated combustion chamber section area ratio, the nozzle extension section of the attitude and orbit control bipropellant liquid rocket engine is combined through a bolt connection structure or an electron beam welding structure to obtain different nozzle extension section area ratios to simultaneously meet the working requirements of the attitude and orbit control engine. The two engines can be used as the attitude control engine and orbit control engine of the same power system respectively.

10. The method for establishing a unified model of an attitude and orbit control bipropellant liquid rocket engine according to claim 9, characterized in that: The step S2 comprises: Step S2.1: Preliminary selection of area ratio ε e '; Step S2.2: The combustion chamber pressure p is known c , mixing ratio γ m and area ratio ε e ', calculate the outlet gas pressure p according to the thermodynamic formula e ; Step S2.3: Calculate the ultimate pressure ratio δ using the following formula: Among them, k represents the outlet gas adiabatic index, M e represents the outlet gas Mach number, and β represents the expansion half angle of the nozzle; Step S2.4: Calculate the separation surface pressure p according to the limit pressure ratio δ s , the formula is as follows: Among them, p a Indicates outlet air pressure; Step S2.5: Compare the separation surface pressure p s and the outlet gas pressure p e The size of p s >p e , then return to step S2.1 and select a smaller area ratio ε e 'Re-iterate the calculation; if p s <p e , then the current area ratio ε e 'Output and store in the area ratio list, return to step S2.1 and select the larger area ratio ε e 'Perform iterative calculation again; Step S2.6: Finally, select the area ratio list, p s Close to but less than p e The area ratio ε e ' as the area ratio of the combustion chamber section.

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