A liquid nitrogen heating and pressurizing system for a launch vehicle and a liquid rocket

Abstract

An embodiment of the present invention provides a liquid nitrogen heating and pressurizing system for a launch vehicle and a liquid rocket, which includes an oxygen tank, a fuel tank, an oxygen tank energy dissipator, a fuel tank energy dissipator, and an engine respectively connected to the oxygen tank and the fuel tank. It further includes a liquid nitrogen tank, a first liquid nitrogen heater in the liquid nitrogen delivery pipeline, and a nitrogen pressurizing pipeline; the liquid nitrogen tank is located inside the oxygen tank, and the top of the liquid nitrogen tank is lower than the initial liquid level of the oxygen tank; the outlet of the liquid nitrogen tank is connected to the inlet of the first liquid nitrogen heater through a pipeline, and the outlet of the first liquid nitrogen heater is connected to the fuel tank energy dissipator through a pipeline; the gas cushion of the liquid nitrogen tank is connected to the liquid nitrogen tank pressurizing pipeline. In the present invention, liquid nitrogen is heated and vaporized into nitrogen as the pressurizing medium, and the liquid nitrogen flows out and is heated and vaporized into nitrogen by means of gas cushion extrusion for pressurizing the fuel tank. This liquid nitrogen heating and pressurizing system can not only reduce the weight of the pressurizing and delivery system and improve the launch vehicle's carrying capacity, but also reduce the manufacturing cost of the pressurizing and delivery system.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace engines, and in particular to a liquid nitrogen heating and pressurization system for a carrier rocket and a liquid rocket. Background Art

[0002] The pressurization and delivery system is one of the important subsystems of large liquid launch vehicles. The improvement and enhancement of its performance plays an important role in improving the overall performance of the rocket. Among them, the pressurization method of the liquid rocket tank (including the oxygen tank and the fuel tank) is a very important task. After the tank is pressurized, the propellant will be continuously supplied to the engine at a certain pressure and flow rate, thereby ensuring the normal operation of the engine during startup and flight. At present, there are three main mainstream tank pressurization methods: autogenous pressurization, room temperature helium pressurization, and cold helium heating.

[0003] Autogenous supercharging means that the liquid oxygen of the engine is heated by the oxygen evaporator (or oxygen autogenous supercharger) installed in each branch of the engine, and then it is collected through the one-way valve and the autogenous supercharging pipe and enters the tank for supercharging. The advantages of the autogenous supercharging system are simple system structure, good working reliability, ability to meet the requirements of the tank supercharging pressure, low cost, and the characteristics of oxygen tank supercharging. However, autogenous supercharging is only suitable for medium with low boiling point and easy vaporization. For normal temperature medium such as kerosene, it cannot reach the vaporization conditions, so it is difficult to use autogenous supercharging for kerosene tanks.

[0004] Normal temperature helium heating and pressurization refers to using helium as the normal temperature pressurization medium, storing the helium in a high-pressure composite gas cylinder, passing through a filter device, and entering a flow control system composed of a solenoid valve and an orifice plate. The pressurized gas then enters the engine helium heater for heating before entering the tank for pressurization. The advantages of the helium heating and pressurization scheme are closed-loop pressurization, controlled tank pressure, high pressurization efficiency, and high reliability. However, it has disadvantages such as a large number of gas cylinders, high cost, and heavy structure. At the same time, the gas cylinder cools down during the deflation process, the density increases, and the residual pressure of the gas cylinder is high, resulting in a helium utilization rate of less than 70% for normal temperature helium heating and pressurization, and helium is very expensive. Therefore, for large rockets, the cost of normal temperature helium heating and pressurization is relatively high.

[0005] Cold helium heating and pressurization refers to immersing the cold helium cylinder of composite materials in the liquid oxygen tank, and the pressurized helium is stored in the cold helium cylinder. After passing through the filter device, it enters the flow control system composed of the solenoid valve and the orifice plate. The pressurized gas then enters the engine helium heater for heating and then enters the tank for pressurization. The main advantages of this solution are low gas source pressure, small gas source volume, and light structure weight, but its technical difficulty is high, the system is complex, and there may be safety issues such as liquid oxygen explosion. Therefore, in general, the pressurization solution has low reliability, and the utilization rate of cold helium is about 50%, which greatly increases the cost of helium pressurization medium.

[0006] From the description and comparison of the above pressurization methods, it can be seen that for the kerosene in the kerosene tank of large launch vehicles at present, due to its high boiling point and low volatility, when using existing technologies, the pressurization cost of the kerosene tank is very high. Therefore, when large launch vehicles use kerosene as fuel, how to achieve a low-cost pressurized delivery system is a problem to be solved. Summary of the Invention

[0007] An embodiment of the present invention provides a liquid nitrogen heating and pressurization system for a launch vehicle and a liquid rocket, which uses the vaporization of liquid nitrogen into high-temperature nitrogen to achieve the pressurization of the storage tank, thereby realizing a low-cost and lightweight pressurized delivery system.

[0008] To achieve the above object, on the one hand, an embodiment of the present invention provides a liquid nitrogen heating and pressurization system for a launch vehicle, including an oxygen tank, a fuel tank, an oxygen tank energy dissipator arranged at the inner top of the oxygen tank, a fuel tank energy dissipator arranged at the inner top of the fuel tank, and an engine connected to the oxygen tank and the fuel tank through pipelines, further including a liquid nitrogen tank for containing liquid nitrogen, and a first liquid nitrogen heater connected to the engine; the liquid nitrogen tank is located inside the oxygen tank, and the top of the liquid nitrogen tank is lower than the initial liquid level of the oxygen tank. The initial liquid level of the oxygen tank refers to the liquid level height of the liquid oxygen in the oxygen tank at the moment when the launch vehicle ignites; the outlet of the liquid nitrogen tank is connected to the inlet of the first liquid nitrogen heater through a pipeline, and the outlet of the first liquid nitrogen heater is connected to the fuel tank energy dissipator through a pipeline; the gas cushion of the liquid nitrogen tank is connected to the liquid nitrogen tank pressurization pipeline.

[0009] On the other hand, an embodiment of the present invention further provides a liquid rocket, which includes the liquid nitrogen heating and pressurization system for a launch vehicle as described above.

[0010] The technical solution has the following beneficial effects:

[0011] In the technical solution of the present invention, liquid nitrogen is used instead of helium as the pressurization medium. After being heated by the liquid nitrogen heater, the liquid nitrogen vaporizes into nitrogen gas, which is used to pressurize the storage tank, thereby overcoming the problems of large helium consumption and high pressurization cost existing in the two existing methods of normal-temperature helium heating and pressurization and cold helium heating and pressurization; at the same time, since the liquid nitrogen is extruded from the liquid nitrogen tank by means of gas cushion extrusion instead of pumping, there is no need to set up a liquid nitrogen pump, further reducing the cost. Therefore, the technical solution realizes a low-cost pressurized delivery system for large launch vehicles.

[0012] In addition, the technical solution also has the following characteristics:

[0013] 1), Since the liquid nitrogen tank is arranged inside the low-temperature oxygen tank, taking advantage of the similar temperature difference between liquid oxygen and liquid nitrogen, the liquid oxygen can be used to cool and insulate the liquid nitrogen tank, so there is no need to set up additional insulation measures for the liquid nitrogen tank, and the space occupation is effectively reduced.

[0014] 2), in this technical solution, whether it is the implementation method of helium gas extrusion or the implementation method of engine gas extrusion, reliable tank pressurization can be provided. In the helium gas extrusion method, the constant pressure of the gas cushion in the liquid nitrogen tank is achieved by setting a pressure reducing valve at the helium gas cylinder, and the constant liquid nitrogen flow rate is achieved through the combination of the constant pressure of the gas cushion in the liquid nitrogen tank and the cavitation tube mode. A constant liquid nitrogen flow rate pressurization method for the fuel tank is achieved; in the engine gas extrusion method, the precise control of the gas cushion pressure in the tank is achieved by controlling the opening and closing of the corresponding pressurization solenoid valve through a pressurization controller. Brief Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is the working principle diagram of a liquid nitrogen heating and pressurization system for a launch vehicle of the present invention;

[0017] Figure 2 It is the structural schematic diagram of the first embodiment of the liquid nitrogen heating and pressurization system for a launch vehicle of the present invention;

[0018] Figure 3 It is the structural schematic diagram of the second embodiment of the liquid nitrogen heating and pressurization system for a launch vehicle of the present invention;

[0019] Figure 4 It is the structural schematic diagram of the third embodiment of the liquid nitrogen heating and pressurization system for a launch vehicle of the present invention;

[0020] Figure 5 It is the ground pressurization schematic diagram before launch in the second embodiment of the present invention;

[0021] Figure 6 It is the position schematic diagram of the exhaust pipe of the liquid nitrogen tank extending into the liquid nitrogen tank in the first embodiment of the present invention;

[0022] Figure 7 It is the ground pressurization schematic diagram before launch in the third embodiment of the present invention;

[0023] Figure 8 It is the control logic diagram of the second solenoid valve group in the second embodiment of the present invention;

[0024] Figure 9 It is the control logic diagram of the first solenoid valve group in the second embodiment of the present invention;

[0025] Figure 10 It is the control logic diagram of the third solenoid valve group in the third embodiment of the present invention;

[0026] Figure 11 It is the control logic diagram of the fourth electromagnetic valve group in the third embodiment of the present invention;

[0027] Reference numerals in the attached drawings:

[0028] 1. Oxygen tank; 2. Fuel tank; 3. Engine; 4. Liquid nitrogen tank; 5. Main liquid nitrogen delivery pipeline; 6. Liquid nitrogen stop valve; 7. Fuel tank pressure boosting controller; 8. First electromagnetic valve group; 9. Cavitation tube; 10. First liquid nitrogen heater;

[0029] 11. Liquid nitrogen check valve; 12. Fuel tank pressure boosting pipeline; 13. Oxygen tank pressure boosting pipeline; 14. Fuel tank gas cushion pressure sensor; 15. Fuel tank energy dissipator; 16. Fuel tank safety valve; 17. Second electromagnetic valve group; 18. Liquid nitrogen orifice plate; 19. Second liquid nitrogen heater; 20. Oxygen tank safety valve;

[0030] 21. Oxygen tank energy dissipator; 23. Oxygen tank gas cushion pressure sensor; 24. Oxygen tank pressure boosting controller; 25. Helium gas cylinder; 26. Helium gas filter; 27. Helium gas boosting electromagnetic valve; 28. Helium gas pressure reducing valve; 29. Liquid nitrogen tank pressure boosting pipeline; 30. Liquid nitrogen tank exhaust pipe;

[0031] 31. Liquid nitrogen tank exhaust valve; 32. Liquid nitrogen tank safety valve; 33. Ground helium gas source; 34. Engine gas generator; 36. Helium gas boosting end plug connector; 37. Pre-launch helium gas boosting pipeline; 38. Liquid nitrogen tank energy dissipator; 39. First helium gas boosting electromagnetic valve; 40. Helium gas check valve;

[0032] 41. Gas check valve; 42. Liquid nitrogen filter; 43. Second helium gas boosting electromagnetic valve; 44. Gas pressure reducing valve; 45. Fourth electromagnetic valve group; 46. Third pre-launch boosting electromagnetic valve; 48. Third electromagnetic valve group;

[0033] 51. Liquid nitrogen filling device; 52. Liquid nitrogen filling valve; 53. Liquid nitrogen filling end plug connector; 56. Oxygen self-booster;

[0034] 70. Ground nitrogen gas source; 71. Nitrogen gas filter; 72. Nitrogen gas pressure reducing valve; 73. Nitrogen gas boosting end plug connector; 89. Inter-stage separation plug connector;

[0035] 111. First nitrogen gas boosting electromagnetic valve; 112. Nitrogen gas orifice plate; 115. Second nitrogen gas boosting electromagnetic valve; 119. Third nitrogen gas boosting electromagnetic valve;

[0036] 131. First electromagnetic valve for secondary boosting; 135. Second electromagnetic valve for secondary boosting; 139. Third electromagnetic valve for secondary boosting; 150. Common bottom of the first-stage common-bottom tank; 170. Common bottom of the second-stage common-bottom tank. Detailed implementation mode

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0038] As Figure 1 shown, the embodiment of the present invention provides a liquid nitrogen heating and pressurizing system for a launch vehicle, including an oxygen tank 1, a fuel tank 2, an oxygen tank energy dissipator 21 arranged at the inner top of the oxygen tank 1, a fuel tank energy dissipator 15 arranged at the inner top of the fuel tank 2, and an engine 3 connected to the oxygen tank 1 and the fuel tank 2 through pipelines, and further including a liquid nitrogen tank 4 for containing liquid nitrogen, and a first liquid nitrogen heater 10 connected to the engine 3; the liquid nitrogen tank 4 is located inside the oxygen tank 1, and the top of the liquid nitrogen tank 4 is lower than the initial liquid level of the oxygen tank 1. The initial liquid level of the oxygen tank 1 refers to the liquid level height of the liquid oxygen in the oxygen tank 1 at the moment when the launch vehicle ignites; the outlet of the liquid nitrogen tank 4 is connected to the inlet of the first liquid nitrogen heater 10 through a pipeline, and the outlet of the first liquid nitrogen heater 10 is connected to the fuel tank energy dissipator 15 through a pipeline; the gas pillow of the liquid nitrogen tank 4 is connected to the liquid nitrogen tank pressurizing pipeline 29.

[0039] To solve the foregoing problems, in this technical solution, liquid nitrogen is used instead of helium as the pressurizing medium. The gas pillow space at the top inside the liquid nitrogen tank 4 is pressurized through the liquid nitrogen tank pressurizing pipeline 29, so that liquid nitrogen can flow out from the lower outlet, enter the first liquid nitrogen heater 10 after passing through the liquid nitrogen delivery main pipeline, and the first liquid nitrogen heater 10 uses the engine 3 connected thereto as the heat source to heat the liquid nitrogen and convert it into high-temperature nitrogen gas, and then enter the fuel tank energy dissipator 15 through the fuel tank pressurizing pipeline 12 to pressurize the fuel tank 2, thereby overcoming the problems of large helium consumption and high pressurizing cost existing in the existing normal-temperature helium heating and pressurizing and cold helium heating and pressurizing methods. At the same time, in this technical solution, the liquid nitrogen tank 4 is also arranged inside the low-temperature oxygen tank 1. By utilizing the characteristic that the temperature difference between liquid oxygen and liquid nitrogen is similar, the liquid oxygen can be used to cool and insulate the liquid nitrogen tank 4, so that no additional heat insulation measures for the liquid nitrogen tank are required, and the space occupation is effectively reduced.

[0040] In the specific implementation process, there are two ways for the liquid nitrogen in the liquid nitrogen tank 4 to be "squeezed" out: the first is the helium squeezing method, and the second is the engine gas squeezing method.

[0041] When the helium squeezing method is adopted, at this time, the fuel tank 2 uses liquid nitrogen heating and pressurizing, and the oxygen tank 1 uses self-pressurization. Its structural schematic diagram is as Figure 2As shown in the figure: The medium in the liquid nitrogen tank pressurization pipeline 29 is helium; the gas pillow of the liquid nitrogen tank 4 is connected to the helium pressure reducing valve 28, the helium pressurization solenoid valve 27, and the helium gas cylinder 25 in sequence through the liquid nitrogen tank pressurization pipeline 29; in this solution, the helium in the helium gas cylinder 25 is used for pressurization, so as to squeeze the liquid nitrogen (although helium is also used in this way, it only serves as the pressurized gas source of the liquid nitrogen tank 4, and the capacity of the liquid nitrogen tank 4 is small, so its usage is much less than that of helium in the existing normal temperature helium heating pressurization and cold helium heating pressurization methods). In this method, the helium pressure reducing valve 28 can control the pressure behind it, and can ensure that the pressure of the gas pillow of the liquid nitrogen tank 4 is always maintained at 3 - 4 MPa, and the stable flow rate of liquid nitrogen outflow is realized by keeping the pressure of the liquid nitrogen tank 4 stable. At the same time, between the liquid nitrogen tank 4 and the first liquid nitrogen heater 10, a cavitation tube 9 is also connected. Through the combined action of the constant pressure of the gas pillow of the liquid nitrogen tank 4 and the cavitation tube 9, a constant flow rate of liquid nitrogen can be achieved, so as to meet the pressurization requirements of the fuel tank.

[0042] Meanwhile, in the helium extrusion method, based on the following considerations, the energy dissipator of the liquid nitrogen tank 4 can be not configured, and the specific description is as follows:

[0043] 1) The helium pressurization flow rate is small, the diameter of the liquid nitrogen tank pressurization pipeline 29 is relatively thick (inner diameter greater than φ20), and the flow velocity when entering the liquid nitrogen tank 4 is not greater than 30 m / s. The flow velocity is low, and it has little impact on the liquid nitrogen liquid level in the liquid nitrogen tank 4;

[0044] 2) Due to reasons such as the small relative molecular mass of helium and the small intermolecular force, the density of helium is low. The density of helium is 1 / 11 of the engine gas (the main component is carbon dioxide) in the subsequent engine gas extrusion method. Therefore, compared with the engine gas, the kinetic energy generated under the same volume flow rate is small. The essence of the energy dissipator is to reduce the kinetic energy of the pressurized gas. Therefore, it is not very necessary for the small flow rate of helium;

[0045] 3) Helium is an inert gas, and the intermolecular force is very weak, resulting in difficulty in liquefying helium in the liquid oxygen temperature range (about 90K);

[0046] 4) The volume of the liquid nitrogen tank 4 is small and the internal space is limited. Installing an energy dissipator will occupy a certain space, reduce the storage volume of liquid nitrogen and reduce the pressurization performance of the rocket. Moreover, the energy dissipator device itself has a certain cost. Therefore, if it is not necessary, try not to install the energy dissipator.

[0047] Furthermore, since the oxygen tank 1 uses self-pressurization in this implementation method, the liquid nitrogen heating and pressurization system of the launch vehicle further includes an oxygen self-pressurizer 56 connected to the engine 3, and the oxygen self-pressurizer 56 is connected to the oxygen tank energy dissipator 21 through a pipeline.

[0048] Furthermore, as Figure 6As shown, a liquid nitrogen tank exhaust pipe 30 is also connected to the top of the liquid nitrogen tank 4; one end of the liquid nitrogen tank exhaust pipe 30 vertically extends into the liquid nitrogen tank 4 by a preset length, and the other end of the liquid nitrogen tank exhaust pipe 30 is located outside the liquid nitrogen tank 4 and is connected to a liquid nitrogen tank exhaust valve 31. That is, the liquid nitrogen tank pressurization pipeline 29 is directly connected to the pressurization port at the top of the liquid nitrogen tank 4, while the liquid nitrogen tank exhaust pipe 30 extends downward from the top of the liquid nitrogen tank 4 by a preset length (preferably 40 mm), which can keep the liquid nitrogen level in the liquid nitrogen tank 4 stable at a position 40 mm away from the top before launch, realizing the constancy of the initial gas pillow volume of the liquid nitrogen tank. The realization process of this process is as follows: during liquid nitrogen filling, by extending the liquid nitrogen tank exhaust pipe 30 downward by 40 mm, it can ensure that the liquid nitrogen level is always controlled at about 40 mm away from the vertex, and the excess liquid nitrogen is discharged through the liquid nitrogen tank exhaust pipe 30, realizing the constancy of the initial gas pillow of the liquid nitrogen tank 4 before launch, and making the initial gas pillow volume controlled at about 3% of the total volume of the liquid nitrogen tank 4.

[0049] Further, as Figure 2 shown, in order to achieve liquid nitrogen filling, the liquid nitrogen heating and pressurization system of the launch vehicle further includes a liquid nitrogen filling device 51, and the liquid nitrogen filling device 51 is connected to the liquid nitrogen tank 4 in a detachable manner (for example, by means of detachment and separation). As Figure 2 shown, the liquid nitrogen filling device 51 is connected to the liquid nitrogen delivery main pipeline 5 through a liquid nitrogen filling valve 52, a liquid nitrogen filling tail-end pluggable connector 53, and a liquid nitrogen one-way valve 11. The upper part of the liquid nitrogen filling tail-end pluggable connector 53 is connected to the on-board part, while the lower part of the liquid nitrogen filling tail-end pluggable connector 53 is connected to the liquid nitrogen filling device 51 on the ground. When the liquid nitrogen filling is completed, the upper and lower parts of the liquid nitrogen filling tail-end pluggable connector 53 can be separated.

[0050] When the engine gas extrusion method is adopted, its structure is as Figure 3 shown. This system can be applied to the liquid nitrogen heating and pressurization system of the first stage of the rocket. At this time, the medium in the liquid nitrogen tank pressurization pipeline 29 is engine gas; the liquid nitrogen heating and pressurization system of the launch vehicle further includes an engine gas generator 34 connected to the engine 3; a liquid nitrogen tank energy dissipator 38 is also provided at the inner top of the liquid nitrogen tank 4, and the engine gas generator 34 is connected to the liquid nitrogen tank energy dissipator 38 through the liquid nitrogen tank pressurization pipeline 29. That is, at this time, the helium gas cylinder 25 is not additionally provided, but the high-temperature gas generated by the engine gas generator 34 is input into the gas pillow space of the liquid nitrogen tank 4, thereby extruding the liquid nitrogen to make it output.

[0051] Furthermore, the launch vehicle liquid nitrogen heating and pressurizing system also includes a second liquid nitrogen heater 19 connected to the engine 3; the outlet of the liquid nitrogen tank 4 is connected to the inlet of the second liquid nitrogen heater 19 through a pipeline, and the outlet of the second liquid nitrogen heater 19 is connected to the oxygen box energy dissipator 21 through a pipeline. At this time, in addition to pressurizing the fuel tank 2 with nitrogen, another set of liquid nitrogen heaters (second liquid nitrogen heaters 19) is introduced, so that the liquid nitrogen is converted into nitrogen after heating, and then enters the oxygen box energy dissipator 21 through the oxygen box pressurizing pipeline 13, which is used to pressurize the oxygen box 1.

[0052] Furthermore, the launch vehicle liquid nitrogen heating and pressurization system also includes an oxygen box boost controller 24 and a fuel tank boost controller 7. The oxygen box 1 is also connected to an oxygen box air pillow pressure sensor 23 connected to the air pillow of the oxygen box 1, and the fuel tank 2 is also connected to a fuel tank air pillow pressure sensor 14 connected to the air pillow of the fuel tank 2. A first solenoid valve group 8 is also connected between the liquid nitrogen tank 4 and the first liquid nitrogen heater 10, and a second solenoid valve group 17 is also connected between the liquid nitrogen tank 4 and the second liquid nitrogen heater 19; the oxygen box air pillow pressure sensor 23 is electrically connected to the second solenoid valve group 17 through the oxygen box boost controller 24; the fuel tank air pillow pressure sensor 14 is electrically connected to the first solenoid valve group 8 through the fuel tank boost controller 7; the first solenoid valve group 8 includes a first main solenoid valve, a first auxiliary solenoid valve and a first backup solenoid valve, and the second solenoid valve group 17 includes a second main solenoid valve, a second auxiliary solenoid valve and a second backup solenoid valve. The first solenoid valve group 8 and the second solenoid valve group 17 are both multiple parallel solenoid valves, which can effectively ensure the precise control of the air pillow pressure of the oxygen tank 1 and the fuel tank 2 during the pressurization process.

[0053] Furthermore, two groups of the engine gas generators 34 are provided, and each engine gas generator 34 is connected to one engine 3. The parallel combination of the two engine gas generators 34 can prevent the risk of insufficient gas supply caused by the stopping of one engine 3, thereby improving the redundancy and reliability of the liquid nitrogen tank boosting system.

[0054] Furthermore, the carrier rocket liquid nitrogen heating and pressurizing system also includes a ground gas source (a ground helium source 33 in the helium extrusion mode and a ground nitrogen source 70 in the engine gas extrusion mode), and the ground gas source is respectively connected to the oxygen box energy absorber 21, the fuel tank energy absorber 15, and the liquid nitrogen tank pressurizing pipeline 29, and is used to heat and pressurize the carrier rocket liquid nitrogen and transport it to pressurize each tank before launch.

[0055] The present technical solution is described in detail below through specific embodiments:

[0056] 1. First embodiment, using Figure 2In the shown structure, the liquid nitrogen tank 4 adopts the helium extrusion method. This system can be used in the first stage of a rocket. Its working process and characteristics are as follows:

[0057] 1) During the first-stage flight, the helium in the normal-temperature helium gas cylinder 25 passes through the helium gas filter 26, two-way helium gas booster solenoid valves 27, and two-way helium gas pressure reducing valves 28, and then merges into one path and is further boosted to the liquid nitrogen tank 4 through the liquid nitrogen tank boosting pipeline 29;

[0058] 2) By using two-way helium gas booster solenoid valves 27 and two-way helium gas pressure reducing valves 28, redundant functions can be achieved, effectively preventing a single-point failure of the system caused by a certain helium gas booster solenoid valve 27. The helium gas booster solenoid valve 27 plays the role of on-off, and the helium gas pressure reducing valve 28 can control the pressure after the valve, ensuring that the gas cushion pressure of the liquid nitrogen tank 4 is always maintained at 3 - 4 MPa. By keeping the pressure of the liquid nitrogen tank 4 stable, a stable liquid nitrogen outflow flow rate is achieved. A constant liquid nitrogen flow rate is beneficial to the pressurization of the fuel tank 2;

[0059] 3) In this specific embodiment, the fuel tank 2 is pressurized by liquid nitrogen heating, and the oxygen tank 1 is self-pressurized;

[0060] 4) During the first-stage flight, the high-temperature oxygen generated by the oxygen self-booster 56 passes through the oxygen tank boosting pipeline 13 and the oxygen tank energy dissipator 21 to perform oxygen self-pressurization on the oxygen tank 1;

[0061] 5) The liquid nitrogen in the liquid nitrogen tank 4 passes through the liquid nitrogen main transfer pipeline 5, the liquid nitrogen stop valve 6, the cavitation tube 9, the first liquid nitrogen heater 10, the liquid nitrogen check valve 11, the fuel tank boosting pipeline 12, and the fuel tank energy dissipator 15 to perform liquid nitrogen heating and pressurization on the fuel tank 2;

[0062] 6) During the first-stage flight, the liquid nitrogen tank 4 is pressurized by normal-temperature helium; the constant control of the liquid nitrogen boosting flow rate is achieved through the constant gas cushion pressure of the liquid nitrogen tank 4 + the cavitation tube 9;

[0063] 7) In this specific embodiment, the liquid nitrogen tank 4 is stored in the oxygen tank 1. Utilizing the characteristic that the temperature difference between liquid oxygen and liquid nitrogen is similar, the liquid oxygen in the oxygen tank 1 can insulate the liquid nitrogen tank 4, avoiding the need for adiabatic coating of the liquid nitrogen tank 4 and reducing the workload of adiabatic coating of the liquid nitrogen tank 4;

[0064] 8) By providing a pressure of 3 - 4 MPa to the liquid nitrogen tank 4, flow control is achieved through the gas cushion pressure of the liquid nitrogen tank 4 + the cavitation tube 9 to pressurize the fuel tank, and liquid nitrogen heating is used to achieve liquid nitrogen heating and pressurization of the fuel tank 2;

[0065] 9) The control of the liquid nitrogen flow rate in this process:

[0066] When the liquid continuously filling the pipeline flows through the contraction surface of the cavitation tube 9, the jet flow will form a local contraction inside the cavitation tube 9, thereby increasing the flow velocity and decreasing the static pressure. When the static pressure of the liquid at the throat drops to the liquid saturation vapor pressure Ps under the local temperature condition, part of the liquid forms steam, and cavitation occurs in the cavitation tube 9. At this time, the mass flow rate reaches the maximum value corresponding to the inlet pressure, and the flow rate q of the cavitation tube 9 m is calculated according to the following formula:

[0067]

[0068] In the formula, q m is the mass flow rate of the liquid under cavitation conditions, unit: kg / s; C is the flow coefficient of the cavitation tube, unit: dimensionless; A0 is the cross-sectional area of the throat of the cavitation tube, unit: m 2 ; P YD is the gas cushion pressure of the liquid nitrogen tank, unit: MPa; ρ YD is the liquid nitrogen density, unit: kg / m 3 ; P s is the saturation vapor pressure under the local temperature condition of the liquid nitrogen tank, unit: MPa; P h is the liquid nitrogen column pressure of the liquid nitrogen tank relative to the cavitation tube, unit: MPa; P ξ is the flow resistance loss of the liquid nitrogen tank delivery system, unit: MPa;

[0069] It can be obtained from the calculation formula that A0, P s , P h , P ξ , ρ YD are constant values. Therefore, only by controlling the gas cushion pressure of the liquid nitrogen tank 4 can a constant liquid nitrogen flow rate be achieved through the constant gas cushion pressure of the liquid nitrogen tank 4 + the cavitation tube 9 mode, thereby meeting the fuel tank pressurization requirements;

[0070] 10), The oxygen tank 1 uses oxygen self-pressurization, and the fuel tank 2 uses liquid nitrogen heating pressurization. The oxygen tank 1 and the fuel tank 2 are separated to prevent the oxygen tank 1 and the fuel tank 2 from gas cross-flow;

[0071] 11), Five oxygen self-boosters 56 are set at the five engines 3. The five oxygen self-boosters 56 are used to heat the liquid oxygen into high-temperature oxygen to pressurize the oxygen tank 1. Four first liquid nitrogen heaters 10 are set at the four engines 3. The four first liquid nitrogen heaters 10 are used to heat and vaporize the liquid nitrogen into high-temperature nitrogen to pressurize the fuel tank 2, which can achieve independent pressurization of the oxygen tank 1 and the fuel tank 2;

[0072] 12), A tee is set on the oxygen tank pressurization pipeline 13 for connecting the oxygen tank pre-launch pressurization pipeline.

[0073] 13) During the pre - launch pressurization on the ground, the pressurization function of the three tanks, namely the oxygen tank 1, the fuel tank 2, and the liquid nitrogen tank 4, can be completed using only one pre - launch helium pressurization pipeline 37.

[0074] 14) A branch is separated before launch for pre - launch pressurization of the fuel tank 2: The ground helium gas source 33 passes through the helium gas filter 26, the helium gas pressure reducing valve 28, the helium pressurization tail end plug - and - play connector 36, and the pre - launch helium pressurization pipeline 37, and then a branch is led out. After passing through the first helium pressurization solenoid valve 39 and the helium check valve 40, it converges into the fuel tank pressurization pipeline 12, and then passes through the fuel tank energy dissipator 15 to perform pre - launch pressurization on the fuel tank 2.

[0075] 15) A branch is separated before launch for pre - launch pressurization of the liquid nitrogen tank 4: The ground helium gas source 33 passes through the helium gas filter 26, the helium gas pressure reducing valve 28, the helium pressurization tail end plug - and - play connector 36, and the pre - launch helium pressurization pipeline 37, and then a branch is led out. After passing through the second helium pressurization solenoid valve 43 and the helium check valve 40, it converges into the liquid nitrogen tank pressurization pipeline 29 to perform pre - launch pressurization on the liquid nitrogen tank 4.

[0076] 16) A branch is separated before launch for pre - launch pressurization of the oxygen tank 1: The ground helium gas source 33 passes through the helium gas filter 26, the helium gas pressure reducing valve 28, the helium pressurization tail end plug - and - play connector 36, and the pre - launch helium pressurization pipeline 37, and then a branch is led out. After passing through the third pre - launch pressurization solenoid valve 46 and the helium check valve 40, it converges into the oxygen tank pressurization pipeline 13 to perform pre - launch pressurization on the oxygen tank 1.

[0077] 17) Separating the oxygen tank pressurization system and the fuel tank pressurization system can achieve independent pressurization of the two tanks, avoiding the reverse flow of gas in the oxygen tank into the fuel tank and preventing safety problems.

[0078] The advantages of this specific embodiment are as follows:

[0079] 1) Provide an "oxygen self - pressurization + liquid nitrogen heating pressurization" system. The oxygen tank 1 adopts the self - pressurization method. After 5 oxygen self - pressurizers 56 are heated, they pressurize the oxygen tank 1. At the same time, using the extrusion method of the liquid nitrogen tank 4, normal - temperature helium gas extrudes the liquid nitrogen in the liquid nitrogen tank 4. After being split by the cavitation tube 9 and heated by 4 first liquid nitrogen heaters 10, it pressurizes the fuel tank 2. By adopting the oxygen self - pressurization method, the specifications and volume of the liquid nitrogen heating pressurization system are reduced, and the development difficulty and complexity of the liquid nitrogen heating pressurization system are also reduced.

[0080] 2) The oxygen tank 1 adopts an open - type pressurization method, the fuel tank 2 adopts liquid nitrogen heating and pressurization, and the liquid nitrogen tank adopts normal - temperature helium gas pressurization; the helium gas pressure reducing valve 28 is used to control the gas pillow pressure of the liquid nitrogen tank 4. The constant gas pillow pressure of the liquid nitrogen tank 4 + the cavitation tube 9 idea is used to achieve a constant liquid nitrogen flow rate, thereby realizing the pressurization of the fuel tank 2 with a constant liquid nitrogen flow rate. By controlling the pressure after the valve with the helium gas pressure reducing valve 28, it can ensure that the gas pillow pressure of the liquid nitrogen tank 4 is always maintained at 4 MPa, and the stable liquid nitrogen outflow flow rate is achieved by maintaining the pressure stability of the liquid nitrogen tank 4.

[0081] 3) By making the exhaust pipe 30 of the liquid nitrogen tank sink 40 mm, the liquid nitrogen tank 4 can maintain a constant gas pillow volume. The excess liquid nitrogen is discharged through the exhaust valve 31 or the safety valve 32 of the liquid nitrogen tank, ensuring a stable gas pillow volume of the liquid nitrogen tank 4, so that the initial gas pillow volume of the liquid nitrogen tank 4 during the pre - launch process is about 3% of the total volume of the liquid nitrogen tank, realizing the customization of the initial gas pillow volume of the liquid nitrogen tank 4.

[0082] II. The second embodiment: The liquid nitrogen tank 4 adopts the engine gas extrusion method, and this system can be used in the first stage of a rocket. The structure is as shown in Figure 3 The working process and characteristics are as follows:

[0083] 1) During the first - stage flight, the oxygen tank 1 adopts liquid nitrogen heating and pressurization. The liquid nitrogen in the liquid nitrogen tank 4 passes through a tee, the main liquid nitrogen delivery pipeline 5, the liquid nitrogen filter 42, the second solenoid valve group 17, and the liquid nitrogen orifice plate 18 and converges into one path. Then, the liquid nitrogen is vaporized into high - temperature nitrogen gas by the second liquid nitrogen heater 19, and then the oxygen tank is pressurized on the rocket through the oxygen tank pressurization pipeline 13 and the oxygen tank energy dissipator 21;

[0084] 2) During the pressurization of the oxygen tank 1, the liquid nitrogen flow rate is controlled by three - way pressurization solenoid valves (the second solenoid valve group 17)+three - way liquid nitrogen orifice plates 18;

[0085] 3) During the first - stage flight, the oxygen tank gas pillow pressure sensor 23 senses the gas pillow pressure of the oxygen tank 1, transmits the data to the oxygen tank pressurization controller 24. The oxygen tank pressurization controller 24 calculates and makes a decision, and controls the opening and closing of the three - way pressurization solenoid valves (K4, K5, K6) in the second solenoid valve group 17 through the oxygen tank pressurization controller 24 to achieve precise control of the gas pillow pressure of the oxygen tank 1;

[0086] 4) During the first - stage flight, the liquid nitrogen in the liquid nitrogen tank 4 passes through a tee, the main liquid nitrogen delivery pipeline 5, the liquid nitrogen filter 42, the first solenoid valve group 8, and the liquid nitrogen orifice plate 35 and converges into one path. Then, the liquid nitrogen is vaporized into high - temperature nitrogen gas by the first liquid nitrogen heater 10, and then the fuel tank is pressurized on the rocket through the fuel tank pressurization pipeline 12 and the fuel tank energy dissipator 15;

[0087] 5) During the pressurization of the fuel tank 2, liquid nitrogen controls the liquid nitrogen flow rate through the three-way pressurization solenoid valve (the first solenoid valve group 8) + the three-way liquid nitrogen orifice plate 18;

[0088] 6) During the first-stage flight, the gas pillow pressure sensor 14 of the fuel tank senses the gas pillow pressure of the fuel tank 2, transmits the data to the fuel tank pressurization controller 7, and the fuel tank pressurization controller 7 calculates and makes a decision to control the opening and closing of the three-way pressurization solenoid valves (K1, K2, K3) in the first solenoid valve group 8 through the fuel tank pressurization controller 7, realizing the precise control of the gas pillow pressure of the fuel tank 2;

[0089] 7) During the first-stage flight, the gas pillow pressure of the fuel tank 2 is maintained at a relatively low pressure, which can prevent the common bottom 150 of the first-stage common-bottom storage tank from bearing back pressure;

[0090] 8) During the first-stage flight, the liquid nitrogen tank 4 adopts extrusion pressurization. The gas generators 34 of the two engines respectively enter the liquid nitrogen tank pressurization pipeline 29 after passing through the gas one-way valve 41 and the gas pressure reducing valve 44, and pressurize the liquid nitrogen tank 4 through the liquid nitrogen tank energy dissipator 38;

[0091] In this process, the high-temperature gas of the engine is used to pressurize the liquid nitrogen tank 4, simplifying the structure of the pressurization system of the liquid nitrogen tank 4; the combination of the gas generators 34 of the two engines and the 2 gas one-way valves 41 can prevent the risk of insufficient gas supply caused by the shutdown of a certain engine, improving the redundancy and reliability of the pressurization system of the liquid nitrogen tank 3.

[0092] In this specific embodiment, to ensure the stability of the common bottom 150 of the first-stage common-bottom storage tank, the corresponding control requirements are as follows:

[0093] t0 represents the ignition moment of the first stage of the rocket flight, and t1 represents the shutdown moment of the first stage of the rocket flight. The pressure borne on the upper side of the common bottom 150 of the first-stage common-bottom storage tank is the gas pillow pressure of the fuel tank 2 + the fuel liquid column pressure, that is, P R1 +ρ R gh R1 n x1 , the pressure borne on the lower side of the common bottom 150 of the first-stage common-bottom storage tank is the gas pillow pressure of the oxygen tank 1, that is, P Y1 , when P Y1 is greater than P R1 +ρ R gh R1 n x1 a negative pressure condition will occur in the common bottom 150 of the first-stage common-bottom storage tank. When the pressure on the upper side of the common bottom 150 of the first-stage common-bottom storage tank is greater than the pressure on the lower side, a negative pressure condition will occur in the common bottom 150 of the first-stage common-bottom storage tank. When a negative pressure condition occurs, the common bottom 150 of the first-stage common-bottom storage tank will collapse and finally be deformed and damaged.

[0094] Therefore, during the period from t0 to t1, the gas pillow pressure P of the fuel tank 2 should be controlled R1 to be kept at a relatively low level to prevent the gas pillow pressure of the fuel tank 2 from being too high during the first-stage flight, which may cause a negative pressure condition in the common bottom 150 of the first-stage common bottom tank at the end of the first-stage flight;

[0095] During the period from t0 to t1, the gas pillow pressure P of the oxygen tank 1 should be controlled Y1 to be kept at a relatively high level to prevent the gas pillow pressure of the first-stage oxygen tank 1 from being too low during the first-stage flight, which may cause a negative pressure condition in the common bottom 150 of the first-stage common bottom tank at the end of the first-stage flight.

[0096] III. Third Embodiment: The liquid nitrogen tank 4 also adopts the engine gas extrusion method and has the Figure 4 structure shown. Its working principle is similar to that of the second embodiment, but there are differences in aspects such as the form of the tank (in this example, the common bottom 170 of the second-stage common bottom tank arches downward, while in the second embodiment, the common bottom 170 of the second-stage common bottom tank arches upward) and the number of engine gas generators 34. It is preferably applied to the second stage of the rocket. Its working process and characteristics are as follows:

[0097] 1) During the second-stage flight, the oxygen tank 1 is heated and pressurized by liquid nitrogen. The liquid nitrogen in the liquid nitrogen tank 4 is collected through the liquid nitrogen main pipeline 5, liquid nitrogen filter 42, fourth solenoid valve group 45, and liquid nitrogen orifice plate 18, and then vaporized into high-temperature nitrogen by the second liquid nitrogen heater 19. Then, it is used to pressurize the oxygen tank 1 on the rocket through the oxygen tank pressurization pipeline 13 and oxygen tank energy dissipator 21;

[0098] 2) During the pressurization of the oxygen tank 1, the liquid nitrogen flow rate is controlled by three-way pressurization solenoid valves (fourth solenoid valve group 45) + three-way liquid nitrogen orifice plates 18;

[0099] 3) During the second-stage flight, the gas pillow pressure sensor 23 of the oxygen tank senses the gas pillow pressure of the oxygen tank 1, transmits the data to the oxygen tank pressurization controller 24. The oxygen tank pressurization controller 24 calculates and makes decisions, and controls the opening and closing of the three-way pressurization solenoid valves (K10, K11, K12) in the fourth solenoid valve group 45 through the oxygen tank pressurization controller 24 to achieve precise control of the gas pillow pressure of the oxygen tank 1;

[0100] 4) During the second-stage flight, the liquid nitrogen in the liquid nitrogen tank 4 is collected through the liquid nitrogen main pipeline 5, liquid nitrogen filter 42, third solenoid valve group 48, and liquid nitrogen orifice plate 18, and then vaporized into high-temperature nitrogen by the first liquid nitrogen heater 10. Then, it is used to pressurize the fuel tank 2 on the rocket through the fuel tank pressurization pipeline 12 and fuel tank energy dissipator 15;

[0101] 5) During the pressurization of the fuel tank 2, the liquid nitrogen flow rate is controlled by three-way pressurization solenoid valves (third solenoid valve group 48) + three-way liquid nitrogen orifice plates 18;

[0102] 6) During the second-stage flight phase, the pressure sensor 14 of the fuel tank gas pillow senses the gas pillow pressure of the fuel tank 2 during flight, transmits the data to the fuel tank pressurization controller 7, and the fuel tank pressurization controller 7 calculates and makes decisions to control the opening and closing of the three-way pressurization solenoid valves (K7, K8, K9) in the third solenoid valve group 48 through the fuel tank pressurization controller 7, so as to achieve precise control of the gas pillow pressure of the fuel tank 2;

[0103] 7) During the second-stage flight process, the gas pillow pressure of the fuel tank 2 is maintained at a relatively low pressure, which can prevent the common bottom 170 of the second-stage common-bottom storage tank from bearing back pressure.

[0104] 8) During the second-stage flight process, the liquid nitrogen tank 4 adopts extrusion pressurization. A gas generator 34 of one engine enters the liquid nitrogen tank pressurization pipeline 29 after passing through the gas check valve 41 and the gas pressure reducing valve 44, and pressurizes the liquid nitrogen tank 4 through the liquid nitrogen tank energy dissipator 38;

[0105] In this process, the high-temperature gas of the engine is used to pressurize the liquid nitrogen tank 4, which simplifies the structure of the pressurization system of the liquid nitrogen tank 4.

[0106] In this specific embodiment, in order to ensure the stability of the common bottom 170 of the second-stage common-bottom storage tank, the corresponding control requirements are as follows:

[0107] t2 represents the ignition moment of the second-stage flight of the rocket, and t3 represents the shutdown moment of the second-stage flight of the rocket. The pressure borne on the upper side of the common bottom 170 of the second-stage common-bottom storage tank is the gas pillow pressure of the oxygen tank 1 + the liquid oxygen liquid column pressure, that is, P Y2 +ρ Y gh Y2 n x2 , the pressure borne on the lower side of the common bottom 170 of the second-stage common-bottom storage tank is the gas pillow pressure of the fuel tank 2, that is, P R2 , when P R2 is greater than P Y2 +ρ Y gh Y2 n x2 a negative pressure condition will occur in the common bottom 170 of the second-stage common-bottom storage tank. When the pressure on the lower side of the common bottom 170 of the second-stage common-bottom storage tank is greater than the pressure on the upper side, a negative pressure condition will occur in the common bottom 170 of the second-stage common-bottom storage tank, resulting in collapse and finally deformation and damage.

[0108] Therefore, during t2~t3, the gas pillow pressure P of the fuel tank 2 should be controlled R2 to be kept low to prevent the gas pillow pressure of the fuel tank 2 from being too large during the second-stage flight, resulting in a negative pressure condition in the common bottom 170 of the second-stage common-bottom storage tank at the end of the second-stage flight.

[0109] During t2~t3, the gas pillow pressure P of the oxygen tank 1 should be controlled Y2Keep it at a relatively high level to prevent the gas pillow pressure in the oxygen tank 1 from being too small during the second-stage flight, which may cause a negative pressure condition in the common bottom 170 of the second-stage common bottom storage tank at the end of the second-stage flight.

[0110] In the third embodiment, the gas pillow pressures of the oxygen tank 1 and the fuel tank 2 in the second stage of the rocket (or the second-stage cabin section) can be precisely controlled. Therefore, in this embodiment, neither the oxygen tank 1 nor the fuel tank 2 is provided with safety valves (in the second embodiment, a fuel tank safety valve 16 and an oxygen tank safety valve 20 need to be provided respectively), which reduces the development difficulty and structural weight of the second-stage pressurization system and improves the rocket's carrying capacity.

[0111] In addition, in this technical solution, referring to Figure 5 , Figure 7 , the purge system, gas seal system, and pre-launch pressurization system of the first and second-stage cabin sections (the first-stage cabin section adopts the structural form of the second embodiment shown in Figure 3 , and the second-stage cabin section adopts the structural form of the third embodiment shown in Figure 4 ) are integrally designed. Using the unified gas supply and distribution technology, the purge system, gas seal system, and pre-launch pressurization system of the first and second-stage cabin sections are integratedly designed, and an integrated system for purge, gas seal, and pre-launch pressurization of the first and second-stage cabin sections is designed.

[0112] 1), The nitrogen gas from the ground nitrogen source 70 passes through the nitrogen filter 71, nitrogen pressure reducing valve 72, nitrogen boost tail-end pluggable connector 73, first nitrogen boost solenoid valve 111, and nitrogen orifice plate 112, and then merges into the liquid nitrogen tank pressurization pipeline 29 of the first-stage cabin section. After that, it passes through the liquid nitrogen tank energy dissipator 38 to perform pre-launch pressurization on the liquid nitrogen tank 4 of the first-stage cabin section;

[0113] 2), The nitrogen gas from the ground nitrogen source 70 passes through the nitrogen filter 71, nitrogen pressure reducing valve 72, nitrogen boost tail-end pluggable connector 73, second nitrogen boost solenoid valve 115, and nitrogen orifice plate 112, and then merges into the fuel tank pressurization pipeline 12 of the first-stage cabin section. After that, it passes through the fuel tank energy dissipator 15 to perform pre-launch pressurization on the fuel tank 2 of the first-stage cabin section;

[0114] 3), The nitrogen gas from the ground nitrogen source 70 passes through the nitrogen filter 71, nitrogen pressure reducing valve 72, nitrogen boost tail-end pluggable connector 73, third nitrogen boost solenoid valve 119, and nitrogen orifice plate 112, and then merges into the oxygen tank pressurization pipeline 13 of the first-stage cabin section. It performs pre-launch pressurization on the oxygen tank 1 of the first-stage cabin section through the oxygen tank energy dissipator 21;

[0115] Use the purge and gas seal system of the first-stage cabin section to perform pre-launch pressurization on the oxygen tank 1, fuel tank 2, and liquid nitrogen tank 4, and integrate the first-stage pre-launch pressurization system with the purge and gas seal system of the first-stage cabin section. At the same time, the purge and gas seal system of the second-stage cabin section is also integrated with the second-stage pre-launch pressurization system.

[0116] 4) The nitrogen gas from the ground nitrogen source 70 passes through the inter-stage separation plug connector 89, the second-stage boost first solenoid valve 131, and the nitrogen orifice plate 112, and then merges into the liquid nitrogen tank boost pipeline 29 of the second-stage section. After that, it is used to pre-launch boost the liquid nitrogen tank 4 of the second-stage section through the liquid nitrogen tank energy dissipator 38;

[0117] 5) The nitrogen gas from the ground nitrogen source 70 passes through the inter-stage separation plug connector 89, the second-stage boost second solenoid valve 135, and the nitrogen orifice plate 112, and then merges into the oxygen tank boost pipeline 13 of the second-stage section, and pre-launch boosts the oxygen tank 1 of the second-stage section through the oxygen tank energy dissipator 21;

[0118] 6) The nitrogen gas from the ground nitrogen source 70 passes through the inter-stage separation plug connector 89, the second-stage boost third solenoid valve 139, and the nitrogen orifice plate 112, and then merges into the fuel tank boost pipeline 12 of the second-stage section. After that, it is used to pre-launch boost the fuel tank 2 of the second-stage section through the fuel tank energy dissipator 15;

[0119] The oxygen tank 1, fuel tank 2, and liquid nitrogen tank 4 of the second-stage section are pre-launch boosted by using the second-stage section purge and gas seal system, and the second-stage pre-launch boost system and the second-stage section purge and gas seal system are integrally designed.

[0120] Regarding the control logic of the solenoid valve group in the second embodiment and the third embodiment, the following description is given:

[0121] As Figure 8 shown, it is the control logic diagram of the second solenoid valve group 17 in the second embodiment of the present invention. Among them, K4 is the main path solenoid valve in the second solenoid valve group 17, K5 is the auxiliary path solenoid valve, K6 is the standby protection path solenoid valve, P Y1 is the gas pillow pressure of the oxygen tank 1, P R10 is the pressure on the upper side of the common bottom 150 of the first-stage common bottom tank, P R10 =P R1 +ρ R gh R1 n x1 , P R1 is the gas pillow pressure of the fuel tank 2; ρ R is the fuel propellant density, unit kg / m 3 ; g is the gravitational acceleration, unit m / s 2 ; h R1 is the fuel liquid level height of the first-stage fuel tank, unit m; n x1 is the overload coefficient during the flight of the first-stage rocket, unit dimensionless; P 01 is the lower limit control band of the tank gas pillow pressure; the units of the pressures involved above are all Pa. The control process is as follows:

[0122] 1. The engine 3 ignites and starts, and then the first-stage flies, and the first-stage enters the first-stage boost timing;

[0123] 2. The oxygen tank air pillow pressure sensor 23 detects the air pillow pressure P of the oxygen tank 1 Y1 and sends it to the oxygen tank pressure boosting controller 24;

[0124] 3. After that, determine whether t0 ≤ t < t1 holds. If not, close the solenoid valves K4, K5, and K6, and then shut down the engine 3 of the first stage to end the first-stage flight process; if so, further determine whether P Y1 ≥ P R10 holds;

[0125] 4. If not, open the solenoid valves K4, K5, and K6, and then return to step 2; if so, further determine whether P R10 + P 01 ≥ P Y1 > P R10 holds;

[0126] 5. If so, open the solenoid valves K4 and K5, and keep the solenoid valve K6 in the previous state, and then return to step 2; if not, further determine whether P R10 + P 02 ≥ P Y1 > P R10 + P 01 holds;

[0127] 6. If so, open the solenoid valve K4, keep the solenoid valve K5 in the previous state, and close the solenoid valve K6, and then return to step 2; if not, open the solenoid valve K4, close the solenoid valves K5 and K6, and then return to step 2.

[0128] As Figure 9 shown, it is the control logic diagram of the first solenoid valve group 8 in the second embodiment of the present invention. Among them, K1 is the main path solenoid valve in the first solenoid valve group 8, K2 is the auxiliary path solenoid valve, and K3 is the standby protection path solenoid valve; P R1 is the air pillow pressure of the fuel tank 2, in Pa; P R1min is the minimum fuel tank air pillow pressure required by the engine 3 of the first-stage cabin section, in Pa; P 01 is the lower limit control band of the storage tank air pillow pressure, in Pa; P 02 : is the upper limit control band of the storage tank air pillow pressure, in Pa; its control process is as follows:

[0129] 1. The engine 3 is ignited and started, and then the first-stage flight begins, and the first stage enters the first-stage pressure boosting time sequence;

[0130] 2. The fuel tank air pillow pressure sensor 14 detects the air pillow pressure P of the fuel tank 2 Y2 and sends it to the fuel tank pressure boosting controller 7;

[0131] 3. Then, determine whether t0 ≤ t < t1 holds. If not, close solenoid valves K1, K2, and K3, and then shut down the engine 3 of the first stage to end the first-stage flight process. If so, further determine whether P R1 ≥ P R1min holds;

[0132] 4. If not, open solenoid valves K1, K2, and K3, and then return to step 2. If so, further determine whether P R1min + P 01 ≥ P R1 > P R1min holds;

[0133] 5. If so, open solenoid valves K1 and K2, and keep solenoid valve K3 in the previous state, and then return to step 2. If not, further determine whether P R1min + P 02 ≥ P R1 > P R1min + P 01 holds;

[0134] 6. If so, open solenoid valve K1, keep solenoid valve K2 in the previous state, and close solenoid valve K3, and then return to step 2. If not, open solenoid valve K1, close solenoid valves K2 and K3, and then return to step 2.

[0135] As Figure 10 shown, it is the control logic diagram of the fourth solenoid valve group 45 in the third embodiment of the present invention. Among them, K10 is the main path solenoid valve in the fourth solenoid valve group 45, K11 is the auxiliary path solenoid valve, K12 is the backup protection path solenoid valve, P Y2 is the gas pillow pressure of the oxygen tank 1 in the second-stage cabin section, P R20 is the upper side pressure of the common bottom 170 of the second-stage common bottom storage tank, P Y20 = P Y2 + ρ Y gh Y2 n x2 , P R2 is the gas pillow pressure of the fuel tank 2; ρ Y is the density of liquid oxygen propellant, with the unit kg / m 3 ; g is the acceleration of gravity, with the unit m / s 2 ; h Y2 is the liquid oxygen liquid level height in the oxygen tank 2, with the unit m; n x2 is the overload coefficient during the second-stage flight process, with the unit dimensionless; P 01 is the lower limit control band of the storage tank gas pillow pressure, with the unit Pa; its control process is as follows:

[0136] 1. The engine 3 is ignited and started, and then the second-stage flight begins. The second stage enters the second-stage pressurization timing sequence;

[0137] 2. The oxygen tank air-cushion pressure sensor 23 detects the air-cushion pressure P of the oxygen tank 1 Y1 and sends it to the oxygen tank pressurization controller 24;

[0138] 3. Then, it is judged whether t2 ≤ t < t3 holds. If not, the solenoid valves K10, K11, and K12 are closed, and then the engine 3 of the second stage is shut down to end the second-stage flight process; if so, it is further judged whether P Y20 ≥ P R2 holds;

[0139] 4. If not, the solenoid valves K10, K11, and K12 are opened, and then it returns to step 2; if so, it is further judged whether P R2 + P 01 ≥ P Y20 > P R2 holds;

[0140] 5. If so, the solenoid valves K10 and K11 are opened, and the solenoid valve K12 is kept in the previous state, and then it returns to step 2; if not, it is further judged whether P R2 + P 02 ≥ P Y20 > P R2 + P 01 holds;

[0141] 6. If so, the solenoid valve K10 is opened, the solenoid valve K11 is kept in the previous state, and the solenoid valve K12 is closed, and then it returns to step 2; if not, the solenoid valve K10 is opened, the solenoid valves K11 and K12 are closed, and then it returns to step 2.

[0142] As Figure 11 shown, it is the control logic diagram of the third solenoid valve group 48 in the third embodiment of the present invention. Among them, K7 is the main path solenoid valve in the third solenoid valve group 48, K8 is the auxiliary path solenoid valve, and K9 is the standby protection path solenoid valve; P R2 is the air-cushion pressure of the fuel tank 2 in the second-stage cabin section, with the unit of Pa; P R2min is the minimum fuel tank air-cushion pressure required for the engine 3 in the second-stage cabin section, with the unit of Pa; P 01 is the lower limit control band of the storage tank air-cushion pressure, with the unit of Pa; P 02 is the upper limit control band of the storage tank air-cushion pressure, with the unit of Pa; its control process is as follows:

[0143] 1. The engine 3 is ignited and started, and then the second-stage flight begins. The second stage enters the second-stage pressurization timing sequence;

[0144] 2. The fuel tank air pillow pressure sensor 14 detects the air pillow pressure P of the fuel tank 2 Y2 and sends it to the fuel tank pressurization controller 7;

[0145] 3. After that, it is judged whether t2 ≤ t < t3 holds. If not, the solenoid valves K7, K8, and K9 are closed, and then the engine 3 at the second stage is shut down, ending the second-stage flight process; if so, it is further judged whether P R2 ≥ P R2min holds;

[0146] 4. If not, the solenoid valves K7, K8, and K9 are opened, and then it returns to step 2; if so, it is further judged whether P R2min + P 01 ≥ P R2 > P R2min holds;

[0147] 5. If so, the solenoid valves K7 and K8 are opened, and the solenoid valve K9 is kept in the previous state, and then it returns to step 2; if not, it is further judged whether P R2min + P 02 ≥ P R2 > P R2min + P 01 holds;

[0148] 6. If so, the solenoid valve K7 is opened, the solenoid valve K8 is kept in the previous state, and the solenoid valve K9 is closed, and then it returns to step 2; if not, the solenoid valve K7 is opened, the solenoid valves K8 and K9 are closed, and then it returns to step 2.

[0149] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be construed as reflecting an intention that the embodiments of the claimed subject matter require more features than those clearly recited in each claim. On the contrary, as reflected in the appended claims, the present invention lies in a state with fewer features than all the features of the disclosed single embodiment. Therefore, the appended claims are hereby clearly incorporated into the detailed description, where each claim stands alone as a separate preferred embodiment of the present invention.

[0150] The above-described disclosed embodiments are described to enable any person skilled in the art to implement or use the present invention. For those skilled in the art; various modifications to these embodiments are obvious, and the general principles defined herein can also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0151] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A liquid nitrogen heating and pressurizing system for a launch vehicle, comprising an oxygen tank (1), a fuel tank (2), an oxygen tank energy dissipator (21) arranged at the inner top of the oxygen tank (1), a fuel tank energy dissipator (15) arranged at the inner top of the fuel tank (2), and an engine (3) connected to the oxygen tank (1) and the fuel tank (2) respectively through pipelines, characterized in that, It further includes a liquid nitrogen tank (4) for containing liquid nitrogen, and a first liquid nitrogen heater (10) connected to the engine (3); The liquid nitrogen tank (4) is located inside the oxygen tank (1), and the top of the liquid nitrogen tank (4) is lower than the initial liquid level of the oxygen tank (1). The initial liquid level of the oxygen tank (1) refers to the liquid level height of the liquid oxygen in the oxygen tank (1) at the moment when the launch vehicle ignites; The outlet of the liquid nitrogen tank (4) is connected to the inlet of the first liquid nitrogen heater (10) through a pipeline, and the outlet of the first liquid nitrogen heater (10) is connected to the fuel tank damper (15) through a pipeline; The gas pillow of the liquid nitrogen tank (4) is connected to a liquid nitrogen tank pressurization pipeline (29).

2. The liquid nitrogen heating and pressurization system of a launch vehicle according to claim 1, wherein The medium in the liquid nitrogen tank pressurization pipeline (29) is helium; The gas pillow of the liquid nitrogen tank (4) is sequentially connected to a helium pressure reducing valve (28), a helium pressurization solenoid valve (27), and a helium gas cylinder (25) through the liquid nitrogen tank pressurization pipeline (29); A cavitation tube (9) is also connected between the liquid nitrogen tank (4) and the first liquid nitrogen heater (10).

3. The liquid nitrogen heating and pressurizing system for a launch vehicle according to claim 2, characterized in that It further includes an oxygen self-booster (56) connected to the engine (3), and the oxygen self-booster (56) is connected to the oxygen tank damper (21) through a pipeline.

4. The liquid nitrogen heating and pressurizing system of a launch vehicle according to claim 2, wherein The top of the liquid nitrogen tank (4) is also connected to a liquid nitrogen tank exhaust pipe (30); one end of the liquid nitrogen tank exhaust pipe (30) vertically extends into the liquid nitrogen tank (4) by a preset length, and the other end of the liquid nitrogen tank exhaust pipe (30) is located outside the liquid nitrogen tank (4) and is connected to a liquid nitrogen tank exhaust valve (31).

5. The liquid nitrogen heating and pressurizing system of a launch vehicle according to claim 2, characterized in that, It further includes a liquid nitrogen filling device (51), and the liquid nitrogen filling device (51) is connected to the liquid nitrogen tank (4) in a detachable manner.

6. The liquid nitrogen heating and pressurizing system for a launch vehicle according to claim 1, characterized in that, The medium in the liquid nitrogen tank pressurization pipeline (29) is engine gas; The liquid nitrogen heating and pressurization system of the launch vehicle further includes an engine gas generator (34) connected to the engine (3); A liquid nitrogen tank damper (38) is also provided on the inner top of the liquid nitrogen tank (4), and the engine gas generator (34) is connected to the liquid nitrogen tank damper (38) through the liquid nitrogen tank pressurization pipeline (29).

7. The liquid nitrogen heating and pressurizing system of a launch vehicle according to claim 6, wherein, It further includes a second liquid nitrogen heater (19) connected to the engine (3); the outlet of the liquid nitrogen tank (4) is connected to the inlet of the second liquid nitrogen heater (19) through a pipeline, and the outlet of the second liquid nitrogen heater (19) is connected to the oxygen tank damper (21) through a pipeline.

8. The liquid nitrogen heating and pressurizing system for a launch vehicle according to claim 7, wherein, It further includes an oxygen tank pressurization controller (24) and a fuel tank pressurization controller (7). An oxygen tank gas pillow pressure sensor (23) connected to the gas pillow of the oxygen tank (1) is also connected to the oxygen tank (1), and a fuel tank gas pillow pressure sensor (14) connected to the gas pillow of the fuel tank (2) is also connected to the fuel tank (2). A first solenoid valve group (8) is also connected between the liquid nitrogen tank (4) and the first liquid nitrogen heater (10), and a second solenoid valve group (17) is also connected between the liquid nitrogen tank (4) and the second liquid nitrogen heater (19); The oxygen tank gas pillow pressure sensor (23) is electrically connected to the second solenoid valve group (17) through the oxygen tank pressurization controller (24); The fuel tank gas pillow pressure sensor (14) is electrically connected to the first solenoid valve group (8) through the fuel tank pressurization controller (7); The first solenoid valve group (8) includes a first main path solenoid valve, a first auxiliary path solenoid valve, and a first standby protection path solenoid valve, and the second solenoid valve group (17) includes a second main path solenoid valve, a second auxiliary path solenoid valve, and a second standby protection path solenoid valve.

9. The liquid nitrogen heating and pressurizing system for a launch vehicle according to any one of claims 1-8, characterized in that, It further includes a ground gas source for pre-launch ground pressurization, and the ground gas source is respectively connected to the oxygen tank energy dissipator (21), the fuel tank energy dissipator (15), and the liquid nitrogen tank pressurization pipeline (29).

10. A liquid rocket, characterized in that, It includes a liquid nitrogen heating and pressurization system for a launch vehicle as described in any one of claims 1-9.

Images