Multi-machine low-temperature liquid carrier rocket pre-cooling system and pre-cooling method

Abstract

The invention relates to the technical field of liquid carrier rockets, and provides a multi-machine low-temperature liquid carrier rocket pre-cooling system and a multi-machine low-temperature liquid carrier rocket pre-cooling method. The plurality of engines are respectively connected with the storage tank through conveying pipes; the backflow ring pipe is suitable for being arranged along the cabin wall of the engine cabin and is provided with a first flow outlet, a second flow outlet and a plurality of flow inlets, the first main backflow pipe is connected between the first flow outlet and the storage box, and the second main backflow pipe is connected between the second flow outlet and the storage box; the plurality of branch return pipes are connected between the plurality of engines and the plurality of flow inlets in a one-to-one correspondence manner; the multiple flow inlets are formed in the annular direction of the backflow annular pipe at intervals, and the flow inlets are formed in the two sides of the first flow outlet and the two sides of the second flow outlet correspondingly. According to the pre-cooling system, good flow characteristics can be obtained, the situation that a large-size multi-way pipe occupies the space of an engine compartment is avoided, and each engine can achieve the good pre-cooling effect.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid launch vehicles, and particularly to a precooling system and a precooling method for a multi-engine cryogenic liquid launch vehicle. Background Art

[0002] Before a cryogenic liquid launch vehicle ignites, the engine and its fuel delivery system must be fully cooled to bring the engine to the temperature required before startup. If the precooling is insufficient, the cryogenic propellant will undergo a violent phase change when heated, and the propellant will enter the turbopump in a state of a gas-liquid two-phase mixed fluid, which will cause cavitation of the pump and lead to abnormal operation of the engine.

[0003] Currently, the precooling methods for cryogenic liquid rocket engines at home and abroad are mainly discharge precooling and circulation precooling. In discharge precooling, the cryogenic propellant flows through the cooling delivery pipeline and the engine and is directly discharged outside the rocket through a drain valve. In circulation precooling, a precooling return pipeline is provided between the engine and the propellant tank, so that the cryogenic propellant flows through the cooling delivery pipeline and the engine and then flows back into the tank through the precooling return pipeline. For a large-thrust launch vehicle with multiple engines in parallel, the precooling demand increases significantly, the propellant flow rate required for precooling is larger, and the volume of the precooling system also increases accordingly. The structure of the traditional precooling system will occupy a large space in the engine compartment and the precooling effect is not good. Summary of the Invention

[0004] The present invention provides a precooling system and a precooling method for a multi-engine cryogenic liquid launch vehicle to solve the problems that the precooling system of the multi-engine cryogenic liquid launch vehicle in the prior art occupies a large space in the engine compartment and has a poor precooling effect.

[0005] The present invention provides a precooling system for a multi-engine cryogenic liquid launch vehicle, including: A tank for storing cryogenic propellant; Multiple engines, each of the multiple engines is connected to the tank through a delivery pipe; A return pipe group, including: a return loop pipe, a first main return pipe, a second main return pipe, and multiple branch return pipes. The return loop pipe is adapted to be arranged along the cabin wall of the engine compartment and is provided with a first outflow port, a second outflow port, and multiple inflow ports; the first main return pipe is connected between the first outflow port and the tank, and the second main return pipe is connected between the second outflow port and the tank; one end of each of the multiple branch return pipes is connected to one of the multiple engines in a one-to-one correspondence, and the other end of each of the multiple branch return pipes is connected to one of the multiple inflow ports in a one-to-one correspondence; the multiple inflow ports are spaced apart in the circumferential direction of the return loop pipe, and the inflow ports are provided on both sides of the first outflow port and both sides of the second outflow port.

[0006] According to a pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, the multiple engines include: multiple circumferential engines, and the multiple circumferential engines are arranged around the center of the engine compartment; The multiple inflow ports include: multiple circumferential inflow ports, and the multiple branch return pipes connected to the multiple circumferential engines are respectively and correspondingly connected to the multiple circumferential inflow ports; Wherein, the lengths of two pipe portions of the return loop pipe between the first outflow port and the second outflow port are equal, and the number of the circumferential inflow ports on the two pipe portions is the same. According to a pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, multiple circumferential inflow ports are symmetrically distributed about the center of the pipe portion on the pipe portion.

[0007] According to a pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, the return loop pipe has an annular structure, and the first outflow port, the second outflow port and the multiple circumferential inflow ports are evenly spaced in the circumferential direction of the return loop pipe.

[0008] According to a pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, the multiple engines further include: a central engine, and the multiple circumferential engines are arranged around the central engine; the multiple inflow ports further include: a central inflow port, and the branch return pipe connected to the central engine is connected to the central inflow port, and the central inflow port and the first outflow port are located at the same position of the return loop pipe.

[0009] According to a pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, the return pipe group further includes: a blind pipe, and the ends of the first main return pipe and the second main return pipe far from the storage tank are both connected with the blind pipe, and the end of the blind pipe far from the storage tank is closed.

[0010] According to a pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, it further includes: A helium ejector device, and the helium ejector device is connected to both the first main return pipe and the second main return pipe.

[0011] According to a pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, the return pipe group further includes: a two-position three-way valve and a discharge pipe, and the two-position three-way valve is connected to both the first outflow port and the second outflow port; the first outlet of the two-position three-way valve corresponding to the first outflow port is connected to the first main return pipe, and the first outlet of the two-position three-way valve corresponding to the second outflow port is connected to the second main return pipe; the second outlets of the two two-position three-way valves are both connected with the discharge pipe, and the end of the discharge pipe far from the two-position three-way valve is connected to the atmosphere.

[0012] A pre-cooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention further includes: A first temperature sensor, which is provided at the inlet of each engine and is used to collect the temperature of the propellant flowing into the engine; A second temperature sensor, which is provided at the outlet of each engine and is used to collect the temperature of the propellant flowing out of the engine; A control unit, and the first temperature sensor, the second temperature sensor, the helium ejector device and the two-way three-way valve are respectively communicatively connected to the control unit.

[0013] The present invention also provides a pre-cooling method for a multi-engine cryogenic liquid launch vehicle, which is applied to any of the above pre-cooling systems for a multi-engine cryogenic liquid launch vehicle, and includes: Start natural circulation pre-cooling; Obtain the first temperature of the propellant at the inlet of each engine and the second temperature of the propellant at the outlet of each engine; After the natural circulation pre-cooling lasts for a first set time period, if it is determined that either the first temperature or the second temperature is greater than the set temperature, start helium injection pre-cooling; After the helium injection pre-cooling lasts for a second set time period, if it is determined that either the first temperature or the second temperature is greater than the set temperature, start discharge pre-cooling.

[0014] The pre-cooling system and pre-cooling method for a multi-engine cryogenic liquid launch vehicle provided by the present invention, by setting a reflux loop pipe, a first main reflux pipe and a second main reflux pipe, the reflux loop pipe is provided with a first outflow port, a second outflow port and a plurality of inflow ports, and inflow ports are provided on both sides of the first outflow port and both sides of the second outflow port. The first main reflux pipe connects the first outflow port and the storage tank, and the second main reflux pipe connects the second outflow port and the storage tank. A plurality of engines are respectively connected to a plurality of inflow ports through a plurality of branch reflux pipes, so that a part of the propellant flowing into the reflux loop pipe converges from both sides of the first outflow port to the first main reflux pipe, and another part of the propellant converges from both sides of the second outflow port to the second main reflux pipe. Good flow characteristics can be obtained without setting a multi-way pipe with a large volume. This not only avoids the occupation of the engine compartment space by the large-volume multi-way pipe, but also enables each engine to achieve a good pre-cooling effect. Moreover, the reflux loop pipe can be arranged along the circumferential direction of the engine compartment close to the cabin wall, and the plurality of inflow ports thereon can be arranged as close as possible to the corresponding engine, which can shorten the length of the reflux branch pipe, simplify the pipeline layout, and further reduce the occupation of the engine compartment space. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are 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 a schematic structural diagram of a return pipe group of a multi-engine cryogenic liquid launch vehicle pre-cooling system provided by the present invention.

[0017] Figure 2 It is a structural block diagram of a multi-engine cryogenic liquid launch vehicle pre-cooling system provided by the present invention.

[0018] Figure 3 It is a schematic structural diagram of a return loop pipe of a multi-engine cryogenic liquid launch vehicle pre-cooling system provided by the present invention.

[0019] Figure 4 is Figure 1 A partially enlarged schematic diagram of the return pipe group corresponding to the first outflow port in.

[0020] Figure 5 is Figure 1 A partially enlarged schematic diagram of the return pipe group corresponding to the second outflow port in.

[0021] Reference numerals: 1, storage tank; 2, return pipe group; 21, first main return pipe; 22, second main return pipe; 23, branch return pipe; 231, central return pipe; 232, circumferential return pipe; 24, return loop pipe; 24a, first pipe section; 24b, second pipe section; 241, first outflow port; 242, second outflow port; 243, inflow port; 2431, central inflow port; 2432, circumferential inflow port; 25, blind pipe; 26, two-position three-way valve; 27, discharge pipe; 3, engine; 41, main delivery pipe; 42, multi-way pipe; 43, branch delivery pipe; 51, helium ejector; 52, helium gas source; 53, filter; 54, check valve; 55, helium gas supply pipe. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings in the present invention. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0023] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "first" and "second" are used for numbering product components for clear description and do not represent any substantial difference. The terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances. In addition, the meaning of "a plurality of" is two or more. In the specification and claims, "and / or" means at least one of the connected objects, and the character " / ", generally represents an "or" relationship between the associated objects before and after.

[0024] The following will describe the multi-engine cryogenic liquid launch vehicle pre-cooling system and pre-cooling method of the present invention in conjunction with Figures 1-5 the following.

[0025] As Figure 1 shown in Figure 2 and

[0026] The multi-engine cryogenic liquid launch vehicle pre-cooling system provided by the embodiments of the present invention includes a storage tank 1, a return pipe group 2, and a plurality of engines 3. The storage tank 1 is used to store cryogenic propellant. The plurality of engines 3 are respectively connected to the storage tank 1 through delivery pipes. The return pipe group 2 includes a return loop pipe 24, a first main return pipe 21, a second main return pipe 22, and a plurality of branch return pipes 23. The return loop pipe 24 is adapted to be arranged along the cabin wall of the engine compartment and is provided with a first outflow port 241, a second outflow port 242, and a plurality of inflow ports 243. The first main return pipe 21 is connected between the first outflow port 241 and the storage tank 1, and the second main return pipe 22 is connected between the second outflow port 242 and the storage tank 1. One ends of the plurality of branch return pipes 23 are respectively connected to the plurality of engines 3 in one-to-one correspondence. The other ends of the plurality of branch return pipes 23 are respectively connected to the plurality of inflow ports 243 in one-to-one correspondence. The plurality of inflow ports 243 are spaced apart in the circumferential direction of the return loop pipe 24, and the inflow ports 243 are provided on both sides of the first outflow port 241 and both sides of the second outflow port 242.

[0027] Specifically, the multiple engines 3, the multiple branch return pipes 23, and the return loop pipe 24 are all located in the engine compartment. At least some of the multiple engines 3 are annularly distributed along the circumference of the engine compartment. The return loop pipe 24 is installed on the bulkhead of the engine compartment along the circumference of the engine compartment and surrounds the multiple engines 3. The storage tank 1 is located above the engine compartment. The first main return pipe 21 and the second main return pipe 22 are distributed on opposite sides of the engine compartment and extend upward from the engine compartment to the storage tank 1.

[0028] Inlet ports 243 are provided on both sides of the first outlet 241 and on both sides of the second outlet 242. It can be understood that the first outlet 241 and the second outlet 242 divide the return loop pipe 24 into a first pipe portion 24a and a second pipe portion 24b. The first pipe portion 24a and the second pipe portion 24b are connected end to end to form the return loop pipe 24, and inlet ports 243 are provided on both the first pipe portion 24a and the second pipe portion 24b. Of course, inlet ports 243 can also be provided at the connection position of the first pipe portion 24a and the second pipe portion 24b.

[0029] Among them, the return loop pipe 24 can be an integral tubular structure, that is, the first pipe portion 24a and the second pipe portion 24b are integrally formed; or, the first pipe portion 24a and the second pipe portion 24b are two independent pipe portions, and the two are connected by a pipe fitting to form the return loop pipe 24. Further, both the first pipe portion 24a and the second pipe portion 24b can be formed by sequentially connecting multiple pipe segments through three-way pipes, and the other interface of the three-way pipe forms the inlet port 243 of the return loop pipe 24.

[0030] The propellant flowing out of the multiple engines 3 flows into the return loop pipe 24 through the multiple branch return pipes 23. Among them, a part of the propellant flowing into the first pipe portion 24a flows into the first main return pipe 21 from the first outlet 241, and another part of the propellant flows to the second main return pipe 22 from the second outlet 242. A part of the propellant flowing into the second pipe portion 24b flows into the first main return pipe 21 from the first outlet 241, and another part of the propellant flows to the second main return pipe 22 from the second outlet 242. Finally, the propellant returns to the storage tank 1 through the first main return pipe 21 and the second main return pipe 22 to complete a cycle of precooling.

[0031] In the related art, the branch return pipes of multiple engines are connected to a multi-way pipe, and the multi-way pipe is connected to a storage tank through a main return pipe, so that the propellant flowing out of the multiple engines flows back into the storage tank. The multi-way pipe needs to be fixed on the bulkhead of the engine compartment, that is, on one side of the multiple engines. When the number of engines is large, the design of the multi-way pipe needs to consider the flow characteristics of the internal fluid, and a flow guiding device needs to be provided inside when necessary, resulting in a relatively large volume of the multi-way pipe, which will occupy a large amount of space in the engine compartment to a large extent, and the pre-cooling effect of the engines far from the main return pipe is poor. Taking the pre-cooling system of a seven-engine cryogenic liquid launch vehicle as an example, the seven branch return pipes connected to the seven engines are connected to the main return pipe through an eight-way pipe, and the eight-way pipe has a relatively large volume, resulting in a large space occupation and poor pre-cooling effect.

[0032] The pre-cooling system of the multi-engine cryogenic liquid launch vehicle provided by the embodiment of the present invention, by setting a return loop pipe 24, a first main return pipe 21 and a second main return pipe 22, the return loop pipe 24 is provided with a first outflow port 241, a second outflow port 242 and a plurality of inflow ports 243, and inflow ports 243 are provided on both sides of the first outflow port 241 and both sides of the second outflow port 242. The first main return pipe 21 connects the first outflow port 241 and the storage tank 1, and the second main return pipe 22 connects the second outflow port 242 and the storage tank 1. The multiple engines 3 are respectively connected to the multiple inflow ports 243 through multiple branch return pipes 23, so that a part of the propellant flowing into the return loop pipe 24 converges from both sides of the first outflow port 241 to the first main return pipe 21, and another part of the propellant converges from both sides of the second outflow port 242 to the second main return pipe 22. Good flow characteristics can be obtained without setting a multi-way pipe with a large volume, which not only avoids the occupation of the engine compartment space by the large-volume multi-way pipe, but also enables each engine to achieve a better pre-cooling effect. Moreover, the return loop pipe 24 can be arranged along the circumferential direction of the engine compartment close to the bulkhead, and the multiple inflow ports 243 thereon can be arranged as close as possible to the corresponding engines 3, which can shorten the length of the branch return pipes 23, simplify the pipeline layout, and further reduce the occupation of the engine compartment space.

[0033] It should be noted that in addition to flowing through the engine, the cryogenic propellant also flows through components such as the turbopump and other pipelines, valves, and channels related to the engine supply system to ensure that the rocket engine and its delivery system reach an appropriate operating temperature before ignition. Therefore, the engine 3 can be directly or indirectly connected to the delivery pipe and the branch return pipe.

[0034] In some embodiments of the present invention, the plurality of engines 3 includes a plurality of circumferential engines, and the plurality of circumferential engines are arranged around the center of the engine compartment. The plurality of inflow ports 243 includes a plurality of circumferential inflow ports 2432. The plurality of branch return pipes 23 connected to the plurality of circumferential engines are connected to the plurality of circumferential inflow ports 2432 in a one-to-one correspondence. Among them, the lengths of two pipe portions of the return loop pipe 24 located between the first outflow port 241 and the second outflow port 242 are equal, and the number of circumferential inflow ports 2432 on the two pipe portions is the same.

[0035] Among them, referring to Figure 2 , the plurality of branch return pipes 23 includes a plurality of circumferential return pipes 232. The plurality of circumferential engines are connected to the plurality of circumferential return ports through the plurality of circumferential return pipes 232 in a one-to-one correspondence. The plurality of circumferential inflow ports 243 are arranged corresponding to the plurality of circumferential engines in a one-to-one correspondence, so that the lengths of the plurality of circumferential return pipes 232 are equal.

[0036] It can be understood that the two pipe portions of the return loop pipe 24 located between the first outflow port 241 and the second outflow port 242 are respectively the first pipe portion 24a and the second pipe portion 24b. The first outflow port 241 is located at the position where one end of the first pipe portion 24a is connected to one end of the second pipe portion 24b, and the second outflow port 242 is located at the position where the other end of the first pipe portion 24a is connected to the other end of the second pipe portion 24b. The lengths of the first pipe portion 24a and the second pipe portion 24b are equal, and the number of circumferential inflow ports 2432 on the first pipe portion 24a and the second pipe portion 24b is the same. In this way, the flow rate of the propellant entering the first pipe portion 24a and the second pipe portion 24b can be made the same, which is beneficial to balancing the pre-cooling effect of the plurality of circumferential engines.

[0037] When the number of circumferential engines is an even number, the plurality of circumferential inflow ports 2432 are also an even number and can be evenly distributed on the two pipe portions. When the number of circumferential engines is an odd number, the plurality of circumferential inflow ports 2432 are also an odd number. Then, one circumferential inflow port 2432 can be arranged at the connection position of the first pipe portion 24a and the second pipe portion 24b, and the other plurality of circumferential inflow ports 2432 are evenly distributed on the two pipe portions.

[0038] Optionally, the return loop pipe 24 has an annular structure, the first outflow port 241 and the second outflow port 24b are located on opposite sides of the annular structure, and both the first pipe portion 24a and the second pipe portion 24b are semi-annular pipe portions, and the same number of circumferential inflow ports 2432 are provided on the two semi-annular pipe portions.

[0039] Further, the plurality of engines 3 further includes a central engine, and the plurality of circumferential engines are arranged around the central engine. The plurality of inflow ports 243 further includes a central inflow port 2431. The branch return pipe 23 connected to the central engine is connected to the central inflow port 2431. The central inflow port 2431 and the first outflow port 241 are located at the same position on the return loop pipe 24.

[0040] It can be understood that the plurality of branch return pipes 23 further includes a central return pipe 231. The central engine is connected to the central inflow port 2431 through the central return pipe 231. The fact that the central inflow port 2431 and the first outflow port 241 are located at the same position on the return loop pipe 24 means that the central inflow port 2431 and the first outflow port 241 are located at the same position in the circumferential direction of the return loop pipe 24, that is, both are located at the position where one end of the first pipe portion 24a is connected to one end of the second pipe portion 24b.

[0041] For example, the precooling system of a seven-engine cryogenic liquid launch vehicle includes one central engine and six circumferential engines, and the return loop pipe 24 is of a circular ring structure. Three circumferential inflow ports 2432 are provided on each of the two semi-circular ring-shaped pipe portions for the propellant return of three circumferential engines. The propellant flowing out of the central engine directly returns to the first main return pipe 21 from the first outflow port 241 after passing through the central inflow port 2431. The propellant flowing out of the six circumferential engines is evenly distributed into the two pipe portions, and the propellant in the two pipe portions is further distributed to the first main return pipe 21 and the second main return pipe 22 at both ends.

[0042] Among them, the central inflow port 2431 and the first outflow port 241 can be oppositely arranged in the diameter direction of the return loop pipe 24. For example, the central inflow port 2431 is provided on the lower side of the return loop pipe 24, and the first outflow port 241 is provided on the upper side of the return loop pipe 24 to facilitate the installation of the central return pipe 231 and the first main return pipe 21.

[0043] In some embodiments of the present invention, a plurality of circumferential inflow ports 2432 are symmetrically distributed about the center of the pipe portion. Specifically, the plurality of circumferential inflow ports 2432 includes a plurality of first circumferential inflow ports and a plurality of second circumferential inflow ports. The plurality of first circumferential inflow ports are provided on the first pipe portion 24a and are symmetrically distributed about the center of the first pipe portion 24a. The plurality of second circumferential inflow ports are provided on the second pipe portion 24b and are symmetrically distributed about the center point of the second pipe portion 24b.

[0044] For example, the number of circumferential engines is six, and three first circumferential inflow ports are provided on the first pipe portion 24a. One of the first circumferential inflow ports is located in the exact middle of the first pipe portion 24a, and the other two first circumferential inflow ports are symmetrically arranged on both sides. Similarly, three second circumferential inflow ports are provided on the second pipe portion 24b. One of the second circumferential inflow ports is located in the exact middle of the second pipe portion 24b, and the other two second circumferential inflow ports are symmetrically arranged on both sides. In this way, the propellant flowing into the first pipe portion 24a and the second pipe portion 24b can be more evenly divided into the first outflow port 241 and the second outflow port 242, which can further balance the pre-cooling effect of multiple circumferential engines.

[0045] As Figure 3 shown, in some embodiments of the present invention, the return loop pipe 24 has an annular structure, and the first outflow port 241, the second outflow port 242, and multiple circumferential inflow ports 2432 are evenly spaced in the circumferential direction of the return loop pipe 24.

[0046] Specifically, the first outflow port 241, multiple second circumferential inflow ports, the second outflow port 242, and multiple first circumferential inflow ports are arranged at equal intervals in sequence along the circumferential direction of the return loop pipe 24. In this way, the pre-cooling effect of multiple circumferential engines can be further balanced. For example, the number of circumferential engines is six, see Figure 3 , the first outflow port 241, three second circumferential inflow ports, the second outflow port 242, and three first circumferential inflow ports are sequentially distributed at a 45° angle on the return loop pipe 24.

[0047] It should be noted that the return loop pipe 24 in the embodiments of the present invention is not limited to an annular structure, and its specific shape is determined according to the inner wall shape of the engine compartment. For example, the return loop pipe 24 is a rectangular ring or an elliptical ring structure, and this embodiment does not limit this. The return loop pipe 24 having an annular structure described in the above embodiments means that the return loop pipe 24 can be a regular annular structure or a structure close to an annular structure, and this embodiment does not limit this.

[0048] Based on the above embodiments, as Figure 1 shown, the return pipe group 2 further includes a blind pipe 25. One end of the first main return pipe 21 and the second main return pipe 22 far from the storage tank 1 are both connected with a blind pipe 25, and one end of the blind pipe 25 far from the storage tank 1 is closed.

[0049] See Figure 4 and Figure 5 , a blind pipe 25 is connected to the bottom end of the first main return pipe 21 and the bottom end of the second main return pipe 22. The first main return pipe 21 and the second main return pipe 22 can be integrally formed with the corresponding blind pipe 25 or connected through pipe fittings.

[0050] During the natural circulation precooling process, the cryogenic propellant entering the blind tube 25 does not flow, and heat accumulation will cause more bubbles to be generated in the blind tube. The bubbles flow into the first main return pipe 21 and the second main return pipe 22 along the blind tube 25, which can enhance the effect of natural circulation precooling.

[0051] Based on the above embodiments, as Figure 1 and Figure 2 shown, the precooling system for a multi-engine cryogenic liquid launch vehicle provided by the embodiment of the present invention further includes a helium ejector device, and the first main return pipe 21 and the second main return pipe 22 are both connected with a helium ejector device.

[0052] Specifically, the helium ejector device includes a helium ejector 51 and a helium gas source 52. Helium ejectors 51 are provided on both the first main return pipe 21 and the second main return pipe 22, and the helium ejector 51 is connected to the helium gas source 52.

[0053] The helium ejector 51 is located inside the corresponding main return pipe, its inlet is connected to the helium gas supply pipe 55, and its outlet faces the storage tank 1, in the same direction as the rocket body heading.

[0054] The helium ejector device further includes a filter 53 and a check valve 54, and the filter 53 and the check valve 54 are arranged on the connection pipeline between the helium gas source 52 and the helium ejector 51. When it is necessary to start helium ejector precooling, the check valve 54 is opened, and helium gas flows through the filter 53, the check valve 54 and the helium ejector 51 in sequence and enters the main return pipe, enhancing the circulation driving force of the propellant, strengthening the precooling effect, and improving the reliability of the precooling system.

[0055] In some embodiments of the present invention, the return pipe group 2 further includes a two-way three-way valve 26 and a discharge pipe 27. Refer to Figure 4 and Figure 5 , both the first outlet 241 and the second outlet 242 are connected with a two-way three-way valve 26. The first outlet of the two-way three-way valve 26 corresponding to the first outlet 241 is connected to the first main return pipe 21. The first outlet of the two-way three-way valve 26 corresponding to the second outlet 242 is connected to the second main return pipe 22. The second outlets of the two two-way three-way valves 26 are both connected with a discharge pipe 27, and the end of the discharge pipe 27 far from the two-way three-way valve 26 is connected to the atmosphere.

[0056] Specifically, the first pipe portion 24a, the second pipe portion 24b and the inlet of the two-way three-way valve 26 can be connected through a three-way pipe, the first outlet of the two-way three-way valve 26, the blind tube 25 and the corresponding main return pipe are connected through a three-way pipe, and the second outlet of the two-way three-way valve 26 is connected to the corresponding discharge pipe 27 through a right-angle connection.

[0057] Among them, the first outlet of the two-position three-way valve 26 is a normally open outlet, and the second outlet is a normally closed outlet. When the natural circulation precooling cannot meet the precooling requirements, or when neither the natural circulation precooling nor the helium injection precooling can meet the precooling requirements, the second outlet of the two-position three-way valve 26 can be controlled to open to start the discharge precooling. The cryogenic propellant is discharged through the discharge pipe 27 to further enhance the precooling effect.

[0058] The multi-engine cryogenic liquid launch vehicle precooling system provided by some embodiments of the present invention further includes a first temperature sensor, a second temperature sensor, and a control unit. A first temperature sensor is provided at the inlet of each engine 3 for collecting the temperature of the propellant flowing into the engine 3. A second temperature sensor is provided at the outlet of each engine 3 for collecting the temperature of the propellant flowing out of the engine 3. The first temperature sensor, the second temperature sensor, the helium injection device, and the two-position three-way valve 26 are respectively communicatively connected to the control unit.

[0059] Specifically, the first temperature sensor collects the inlet propellant temperature of the engine, and the second temperature sensor collects the outlet propellant temperature of the engine. The first temperature sensor and the second temperature sensor send the collected temperature data to the control unit, and the control unit determines whether to start the helium injection precooling and the discharge precooling according to the collected temperature data. When it is necessary to start the helium injection precooling, the control unit controls the one-way valve 54 and the helium injector 51 to open. When it is necessary to start the discharge precooling, the control unit controls the second outlet of the two-position three-way valve 26 to open. When the inlet propellant temperature and the outlet propellant temperature of the engine 3 are both lower than the set temperature, it is determined that the precooling is completed.

[0060] The multi-engine cryogenic liquid launch vehicle precooling system provided by the embodiments of the present invention realizes natural circulation precooling by setting the reflux loop 24, the first main reflux pipe 21, the second main reflux pipe 22, and a plurality of branch reflux pipes 23; further, enhanced natural circulation precooling is realized by setting the blind pipe 25; further, a helium injector 51 is added to the first main reflux pipe 21 and the second main reflux pipe 22 to realize helium injection precooling; further, a discharge pipe 27 is connected to the first main reflux pipe 21 and the second main reflux pipe 22 to realize discharge precooling.

[0061] During the pre-cooling process of the rocket, enhanced natural circulation pre-cooling can be carried out first. When the enhanced natural circulation pre-cooling cannot meet the pre-cooling requirements, helium jet pre-cooling and / or discharge pre-cooling are started. By means of multiple redundancies to face the impacts brought by various uncertainties during pre-cooling, it not only improves the reliability of the pre-cooling scheme before ignition but also avoids direct discharge pre-cooling, resulting in waste of propellant. The structural layout of the return pipe group 2 adopts the method of a return loop pipe 24 plus a first main return pipe 21 and a second main return pipe 22 to solve the problem of limited space in the engine compartment, improving the pre-cooling effect and meeting the pre-cooling balance requirements of multiple engines at the same time. It is applicable to new large-thrust recoverable launch vehicles with a large number of engines and complex pipeline distributions. In particular, a seven-engine cryogenic liquid launch vehicle with a large number of engines and complex pipeline distributions has great engineering application value.

[0062] An embodiment of the present invention also provides a pre-cooling method for a multi-engine cryogenic liquid launch vehicle. The pre-cooling method for a multi-engine cryogenic liquid launch vehicle is applied to the pre-cooling system for a multi-engine cryogenic liquid launch vehicle described in any of the above embodiments. The pre-cooling method for a multi-engine cryogenic liquid launch vehicle includes the steps: Step S1, start natural circulation pre-cooling.

[0063] Step S2, obtain the first temperature of the propellant at the inlet of each engine and the second temperature of the propellant at the outlet of each engine.

[0064] Step S3, after the natural circulation pre-cooling lasts for a first set duration, if it is determined that any one of the first temperature and the second temperature is greater than the set temperature, start helium jet pre-cooling.

[0065] Step S4, after the helium jet pre-cooling lasts for a second set duration, if it is determined that any one of the first temperature and the second temperature is greater than the set temperature, start discharge pre-cooling.

[0066] Specifically, valves are provided on the delivery pipe group, and by controlling the corresponding valves to open, natural circulation pre-cooling is started. During the natural circulation pre-cooling process, the first temperature of the propellant at the inlet of each engine 3 and the second temperature of the propellant at the outlet are obtained in real time. For example, the set temperature is 92K. During the pre-cooling process, when both the first temperature and the second temperature are lower than 92K, it means that the pre-cooling requirements are met.

[0067] After the natural circulation pre-cooling lasts for the first set duration, for example, after 2 minutes, if any one of the first temperature and the second temperature does not drop to the set temperature or below, it means that the natural circulation pre-cooling cannot meet the pre-cooling requirements. At this time, the helium jet device is started to start helium jet pre-cooling.

[0068] After the helium jet pre-cooling lasts for the second set duration, for example, after 2 minutes, if either the first temperature or the second temperature does not drop to the set temperature or below, it means that the natural circulation pre-cooling plus the helium jet pre-cooling cannot meet the pre-cooling requirements either. At this time, the second outlet of the two-position three-way valve 26 corresponding to the first main return pipe 21 and the second main return pipe 22 is controlled to open to start the discharge pre-cooling, so that the propellant is discharged through the two discharge pipes 27. This pre-cooling method for the multi-engine cryogenic liquid launch vehicle faces the impacts brought by various uncertain factors during pre-cooling through multiple redundant means, which not only improves the reliability of the pre-cooling scheme before ignition but also avoids direct discharge pre-cooling and causes waste of propellant.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-engine cryogenic liquid launch vehicle precooling system, characterized in that: include: A tank for storing cryogenic propellant; A plurality of engines, each of which is connected to the tank via a delivery pipe; A return pipe group, comprising: a return ring pipe, a first main return pipe, a second main return pipe and a plurality of branch return pipes, wherein the return ring pipe is suitable for being arranged along the bulkhead of the engine compartment and is provided with a first outlet, a second outlet and a plurality of inlets; the first main return pipe is connected between the first outlet and the tank, and the second main return pipe is connected between the second outlet and the tank; One end of the multiple branch return pipes is connected to the multiple engines one by one, and the other end of the multiple branch return pipes is connected to the multiple inlets one by one; the multiple inlets are arranged at intervals in the annular direction of the return ring pipe, and the inlets are provided on both sides of the first outlet and both sides of the second outlet.

2. The multi-engine cryogenic liquid launch vehicle precooling system according to claim 1, characterized in that: The plurality of engines include: a plurality of circumferential engines, the plurality of circumferential engines being arranged around the center of the engine compartment; The plurality of inlets include: a plurality of circumferential inlets, a plurality of branch return pipes connected to the plurality of circumferential engines being connected to the plurality of circumferential inlets in a one-to-one correspondence; Wherein, the two sections of the pipe portion on the return ring pipe between the first outlet and the second outlet are of equal length, and the numbers of the circumferential inlets on the two sections of the pipe portion are the same.

3. The multi-engine cryogenic liquid launch vehicle precooling system according to claim 2, characterized in that: The tube portion is provided with a plurality of circumferential inlet ports symmetrically distributed about the center of the tube portion.

4. The multi-engine cryogenic liquid launch vehicle precooling system according to claim 2, characterized in that: The return ring pipe is in a circular ring structure, and the first outlet, the second outlet and the plurality of circumferential inlets are evenly spaced in the annular direction of the return ring pipe.

5. The multi-engine cryogenic liquid launch vehicle precooling system according to claim 2, characterized in that: The multiple engines also include: a central engine, and the multiple circumferential engines are arranged around the central engine; the multiple inlets also include: a central inlet, the branch return pipe connected to the central engine is connected to the central inlet, and the central inlet and the first outlet are located at the same position of the return ring pipe.

6. The multi-engine cryogenic liquid launch vehicle precooling system according to claim 1, characterized in that: The return pipe group further includes a blind pipe, to which the first main return pipe and the second main return pipe are connected at one end away from the storage tank, and the blind pipe is closed at one end away from the storage tank.

7. The multi-engine cryogenic liquid launch vehicle precooling system according to any one of claims 1 to 6, characterized in that: Also includes: A helium ejector device is connected to the first main return pipe and the second main return pipe.

8. The multi-engine cryogenic liquid launch vehicle precooling system according to claim 7, characterized in that: The reflux pipe group also includes: a two-position three-way valve and a discharge pipe, the first outlet and the second outlet are both connected to the two-position three-way valve; the first outlet of the two-position three-way valve corresponding to the first outlet is connected to the first main reflux pipe, and the first outlet of the two-position three-way valve corresponding to the second outlet is connected to the second main reflux pipe; the second outlets of the two two-position three-way valves are both connected to the discharge pipe, and the end of the discharge pipe away from the two-position three-way valve is connected to the atmosphere.

9. The multi-engine cryogenic liquid launch vehicle precooling system according to claim 8, characterized in that: Also includes: A first temperature sensor, the inlet of each of the engines is provided with the first temperature sensor, for collecting the temperature of the propellant flowing into the engine; A second temperature sensor, each of the engine outlets is provided with the second temperature sensor, for collecting the temperature of the propellant flowing out of the engine; A control unit, wherein the first temperature sensor, the second temperature sensor, the helium ejection device and the two-position three-way valve are respectively connected to the control unit for communication.

10. A method for precooling a multi-engine cryogenic liquid launch vehicle, applied to a precooling system for a multi-engine cryogenic liquid launch vehicle as claimed in any one of claims 1 to 9, characterized in that: include: Start natural circulation precooling; obtaining a first temperature of the propellant at an inlet of each of the engines, and a second temperature of the propellant at an outlet of each of the engines; After the natural circulation precooling continues for a first set time, if it is determined that either the first temperature or the second temperature is greater than a set temperature, helium injection precooling is started; After the helium injection pre-cooling continues for a second set time period, if it is determined that either the first temperature or the second temperature is greater than the set temperature, exhaust pre-cooling is initiated.

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