Carrier rocket propellant sinking method and system based on solid-liquid rocket engine

Abstract

The invention relates to the technical field of spaceflight, and discloses a carrier rocket propellant sinking method and system based on a solid-liquid rocket engine, the carrier rocket propellant sinking system comprises a main body assembly, the main body assembly comprises a main engine, a kerosene storage tank is arranged on one side of the main engine, and a liquid oxygen storage tank and a sinking engine combustion chamber are arranged on one side of the kerosene storage tank; and the air inlet is arranged on the liquid oxygen storage tank. The solid-liquid rocket engine has the beneficial effects that the oxygen air pillow of the liquid oxygen storage box is adopted as an oxidant of a combustion chamber of the bottom-sinking engine, the solid-liquid rocket engine is formed by matching with a polyethylene solid fuel grain or materials such as HTPB and PMMA which are commonly used for engine grains, and the fan-shaped vibration isolation plate is arranged in front of the grains to restrain the unstable combustion phenomenon; multiple times of starting are achieved through high-power laser ignition, compared with a traditional scheme, the higher specific impulse and propellant utilization rate are achieved, the negative weight is reduced, the efficient and light-weight requirements of the recoverable rocket are met, propellant management can be achieved in the low-gravity environment, and deceleration thrust can be provided during returning.

Description

Technical Field

[0001] This invention relates to the field of aerospace technology, and in particular to a method and system for sinking propellant to the bottom of a launch vehicle based on a solid-liquid rocket engine. Background Technology

[0002] With the rapid development of aerospace technology, reusable launch vehicles, as a core solution for low-cost and high-efficiency access to space, have received widespread global attention. Their typical mission process covers key stages such as launch, ascent, interstage separation, in-flight roll, retro-rockets ignition, reentry ignition, and vertical landing. After the first and second stages of the rocket separate and complete the in-flight roll, the propellant in the tank is in a microgravity environment, and the stability of the gas-liquid interface decreases significantly. This makes it very easy for liquid to carry gas into the pump body, which can lead to pump cavitation and seriously affect the normal operation of the engine. Therefore, it is necessary to ensure that the liquid propellant is stably accumulated at the tank outlet before the main engine starts through propellant management technology. Currently, using a bottom-mounted engine to create an artificial gravity field is the mainstream solution for cryogenic propellant management. However, existing technologies have obvious limitations. The specific impulse of cold gas propulsion is relatively low, and the bottom-mounting process consumes a large amount of gaseous working fluid, which significantly restricts the improvement of the overall engine performance. On the other hand, the single-component propulsion method requires an independent configuration of the entire engine system, which adds extra negative weight to the rocket and directly affects the carrying capacity, making it difficult to meet the technical requirements of high efficiency and lightweight reusable rockets. Summary of the Invention

[0003] In view of the problems existing in the above and / or existing methods and systems for sinking propellant in launch vehicles based on solid-liquid rocket engines, the present invention is proposed.

[0004] Therefore, the problem that this invention aims to solve is that in the prior art, cold gas propulsion has low specific impulse and high gas consumption, and single-component propulsion increases negative weight, both of which are difficult to meet the requirements of high efficiency and lightweight reusable rockets.

[0005] To solve the above technical problems, the present invention provides the following technical solution: a method and system for sinking propellant in a launch vehicle based on a solid-liquid rocket engine, which includes a main component (100), including a main engine (101), a kerosene tank (102) is provided on one side of the main engine (101), and a liquid oxygen tank (103) is provided on one side of the kerosene tank (102). A bottom-mounted engine (200) is installed on the liquid oxygen storage tank (103). The bottom-mounted engine (200) includes an oxygen pipeline (201) and a bottom-mounted engine combustion chamber (202). The bottom-mounted engine combustion chamber (202) contains a propellant charge (2021), a laser igniter (2022), a vibration damping plate (2023), and a nozzle (2024).

[0006] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, the sinking engine (200) further includes a sinking engine combustion chamber (202), the sinking engine combustion chamber (202) includes a propellant grain (2021), and the propellant grain (2021) is fixed to the inner wall of the sinking engine combustion chamber (202).

[0007] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, a laser igniter (2022) is provided on one side of the propellant grain (2021), and the laser igniter (2022) is fixed to the inner wall of the combustion chamber (202) of the sinking engine.

[0008] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, wherein: a vibration isolation plate is fixed to the inner wall of the combustion chamber of the sinking engine, and the vibration isolation plate is located on one side of the propellant grain.

[0009] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, wherein: a nozzle is fixed at one end of the combustion chamber of the sinking engine, and the nozzle is disposed at one end of the propellant grain.

[0010] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, the propellant grain is hollow, and the material of the propellant grain is not limited to polyethylene.

[0011] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, wherein: a propellant grain is provided in the combustion chamber of the sinking engine, and the propellant grain is fixed in the combustion chamber of the sinking engine.

[0012] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, the vibration isolation plate is composed of two vertically placed fan-shaped blades, which suppresses the oscillation of the combustion chamber pressure in the combustion chamber of the sinking engine, so that the combustion chamber of the sinking engine outputs a stable thrust.

[0013] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, the laser igniter has a power of not less than 10W and a spot diameter of less than 2mm. The laser igniter can generate a heat flow of about 3MW / m2 on the fuel wall surface. This heat flow intensity is sufficient to promote the pyrolysis and combustion reaction of the fuel. The flame formed in the initial stage of ignition will be transmitted downstream along the flow direction of the oxidizer, thereby igniting the entire fuel.

[0014] As a preferred embodiment of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines described in this invention, the following steps are taken: During rocket takeoff, kerosene tanks and liquid oxygen tanks are connected to the main engine. Kerosene and liquid oxygen enter the main engine for combustion to generate thrust. After the main engine shuts down, gaseous oxygen from the liquid oxygen tank enters the sinking engine combustion chamber along the gas-oxygen pipeline, where it burns with the propellant to generate fuel gas. A laser igniter ignites the fuel gas and solid fuel in the combustion chamber. The high-temperature fuel gas generated by combustion is discharged through the nozzle to generate thrust. The artificial gravity generated by the sinking engine combustion chamber causes kerosene to form a stable liquid surface in the kerosene tank and also causes liquid oxygen to form a stable liquid surface in the liquid oxygen tank, thus achieving propellant sinking and preventing gas-entrained propellant from entering the main engine. This provides a reliable guarantee for the main engine to restart, and the sinking engine combustion chamber can be restarted multiple times to provide deceleration thrust during reentry. Vibration isolation plates can suppress combustion instability phenomena occurring in the combustion chamber.

[0015] The beneficial effects of this invention are as follows: using the oxygen cushion of the liquid oxygen storage tank as the oxidizer in the combustion chamber of the bottom-mounted engine, and combining it with polyethylene solid fuel propellant grains or materials commonly used in engine propellant grains such as HTPB and PMMA to form a solid-liquid rocket engine, by setting a fan-shaped vibration isolation plate in front of the propellant grain to suppress unstable combustion, and using high-power laser ignition to achieve multiple starts, it has a higher specific impulse and propellant utilization rate compared with traditional solutions, reduces negative weight, meets the high efficiency and lightweight requirements of reusable rockets, can achieve propellant management in low gravity environments, and can also provide deceleration thrust during reentry. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a structural diagram of the propellant sinking method and system for launch vehicles based on solid-liquid rocket engines.

[0017] Figure 2 This is a cross-sectional structural diagram of a propellant sinking method and system for launch vehicles based on solid-liquid rocket engines.

[0018] Figure 3 This is a structural diagram of the combustion chamber of a bottom-sinking engine for a launch vehicle propellant sinking method and system based on a solid-liquid rocket engine. Detailed Implementation

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0022] Example 1 Reference Figures 1-3 This is the first embodiment of the present invention. This embodiment provides a method and system for sinking propellant at the bottom of a launch vehicle based on a solid-liquid rocket engine. The method and system for sinking propellant at the bottom of a launch vehicle based on a solid-liquid rocket engine includes a main component and a sinking engine unit. The two can work together to form a solid-liquid sinking engine by using an oxygen cushion from a liquid oxygen tank and a polyethylene propellant grain. A fan-shaped vibration isolation plate is set up and multiple starts are achieved by high-power laser ignition. Compared with traditional solutions, it has a higher specific impulse and propellant utilization rate, reduces negative weight, meets the high efficiency and lightweight requirements of reusable rockets, enables propellant management in low gravity environments, and provides deceleration thrust during reentry.

[0023] The main component 100 includes a main engine 101, a kerosene tank 102 on one side of the main engine 101, and a liquid oxygen tank 103 on one side of the kerosene tank 102.

[0024] The main engine 101 is the primary power source of the rocket. It generates thrust by burning kerosene and liquid oxygen to produce high-temperature, high-pressure gas, propelling the rocket through the takeoff and ascent phases of flight. The kerosene tank 102 stores kerosene fuel and delivers it to the main engine 101 during rocket operation, where it participates in the combustion reaction as fuel. The liquid oxygen tank 103 stores liquid oxygen oxidizer and delivers it to the main engine 101 during operation, where it mixes with kerosene for combustion to generate thrust. Simultaneously, the gaseous oxygen in its cushion section can serve as an oxidizer in the bottom-mounted engine combustion chamber 202, participating in the propellant sinking process.

[0025] The bottom-mounted engine 200 is installed on the liquid oxygen storage tank 103. The bottom-mounted engine 200 includes an oxygen pipeline 201 and a bottom-mounted engine combustion chamber 202. The bottom-mounted engine combustion chamber 202 contains a propellant 2021, a laser igniter 2022, a vibration damping plate 2023, and a nozzle 2024.

[0026] The gas oxygen pipeline 201 is used to connect the liquid oxygen storage tank 103 and the bottom-mounted engine combustion chamber 202, and to transport the gas oxygen in the liquid oxygen storage tank 103 to the bottom-mounted engine combustion chamber 202. The bottom-mounted engine combustion chamber 202 generates thrust by burning gas oxygen and solid fuel, thereby achieving propellant sinking and rocket attitude control. When the rocket is in a microgravity environment, the gas oxygen in the liquid oxygen storage tank 103 enters the bottom-mounted engine combustion chamber 202 through the gas oxygen pipeline 201. The laser igniter 2022 ignites the propellant grain 2021, and the gas oxygen reacts with the fuel to generate thrust, causing the propellant to sink to the bottom in the liquid oxygen storage tank 103, ensuring that there is no gas entrainment at the pump inlet when the main engine 101 restarts.

[0027] Example 2 Reference Figure 2 and Figure 3 This is the second embodiment of the present invention, which is based on the previous embodiment.

[0028] Specifically, the bottom-mounted engine unit 200 also includes a bottom-mounted engine combustion chamber 202, which includes a propellant grain 2021 fixed to the inner wall of the bottom-mounted engine combustion chamber 202.

[0029] The propellant 2021 is solid fuel in the combustion chamber 202 of the bottom-mounted engine. It reacts with the oxygen supplied by the oxygen supply line 201 to produce high-temperature gas, which provides thrust to the bottom-mounted engine 200.

[0030] Specifically, a laser igniter 2022 is installed on one side of the propellant 2021, and the laser igniter 2022 is fixed to the inner wall of the combustion chamber 202 of the bottom-mounted engine.

[0031] The laser igniter 2022 is used to ignite the propellant charge 2021, causing it to undergo a combustion reaction with gaseous oxygen. The laser igniter 2022 irradiates the surface of the propellant charge 2021 with a high-energy laser beam, generating sufficient heat to pyrolyze and ignite the fuel. As a re-triggerable ignition device, the laser igniter 2022 supports multiple starts of the bottom-mounted engine 200 in different flight phases.

[0032] Specifically, a vibration isolation plate 2023 is fixed to the inner wall of the combustion chamber 202 of the bottom-mounted engine, and the vibration isolation plate 2023 is located on one side of the propellant grain 2021.

[0033] Vibration damping plate 2023 is used to suppress pressure oscillations in the combustion chamber 202 of the undercarriage engine during operation, ensuring stable thrust output.

[0034] Specifically, a nozzle 2024 is fixed at one end of the bottom-mounted engine combustion chamber 202, and the nozzle 2024 is located at one end of the propellant grain 2021.

[0035] The nozzle 2024 is used to accelerate the expansion of the high-temperature gas generated in the combustion chamber and then discharge it, thereby generating thrust.

[0036] Example 3 Reference Figures 1-3 This is the third embodiment of the present invention, which is based on the first two embodiments.

[0037] Specifically, the 2021 precipitate is hollow and made of polyethylene.

[0038] The propellant grain 2021 is hollow, which allows gaseous oxygen to pass through the central hole and make full contact with the surface of the propellant grain 2021. The propellant grain 2021 uses polyethylene as solid fuel, which can react with the gaseous oxygen entering the combustion chamber to produce high-temperature gas, which provides thrust to the bottom-mounted engine combustion chamber 202. The high-temperature gas is accelerated and ejected through the nozzle to generate thrust, forming artificial gravity and realizing the propellant sinking to the bottom.

[0039] The propellant grain 2021 is made of polyethylene, which can react with the oxygen gas entering the combustion chamber to produce high-temperature gas, providing thrust to the bottom-mounted engine combustion chamber 202 and enabling the propellant to sink to the bottom.

[0040] Specifically, a combustion chamber is provided inside the bottom-mounted engine combustion chamber 202, and the propellant grain 2021 is fixed inside the combustion chamber.

[0041] The combustion chamber provides space for the combustion reaction of the propellant grain 2021 and gaseous oxygen, allowing the two to mix and burn fully, generating high-temperature gas, which provides thrust to the bottom-mounted engine combustion chamber 202 to achieve propellant sinking to the bottom.

[0042] Specifically, the vibration damping plate 2023 consists of two vertically placed fan-shaped blades, which suppress the pressure oscillation in the combustion chamber of the undercarriage engine 202, so that the undercarriage engine combustion chamber 202 outputs a stable thrust.

[0043] The vibration damping plate 2023, with its structure of two vertically placed fan-shaped blades, can disrupt the airflow distribution in the combustion chamber, change the sound wave reflection path, consume oscillation energy, suppress pressure fluctuations, and ensure that the combustion chamber 202 of the bottom-mounted engine outputs stable thrust, thus avoiding thrust fluctuations or structural damage caused by unstable combustion.

[0044] Specifically, the laser igniter 2022 has a power of no less than 10W and a spot diameter of less than 2mm. The laser igniter 2022 can generate approximately 3MW / m² on the fuel wall. 2 The heat flow is strong enough to cause the fuel to undergo a pyrolysis and combustion reaction. The flame formed in the initial stage of ignition will be transmitted downstream along the flow direction of the oxidant, thereby igniting the entire fuel.

[0045] The laser igniter 2022 generates sufficient heat flow to ignite the propellant charge 2021 with a power of over 10W and a light spot of less than 2mm, allowing the initial flame to flow with the oxidizer and ignite the entire fuel. At the same time, using off-the-shelf products can reduce costs and improve efficiency, ensuring reliable start-up and stable operation of the bottom-mounted engine combustion chamber 202.

[0046] Specifically, during rocket takeoff, the kerosene tank 102 and liquid oxygen tank 103 are connected to the main engine 101. Kerosene and liquid oxygen enter the main engine 101 for combustion to generate thrust. After the main engine 101 shuts down, the gaseous oxygen in the liquid oxygen tank 103 enters the bottom-mounted engine combustion chamber 202 along the gas-oxygen pipeline 201, where it burns with the propellant grain 2021 to generate gas. The laser igniter 2022 ignites the gaseous oxygen and solid fuel in the combustion chamber. The high-temperature gas generated by combustion is discharged through the nozzle 2024 to generate thrust, thus achieving propellant bottom-mounting. This allows kerosene to form a stable liquid level in the kerosene tank and liquid oxygen to form a stable liquid level in the liquid oxygen tank 103, achieving propellant bottom-mounting and preventing gas-entrained propellant from entering the main engine 101. This provides a reliable guarantee for the restart of the main engine 101, and the bottom-mounted engine combustion chamber 202 can be restarted multiple times to provide deceleration thrust during reentry. The vibration isolation plate 2023 suppresses combustion instability.

[0047] The main engine 101 works in conjunction with the kerosene tank 102 and the liquid oxygen tank 103 to ensure power during takeoff. After the main engine 101 shuts down, the gas-oxygen pillow in the liquid oxygen tank 103 is supplied to the bottom-mounted engine combustion chamber 202 via the gas-oxygen pipeline 201. Combined with the vibration damping plate 2023 for stable combustion, the laser igniter 2022 for reliable ignition, and the nozzle 2024 for efficient thrust conversion, the propellant can be deposited at the bottom to ensure a stable propellant supply when the main engine restarts. Furthermore, because the bottom-mounted engine combustion chamber 202 can be restarted multiple times, it provides deceleration thrust during the return phase. Overall, the negative weight of the additional systems is reduced, the propellant utilization rate and the rocket's mission adaptability are improved, and the requirements for high efficiency and lightweight reusable rockets are met.

[0048] During use, during the rocket's takeoff phase, the kerosene tank 102 and the liquid oxygen tank 103 are connected to the main engine 101. Kerosene and liquid oxygen enter the main engine 101 through their respective pipelines. The two mix and burn in the main engine 101 to produce high-temperature and high-pressure gas, which is then expanded and discharged through the nozzle of the main engine 101 to generate thrust, propelling the rocket to complete the takeoff and ascent process.

[0049] When the main engine 101 shuts down according to the procedure, the rocket is in a microgravity environment. The propellant gas-liquid interface in the liquid oxygen tank 103 is unstable. At this time, the gas-oxygen pillow in the liquid oxygen tank 103 is transported to the bottom-mounted engine combustion chamber 202 through the gas-oxygen pipeline 201. The gas-oxygen first passes through the vibration isolation plate 2023 fixed on the inner wall of the bottom-mounted engine combustion chamber 202. The vibration isolation plate 2023 is composed of two vertically placed fan-shaped blades, which can effectively suppress the oscillation of the combustion chamber pressure in the bottom-mounted engine combustion chamber 202 and ensure the stable operation of the subsequent combustion process.

[0050] Subsequently, the laser igniter 2022, fixed to the inner wall of the combustion chamber 202 of the bottom-mounted engine, is activated. The laser igniter 2022 is a shelf-mounted product with a power of 10W or more and a spot diameter of less than 2mm, which can generate 3MW / m² on the wall of the propellant column 2021. 2 The heat flow from left and right is sufficient to pyrolyze and burn the propellant grain 2021. The initial flame is transmitted downstream with the flow of oxidizer, igniting the oxygen and the hollow polyethylene propellant grain 2021 in the combustion chamber. The two react to produce high-temperature gas. After the high-temperature gas is fully mixed in the combustion chamber, it is accelerated and expanded and discharged through the nozzle 2024 fixed at one end of the bottom-mounted engine combustion chamber 202, generating thrust. Under the action of this thrust, the propellant in the liquid oxygen storage tank 103 forms a stable liquid surface under the action of artificial gravity, realizing the propellant sinking to the bottom and ensuring that cavitation will not occur due to entrained gas when the main engine 101 is restarted.

[0051] In addition, the bottom-mounted engine combustion chamber 202 can be activated multiple times according to mission requirements. During the rocket's return phase, the bottom-mounted engine combustion chamber 202 can be activated again, and the thrust generated can be used as deceleration thrust to assist the rocket in achieving a smooth landing.

[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A propellant sinking system for a launch vehicle based on a solid-liquid rocket engine, characterized in that: include, The main component (100) includes a main engine (101), a kerosene tank (102) is provided on one side of the main engine (101), and a liquid oxygen tank (103) is provided on one side of the kerosene tank (102). A bottom-mounted engine (200) is installed on the liquid oxygen storage tank (103). The bottom-mounted engine (200) includes an oxygen pipeline (201) and a bottom-mounted engine combustion chamber (202). The bottom-mounted engine combustion chamber (202) contains a propellant charge (2021), a laser igniter (2022), a vibration damping plate (2023), and a nozzle (2024).

2. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 1, characterized in that: The bottom-mounted engine (200) also includes a bottom-mounted engine combustion chamber (202), which includes a propellant grain (2021) fixed to the inner wall of the bottom-mounted engine combustion chamber (202).

3. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 2, characterized in that: A laser igniter (2022) is provided on one side of the propellant column (2021), and the laser igniter (2022) is fixed to the inner wall of the bottom-mounted engine combustion chamber (202).

4. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 3, characterized in that: The inner wall of the bottom-mounted engine combustion chamber (202) is fixed with a vibration isolation plate (2023), which is located on one side of the propellant grain (2021).

5. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 4, characterized in that: A nozzle (2024) is fixed at one end of the bottom-mounted engine combustion chamber (202), and the nozzle (2024) is located at one end of the propellant grain (2021).

6. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 5, characterized in that: The drug column (2021) is hollow, and the material of the drug column (2021) is including but not limited to polyethylene.

7. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 6, characterized in that: The bottom-mounted engine (200) is equipped with a propellant charge (2021), which is fixed inside the combustion chamber (202) of the bottom-mounted engine.

8. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 7, characterized in that: The vibration isolation plate (2023) is composed of two vertically placed fan-shaped blades, which suppresses the pressure oscillation in the combustion chamber of the bottom-mounted engine (202) and enables the bottom-mounted engine combustion chamber (202) to output a stable thrust.

9. The propellant sinking system for a launch vehicle based on a solid-liquid rocket engine as described in claim 8, characterized in that: The laser igniter (2022) has a power of not less than 10W and a spot diameter of less than 2mm. The laser igniter (2022) is capable of generating 3MW / m² on the fuel wall. 2 The heat flow is strong enough to cause the fuel to undergo a pyrolysis and combustion reaction. The flame formed in the initial stage of ignition will be transmitted downstream along the flow direction of the oxidant, thereby igniting the entire fuel.

10. A method for sinking propellant in a launch vehicle based on a solid-liquid rocket engine, characterized in that: Including the launch vehicle propellant sinking system as described in any one of claims 1-9, comprising, When the rocket takes off, the kerosene tank (102) and the liquid oxygen tank (103) are connected to the main engine (101). The kerosene and liquid oxygen enter the main engine (101) and burn to generate thrust. After the main engine (101) is shut down, the gaseous oxygen in the liquid oxygen tank (103) enters the bottom engine combustion chamber (202) along the gaseous oxygen pipeline (201) and burns with the propellant grain (2021) to generate gas. The laser igniter (2022) ignites the gaseous oxygen and the solid fuel in the combustion chamber. The vibration isolation plate (2023) suppresses the combustion instability. The high-temperature gas generated by the combustion is discharged through the nozzle (2024) to generate thrust. It also makes the liquid oxygen form a stable liquid surface in the liquid oxygen tank (103), realizes the propellant sinking to the bottom, avoids the gas-entrained propellant from entering the main engine (101), provides a reliable guarantee for the main engine (101) to restart, and the bottom engine combustion chamber (202) can be started multiple times to provide deceleration thrust during return.

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