Liquid nitrogen vaporization pressurization system and liquid rocket

Abstract

This invention provides a liquid nitrogen vaporization pressurization system and a liquid rocket. The liquid nitrogen vaporization pressurization system includes a liquid oxygen tank, a fuel tank, a liquid nitrogen tank, a liquid nitrogen pump, a cavitation pipe, and a heater assembly. The liquid oxygen tank stores liquid oxygen, the fuel tank stores fuel, and the liquid nitrogen tank stores liquid nitrogen. The liquid nitrogen tank is located inside the liquid oxygen tank, and the fuel tank is located on the side of the liquid oxygen tank closer to the engine. The liquid nitrogen pump increases the output pressure of the liquid nitrogen, the cavitation pipe stabilizes the liquid nitrogen flow rate, and the heater assembly vaporizes the liquid nitrogen and heats it into high-temperature nitrogen gas. A liquid nitrogen delivery pipe is located at the bottom of the liquid nitrogen tank, and the liquid nitrogen pump is mounted on the liquid nitrogen delivery pipe. The end of the liquid nitrogen delivery pipe away from the liquid nitrogen pump is connected to the inlet of the heater assembly. The liquid oxygen tank cushion, the fuel tank cushion, and the liquid nitrogen tank cushion are each connected to the outlet of the heater assembly via pipelines. The liquid nitrogen vaporization pressurization system and liquid rocket provided by this invention can effectively reduce the cost and weight of the pressurization system.

Description

Technical Field

[0001] This invention relates to the field of rocket technology, and in particular to a liquid nitrogen vaporization pressurization system and a liquid rocket. Background Technology

[0002] The new generation of launch vehicles is primarily designed as transportation tools for deep space probes and utilizes a novel propulsion system. This new system replaces conventional toxic and polluting propellants with non-toxic and pollution-free ones. Due to the high reliability requirements for deep space probe launches, the reliability requirements for the new generation of launch vehicles are even higher compared to conventional launch vehicles. The pressurization and delivery system is a crucial system of the launch vehicle, directly affecting its flight reliability. Therefore, high reliability should be the primary consideration when designing the pressurization and delivery system for the new generation of launch vehicles.

[0003] The selection of pressurization schemes for launch vehicles at home and abroad mainly considers factors such as improving pressurization efficiency, system simplicity and reliability, and technical capabilities. Currently, mainstream cryogenic engines mainly use a combination of liquid oxygen and kerosene propellants. Common pressurization schemes mainly consist of four types: self-generated pressurization, ambient temperature helium pressurization, ambient temperature helium heated pressurization, and cold helium heated pressurization. For liquid oxygen / kerosene engines, the kerosene tank mainly adopts the ambient temperature helium pressurization scheme.

[0004] In the process of realizing this invention, the inventors discovered at least the following problems in the prior art:

[0005] Room temperature helium pressurization requires independent pressurization gas source storage devices such as high-pressure cylinders, as well as supporting pipelines and valves. The system composition is relatively complex and costly. For large and heavy launch vehicles, especially for pressurizing the propellant tanks of cryogenic rockets, the required gas volume is large, and the number of gas storage devices is numerous. At the same time, the cylinders cool down during the venting process, increasing their density, and the remaining pressure in the cylinders is relatively high. This results in the helium utilization rate of room temperature helium pressurization being less than 70%. In addition, helium is very expensive. Therefore, room temperature helium pressurization is costly for large rockets.

[0006] By explaining and comparing the above pressurization methods, it is clear that kerosene in the kerosene tanks of large launch vehicles is difficult to pressurize due to its high boiling point, resulting in high pressurization costs and heavy pressurization systems. Therefore, it is urgent and of great significance to carry out engineering application research on low-cost, lightweight pressurization systems based on kerosene tanks. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a liquid nitrogen vaporization pressurization system and a liquid rocket to improve the problems of high pressurization cost and large weight of pressurization system in the prior art.

[0008] In a first aspect, embodiments of the present invention provide a liquid nitrogen vaporization pressurization system for a liquid rocket, comprising a liquid oxygen tank, a fuel tank, a liquid nitrogen tank, a liquid nitrogen pump cavitation pipe, and a heater assembly; the liquid oxygen tank is used to store liquid oxygen, the fuel tank is used to store fuel, and the liquid nitrogen tank is used to store liquid nitrogen, the liquid nitrogen tank being disposed inside the liquid oxygen tank, the fuel tank being disposed on the side of the liquid oxygen tank closer to the engine, the liquid nitrogen pump being used to increase the output pressure of the liquid nitrogen, the cavitation pipe being used to stabilize the liquid nitrogen flow rate, and the heater assembly being used to heat the liquid nitrogen into high-temperature nitrogen gas; a liquid nitrogen delivery pipe is provided at the bottom of the liquid nitrogen tank, the liquid nitrogen pump is disposed on the liquid nitrogen delivery pipe, the end of the liquid nitrogen delivery pipe away from the liquid nitrogen pump is connected to the inlet of the heater assembly, and the liquid oxygen tank cavitation pipe, the fuel tank cavitation pipe, and the liquid nitrogen tank cavitation pipe are respectively connected to the outlet of the heater assembly via pipelines.

[0009] Furthermore, the liquid nitrogen vaporization pressurization system also includes a main pressurization pipeline, a liquid nitrogen tank pressurization pipeline, and a fuel tank pressurization pipeline; the liquid oxygen tank cushion is connected to the heater assembly through the main pressurization pipeline; one end of the liquid nitrogen tank pressurization pipeline is connected to the liquid nitrogen tank cushion, and the other end is connected to the main pressurization pipeline; one end of the fuel tank pressurization pipeline is connected to the fuel tank cushion, and the other end is connected to the main pressurization pipeline between the liquid nitrogen tank pressurization pipeline and the heater assembly.

[0010] Furthermore, the liquid nitrogen vaporization pressurization system also includes an integrated purging and pressurization assembly. This assembly comprises a main pipeline and multiple branch pipelines. The end of the main pipeline near the engine is connected to a ground-based nitrogen source. The inlet of each branch pipeline is connected to the main pipeline. The outlet of the first branch pipeline is connected to the engine's liquid oxygen discharge pipeline to provide a gas seal for the liquid oxygen discharge pipeline. The outlet of the second branch pipeline is connected to the stern section purging pipe to purge the first-stage stern section. The outlet of the third branch pipeline is connected to the interstage purging pipe to purge the interstage section. The outlet of the fourth branch pipeline is connected to the liquid nitrogen tank pressurization pipe to pressurize the liquid nitrogen tank. The outlet of the fifth branch pipeline is connected to the liquid oxygen tank exhaust pipeline to provide a gas seal for the liquid oxygen tank exhaust pipeline. The outlet of the sixth branch pipeline is connected to the interstage purging pipe to purge the interstage section.

[0011] Furthermore, the liquid nitrogen vaporization pressurization system also includes a first liquid nitrogen filling and precooling assembly. The first liquid nitrogen filling and precooling assembly includes a first liquid nitrogen filling and precooling pipeline and a liquid nitrogen shut-off valve. The liquid nitrogen shut-off valve is located on the first liquid nitrogen filling and precooling pipeline. One end of the first liquid nitrogen filling and precooling pipeline is connected to the pipeline between the liquid nitrogen pump and the heater assembly, and the other end is used to be detachably connected to the liquid nitrogen filling system and the first liquid nitrogen discharge shut-off valve, respectively.

[0012] Furthermore, the liquid nitrogen vaporization pressurization system also includes a liquid oxygen tank pressurization assembly, a fuel tank pressurization assembly, and a first pre-launch pressurization assembly;

[0013] The liquid oxygen tank pressurization assembly includes a liquid oxygen tank pressurization pipeline, one end of which is connected to a liquid oxygen tank pressurization helium cylinder, and the other end is connected to the main pressurization pipeline; a liquid oxygen tank pressurization solenoid valve and a liquid oxygen tank pressurization orifice plate are sequentially arranged on the liquid oxygen tank pressurization pipeline from the liquid oxygen tank pressurization helium cylinder toward the main pressurization pipeline;

[0014] The fuel tank pressurization assembly includes a fuel tank pressurization pipeline, one end of which is connected to a fuel tank pressurization helium cylinder, and the other end is connected to the fuel tank booster pipe; the fuel tank pressurization pipeline is provided with a fuel tank pressurization solenoid valve and a fuel tank pressurization orifice plate in sequence from the fuel tank pressurization helium cylinder toward the fuel tank booster pipe;

[0015] One end of the first pre-launch pressurization component is connected to the main pressurization pipeline between the liquid nitrogen tank pressurization pipe and the heater assembly, and the other end is used for detachable connection to the ground helium source; the first pre-launch pressurization component includes a first pre-launch pressurization check valve and a first pre-launch pressurization solenoid valve sequentially arranged from the main pressurization pipeline to the ground helium source.

[0016] Furthermore, the liquid nitrogen vaporization pressurization system also includes a main pressurization pipeline, a liquid nitrogen tank pressurization pipeline, and a fuel tank pressurization pipeline; the liquid nitrogen pump includes a first liquid nitrogen pump and a second liquid nitrogen pump connected in parallel; and the heater assembly includes a first heater assembly and a second heater assembly.

[0017] The first liquid nitrogen pump is connected to one end of the main pressurization pipeline via the first heater assembly, and the other end of the main pressurization pipeline is connected to the liquid oxygen tank cushion; the second liquid nitrogen pump is connected to one end of the fuel tank pressurization pipe via the second heater assembly, and the other end of the fuel tank pressurization pipe is connected to the fuel tank cushion; one end of the liquid nitrogen tank pressurization pipe is connected to the liquid nitrogen tank cushion, and the other end is connected to the main pressurization pipeline;

[0018] Furthermore, the liquid nitrogen vaporization pressurization system also includes a second liquid nitrogen filling and precooling assembly. The second liquid nitrogen filling and precooling assembly includes a second liquid nitrogen filling and precooling pipeline, a pipeline check valve, and a second liquid nitrogen discharge shut-off valve. The pipeline check valve is located on the second liquid nitrogen filling and precooling pipeline. One end of the second liquid nitrogen filling and precooling pipeline is connected to the pipeline between the liquid nitrogen pump and the liquid nitrogen tank, and the other end is used for detachable connection with the liquid nitrogen filling system. The second liquid nitrogen discharge shut-off valve is connected to the outlet ends of the two liquid nitrogen pumps respectively through pipelines.

[0019] Furthermore, the liquid nitrogen vaporization pressurization system also includes a second pre-launch pressurization component and a third pre-launch pressurization component. One end of the second pre-launch pressurization component is connected to the main pressurization pipeline between the liquid nitrogen tank pressurization pipe and the first heater component, and the other end is used for detachable connection to the ground helium source. One end of the third pre-launch pressurization component is connected to the fuel tank pressurization pipe, and the other end is used for detachable connection to the ground helium source.

[0020] Furthermore, the gas generators of at least two engines are connected in parallel for redundancy and used together to provide high-temperature gas for the liquid nitrogen pump, which serves as the driving force for the liquid nitrogen pump.

[0021] Secondly, embodiments of the present invention provide a liquid rocket, including the liquid nitrogen vaporization pressurization system described above.

[0022] The above technical solution has the following beneficial effects: The liquid nitrogen vaporization pressurization system provided in this application stores the pressurizing medium nitrogen in liquid form. During rocket pressurization, the liquid nitrogen is heated and vaporized into nitrogen gas, which is then used to pressurize the liquid oxygen tank, fuel tank, and liquid nitrogen tank. Compared with the method of pressurizing with room temperature helium gas, the consumption of helium resources is reduced, and its cost is significantly lowered. The liquid nitrogen vaporization pressurization system of this application stores the pressurizing medium nitrogen in liquid form, and its utilization rate of the pressurizing medium is significantly improved compared with the helium pressurization method. At the same time, the liquid nitrogen tank is immersed in the liquid oxygen tank, and the fixed mechanical load of the liquid nitrogen tank is reduced by utilizing the buoyancy of liquid oxygen. The liquid nitrogen vaporization pressurization system of this application is lighter than the room temperature helium pressurization system, which improves the carrying capacity of the liquid rocket. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0024] Figure 1 This is a schematic diagram of the overall structure of a liquid nitrogen vaporization pressurization system according to an embodiment of this application.

[0025] Figure 2 yes Figure 1 A partial structural diagram of a liquid nitrogen vaporization pressurization system.

[0026] Figure 3 yes Figure 1 A schematic diagram of the liquid nitrogen pump gas drive system structure of the liquid nitrogen vaporization pressurization system.

[0027] Figure 4 yes Figure 1A schematic diagram of the integrated booster component of the liquid nitrogen vaporization booster system.

[0028] Figure 5 yes Figure 1 A schematic diagram of the structure of the first liquid nitrogen filling and precooling component of the liquid nitrogen vaporization pressurization system.

[0029] Figure 6 yes Figure 1 A schematic diagram of the control logic of the one-way valve regulating the liquid oxygen tank in a liquid nitrogen vaporization pressurization system.

[0030] Figure 7 yes Figure 1 A schematic diagram of the control logic of the fuel tank regulating check valve in a liquid nitrogen vaporization booster system.

[0031] Figure 8 yes Figure 1 The pressure curve of the gas pillow in the liquid oxygen tank of the liquid nitrogen vaporization pressurization system.

[0032] Figure 9 yes Figure 1 The pressure curve of the fuel tank cushion of the liquid nitrogen vaporization booster system.

[0033] Figure 10 This is a schematic diagram of the overall structure of a liquid nitrogen vaporization pressurization system according to another embodiment of this application.

[0034] Figure 11 yes Figure 2 A partial structural diagram of a liquid nitrogen vaporization pressurization system.

[0035] Figure 12 yes Figure 2 A schematic diagram of the liquid nitrogen pump gas drive system structure of the liquid nitrogen vaporization pressurization system.

[0036] Figure 13 yes Figure 2 A schematic diagram of the structure of the second liquid nitrogen filling and precooling component of the liquid nitrogen vaporization pressurization system.

[0037] Figure 14 yes Figure 2 Schematic diagram of the structure of the second and third pre-launch pressurization components of the liquid nitrogen vaporization pressurization system.

[0038] The meanings of the labels in the attached diagram are as follows:

[0039] 10. Liquid oxygen tank; 11. Main pressurization pipeline; 12. Liquid oxygen tank regulating check valve; 13. Liquid oxygen tank energy dissipator; 14. Liquid oxygen tank gas pillow pressure sensor; 15. Liquid oxygen tank pressurization controller; 16. Liquid oxygen tank safety overflow valve; 17. Liquid oxygen tank pressurization assembly; 171. Liquid oxygen tank pressurization helium cylinder; 172. Liquid oxygen tank pressurization pipeline; 173. Liquid oxygen tank pressurization solenoid valve; 174. Liquid oxygen tank pressurization orifice plate;

[0040] 20. Fuel tank; 21. Fuel tank booster pipe; 22. Fuel tank regulating check valve; 23. Fuel tank air cushion pressure sensor; 24. Fuel tank booster controller; 25. Fuel tank energy dissipator; 26. Fuel tank pressurization assembly; 261. Fuel tank pressurization pipeline; 262. Fuel tank pressurization orifice plate; 263. Fuel tank pressurization solenoid valve; 264. Fuel tank pressurization helium cylinder; 27. Fuel tank safety relief valve; 28. Liquid nitrogen tank vent pipe; 29. ​​Liquid nitrogen tank safety valve;

[0041] 30. Liquid nitrogen tank; 31. Liquid nitrogen delivery pipe; 32. Liquid nitrogen tank pressurization pipe; 33. Liquid nitrogen tank check valve; 34. Liquid nitrogen pump; 341. Orifice plate; 342. First liquid nitrogen pump; 343. Second liquid nitrogen pump; 35. First liquid nitrogen filling and precooling assembly; 351. First liquid nitrogen filling and precooling pipeline; 352. Liquid nitrogen shut-off valve; 353. Tail-end plug-in connector; 36. Liquid nitrogen filling system; 361. Liquid nitrogen filling valve; 362. Liquid nitrogen filling check valve; 363. First liquid nitrogen discharge shut-off valve; 37. Liquid nitrogen tank vent valve; 38. Liquid nitrogen tank safety valve; 39. Second liquid nitrogen filling and precooling assembly; 391. Second liquid nitrogen filling and precooling pipeline; 392. Pipeline check valve; 393. Second liquid nitrogen discharge shut-off valve;

[0042] 40. First pre-injection pressurization assembly; 41. First pre-injection pressurization check valve; 42. First pre-injection pressurization solenoid valve; 43. First stage tail-end plug-in connector;

[0043] 50. Purge and pressurization integrated assembly; 51. First branch pipeline; 511. Liquid oxygen discharge pipeline; 52. Second branch pipeline; 521. Aft section purge pipe; 53. Third branch pipeline; 531. Inter-stage purge pipe; 54. Fourth branch pipeline; 55. Fifth branch pipeline; 551. Exhaust pipeline; 56. Sixth branch pipeline; 561. Inter-stage purge pipe; 57. Main pipeline; 58. Ground nitrogen source; 581. Nitrogen filter; 582. Nitrogen pressure reducing valve;

[0044] 60. Engine; 61. Heater unit; 611. Heater check valve; 612. Liquid nitrogen heater; 613. Cavitation pipe; 614. Heater liquid nitrogen shut-off valve; 62. Liquid nitrogen shut-off valve control solenoid valve; 63. Control gas cylinder; 64. Gas generator; 65. Check valve;

[0045] 70. Second pre-injection pressurization assembly; 71. Second pre-injection pressurization check valve; 72. Second pre-injection pressurization solenoid valve;

[0046] 80. Third pre-injection pressurization assembly; 81. Third pre-injection pressurization check valve; 82. Third pre-injection pressurization solenoid valve;

[0047] 90. Ground helium source; 91. Filter; 92. Pressure reducer. Detailed Implementation

[0048] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. In the accompanying drawings and the following description, at least some well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the invention; and, for clarity, the dimensions of some structures may be exaggerated. Furthermore, the features, structures, or characteristics described below may be combined in any suitable manner in one or more embodiments.

[0049] This application provides a liquid rocket, which includes a first-stage rocket system, a liquid nitrogen vaporization pressurization system, and nine engines 60.

[0050] like Figure 1 and Figure 2 As shown, the liquid nitrogen vaporization pressurization system includes a liquid oxygen tank 10, a fuel tank 20, a liquid nitrogen tank 30, a liquid nitrogen pump 34, a cavitation pipe 613, and a heater assembly. The liquid oxygen tank 10 is used to store liquid oxygen, the fuel tank 20 is used to store fuel, and the liquid nitrogen tank 30 is used to store liquid nitrogen. The liquid nitrogen tank 30 is located inside the liquid oxygen tank 10, and the fuel tank 20 is located on the side of the liquid oxygen tank 10 closer to the engine 60. The liquid nitrogen pump 34 is used to increase the output pressure of liquid nitrogen, the cavitation pipe 613 is used to stabilize the liquid nitrogen flow rate, and the heater assembly is used to vaporize the liquid nitrogen and heat it into high-temperature nitrogen gas. A liquid nitrogen delivery pipe 31 is provided at the bottom of the liquid nitrogen tank 30, and the liquid nitrogen pump 34 is located on the liquid nitrogen delivery pipe 31. The end of the liquid nitrogen delivery pipe 31 away from the liquid nitrogen pump 34 is connected to the inlet of the heater assembly. The liquid oxygen tank cushion, the fuel tank cushion, and the liquid nitrogen tank cushion are respectively connected to the outlet of the heater assembly through pipelines. The liquid nitrogen vaporization pressurization system of this application simplifies the overall structure of the liquid nitrogen vaporization pressurization system by heating liquid nitrogen into high-temperature nitrogen gas and then using it to simultaneously pressurize the liquid oxygen tank 10, the fuel tank 20 and the liquid nitrogen tank 30. Compared with the pressurization method of helium, it significantly reduces the pressurization cost and the utilization rate of the pressurization medium.

[0051] In this embodiment, the liquid nitrogen vaporization pressurization system immerses the liquid nitrogen tank 30 in the liquid oxygen tank 10. The buoyancy of the liquid oxygen in the liquid oxygen tank 10 reduces the fixed mechanical load on the liquid nitrogen tank 30. Immersing the liquid nitrogen tank 30 in the liquid oxygen of the liquid oxygen tank 10 creates an upward buoyancy force on the liquid nitrogen tank 30, which can counteract the gravitational load and other loads on the liquid nitrogen tank 30, thereby reducing its mechanical load. As rocket flight overload increases, the benefits of the liquid nitrogen tank's mechanical load conditions caused by the buoyancy of the liquid oxygen will become more pronounced. In some embodiments, the liquid nitrogen vaporization pressurization system further includes a main pressurization line 11, a liquid nitrogen tank pressurization line 32, and a fuel tank pressurization line 21; the liquid oxygen tank cushion is connected to the heater assembly through the main pressurization line 11; one end of the liquid nitrogen tank pressurization line 32 is connected to the liquid nitrogen tank cushion, and the other end is connected to the main pressurization line 11; one end of the fuel tank pressurization line 21 is connected to the fuel tank cushion, and the other end is connected to the main pressurization line 11 between the liquid nitrogen tank pressurization line 32 and the heater assembly.

[0052] Specifically, such as Figure 2 and Figure 3 As shown, the heater assemblies are correspondingly arranged with respect to the engines 60. In this embodiment, the nine engines 60 correspond to nine sets of heater units 61. Each set of heater units 61 includes a heater liquid nitrogen shut-off valve 614, a cavitation pipe 613, a liquid nitrogen heater 612, and a heater check valve 611, which are sequentially arranged on the pipeline. Each heater liquid nitrogen shut-off valve 614 is connected to a control gas cylinder 63 through a liquid nitrogen shut-off valve control solenoid valve 62. The heater check valve 611 is located near the main booster pipeline 11, and the nine sets of heater units 61 are connected in parallel. The liquid oxygen tank's gas pillow contains a liquid oxygen tank energy extinguisher 13. One end of the main pressurization line 11 is connected to the liquid oxygen tank energy extinguisher 13. A liquid oxygen tank regulating check valve 12 is also installed on the main pressurization line 11 between the liquid oxygen tank energy extinguisher 13 and the liquid nitrogen tank pressurization line 32. The liquid oxygen tank regulating check valve 12 is connected via a pipeline to a liquid oxygen tank gas pillow pressure sensor 14 and a liquid oxygen tank pressurization controller 15 fixed to the outer wall of the liquid oxygen tank 10. The liquid nitrogen tank pressurization line 32 is connected to the main pressurization line 11 via a tee. A liquid nitrogen tank check valve 33 is installed on the liquid nitrogen tank pressurization line 32. The fuel tank's gas pillow contains a fuel tank energy extinguisher 25. One end of the fuel tank pressurization line 21 is connected to the fuel tank energy extinguisher 25, and the other end is connected to the main pressurization line 11 via a tee. A fuel tank regulating check valve 22 is provided on the fuel tank boost pipe 21. The fuel tank regulating check valve 22 is connected to the fuel tank air cushion pressure sensor 23 and the fuel tank boost controller 24, which are fixed on the outer wall of the fuel tank 20, through a pipeline.

[0053] During the first stage of rocket flight, the liquid nitrogen in the liquid nitrogen tank 30 is divided into three paths after passing through the liquid nitrogen delivery pipe 31, liquid nitrogen pump 34, heater liquid nitrogen shut-off valve 614, cavitation pipe 613, liquid nitrogen heater 612, heater check valve 611, and pressurization main pipe 57. One path enters the fuel tank pressurization pipe 21, passes through the fuel tank regulating check valve 22 and fuel tank energy dissipator 25, and then enters the fuel tank air cushion to pressurize the fuel tank air cushion. Another path passes through the liquid oxygen tank regulating check valve 12 and liquid oxygen tank energy dissipator 13 to enter the liquid oxygen tank air cushion to pressurize the liquid oxygen tank air cushion. The third path enters the liquid nitrogen tank pressurization pipe 32, and pressurizes the liquid nitrogen tank 30 through the liquid nitrogen tank check valve 33.

[0054] In this embodiment, the liquid nitrogen vaporization pressurization system places the liquid nitrogen tank 30 inside the liquid oxygen tank 10. The liquid nitrogen pressure is increased by the liquid nitrogen pump 34, and the flow rate is controlled by the cavitation pipe 613. The liquid nitrogen is heated by the liquid nitrogen heater assembly, and then divided into three streams: one stream pressurizes the liquid oxygen tank 10, one stream pressurizes the fuel tank 20, and one stream pressurizes the liquid nitrogen tank 30. In other words, the liquid nitrogen heats up all three tanks. The liquid oxygen tank 10, fuel tank 20, and liquid nitrogen tank 30 all employ a liquid nitrogen heating and pressurization scheme. After being heated by the liquid nitrogen heater assembly to form nitrogen gas, the liquid nitrogen is divided into three streams: one stream, controlled by the liquid oxygen tank regulating check valve 12 (which also controls the flow direction), pressurizes the liquid oxygen tank 10; another stream, controlled by the fuel tank regulating check valve 22, pressurizes the fuel tank 20; and finally, a small portion is used to pressurize the liquid nitrogen tank 30. In this embodiment, both the liquid oxygen tank 10 and the fuel tank 20 adopt a closed pressurization scheme, while the liquid nitrogen tank 30 adopts an open liquid nitrogen heating and pressurization scheme.

[0055] like Figure 1 As shown, the liquid nitrogen tank 30 in this embodiment is also provided with a liquid nitrogen tank exhaust pipe 28 and two liquid nitrogen tank safety valves 29. One end of the liquid nitrogen tank exhaust pipe 28 is connected to the top of the liquid nitrogen tank 30, and the other end is connected to the atmosphere. The two liquid nitrogen tank safety valves 29 are connected in parallel to the liquid nitrogen tank exhaust pipe 28.

[0056] In this embodiment, the liquid nitrogen tank 30 uses two safety valves (liquid nitrogen tank safety valve 29) of DN4 (opening pressure 1.5MPa) and DN20 (opening pressure 2.0MPa) for venting. The technical features are as follows:

[0057] By installing a safety valve (liquid nitrogen tank safety valve 29), the liquid nitrogen tank 30 can always maintain a positive pressure of approximately 1.5 MPa, effectively preventing the liquid nitrogen tank 30 from collapsing due to negative pressure caused by external pressure exceeding the liquid nitrogen tank's pressure cushion. Simultaneously, the pressure cushion of the liquid nitrogen tank can be controlled by opening and closing the DN4 safety valve, reducing the frequency of opening the DN20 safety valve and extending its lifespan.

[0058] Precise initial pressure relief: When the pressure inside the liquid nitrogen tank rises to 1.5 MPa, the DN4 safety valve opens first to release pressure. During this stage, the system pressure changes gradually, and the small flow of venting from the DN4 safety valve can accurately stabilize the pressure at approximately 1.5 MPa, preventing the pressure from continuing to rise rapidly and providing initial pressure protection for the system.

[0059] Rapid and powerful pressure relief: If the pressure continues to rise to 2.0 MPa, the DN20 safety valve opens, allowing for a large-flow venting and pressure relief. At this time, the DN20 safety valve can quickly reduce the pressure inside the liquid nitrogen tank 30, preventing excessive pressure from damaging the liquid nitrogen tank 30 or even causing serious accidents such as explosions, playing a crucial secondary protection role.

[0060] Fault Backup: Two safety valves (liquid nitrogen tank safety valve 29) serve as backups for each other. When the DN4 safety valve fails to open due to a malfunction, the DN20 safety valve can still function to relieve pressure when the pressure reaches 2.0 MPa. When the DN4 safety valve fails to close properly, the pressure change of the liquid nitrogen tank cushion is slow, and the liquid nitrogen tank pressure can still meet the design requirements. Conversely, if the DN20 safety valve fails to open, the DN4 safety valve can still provide some protection at 1.5 MPa, reducing the risk of safety accidents caused by valve failure.

[0061] This embodiment utilizes only one liquid nitrogen delivery pipe 31, one liquid nitrogen pump 34, and one main pressurization pipeline 11 to pressurize the liquid oxygen tank 10, fuel tank 20, and liquid nitrogen tank 30. Compared to the traditional design of three pressurization devices, this embodiment only requires one pressurization device to pressurize the three tanks, reducing the number of pressurization devices used, lowering production costs and structural complexity. At the same time, this embodiment uses one liquid nitrogen vaporization pressurization system to pressurize the three tanks and adopts a unified gas supply and distribution pressurization technology, which greatly reduces the types and number of pre-launch pressurization pipelines.

[0062] In this embodiment, the liquid nitrogen is heated into high-temperature nitrogen gas by the liquid nitrogen heater 612 of the nine engines 60. The pressurization flow rate of the liquid oxygen tank 10 is adjusted by the liquid oxygen tank regulating check valve 12, the pressurization flow rate of the fuel tank 20 is adjusted by the fuel tank regulating check valve 22, and the pressurization flow rate of the liquid nitrogen tank 30 is controlled by the liquid nitrogen tank check valve 33.

[0063] This embodiment utilizes a main pressurization pipeline 11 and two flow regulating check valves (liquid oxygen tank regulating check valve 12 and fuel tank regulating check valve 22) to control the flow of the two tanks respectively, and a liquid nitrogen tank check valve 33 to control the pressurization flow of the liquid nitrogen tank 30. The regulating check valve in this embodiment integrates the flow regulating valve and the check valve design, simultaneously possessing the functions of pressurization flow regulation and reverse sealing check valve.

[0064] During the refueling of liquid oxygen tank 10 and fuel tank 20, one-way valves 65 are installed on the main pressurization line 11, the liquid nitrogen tank pressurization line 32 and the fuel tank pressurization line 21 respectively. These valves can prevent propellant vapor from backflowing into other tanks and prevent safety risks such as explosions caused by the mixing of kerosene vapor from fuel tank 20 and oxygen vapor from liquid oxygen tank 10.

[0065] like Figure 4 As shown, the liquid nitrogen vaporization pressurization system in this embodiment also includes a purge and pressurization integrated assembly 50. The purge and pressurization integrated assembly 50 includes a main pipeline 57 and multiple branch pipelines. The end of the main pipeline 57 near the engine 60 is used to connect to the ground nitrogen source 58. The inlet of each branch pipeline is connected to the main pipeline 57. The outlet of the first branch pipeline 51 is connected to the liquid oxygen discharge pipeline 511 of the engine 60 to provide a gas seal for the liquid oxygen discharge pipeline 511. The outlet of the second branch pipeline 52 is connected to the purge pipe 521 of the stern section. The first branch pipe 53 is connected to the interstage purging pipe 531 for purging the interstage section; the second branch pipe 54 is connected to the liquid nitrogen tank pressurization pipe 32 for pressurizing the liquid nitrogen tank 30; the third branch pipe 55 is connected to the exhaust pipe 551 of the liquid oxygen tank 10 for providing a gas seal for the exhaust pipe 551 of the liquid oxygen tank 10; and the sixth branch pipe 56 is connected to the interstage purging pipe 561 for purging the interstage section.

[0066] Specifically, branch orifice plates are provided on the first branch pipe 51, the second branch pipe 52, the third branch pipe 53, the fourth branch pipe 54, the fifth branch pipe 55, and the sixth branch pipe 56. The outlet of the first branch pipe 51 is connected to the liquid oxygen discharge pipe 511 of the nine engines 60. A branch one-way valve is provided in front of the branch orifice plate of the fourth branch pipe 54. The outlet of the fourth branch pipe 54 is connected to the liquid nitrogen tank pressurization pipe 32 after the liquid nitrogen tank one-way valve 33. The outlet of the fifth branch pipe 55 is connected to the liquid oxygen tank exhaust gas seal interface of the exhaust pipe 551 of the liquid oxygen tank 10. The ground nitrogen source 58, nitrogen filter 581, and nitrogen pressure reducing valve 582 are connected in sequence through pipelines and then detachably connected to the main pipeline 57 through a first-stage tail-end plug-in connector.

[0067] This embodiment integrates the pre-launch pressurization system of the liquid nitrogen tank with the rocket's section purging system. The ground-based nitrogen source 58, after passing through a nitrogen filter 581, a nitrogen pressure reducing valve 582, and a first-stage tail-end plug-in connector, is divided into six paths. The first path provides a gas seal to the nine-engine parallel liquid oxygen discharge pipeline 511 via a branch orifice plate on the first branch pipeline 51 and a liquid oxygen discharge gas seal interface, preventing water vapor from being drawn back into the liquid oxygen discharge pipeline 511, thus preventing water vapor condensation and blockage of the liquid oxygen discharge pipeline 511. The second path enters the tail-end section purging pipe 521 via a branch orifice plate on the second branch pipeline 52 to purge the first-stage tail-end section. The third path enters the inter-tank section purging via a branch orifice plate on the third branch pipeline 53. Pipe 531 purges the interstage section; the fourth path enters the liquid nitrogen tank 30 via the branch check valve and branch orifice plate on the fourth branch pipe 54 to pressurize the liquid nitrogen tank 30; the fifth path provides an air seal to the exhaust pipe 551 of the liquid oxygen tank 10 via the branch orifice plate and the liquid oxygen tank exhaust gas seal interface on the fifth branch pipe 55 to prevent water vapor from being drawn back into the exhaust pipe 551 and to avoid blockage of the exhaust pipe 551 and the liquid oxygen tank safety overflow valve 16 due to water vapor condensation; the sixth path enters the interstage section purge pipe 561 via the branch orifice plate on the sixth branch pipe 56 to purge the first and second stage interstage sections.

[0068] During the rocket's refueling and parking phases on the ground, the modules can be purged to reduce the moisture content inside the modules and minimize the impact of frost on the equipment. Purging can also dilute any potential oxygen leaks in the module's piping and slow down the temperature drop inside the modules.

[0069] Annular purging pipes are installed in the forward bilge compartment of the liquid oxygen tank and the engine compartment to purge the compartments with heated nitrogen. Nitrogen heating can be achieved using a water bath, with the water bath heat exchanger located at the outlet of the gas distribution platform. The purging pipes connect to the on-rocket plug-in connector after heat exchange in the heat exchanger. A bypass is provided for the purging pipes passing through the heat exchanger; during testing, the heat exchanger is not operational, and the bypass is used for gas supply. Purging begins 5 minutes after liquid oxygen refueling commences.

[0070] like Figure 1 and Figure 5 As shown, the liquid nitrogen vaporization pressurization system of this embodiment also includes a first liquid nitrogen filling and precooling assembly 35. The first liquid nitrogen filling and precooling assembly 35 includes a first liquid nitrogen filling and precooling pipeline 351 and a liquid nitrogen shut-off valve 352. The liquid nitrogen shut-off valve 352 is provided on the first liquid nitrogen filling and precooling pipeline 351. One end of the first liquid nitrogen filling and precooling pipeline 351 is connected to the pipeline between the liquid nitrogen pump 34 and the heater assembly, and the other end is used to be detachably connected to the liquid nitrogen filling system 36 and the first liquid nitrogen discharge shut-off valve 363 respectively.

[0071] Specifically, in this embodiment, one end of the first liquid nitrogen pre-cooling pipeline 351 is connected to the pipeline between the liquid nitrogen pump 34 and the heater assembly via a tee, and the other end is detachably connected to the liquid nitrogen filling system 36 via a plug-in connector 353. A liquid nitrogen filling check valve 362 and a liquid nitrogen filling valve 361 are sequentially installed on the pipeline between the plug-in connector 353 and the liquid nitrogen filling system 36. The inlet of the first liquid nitrogen discharge shut-off valve 363 is connected to the pipeline between the plug-in connector 353 and the liquid nitrogen filling check valve 362 via a pipeline, and its outlet is open to the atmosphere.

[0072] The liquid nitrogen filling system 36 delivers liquid nitrogen to the liquid nitrogen tank 30 via the liquid nitrogen filling valve 361, the liquid nitrogen filling check valve 362, the tail plug-in connector 353, the liquid nitrogen shut-off valve 352 and the liquid nitrogen delivery pipe 31, thereby filling the liquid nitrogen tank 30 with liquid nitrogen.

[0073] During rocket flight, the tail connector 353 disengages, and the liquid nitrogen shut-off valve 352 ensures that the liquid nitrogen in the liquid nitrogen tank 30 does not leak. Positioning the liquid nitrogen filling port downstream of the liquid nitrogen pump 34 allows for pre-cooling of the pump during liquid nitrogen filling, improving the reliability of the pre-cooling process.

[0074] When the liquid nitrogen pump 34 is started, it needs to be pre-cooled. The cryogenic coolant flows through the liquid nitrogen delivery pipe 31 and the turbine pump chamber of the liquid nitrogen pump 34, and after cooling the liquid nitrogen delivery pipe 31 and the turbine pump body, it is pre-cooled and discharged from the liquid nitrogen pump body to the outside of the rocket. This pre-cooling method is called discharge pre-cooling.

[0075] Due to the low-temperature characteristics of liquid nitrogen, the engine 60, liquid nitrogen delivery pipe 31, and the external environment form a high-temperature heat source relative to the liquid nitrogen. When the liquid nitrogen enters the liquid nitrogen pump 34, it boils and vaporizes due to the heat, which affects the blades of the liquid nitrogen pump 34, leading to cavitation. To ensure the normal operation of the liquid nitrogen pump 34, it needs to be pre-cooled to the same temperature as the liquid nitrogen to prevent the liquid nitrogen from vaporizing into gas when passing through the pump during normal operation.

[0076] During the pre-cooling process of the ground liquid nitrogen pump 34, the liquid nitrogen in the liquid nitrogen tank 30 is directly discharged to the atmosphere after passing through the liquid nitrogen delivery pipe 31, the liquid nitrogen pump 34, the liquid nitrogen shut-off valve 352, the tail plug-in connector 353 and the first liquid nitrogen discharge shut-off valve 363, to ensure the reliable operation of the liquid nitrogen pump 34 during ignition and to prevent cavitation caused by the vaporization of liquid nitrogen when the liquid nitrogen pump 34 is ignited.

[0077] During rocket ignition and flight, the first liquid nitrogen discharge shut-off valve 363 remains closed, and the liquid nitrogen after the liquid nitrogen pump 34 is heated into high-temperature nitrogen gas by the heater assembly to pressurize the liquid oxygen tank 10 and the fuel tank 20.

[0078] The liquid nitrogen pump discharge precooling is only performed before the liquid nitrogen pump 34 starts working. After the liquid nitrogen pump 34 starts working, the liquid nitrogen pump discharge precooling is not performed. Therefore, the first liquid nitrogen discharge shut-off valve 363 is closed.

[0079] This embodiment integrates the liquid nitrogen filling system and the liquid nitrogen pump precooling system. The first liquid nitrogen filling and precooling component 35 is located downstream of the liquid nitrogen pump 34, enabling precooling of the liquid nitrogen pump 34 during liquid nitrogen filling. The first liquid nitrogen discharge shut-off valve 363 is located on the liquid nitrogen filling pipeline, allowing the first liquid nitrogen filling and precooling component 35 to perform both liquid nitrogen filling and liquid nitrogen discharge precooling functions.

[0080] like Figure 1 As shown, the liquid nitrogen vaporization pressurization system of this embodiment also includes a liquid oxygen tank pressurization assembly 17, a fuel tank pressurization assembly 26, and a first pre-launch pressurization assembly 40.

[0081] The liquid oxygen tank pressurization assembly 17 includes a liquid oxygen tank pressurization pipeline 172, one end of which is connected to a liquid oxygen tank pressurization helium cylinder 171, and the other end is connected to the main pressurization pipeline 11. A liquid oxygen tank pressurization solenoid valve 173 and a liquid oxygen tank pressurization orifice plate 174 are sequentially arranged on the liquid oxygen tank pressurization pipeline 172 from the liquid oxygen tank pressurization helium cylinder 171 toward the main pressurization pipeline 11.

[0082] Specifically, the liquid oxygen tank pressurization pipeline 172 is connected via a tee to the main pressurization pipeline 11 between the liquid oxygen tank regulating check valve 12 and the liquid oxygen tank energy dissipator 13. When the rocket engine 60 ignites at time t0, the liquid oxygen tank pressurization solenoid valve 173 is opened, and the helium in the liquid oxygen tank pressurization helium cylinder 171 pressurizes the liquid oxygen tank 10 through the liquid oxygen tank pressurization solenoid valve 173, the liquid oxygen tank pressurization orifice plate 174, and the liquid oxygen tank energy dissipator 13. When the rocket engine 60 shuts down at time t1, the liquid oxygen tank pressurization solenoid valve 173 is closed.

[0083] The fuel tank pressurization assembly 26 includes a fuel tank pressurization pipeline 261, one end of which is connected to a fuel tank pressurization helium cylinder 264, and the other end is connected to a fuel tank booster pipe 21. The fuel tank pressurization pipeline 261 is provided with a fuel tank pressurization solenoid valve 263 and a fuel tank pressurization orifice plate 262 in sequence from the fuel tank pressurization helium cylinder 264 to the fuel tank booster pipe 21.

[0084] Specifically, the fuel tank pressurization line 261 is connected to the fuel tank pressurization pipe 21 between the fuel tank regulating check valve 22 and the main pressurization line 11. At the moment of rocket engine ignition t0, the fuel tank pressurization solenoid valve 263 is opened, and helium in the fuel tank pressurization helium cylinder 264 pressurizes the fuel tank 20 through the fuel tank pressurization solenoid valve 263, the fuel tank pressurization orifice plate 262, the fuel tank regulating check valve 22, and the fuel tank energy dissipator 25.

[0085] One end of the first pre-launch pressurization assembly 40 is connected via a tee to the main pressurization pipeline 11 between the liquid nitrogen tank pressurization pipe 32 and the heater assembly, and the other end is used for detachable connection to the ground helium source 90. The first pre-launch pressurization assembly 40 includes a first pre-launch pressurization check valve 41 and a first pre-launch pressurization solenoid valve 42, which are sequentially arranged from the main pressurization pipeline 11 to the ground helium source 90.

[0086] Specifically, in this embodiment, the first pre-launch pressurization assembly 40 is detachably connected to the ground helium source via a primary tail plug-in connector 43.

[0087] During pre-launch pressurization on the ground, the ground helium source pressurizes the liquid oxygen tank 10, liquid nitrogen tank 30 and fuel tank 20 via the ground pressurization pipeline, the first-stage tail plug-in connector 43, the first pre-launch pressurization solenoid valve 42, the first pre-launch pressurization check valve 41 and the main pressurization pipeline 11.

[0088] The pre-launch pressurization flow rate of liquid oxygen tank 10 is controlled by adjusting check valve 12 of liquid oxygen tank, and the pre-launch pressurization flow rate of fuel tank 20 is controlled by adjusting check valve 22 of fuel tank. The pressurization flow rate of liquid nitrogen tank 30 is controlled by checking valve 33 of liquid nitrogen tank.

[0089] This embodiment employs a unified gas supply and pressurization technology, using a single main pipeline 57 to pressurize three storage tanks. This reduces the variety and complexity of pressurization systems, thereby lowering the difficulty of rocket development and the number and cost of supporting components. Simultaneously, the first pre-launch pressurization assembly 40 utilizes the main pressurization pipeline 11 to pre-launch pressurize each storage tank, significantly reducing the number of pipelines used and making the overall structure more compact and rational.

[0090] In this embodiment, the liquid oxygen tank 10 is a primary liquid oxygen tank. A liquid oxygen tank overflow valve 16 is also installed on the primary liquid oxygen tank, integrating the safety valve and the vent valve. When the ground oxygen tank is refueling the primary liquid oxygen tank, the liquid oxygen tank overflow valve 16 opens. In this embodiment, the fuel tank 20 is a primary fuel tank, equipped with a fuel tank overflow valve 27, which integrates the safety valve and the vent valve. When the ground fuel tank is refueling the primary fuel tank, the fuel tank overflow valve 27 opens.

[0091] During first-stage flight, when the pressure of the liquid oxygen tank cushion is higher than the opening pressure of the liquid oxygen tank overflow valve 16, the liquid oxygen tank overflow valve 16 opens; when the pressure of the cushion is lower than the closing pressure of the liquid oxygen tank overflow valve 16, the liquid oxygen tank overflow valve 16 closes. When the pressure of the fuel tank cushion is higher than the opening pressure of the fuel tank overflow valve 27, the fuel tank overflow valve 27 opens; when the pressure of the cushion is lower than the closing pressure of the fuel tank overflow valve 27, the fuel tank overflow valve 27 closes.

[0092] The pressure of the liquid oxygen tank's gas pillow is controlled by adjusting one-way valve 12. The control logic of adjusting one-way valve 12 is as follows: Figure 6 As shown. P Y1 P indicates the lower limit of the pressure control zone for the liquid oxygen tank. Y2 Indicates the upper limit of the pressure control zone for the liquid oxygen tank, O Y1 This indicates the minimum opening degree of the one-way valve regulating the liquid oxygen tank, O Y2 This indicates the maximum opening degree of the one-way valve regulating the liquid oxygen tank.

[0093] The fuel tank pressure is controlled by the fuel tank regulating check valve 22. The control logic of the fuel tank regulating check valve 22 is as follows: Figure 7 As shown. Where, P R1 P indicates the lower limit of the fuel tank pressure control band. R2 Indicates the upper limit of the fuel tank pressure control band, O R1 This indicates the minimum opening degree of the fuel tank regulating check valve, O R2 This indicates the maximum opening degree of the fuel tank regulating check valve.

[0094] The pressure curve of the gas pillow in the primary liquid oxygen tank is shown in the figure below. Figure 8 As shown, P Ybxfdk Indicates the opening pressure of the liquid oxygen tank's overflow valve, P Ybxfgb P indicates the closing pressure of the liquid oxygen tank's relief valve. Y0 P represents the pressure of the liquid oxygen tank's gas pillow. Ymin This indicates the minimum oxygen tank pressure required by the engine. The oxygen tank pressure curve for fuel tank 20 is shown below. Figure 9 As shown, P Rbxfdk P indicates the opening pressure of the fuel tank relief valve. Rbxfgb P indicates the closing pressure of the fuel tank relief valve. R0 P represents the pressure of the fuel tank cushion. Rmin This indicates the minimum pressure required by the fuel tank for the engine.

[0095] like Figure 3 As shown, the gas generators 64 of at least two engines 60 are connected in parallel to provide driving force for the liquid nitrogen pump 34. For example, in this embodiment, the gas generators 64 of the two engines 60 are each connected to a one-way valve 65 and then connected in parallel to merge. They are then connected to the turbine of the liquid nitrogen pump 34 through a tee and an orifice plate 341. The high-temperature gas generated by the two gas generators 64 passes through two one-way valves 65 and then merges into one path through the tee. The gas then reaches the turbine of the liquid nitrogen pump 34 through the orifice plate 341, providing driving gas for the liquid nitrogen pump turbine. After driving the liquid nitrogen pump turbine, the gas is discharged directly into the atmosphere through the exhaust pipe.

[0096] By utilizing the gas generators 64 of both engines 60 to supply fuel gas, the risk of shutting down the driving fuel source when one engine 60 is turned off can be prevented, thus improving system redundancy and reliability. Through the gas generators 64 of the two engines 60 and the corresponding two one-way valves 65, driving fuel gas can still be supplied even when one engine 60 is turned off, ensuring the operational reliability of the liquid nitrogen pump 34.

[0097] In this embodiment, the high-temperature gas generated by the gas generator 64 of the engine 60 drives the liquid nitrogen pump 34, ensuring the reliable operation of the liquid nitrogen pump 34. Compared with using an independent gas source to drive the liquid nitrogen pump or using an electric motor to drive the liquid nitrogen pump, this solution uses the gas in the existing gas generator 64 to drive the liquid nitrogen pump 34, which has a higher system integration and simplifies the drive system of the liquid nitrogen pump 34.

[0098] An orifice plate 341 is installed at the inlet of the liquid nitrogen pump 34. During the system test phase, the gas flow rate of the liquid nitrogen pump 34 can be adjusted by changing or replacing the size of the orifice plate 341. By adjusting the size of the orifice plate 341, the gas intake flow rate of the liquid nitrogen pump 34 can be controlled, thereby controlling the power of the liquid nitrogen pump 34 and the liquid nitrogen head of the liquid nitrogen pump 34.

[0099] The liquid nitrogen vaporization pressurization system in this embodiment stores the pressurization medium in liquid form. During rocket pressurization, the liquid nitrogen is heated and vaporized into nitrogen gas, which is then used to heat and pressurize the liquid oxygen tank 10, fuel tank 20, and liquid nitrogen tank 30. Compared to the pressurization method using room-temperature helium heating for liquid oxygen tank 10 and fuel tank 20, this solution uses a liquid nitrogen vaporization pressurization system, reducing the use of experimental cold helium cylinders and expensive helium resources, resulting in a lower cost for liquid nitrogen heating and pressurization.

[0100] This embodiment uses liquid nitrogen for heating and pressurization, with the remaining pressurizing medium stored in liquid form. 4 kg of liquid nitrogen remained during rocket flight, achieving a utilization rate of 99.5%. In contrast, traditional cold helium heating and pressurization involves rapid cooling during helium release. The helium in the cold helium cylinder drops from an initial 90K to 50K, leaving a cylinder pressure of 5MPa. The density of helium at 90K and 23MPa is 90 kg / m³, while the density at 50K and 5MPa is 42.97 kg / m³. 3 During the cold helium heating process, the helium utilization rate of the helium cylinder was 52%. For room temperature helium heating and pressurization, the gas pressure decreased from 288K to 190K, leaving a cylinder pressure of 5MPa. The density of helium at 288K and 23MPa is 34.5kg / m³. 3 At 190K and 5MPa, the density of helium gas is 12.2 kg / m³. 3 During the room-temperature helium heating process, the helium utilization rate of the helium cylinder is 64%.

[0101] In summary, compared to the 52% helium pressurization efficiency of cold helium heating and the 64% helium pressurization efficiency of room temperature helium heating, the liquid nitrogen heating and pressurization in this embodiment can leave a small amount of liquid nitrogen. When the liquid nitrogen heating and pressurization leaves a pressurization medium, the liquid utilization rate can be increased to 99.5%, which greatly improves the utilization rate of the pressurization medium.

[0102] Through feasibility studies, the liquid nitrogen vaporization pressurization system in this embodiment is comparable in weight to the cold helium heating pressurization system, and is 420 kg lighter than the room temperature helium heating pressurization system, thus improving the rocket's carrying capacity.

[0103] The liquid nitrogen vaporization pressurization system in this embodiment uses a liquid nitrogen pump 34 to pressurize the liquid nitrogen. The liquid nitrogen flow rate is controlled by the cavitation pipe 613. Nine liquid nitrogen heaters 612 heat the liquid nitrogen to vaporize it into high-temperature nitrogen gas, which is then divided into three streams to pressurize the liquid oxygen tank 10, the fuel tank 20, and the liquid nitrogen tank 30, respectively. This greatly simplifies the system development and system matching difficulties.

[0104] The liquid nitrogen vaporization pressurization system in this embodiment adopts a unified gas supply and distribution technology. It uses a liquid nitrogen delivery pipe 31, a liquid nitrogen pump 34, and a main pressurization pipeline 11 to realize the pressurization control of the three storage tanks. By adopting a unified gas supply and distribution pressurization technology, the types and number of pressurization pipelines are reduced, thereby reducing the development difficulty, supporting quantity, and supporting cost of the pressurization system.

[0105] This embodiment provides high-temperature driving gas through the gas generators 64 of two engines 60 and two one-way valves 65, effectively avoiding the risk of insufficient gas supply caused by the failure of one of the engines 60, and improving the reliability of the liquid nitrogen vaporization booster system.

[0106] In this embodiment, an orifice plate 341 is installed at the gas inlet of the liquid nitrogen pump 34. During ground testing, the intake flow rate of the liquid nitrogen pump 34 can be controlled by adjusting the size of the orifice plate 341, thereby controlling and determining the power of the liquid nitrogen pump 34. The size of the orifice plate 341 is determined by whether the liquid nitrogen pump 34 reaches its rated power during the test. This design reduces the difficulty of system development, design, and simulation.

[0107] The liquid nitrogen vaporization boosting system in this embodiment uses the high-temperature gas generated by the gas generator 64 of the engine 60 to drive the liquid nitrogen pump 34, ensuring the reliable operation of the liquid nitrogen pump 34. Compared with using an independent gas source to drive the liquid nitrogen pump or using an electric motor to drive the liquid nitrogen pump, this solution uses the gas in the gas generator 64 of the engine 60 to drive the liquid nitrogen pump 34, which has a higher system integration, simplifies the drive system of the liquid nitrogen pump 34, and reduces the effective mass of the boosting system.

[0108] In this embodiment, the liquid nitrogen vaporization booster system is equipped with a one-way valve 65 at the outlet of the gas generator 64. This effectively prevents the gas generated by the normally operating engine 60 from flowing out through the gas generator 64 of the damaged engine 60 when one of the engines 60 is damaged, thus improving the system's resilience.

[0109] The liquid nitrogen vaporization boosting system in this embodiment uses the liquid nitrogen heaters 612 of nine engines 60 to heat liquid nitrogen into high-temperature nitrogen gas. Then, using unified gas supply and distribution boosting technology, the boosting flow of liquid oxygen tank 10 is closed-loop controlled through a main boosting pipeline 11 and a liquid oxygen tank regulating check valve 12. The boosting flow of fuel tank 20 is closed-loop controlled through a fuel tank regulating check valve 22. The boosting flow of liquid nitrogen tank 30 is limited through a liquid nitrogen tank check valve 33. At the same time, the boosting of the three tanks, liquid oxygen tank 10, fuel tank 20 and liquid nitrogen tank 30, is achieved.

[0110] The liquid nitrogen vaporization pressurization system of this embodiment is equipped with a first pre-launch pressurization component 40 on the main pressurization pipeline 11, which can effectively shorten the length of the pre-launch pressurization pipeline. At the same time, the unified gas supply and distribution pressurization technology is adopted, which integrates the pre-launch pressurization pipeline and the main pressurization pipeline 11, improves the integration of the main pressurization pipeline 11, and can achieve pressure control of three tanks using only one pre-launch pressurization pipeline.

[0111] The liquid nitrogen vaporization pressurization system of this embodiment integrates the liquid nitrogen filling system and the liquid nitrogen pump precooling system. The liquid nitrogen filling system is located downstream of the liquid nitrogen pump 34, so that the liquid nitrogen pump 34 can be precooled during the liquid nitrogen filling process. By setting a liquid nitrogen discharge shut-off valve in the liquid nitrogen ground filling pipeline, the first liquid nitrogen filling and precooling component 35 can simultaneously meet the dual functions of liquid nitrogen filling and liquid nitrogen pump 34 precooling discharge.

[0112] To ensure the smooth start-up process of the rocket, the liquid nitrogen vaporization pressurization system in this embodiment is equipped with a pressurization component. Tests have verified that this pressurization component can adequately meet the start-up requirements of engine 60. This pressurization component is relatively simple, with a limited number and variety of valves and pipelines, resulting in low development difficulty and a short manufacturing cycle.

[0113] like Figure 10 and Figure 11 As shown, in another embodiment, the liquid nitrogen vaporization pressurization system further includes a main pressurization pipeline 11, a liquid nitrogen tank 30 pressurization pipe and a fuel tank pressurization pipe 21; the liquid nitrogen pump 34 includes a first liquid nitrogen pump 342 and a second liquid nitrogen pump 343 connected in parallel, and the heater assembly includes a first heater assembly and a second heater assembly.

[0114] The first liquid nitrogen pump 342 is connected to one end of the main booster line 11 through the first heater assembly, and the other end of the main booster line 11 is connected to the liquid oxygen tank cushion; the second liquid nitrogen pump 343 is connected to one end of the fuel tank booster pipe 21 through the second heater assembly, and the other end of the fuel tank booster pipe 21 is connected to the fuel tank cushion; one end of the liquid nitrogen tank booster pipe 32 is connected to the liquid nitrogen tank cushion, and the other end is connected to the main booster line 11.

[0115] Specifically, such as Figure 11 and Figure 12 As shown, in this embodiment, the nine sets of heater units 61 of the nine engines 60 are divided into two parts. The first part is the first heater assembly, which includes five sets of heater units 61. The second part is the second heater assembly, which includes four sets of heater units 61. Each heater unit 61 includes a heater liquid nitrogen shut-off valve 614, a liquid nitrogen heater 612, and a heater check valve 611, which are sequentially arranged on the pipeline. In other embodiments, the heater unit 61 may also have the same components as the heater unit 61 in the above embodiment. This embodiment only illustrates one composition of the heater unit 61. In this embodiment, one end of the liquid nitrogen delivery pipe 31 is connected to the bottom of the liquid nitrogen tank 30, and the other end is connected to the first nitrogen pump through a tee, and then connected to one end of the main booster pipeline 11 through the first heater assembly. The other end of the main booster pipeline 11 is connected to the liquid oxygen tank energy dissipator 13. One end of the liquid nitrogen tank pressurization pipe 32 is connected to the main pressurization pipe 11 via a tee, and the other end is connected to the top of the liquid nitrogen tank 30. A liquid nitrogen tank check valve 33 is also provided on the liquid nitrogen tank pressurization pipe 32. In this embodiment, the liquid nitrogen tank 30 is also provided with a liquid nitrogen tank exhaust valve 37 and a liquid nitrogen tank safety valve 38. The liquid nitrogen tank exhaust valve 37 and the liquid nitrogen tank safety valve 38 are connected to the liquid nitrogen tank pressurization pipe 32 located inside the liquid oxygen tank 10 via pipelines. In this embodiment, one end of the liquid nitrogen delivery pipe 31 is connected to the bottom of the liquid nitrogen tank 30, and the other end is connected to the second liquid nitrogen pump 343. After that, it is connected to one end of the fuel tank pressurization pipe 21 via the second heater assembly. The other end of the fuel tank pressurization pipe 21 is connected to the fuel tank air cushion via the fuel tank energy dissipator 25.

[0116] During the first stage of rocket flight, liquid nitrogen in liquid nitrogen tank 30 is used to pressurize liquid oxygen tank 10 via liquid nitrogen delivery pipe 31, first liquid nitrogen pump 342, first heater assembly, main pressurization pipeline 11, and liquid oxygen tank energy dissipator 13.

[0117] The liquid nitrogen in the liquid nitrogen tank 30 is pressurized by the liquid nitrogen delivery pipe 31, the second liquid nitrogen pump 343, the second liquid nitrogen heater 612 assembly, the fuel tank 20 pressurization pipe, and the fuel tank energy dissipator 25.

[0118] During the first stage of flight, liquid nitrogen in liquid nitrogen tank 30 is pressurized through liquid nitrogen delivery pipe 31, first liquid nitrogen pump 342, first liquid nitrogen heater 612 assembly, main pressurization pipeline 11, liquid nitrogen tank pressurization pipe 32, and liquid nitrogen tank check valve 33.

[0119] In this embodiment, liquid nitrogen tank 30 is stored in liquid oxygen tank 10. The liquid nitrogen pressure is increased by two liquid nitrogen pumps, one of which pressurizes liquid oxygen tank 10 and the other of which pressurizes fuel tank 20. A T-junction is set on the main pressurization pipeline 11 of liquid oxygen tank, and one branch is set to pressurize liquid nitrogen tank 30. That is, the pressurization of the three tanks is achieved by heating with liquid nitrogen.

[0120] The liquid oxygen tank 10 adopts a liquid nitrogen heating and pressurization scheme. After being heated by the liquid nitrogen heater 612, the liquid nitrogen forms nitrogen gas. The high-temperature nitrogen gas pressurizes the liquid oxygen tank 10 through the main pressurization pipeline 11, pressurizes the fuel tank 20 through the fuel tank pressurization pipeline 21, and a small stream of high-temperature nitrogen gas is separated from the liquid oxygen tank 10 and pressurizes the liquid nitrogen tank 30 through the liquid nitrogen tank check valve 33 and the liquid nitrogen tank pressurization pipeline 32.

[0121] The liquid nitrogen vaporization pressurization system of this embodiment uses the liquid nitrogen heaters 612 of five engines 60 to heat the liquid nitrogen into high-temperature nitrogen gas to pressurize the liquid oxygen tank 10, and uses the liquid nitrogen heaters 612 of four engines 60 to heat the liquid nitrogen into high-temperature nitrogen gas to pressurize the fuel tank 20, thus enabling independent pressurization of the liquid oxygen tank 10 and the fuel tank 20.

[0122] like Figure 13 As shown, the liquid nitrogen vaporization pressurization system of this embodiment also includes a second liquid nitrogen filling and precooling assembly 39. The second liquid nitrogen filling and precooling assembly 39 includes a second liquid nitrogen filling and precooling pipeline 391, a pipeline check valve 392, and a second liquid nitrogen discharge shut-off valve 393. The pipeline check valve 392 is installed on the second liquid nitrogen filling and precooling pipeline 391. One end of the second liquid nitrogen filling and precooling pipeline 391 is connected to the pipeline between the liquid nitrogen pump 34 and the liquid nitrogen tank 30, and the other end is used for detachable connection with the liquid nitrogen filling system 36. The second liquid nitrogen discharge shut-off valve 393 is connected to the outlet ends of the two liquid nitrogen pumps through pipelines respectively.

[0123] Specifically, the second liquid nitrogen pre-cooling pipeline 391 is detachably connected to the liquid nitrogen filling system 36 via a primary end plug-in connector. A liquid nitrogen filling valve 361 is also provided between the primary end plug-in connector and the liquid nitrogen filling system 36. The two liquid nitrogen pumps are connected in parallel and then connected to the inlet of the second liquid nitrogen discharge shut-off valve 393.

[0124] When the liquid nitrogen tank 30 is filled, the liquid nitrogen filling system 36 sends liquid nitrogen into the liquid nitrogen tank 30 through the liquid nitrogen filling valve 361, the first-stage tail plug connector, the second liquid nitrogen filling pre-cooling pipeline 391, the pipeline check valve 392 and the liquid nitrogen delivery pipe 31 to fill it with liquid nitrogen.

[0125] During rocket flight, the tail connector of the first stage disengages, and the liquid nitrogen in the liquid nitrogen tank 30 is prevented from leaking through the liquid nitrogen filling check valve 362.

[0126] During the pre-cooling process of the ground-based liquid nitrogen pump 34, the liquid nitrogen in the liquid nitrogen tank 30 is divided into two paths after passing through the liquid nitrogen delivery pipe 31. One path passes through the first liquid nitrogen pump 342 and the second liquid nitrogen discharge shut-off valve 393 to directly discharge the liquid nitrogen into the atmosphere, ensuring the reliability of the ignition of the first liquid nitrogen pump 342. The other path passes through the second liquid nitrogen pump 343 and the second liquid nitrogen discharge shut-off valve 393 to directly discharge the pre-cooled liquid nitrogen into the atmosphere, ensuring the reliability of the ignition of the second liquid nitrogen pump 343.

[0127] During rocket ignition and flight, the liquid nitrogen discharge shut-off valve remains closed. The liquid nitrogen after the liquid nitrogen pump 34 is heated into high-temperature nitrogen gas by the liquid nitrogen heater 612, which pressurizes the liquid oxygen tank 10 and the fuel tank 20.

[0128] The pre-cooling of liquid nitrogen pump 34 is only performed before liquid nitrogen pump 34 starts working. After liquid nitrogen pump 34 starts working, the pre-cooling of liquid nitrogen pump 34 is not performed. Therefore, the second liquid nitrogen discharge shut-off valve 393 is closed.

[0129] like Figure 14 As shown, the liquid nitrogen vaporization pressurization system of this embodiment also includes a second pre-launch pressurization component 70 and a third pre-launch pressurization component 80. One end of the second pre-launch pressurization component 70 is connected to the main pressurization pipeline 11 between the pressurization pipe of the liquid nitrogen tank 30 and the first heater component via a tee, and the other end is used for detachable connection with the ground helium source 90. One end of the third pre-launch pressurization component 80 is connected to the pressurization pipe of the fuel tank 20 via a tee, and the other end is used for detachable connection with the ground helium source 90.

[0130] Specifically, in this embodiment, the second pre-launch pressurization assembly 70 includes a second pre-launch pressurization check valve 71 and a second pre-launch pressurization solenoid valve 72, which are sequentially connected to the main pressurization pipeline 11 via pipelines. The third pre-launch pressurization assembly 80 includes a third pre-launch pressurization check valve 81 and a third pre-launch pressurization solenoid valve 82, which are sequentially connected to the pressurization pipe of the fuel tank 20 via pipelines. The second and third pre-launch pressurization assemblies 70 and 80 are detachably connected to the ground helium source 90 via a primary tail-end plug-in connector. In this embodiment, there are also two ground helium sources 90. The first ground helium source 90 is sequentially connected to a filter 91 and a pressure reducer 92. The outlet of one pressure reducer 92 is connected to the second pre-launch pressurization assembly 70 via a primary tail-end plug-in connector, and the outlet of the other pressure reducer 92 is connected to the third pre-launch pressurization assembly 80 via a primary tail-end plug-in connector.

[0131] During pre-launch pressurization on the ground, the ground helium source 90 pressurizes the liquid oxygen tank 10 before launch via filter 91, pressure reducer 92, primary tail plug connector, second pre-launch pressurization solenoid valve 72, second pre-launch pressurization check valve 71, second pre-launch pressurization pipeline and liquid oxygen tank energy dissipator 13.

[0132] During pre-launch pressurization on the ground, the ground helium source 90 pressurizes the fuel tank 20 before launch via filter 91, pressure reducer 92, first-stage tail plug-in connector, third pre-launch pressurization solenoid valve 82, third pre-launch pressurization check valve 81, third pre-launch pressurization pipeline and fuel tank energy dissipator 25.

[0133] The liquid nitrogen vaporization pressurization system in this embodiment separates the liquid oxygen tank pressurization system and the fuel tank pressurization system, enabling independent pressurization of the two tanks and preventing gas from the liquid oxygen tank 10 from flowing back into the fuel tank 20, which could cause safety issues.

[0134] The second pre-launch pressurization assembly 70 and the third pre-launch pressurization assembly 80 in this embodiment also have a pressure replenishment function, which integrates the pre-launch pressurization system and the pressure replenishment system into a single design.

[0135] After the rocket's propulsion system is tested and ignited, the liquid oxygen tank is pressurized using liquid nitrogen heating. The method of delivering the liquid nitrogen during this pressurization is the same as during the first stage of the rocket's flight, and will not be repeated here. Similarly, the fuel tank is pressurized using liquid nitrogen heating. The method of delivering the liquid nitrogen during this pressurization is the same as during the first stage of the rocket's flight, and will not be repeated here.

[0136] During the test run of the power system, the liquid oxygen tank 10 is pressurized using the second pre-launch pressurization component 70. During the test run of the first stage power system, the pressurization process of the liquid oxygen tank 10 is the same as that during the pre-launch pressurization on the ground, and will not be described again.

[0137] During the power system test, the fuel tank 20 is pressurized by the third pre-launch pressurization component 80. During the first stage power system test, the pressurization process of the fuel tank 20 is the same as that during the ground pre-launch pressurization process, and will not be described again.

[0138] The pre-launch pressurization solenoid valves in the second and third pre-launch pressurization assemblies 70 and 80 serve both to control the pre-launch pressurization of the liquid oxygen tank before the power system test ignition and to provide logical control for the ground pressurization system of the liquid oxygen tank after the power system test ignition. This allows a simple pre-launch pressurization solenoid valve to perform multiple functions, simplifying the structure of the ground pressurization system. Furthermore, the overall structure of this pre-launch pressurization assembly is simple, with a limited number and variety of valves and pipelines, resulting in low development difficulty and a short manufacturing cycle.

[0139] like Figure 12As shown, the gas generators 64 of at least two engines 60 are connected in parallel to provide driving force for the liquid nitrogen pump 34. For example, in this embodiment, the gas generators 64 of the two engines 60 are connected to a one-way valve 65 respectively and then connected in parallel to the first liquid nitrogen pump 342 and the second liquid nitrogen pump 343 respectively through a three-way valve. An orifice plate 341 is also provided between the liquid nitrogen pump and the three-way valve. The high-temperature gas generated by the two gas generators 64 passes through two one-way valves 65 respectively, and then is combined into one path through the three-way valve and split into two paths. These paths pass through the orifice plate 341 respectively to provide driving gas for the first liquid nitrogen pump 342 and the second liquid nitrogen pump 343.

[0140] This embodiment can also be similar to the above embodiment, with a liquid oxygen tank overflow valve 16 installed on the liquid oxygen tank 10, which will not be described in detail here.

[0141] The liquid nitrogen vaporization pressurization system provided in this embodiment utilizes two liquid nitrogen pumps 34 to heat the liquid nitrogen. The first liquid nitrogen pump 342 pressurizes the liquid nitrogen, which is then heated by five liquid nitrogen heaters 612 before being used to pressurize the liquid oxygen tank 10, with a branch line also supplying pressure to the liquid nitrogen tank 30. The second liquid nitrogen pump 343 pressurizes the liquid nitrogen, which is then heated by four liquid nitrogen heaters 612 before being used to pressurize the fuel tank 20. Both the liquid oxygen tank 10 and the fuel tank 20 employ an open-loop pressurization method, greatly simplifying the system development and integration.

[0142] This embodiment provides high-temperature driving gas by using gas generators from two engines and two one-way valves, effectively avoiding the problem of insufficient gas supply due to the failure of one engine, and improving the reliability of the turbocharging system.

[0143] In this embodiment, an orifice plate 341 is provided at the gas inlet of the liquid nitrogen pump 34. During the ground test, the intake flow of the first liquid nitrogen pump 342 and the second liquid nitrogen pump 343 can be controlled by adjusting the size of the orifice plate 341, thereby controlling and determining the power of the liquid nitrogen pump. The size of the orifice plate 341 is determined by the rated power reached by the liquid nitrogen pump 34 during the test, which helps to reduce the difficulty of system development, design and simulation.

[0144] This embodiment utilizes the high-temperature gas generated by the gas generator 64 of the engine 60 to drive the liquid nitrogen pump, ensuring the reliable operation of the liquid nitrogen pump. Compared with using an independent gas source to drive the liquid nitrogen pump or using an electric motor to drive the liquid nitrogen pump, this solution utilizes the gas in the gas generator 64 of the engine 60 to drive the liquid nitrogen pump, resulting in a higher system integration, simplifying the liquid nitrogen pump drive system, and reducing the effective mass of the booster system.

[0145] In this embodiment, the liquid nitrogen vaporization booster system is equipped with a one-way valve 65 at the outlet of the gas generator 64. This effectively prevents the gas generated by the normally functioning engine 60 from flowing out through the gas generator 64 of the damaged engine when one of the engines 60 is damaged, thus improving the system's resilience.

[0146] In this embodiment, liquid nitrogen is heated into high-temperature nitrogen gas by the liquid nitrogen heaters 612 of five engines to pressurize the liquid oxygen tank 10, and liquid nitrogen is heated into high-temperature nitrogen gas by the liquid nitrogen heaters 612 of four engines to pressurize the fuel tank 20, thus enabling independent pressurization of the liquid oxygen tank 10 and the fuel tank 20.

[0147] By installing pre-launch booster lines on the main booster line 11 of the liquid oxygen tank 10 and the fuel tank booster line 21, the length of the pre-launch booster lines can be effectively shortened, allowing the pre-launch booster lines and the main booster line 11 to be designed as a single unit. This improves the integration of the main booster line 11.

[0148] In this embodiment, the pre-launch pressurization system (second pre-launch pressurization component 70 and third pre-launch pressurization component 80) serves two purposes during the ground pre-launch pressurization process: the pre-launch pressurization solenoid valve not only pressurizes the liquid oxygen tank before the power system test ignition, but also acts as the logic control system for the liquid oxygen tank ground pressurization system after the power system test ignition. This allows a simple pre-launch pressurization solenoid valve to perform multiple functions, simplifying the structure of the ground pressurization system. Furthermore, the pressurization and pressurization system (second pre-launch pressurization component 70 and third pre-launch pressurization component 80) has a simple structure, with a limited variety and quantity of valves and pipelines, resulting in low development difficulty and a short manufacturing cycle.

[0149] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0150] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0151] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A liquid nitrogen vaporization pressurization system for use in liquid rockets, characterized in that, The system includes a liquid oxygen tank (10), a fuel tank (20), a liquid nitrogen tank (30), a liquid nitrogen pump (34), a cavitation pipe (613), and a heater assembly. The liquid oxygen tank (10) stores liquid oxygen, the fuel tank (20) stores fuel, and the liquid nitrogen tank (30) stores liquid nitrogen. The liquid nitrogen tank (30) is located inside the liquid oxygen tank (10). The fuel tank (20) is located on the side of the liquid oxygen tank (10) near the engine (60). The liquid nitrogen pump (34) increases the output pressure of the liquid nitrogen, and the cavitation pipe (613) stabilizes the liquid nitrogen flow rate. The heater assembly is used to vaporize liquid nitrogen and heat it into high-temperature nitrogen gas; the bottom of the liquid nitrogen tank (30) is provided with a liquid nitrogen delivery pipe (31), the liquid nitrogen pump (34) is provided on the liquid nitrogen delivery pipe (31), the end of the liquid nitrogen delivery pipe (31) away from the liquid nitrogen pump (34) is connected to the inlet of the heater assembly, the liquid oxygen tank cushion, the fuel tank cushion and the liquid nitrogen tank cushion are respectively connected to the outlet of the heater assembly through pipelines; the gas generators (64) of at least two engines (60) are connected in parallel for redundancy and are used together to provide driving force for the liquid nitrogen pump (34).

2. The liquid nitrogen vaporization pressurization system as described in claim 1, characterized in that, It also includes a main pressurization line (11), a liquid nitrogen tank pressurization line (32), and a fuel tank pressurization line (21); the liquid oxygen tank cushion is connected to the heater assembly through the main pressurization line (11); one end of the liquid nitrogen tank pressurization line (32) is connected to the liquid nitrogen tank cushion, and the other end is connected to the main pressurization line (11); one end of the fuel tank pressurization line (21) is connected to the fuel tank cushion, and the other end is connected to the main pressurization line (11) between the liquid nitrogen tank pressurization line (32) and the heater assembly.

3. The liquid nitrogen vaporization pressurization system as described in claim 2, characterized in that, It also includes a purge-pressurization integrated assembly (50), which includes a main pipeline (57) and multiple branch pipelines. The end of the main pipeline (57) near the engine (60) is used to connect to a ground nitrogen source (58). The inlet of each branch pipeline is connected to the main pipeline (57). The outlet of the first branch pipeline (51) is connected to the liquid oxygen discharge pipeline (511) of the engine (60) to provide a gas seal for the liquid oxygen discharge pipeline (511). The outlet of the second branch pipeline (52) is connected to the purge pipe (521) of the stern section to provide a gas seal for the liquid oxygen discharge pipeline (511). The first-stage tail section is purged; the outlet of the third branch pipe (53) is connected to the inter-tank purging pipe (531) for purging the inter-tank section; the outlet of the fourth branch pipe (54) is connected to the liquid nitrogen tank pressurization pipe (32) for pressurizing the liquid nitrogen tank (30); the outlet of the fifth branch pipe (55) is connected to the exhaust pipe (551) of the liquid oxygen tank (10) for providing a gas seal for the exhaust pipe (551) of the liquid oxygen tank (10); the outlet of the sixth branch pipe (56) is connected to the inter-stage purging pipe (561) for purging the inter-stage section.

4. The liquid nitrogen vaporization pressurization system as described in claim 2, characterized in that, It also includes a first liquid nitrogen filling and precooling assembly (35), which includes a first liquid nitrogen filling and precooling pipeline (351) and a liquid nitrogen shut-off valve (352). The liquid nitrogen shut-off valve (352) is located on the first liquid nitrogen filling and precooling pipeline (351). One end of the first liquid nitrogen filling and precooling pipeline (351) is connected to the pipeline between the liquid nitrogen pump (34) and the heater assembly, and the other end is used to detachably connect to the liquid nitrogen filling system (36) and the first liquid nitrogen discharge shut-off valve (363), respectively.

5. The liquid nitrogen vaporization pressurization system as described in claim 2, characterized in that, It also includes a liquid oxygen tank pressurization assembly (17), a fuel tank pressurization assembly (26), and a first pre-launch pressurization assembly (40); The liquid oxygen tank pressurization assembly (17) includes a liquid oxygen tank pressurization pipeline (172), one end of which is connected to a liquid oxygen tank pressurization helium cylinder (171), and the other end is connected to the main pressurization pipeline (11); a liquid oxygen tank pressurization solenoid valve (173) and a liquid oxygen tank pressurization orifice plate (174) are sequentially provided on the liquid oxygen tank pressurization pipeline (172) from the liquid oxygen tank pressurization helium cylinder (171) toward the main pressurization pipeline (11); The fuel tank pressurization assembly (26) includes a fuel tank pressurization pipeline (261), one end of which is connected to a fuel tank pressurization helium cylinder (264), and the other end is connected to the fuel tank booster pipe (21). The fuel tank pressurization pipeline (261) is provided with a fuel tank pressurization solenoid valve (263) and a fuel tank pressurization orifice plate (262) in sequence from the fuel tank pressurization helium cylinder (264) toward the fuel tank booster pipe (21). One end of the first pre-launch pressurization assembly (40) is connected to the main pressurization pipeline (11) between the liquid nitrogen tank pressurization pipe (32) and the heater assembly, and the other end is used for detachable connection to the ground helium source (90); the first pre-launch pressurization assembly (40) includes a first pre-launch pressurization check valve (41) and a first pre-launch pressurization solenoid valve (42) arranged sequentially from the main pressurization pipeline (11) to the ground helium source (90).

6. The liquid nitrogen vaporization pressurization system as described in claim 1, characterized in that, It also includes a main pressurization line (11), a liquid nitrogen tank pressurization line (32), and a fuel tank pressurization line (21); the liquid nitrogen pump (34) includes a first liquid nitrogen pump (342) and a second liquid nitrogen pump (343) connected in parallel; the heater assembly includes a first heater assembly and a second heater assembly. The first liquid nitrogen pump (342) is connected to one end of the main pressurization pipeline (11) through the first heater assembly, and the other end of the main pressurization pipeline (11) is connected to the liquid oxygen tank cushion; the second liquid nitrogen pump (343) is connected to one end of the fuel tank pressurization pipe (21) through the second heater assembly, and the other end of the fuel tank pressurization pipe (21) is connected to the fuel tank cushion; one end of the liquid nitrogen tank pressurization pipe (32) is connected to the liquid nitrogen tank cushion, and the other end is connected to the main pressurization pipeline (11).

7. The liquid nitrogen vaporization pressurization system as described in claim 6, characterized in that, It also includes a second liquid nitrogen filling and precooling assembly (39), which includes a second liquid nitrogen filling and precooling pipeline (391), a pipeline check valve (392), and a second liquid nitrogen discharge shut-off valve (393). The pipeline check valve (392) is installed on the second liquid nitrogen filling and precooling pipeline (391). One end of the second liquid nitrogen filling and precooling pipeline (391) is connected to the pipeline between the liquid nitrogen pump and the liquid nitrogen tank (30), and the other end is used for detachable connection with the liquid nitrogen filling system (36). The second liquid nitrogen discharge shut-off valve (393) is connected to the outlet ends of the two liquid nitrogen pumps through pipelines respectively.

8. The liquid nitrogen vaporization pressurization system as described in claim 6, characterized in that, It also includes a second pre-launch pressurization assembly (70) and a third pre-launch pressurization assembly (80). One end of the second pre-launch pressurization assembly (70) is connected to the main pressurization pipeline (11) between the liquid nitrogen tank pressurization pipe (32) and the first heater assembly, and the other end is used for detachable connection to the ground helium source (90). One end of the third pre-launch pressurization assembly (80) is connected to the fuel tank pressurization pipe (21), and the other end is used for detachable connection to the ground helium source (90).

9. A liquid rocket, characterized in that, Includes the liquid nitrogen vaporization pressurization system as described in any one of claims 1 to 8.

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