Gradient temperature control filling system for liquid oxygen storage tank of launch vehicle

Abstract

The utility model provides a gradient temperature regulation and control filling system for carrying rocket liquid oxygen storage tank, including storage tank, low temperature propellant supply system and discharge system, the inside of storage tank is used for storing propellant, and the propellant is divided into lower low temperature propellant and upper high temperature propellant, the storage tank is communicated with low temperature propellant supply system through bottom filling pipeline, is provided with bottom valve on bottom filling pipeline, the storage tank is communicated with discharge system through upper auxiliary pipeline, is provided with high temperature propellant discharge valve on upper auxiliary pipeline, one end of upper auxiliary pipeline and storage tank communication extends to the below preset depth of gas -liquid interface in the storage tank. The utility model on the basis of traditional filling pipeline, add upper auxiliary pipeline, realize the special discharge of upper high temperature propellant, make propellant temperature always be in the use range, and this filling system can selectively remove the upper high temperature propellant of storage tank, and can be compatible with existing storage tank, need not to carry out large -scale reform to existing storage tank.

Description

Technical Field

[0001] This utility model relates to the field of aerospace propellant refueling technology, specifically to a gradient temperature control refueling system for a liquid oxygen tank of a launch vehicle, and more particularly to a system for controlling the temperature stratification of cryogenic propellant in the tank during the ground parking period before launch. Background Technology

[0002] Cryogenic liquid oxygen (LOX) is a widely used oxidizer in modern launch vehicles. Rockets are filled with liquid oxygen several hours before launch and undergo a ground-based storage phase. Due to unavoidable heat leakage from the propellant tanks, significant temperature stratification (thermal stratification) occurs: the lower layer of liquid oxygen is cooler, while the upper layer, being closer to the gas cushion and affected by heat leakage from the walls, experiences a greater temperature rise. This results in the rocket drawing in the warmer upper layer of liquid oxygen at the engine pump inlet later in the flight mission. If this liquid oxygen temperature exceeds the engine pump's design tolerance, it can cause cavitation, leading to decreased engine performance or even premature shutdown, threatening mission success.

[0003] Currently, existing cryogenic propellant loading technologies mainly employ the following methods: 1) Traditional Flush System: Traditional cryogenic propellant flushing systems typically employ a single bottom-filling pipeline and a top-venting port design. Cryogenic propellant is added from the bottom of the tank, and venting occurs from the top. This structure is simple, but it cannot solve the problem of cryogenic propellant temperature stratification. During rocket ground storage, due to heat leakage from the tank, significant temperature stratification occurs in the cryogenic propellant—the lower layer of cryogenic propellant has a lower temperature, while the upper layer has a higher temperature.

[0004] 2) Circulating subcooling system: Such as the system developed by Jiangsu Tianbing Aerospace Technology Co., Ltd., which adopts the method of "filling first and then subcooling". It subcools the liquid oxygen in the rocket's oxygen tank by setting up a circulating subcooling pipeline with a liquid oxygen pump. The system includes a liquid oxygen filling pipeline, a circulating subcooling pipeline, and a liquid nitrogen pipeline, which reduces the temperature of the liquid oxygen through circulation.

[0005] 3) Fully subcooled refueling system: Such as the system developed by Beijing Tianbing Technology Co., Ltd., which uses dual liquid nitrogen subcooling (a conventional liquid nitrogen first subcooler and a vacuum-evacuated liquid nitrogen second subcooler) to subcool liquid oxygen to about 78K, achieving deep subcooling of liquid oxygen. This method improves subcooling efficiency, but the system is complex and costly.

[0006] The current mainstream technical solutions have the following drawbacks / deficiencies: 1) Structural limitations of traditional fueling and venting systems: Existing systems mostly employ a single bottom fueling line and a top vent. This structure determines its functional limitations: the bottom fueling line is primarily used for rapidly filling the tank, while the top vent is mainly used for controlling tank pressure. No existing line is designed or capable of selectively venting the upper layer of heated liquid oxygen after fueling and before launch. When it is necessary to vent the upper layer of high-temperature cryogenic propellant, existing systems are incapable. If venting through the bottom line, the lower layer of cryogenic propellant will be vented first; if venting through the top vent, only gas can be vented, and liquid cannot be effectively vented. This structural "functional deficiency" directly results in the inability to remove the high-temperature cryogenic propellant.

[0007] 2) Passive nature of thermal management during ground parking: Current technologies for thermal management during ground parking are relatively passive, mainly relying on the insulation layer of the tank to slow down heat leakage, but cannot completely prevent heat transfer. Although some technologies use circulating recirculation subcooling to try to lower the overall temperature of cryogenic propellants, this method is complex, energy-intensive, and only addresses the symptoms, not the root cause—the physical phenomena of natural convection and temperature stratification of cryogenic propellants under gravity still exist, and the temperature of the upper layer of propellant is still relatively higher than that of the lower layer, failing to fundamentally solve the stratification problem.

[0008] 3) The Inevitability and Control Challenges of Temperature Stratification: When cryogenic propellants are stationary in a gravitational field, their physical properties and heat transfer characteristics inevitably lead to temperature stratification. Heat leakage from the tank walls causes the temperature of the cryogenic propellant near the walls to rise, resulting in a decrease in density and its upward movement. This creates a temperature gradient from top to bottom within the tank. Even if sensors detect a higher temperature in the upper layer, existing systems lack a simple, compatible actuator to precisely eliminate this stratification.

[0009] 4) The contradiction between system complexity and reliability: In order to improve performance, some existing technologies have adopted complex circulation loops and multiple subcoolers (such as CN117342515A and CN117905607B), which increases the complexity of the system and the number of failure points. The increase in system complexity means more potential failure points, higher manufacturing costs and more complicated operating procedures. Utility Model Content

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a gradient temperature control refueling system for liquid oxygen storage tanks in launch vehicles.

[0011] The gradient temperature control refueling system for a liquid oxygen tank of a launch vehicle provided by this utility model includes a tank, a cryogenic propellant supply system and a discharge system. The tank is used to store propellant, which is divided into a lower layer of cryogenic propellant and an upper layer of high-temperature propellant. The tank is connected to the cryogenic propellant supply system via a bottom filling pipeline, and a bottom valve is installed on the bottom filling pipeline. The storage tank is connected to the discharge system via an upper auxiliary pipeline, and a high-temperature propellant discharge valve is installed on the upper auxiliary pipeline; One end of the upper auxiliary pipeline, which is connected to the storage tank, extends to a predetermined depth below the gas-liquid interface inside the storage tank, for discharging the upper high-temperature propellant.

[0012] Preferably, the upper auxiliary pipeline includes a tank connecting pipe section, an auxiliary filling pipe section, and a discharge pipe section; One end of the tank connecting pipe is connected to the tank, and the other end of the tank connecting pipe is connected to one end of the auxiliary refueling pipe and one end of the discharge pipe. The other end of the auxiliary refueling pipe is connected to the cryogenic propellant supply system, and the other end of the discharge pipe is connected to the discharge system.

[0013] Preferably, an upper valve is provided on the tank connecting pipe section.

[0014] Preferably, the high-temperature propellant discharge valve is installed on the discharge pipe section.

[0015] Preferably, the auxiliary filling pipe section is equipped with an upper filling valve.

[0016] Preferably, the top of the storage tank has an air cushion area for storing air cushions.

[0017] Preferably, the top of the storage tank is provided with an exhaust valve for discharging gas from the air cushion area.

[0018] Preferably, the end of the upper auxiliary pipeline that connects to the storage tank is not higher than the interface between the lower cryogenic propellant and the upper high-temperature propellant.

[0019] Preferably, the preset depth is 1.5-4 meters.

[0020] Preferably, it also includes a control system, which is electrically connected to the bottom valve, the top valve, the high-temperature propellant discharge valve, and the top filling valve.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention adds an upper auxiliary pipeline to the traditional bottom filling pipeline, thereby realizing the dedicated discharge of high-temperature propellant in the upper layer. This ensures that the temperature of the propellant drawn into the engine pump inlet is always within the operating range. This filling system can selectively remove high-temperature propellant in the upper layer of the tank without significantly increasing the complexity of the system, and it is compatible with the existing tank structure without the need for large-scale modification of the existing tank. Attached Figure Description

[0022] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0023] The diagram shows: Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0025] This utility model discloses a gradient temperature control refueling system for liquid oxygen tanks of launch vehicles. Based on the traditional bottom refueling pipeline, an upper auxiliary pipeline is added to achieve dedicated discharge of high-temperature propellant in the upper layer, so that the temperature of the propellant drawn in by the engine pump inlet is always within the operating range. This refueling system can selectively remove high-temperature propellant in the upper layer of the tank without significantly increasing the complexity of the system, and it is compatible with the existing tank structure without the need for large-scale modification of the existing tank.

[0026] The gradient temperature control refueling system for a liquid oxygen tank in a launch vehicle, provided by this utility model, includes: Bottom filling line 1 is connected to the bottom of tank 12 for filling and replenishing cryogenic propellant; Bottom valve 2 controls the opening and closing of bottom filling pipeline 1; The upper auxiliary pipeline 3 extends to a preset depth below the gas-liquid interface 13 inside the storage tank 12 at its inlet end, and has both filling and discharging functions. In a preferred embodiment, the upper auxiliary pipeline 3 includes a tank connecting pipe section, an auxiliary filling pipe section, and a discharge pipe section; one end of the tank connecting pipe section is connected to the tank 12, the other end of the tank connecting pipe section is connected to one end of the auxiliary filling pipe section and one end of the discharge pipe section, the other end of the auxiliary filling pipe section is connected to the cryogenic propellant supply system 7, and the other end of the discharge pipe section is connected to the discharge system 8.

[0027] Upper valve 4 controls the opening and closing of the tank connecting pipe section in the upper auxiliary pipeline 3; High-temperature propellant discharge valve 5 is used to control the safe discharge of upper high-temperature propellant 10; Upper filling valve 6 controls the opening and closing of the auxiliary filling pipe section in the upper auxiliary pipeline 3; Cryogenic propellant supply system 7 provides cryogenic propellant; Discharge system 8 is used for the safe discharge of high-temperature propellant; Lower layer cryogenic propellant 9, storing cryogenic propellant at low temperatures; The upper high-temperature propellant 10 includes a high-temperature cryogenic propellant; Air pillow area 11, for storing air pillows; Tank 12 is used to store cryogenic propellant; Gas-liquid interface 13, the interface between air cushion region 11 and liquid region; Exhaust valve 14 controls the pressure of storage tank 12; Control system: The control system 15 is electrically connected to the bottom valve 2, the upper valve 4, the high-temperature propellant discharge valve 5, and the upper filling valve 6, and is used to control the opening and closing of the valves of the main filling pipeline and the valves of the auxiliary pipeline in sequence.

[0028] In a preferred embodiment, the end of the upper auxiliary pipeline 3 that connects to the tank 12 is not higher than the interface between the lower cryogenic propellant 9 and the upper high-temperature propellant 10, and the inlet end of the upper auxiliary pipeline 3 extends to a preset depth of 1.5-4 meters below the gas-liquid interface 13 inside the tank 12.

[0029] Example 1: This embodiment discloses a gradient temperature control refueling system for a liquid oxygen tank of a launch vehicle. This system can effectively remove the high-temperature liquid oxygen in the upper layer of the tank before launch and replenish it with low-temperature liquid oxygen, significantly reducing liquid oxygen temperature stratification and ensuring that the liquid oxygen temperature entering the pump always meets the engine requirements. Moreover, the system requires minimal modification and is simple and reliable to implement.

[0030] like Figure 1 As shown, the system is divided into two subsystems: The first subsystem consists of a propellant tank 12, a bottom filling pipeline 1, a bottom valve 2, and a cryogenic propellant supply system 7. The cryogenic propellant supply system 7 is connected to the propellant tank 12 via the bottom filling pipeline 1 and the bottom valve 2, enabling the supercooled cryogenic propellant to be added to the predetermined liquid level in the tank. After filling, the rocket enters a parking state for 2-4 hours. During this period, a clear temperature stratification occurs in the propellant within the tank. The upper layer of high-temperature propellant 10 is located 1.5-4 meters below the designed liquid level (this location is determined by CFD thermal stratification calculations). Below the upper layer of high-temperature propellant 10 is the lower layer of cryogenic propellant 9. The area above the gas-liquid interface 13 is the gas cushion region 11. An exhaust valve 14 is installed on the top of the tank to control the tank pressure.

[0031] The second subsystem consists of an upper auxiliary pipeline 3, an upper valve 4, a cryogenic propellant discharge valve 5, an upper filling valve 6, a discharge system 8, and a cryogenic propellant supply system 7. The tank and discharge system 8 are connected via upper auxiliary pipeline 3, upper valve 4, and cryogenic propellant discharge valve 5, allowing the high-temperature propellant 10 in the upper layer of the tank, after being left to stand, to be discharged into the discharge system 8. The tank and cryogenic propellant supply system 7 are connected via upper auxiliary pipeline 3, upper valve 4, and upper filling valve 6, allowing the cryogenic propellant supply system 7 to fill the upper layer of the tank.

[0032] This embodiment, through the proposed dual-pipeline architecture, constitutes a control system that can operate collaboratively or independently, achieving refined differentiation and management of propellants with different properties (such as different temperatures) within the tank from a hardware perspective. Initial filling (using bottom filling pipeline 1): close the upper valve 4, open the vent valve 14 at the top of the tank, and open the bottom valve 2. Cryogenic propellant is added from the cryogenic propellant supply system 7, via the bottom filling pipeline 1, from the bottom of the tank 12 until the predetermined liquid level is reached.

[0033] After the above process is completed, the system is left to stand. The influx of external heat causes the fluid in the tank to stratify at different temperatures: the temperature of the upper propellant rises, forming a high-temperature propellant 10, while the temperature of the lower-temperature propellant 9 remains low.

[0034] 0.5-1 hour before launch, bottom valve 2 is closed and top valve 4 is opened. The upper high-temperature propellant 10 in tank 12 is precisely drawn in by upper auxiliary pipeline 3, flows through the opened top valve 4 and the opened high-temperature propellant discharge valve 5, and finally enters the discharge system 8 for processing. Only the upper high-temperature propellant 10 with excessive temperature is selectively discharged, while a large amount of qualified lower cryogenic propellant 9 is retained.

[0035] After the above process is completed, there are three replenishment procedures: First, the high-temperature propellant discharge valve 5 is closed and the bottom valve 2 is opened. The cryogenic propellant supply system 7 then supplies cryogenic propellant again, replenishing it from the bottom of the storage tank 12 through the bottom filling pipeline 1 until the liquid level is restored.

[0036] Second, the high-temperature propellant discharge valve 5 is closed, and the bottom valve 2 is closed. The cryogenic propellant supply system 7 then supplies cryogenic propellant again, replenishing it from the upper layer of the storage tank 12 via the upper auxiliary pipeline 3 until the liquid level is restored.

[0037] Third, by simultaneously carrying out the two replenishment processes mentioned above, the overall temperature of the fluid in tank 12 is significantly reduced and homogenized, ensuring the quality of the propellant during subsequent use (such as the engine pump inlet temperature requirements).

[0038] This invention adds an auxiliary filling / discharging pipeline located at the top of the tank to the traditional bottom filling pipeline. The optimal opening position of the upper auxiliary pipeline 3 is optimized and determined through computational fluid dynamics (CFD) simulation and experimental data, thereby ensuring the accurate discharge of liquid oxygen layers with excessive temperature. The newly added upper auxiliary pipeline makes full use of existing interfaces and space layout to ensure compatibility with various types of tanks and minimize changes to the existing design.

[0039] This invention directly and physically removes the heated upper layer of liquid oxygen, eliminating the risk of engine performance degradation due to excessively high upper liquid oxygen temperatures. It eliminates the need for complex liquid nitrogen supercooling systems or intermediate storage tanks, primarily utilizing existing refueling pipelines with the addition of a branch upper layer discharge pipeline. This low-cost, highly reliable approach can be widely applied to various launch vehicles, missiles, and other spacecraft employing cryogenic propellants, particularly those space launch systems with stringent requirements for the temperature of the cryogenic propellant at the engine inlet. The temperature stability of the cryogenic propellant directly affects engine performance and mission success rate.

[0040] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] The specific embodiments of this utility model have been described above. It should be understood that this utility model is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the substantive content of this utility model. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A gradient temperature control refueling system for a liquid oxygen storage tank in a launch vehicle, characterized in that, It includes a storage tank (12), a cryogenic propellant supply system (7) and an exhaust system (8). The storage tank (12) is used to store propellant, which is divided into a lower layer of cryogenic propellant (9) and an upper layer of high-temperature propellant (10). The tank (12) is connected to the cryogenic propellant supply system (7) through the bottom filling pipeline (1), and a bottom valve (2) is provided on the bottom filling pipeline (1). The storage tank (12) is connected to the discharge system through the upper auxiliary pipeline (3), and a high-temperature propellant discharge valve (5) is installed on the upper auxiliary pipeline (3). The upper auxiliary pipeline (3) is connected to the storage tank (12) at one end, which extends to a predetermined depth below the gas-liquid interface (13) inside the storage tank (12) for discharging the upper high-temperature propellant (10).

2. The gradient temperature control and refueling system for a liquid oxygen storage tank of a launch vehicle according to claim 1, characterized in that, The upper auxiliary pipeline (3) includes a tank connecting pipe section, an auxiliary filling pipe section, and a discharge pipe section; One end of the tank connecting pipe is connected to the tank (12), and the other end of the tank connecting pipe is connected to one end of the auxiliary filling pipe and one end of the discharge pipe respectively. The other end of the auxiliary filling pipe is connected to the cryogenic propellant supply system (7), and the other end of the discharge pipe is connected to the discharge system (8).

3. The gradient temperature control and refueling system for a liquid oxygen storage tank of a launch vehicle according to claim 2, characterized in that, An upper valve (4) is installed on the connecting pipe section of the storage tank.

4. The gradient temperature control and refueling system for a liquid oxygen storage tank of a launch vehicle according to claim 2, characterized in that, The high-temperature propellant discharge valve (5) is installed on the discharge pipe section.

5. The gradient temperature control and refueling system for a liquid oxygen tank in a launch vehicle according to claim 3, characterized in that, An upper filling valve (6) is installed on the auxiliary filling pipe section.

6. The gradient temperature control and refueling system for a liquid oxygen tank in a launch vehicle according to claim 1, characterized in that, The top of the storage tank (12) has an air cushion area (11) for storing air cushions.

7. The gradient temperature control and refueling system for a liquid oxygen storage tank of a launch vehicle according to claim 6, characterized in that, The top of the storage tank (12) is provided with an exhaust valve (14) for venting gas in the air cushion area (11).

8. The gradient temperature control and refueling system for a liquid oxygen tank in a launch vehicle according to claim 1, characterized in that, The end of the upper auxiliary pipeline (3) that connects to the tank (12) is not higher than the interface between the lower cryogenic propellant (9) and the upper high-temperature propellant (10).

9. The gradient temperature control refueling system for a liquid oxygen tank in a launch vehicle according to claim 1, characterized in that, The preset depth is 1.5-4 meters.

10. The gradient temperature control refueling system for a liquid oxygen tank in a launch vehicle according to claim 5, characterized in that, It also includes a control system (15), which is electrically connected to the bottom valve (2), the upper valve (4), the high-temperature propellant discharge valve (5), and the upper filling valve (6).

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