Precooling System and Precooling Method for Multi-Aircraft Cryogenic Liquid Launch Vehicle

Abstract

This invention relates to the field of liquid propellant launch vehicle technology, and provides a precooling system and method for a multi-engine cryogenic liquid propellant launch vehicle. The precooling system includes: a tank for storing cryogenic propellant; multiple engines connected to the tank via delivery pipes; a return loop pipe adapted to be installed along the engine compartment wall and equipped with a first outlet, a second outlet, and multiple inlets; a first main return pipe connected between the first outlet and the tank; a second main return pipe connected between the second outlet and the tank; and multiple branch return pipes correspondingly connected to the multiple engines and multiple inlets. The multiple inlets are spaced apart in the circumferential direction of the return loop pipe, with inlets located on both sides of the first outlet and both sides of the second outlet. This precooling system achieves better flow characteristics, not only avoiding the occupation of engine compartment space by large-volume multi-port pipes, but also enabling each engine to achieve a good precooling effect.

Description

Technical Field

[0001] This invention relates to the field of liquid launch vehicle technology, and in particular to a precooling system and method for a multi-engine cryogenic liquid launch vehicle. Background Technology

[0002] Before ignition, the engine and its fuel delivery system must be adequately cooled to bring the engine to the required pre-start temperature. Insufficient pre-cooling will cause the cryogenic propellant to undergo a violent phase change upon heating, resulting in the propellant entering the turbopump as a gas-liquid two-phase mixture. This can cause pump cavitation and prevent the engine from functioning properly.

[0003] Currently, the main precooling methods for cryogenic liquid rocket engines both domestically and internationally are exhaust precooling and recirculation precooling. Exhaust precooling involves the cryogenic propellant flowing through the cooling delivery pipeline and the engine, then being directly discharged outside the rocket body via a vent valve. Recirculation precooling involves installing a precooling return pipeline between the engine and the propellant tank, allowing the cryogenic propellant to flow back into the tank after passing through the cooling delivery pipeline and the engine. For high-thrust launch vehicles employing multiple engines in parallel, the precooling requirement increases significantly, requiring a larger propellant flow rate and consequently increasing the size of the precooling system. Traditional precooling systems occupy considerable engine compartment space and offer poor precooling performance. Summary of the Invention

[0004] This invention provides a precooling system and method for multi-engine cryogenic liquid launch vehicles, which solves the problems of existing precooling systems for multi-engine cryogenic liquid launch vehicles occupying a large amount of engine compartment space and having poor precooling effect.

[0005] This invention provides a precooling system for a multi-aircraft cryogenic liquid launch vehicle, comprising:

[0006] The tank is used to store cryogenic propellant;

[0007] Multiple engines, each of which is connected to the storage tank via a delivery pipe;

[0008] The return pipe assembly includes: a return ring pipe, a first main return pipe, a second main return pipe, and multiple branch return pipes. The return ring pipe is adapted to be installed along the bulkhead of the engine compartment and has a first outlet, a second outlet, and multiple 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 each of the multiple branch return pipes is connected to one of the multiple engines, and the other end of each of the multiple branch return pipes is connected to one of the multiple inlets. The multiple inlets are spaced apart in the annular direction of the return ring pipe, and inlets are provided on both sides of the first outlet and both sides of the second outlet.

[0009] According to the present invention, a precooling system for a multi-engine cryogenic liquid launch vehicle is provided, wherein the multiple engines include: multiple circumferential engines, and the multiple circumferential engines are arranged around the center of the engine compartment;

[0010] The plurality of inlets includes: a plurality of circumferential inlets, and a plurality of branch return pipes connected to the plurality of circumferential engines are connected one-to-one with the plurality of circumferential inlets;

[0011] In this system, the two pipe sections located between the first outlet and the second outlet on the return loop pipe are of equal length, and the number of circumferential inlets on the two pipe sections is the same. According to the precooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention, a plurality of circumferential inlets are symmetrically distributed about the center of the pipe section.

[0012] According to the present invention, a precooling system for a multi-engine cryogenic liquid launch vehicle is provided, wherein the reflux ring tube has a circular annular structure, and the first outlet, the second outlet, and a plurality of the circumferential inlets are evenly spaced along the annular direction of the reflux ring tube.

[0013] According to the present invention, a precooling system for a multi-engine cryogenic liquid launch vehicle includes a central engine, wherein a plurality of circumferential engines are arranged around the central engine; and a central inlet is further included, wherein a 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 on the return ring pipe.

[0014] According to the present invention, a precooling system for a multi-engine cryogenic liquid launch vehicle is provided, wherein the reflux pipe assembly further includes a blind pipe, wherein the ends of the first main reflux pipe and the second main reflux pipe away from the tank are both connected to the blind pipe, and the ends of the blind pipe away from the tank are closed.

[0015] A precooling system for a multi-engine cryogenic liquid launch vehicle according to the present invention further includes:

[0016] A helium ejector device, wherein both the first main return pipe and the second main return pipe are connected to the helium ejector device.

[0017] According to the present invention, a precooling system for a multi-engine cryogenic liquid launch vehicle includes a reflux pipe assembly further comprising: a two-position three-way valve and a discharge pipe, wherein 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.

[0018] A precooling system for a multi-engine cryogenic liquid launch vehicle according to the present invention further includes:

[0019] A first temperature sensor is provided at the inlet of each of the engines to collect the temperature of the propellant flowing into the engine.

[0020] A second temperature sensor is provided at the outlet of each of the engines to collect the temperature of the propellant flowing out of the engine.

[0021] The control unit is connected in communication with the first temperature sensor, the second temperature sensor, the helium ejector, and the two-position three-way valve.

[0022] This invention also provides a precooling method for a multi-engine cryogenic liquid launch vehicle, applicable to any of the above-mentioned multi-engine cryogenic liquid launch vehicle precooling systems, comprising:

[0023] Initiate natural circulation precooling;

[0024] A first temperature of the propellant at the inlet of each engine and a second temperature of the propellant at the outlet of each engine are obtained.

[0025] After the natural circulation precooling has continued for a first set time, if it is determined that either the first temperature or the second temperature is greater than the set temperature, then helium ejection precooling is initiated.

[0026] After the helium ejection precooling is carried out for a second set duration, if it is determined that either the first temperature or the second temperature is greater than the set temperature, then emission precooling is initiated.

[0027] The precooling system and method for multi-engine cryogenic liquid launch vehicles provided by this invention achieve good flow characteristics by setting up a reflux ring pipe, a first main reflux pipe, and a second main reflux pipe. The reflux ring pipe has a first outlet, a second outlet, and multiple inlets, with inlets on both sides of the first outlet and the second outlet. The first main reflux pipe connects the first outlet to the storage tank, and the second main reflux pipe connects the second outlet to the storage tank. Multiple engines are connected to multiple inlets through multiple branch reflux pipes, so that a portion of the propellant flowing into the reflux ring pipe flows from both sides of the first outlet to the first main reflux pipe, and another portion flows from both sides of the second outlet to the second main reflux pipe. This eliminates the need for a large multi-pass pipe to achieve good flow characteristics, avoiding the space occupation of the engine compartment by a large multi-pass pipe and enabling each engine to achieve a good precooling effect. Furthermore, the return loop pipe can be installed close to the bulkhead along the circumference of the engine compartment, and its multiple inlets can be installed as close as possible to the corresponding engines, which can shorten the length of the return branch pipe, simplify the pipeline layout, and further reduce the space occupied in the engine compartment. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the reflux pipe assembly structure of the precooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention.

[0030] Figure 2 This is a structural block diagram of the precooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention.

[0031] Figure 3 This is a schematic diagram of the reflux ring pipe structure of the precooling system for a multi-engine cryogenic liquid launch vehicle provided by the present invention.

[0032] Figure 4 yes Figure 1 The enlarged schematic diagram of the return pipe assembly corresponding to the first outlet is shown in the figure.

[0033] Figure 5 yes Figure 1 The enlarged schematic diagram of the return pipe assembly corresponding to the second outlet is shown in the figure.

[0034] Figure label:

[0035] 1. Storage tank; 2. Return pipe assembly; 21. First main return pipe; 22. Second main return pipe; 23. Branch return pipe; 231. Central return pipe; 232. Circumferential return pipe; 24. Return ring pipe; 24a. First pipe section; 24b. Second pipe section; 241. First outlet; 242. Second outlet; 243. Inlet; 2431. Central inlet; 2432. Circumferential inlet; 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 source; 53. Filter; 54. Check valve; 55. Helium supply pipe. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "first" and "second" are numbered for the purpose of clearly identifying product components and do not represent any substantial difference. The terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances. Furthermore, "multiple" means two or more. In the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0038] The following is combined with Figures 1-5 The present invention describes a precooling system and precooling method for a multi-aircraft cryogenic liquid launch vehicle.

[0039] like Figure 1 and Figure 2As shown, the precooling system for a multi-engine cryogenic liquid launch vehicle provided in this embodiment of the invention includes a tank 1, a return pipe assembly 2, and multiple engines 3. The tank 1 stores cryogenic propellant. Multiple engines 3 are connected to the tank 1 via delivery pipes. The return pipe assembly 2 includes a return loop pipe 24, a first main return pipe 21, a second main return pipe 22, and multiple branch return pipes 23. The return loop pipe 24 is adapted to be installed along the wall of the engine compartment and has a first outlet 241, a second outlet 242, and multiple inlets 243. The first main return pipe 21 connects the first outlet 241 and the tank 1, and the second main return pipe 22 connects the second outlet 242 and the tank 1. One end of each branch return pipe 23 is connected to one of the multiple engines 3. The other end of each branch return pipe 23 is connected to one of the multiple inlets 243. Multiple inlets 243 are spaced apart in the annular direction of the return loop pipe 24, and inlets 243 are provided on both sides of the first outlet 241 and both sides of the second outlet 242.

[0040] The precooling system for this multi-engine cryogenic liquid launch vehicle also includes a delivery pipe assembly located above the engine compartment. This assembly comprises a main delivery pipe 41, a multi-port pipe 42, and multiple branch delivery pipes 43. The propellant tank 1 is connected to the inlet of the multi-port pipe 42 via the main delivery pipe 41. The multiple outlets of the multi-port pipe 42 are connected one-to-one with the propellant inlets of the multiple engines 3 via the branch delivery pipes 43. The propellant in the tank 1 flows naturally downwards into the multiple engines 3 under gravity, precooling them. Taking a seven-engine cryogenic liquid launch vehicle precooling system as an example, the main delivery pipe 41 is connected to seven branch delivery pipes 43 via an eight-port pipe to simultaneously deliver propellant to all seven engines.

[0041] Specifically, multiple engines 3, multiple branch return pipes 23, and a return ring pipe 24 are all located within the engine compartment. At least a portion of the multiple engines 3 are arranged in a ring around the circumference of the engine compartment. The return ring pipe 24 is installed on the bulkhead of the engine compartment and surrounds the multiple engines 3. The reservoir 1 is located above the engine compartment, and 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 reservoir 1.

[0042] Inlet ports 243 are provided on both sides of the first outlet 241 and both sides of the second outlet 242. This can be understood as the first outlet 241 and the second outlet 242 dividing the return loop pipe 24 into a first pipe section 24a and a second pipe section 24b. The first pipe section 24a and the second pipe section 24b are connected end-to-end to form the return loop pipe 24, and both the first pipe section 24a and the second pipe section 24b are provided with inlet ports 243. Of course, inlet ports 243 can also be provided at the connection point between the first pipe section 24a and the second pipe section 24b.

[0043] The return loop pipe 24 can be a one-piece tubular structure, i.e., the first pipe section 24a and the second pipe section 24b are integrally formed; or, the first pipe section 24a and the second pipe section 24b are two independent pipe sections connected by pipe fittings to form the return loop pipe 24. Further, both the first pipe section 24a and the second pipe section 24b can be formed by connecting multiple pipe segments sequentially through a tee pipe, with the other port of the tee pipe forming the inlet 243 of the return loop pipe 24.

[0044] Propellant flowing from multiple engines 3 flows into a return loop pipe 24 through multiple branch return pipes 23. A portion of the propellant flowing into the first pipe section 24a flows into the first main return pipe 21 from the first outlet 241, while another portion flows from the second outlet 242 to the second main return pipe 22. Similarly, a portion of the propellant flowing into the second pipe section 24b flows into the first main return pipe 21 from the first outlet 241, while another portion flows from the second outlet 242 to the second main return pipe 22. Finally, the propellant returns to the storage tank 1 through the first main return pipe 21 and the second main return pipe 22, completing one cycle of pre-cooling.

[0045] In related technologies, multiple engine branch return pipes are connected to a multi-port pipe, which in turn connects to a main return pipe and then to a propellant tank, allowing propellant from multiple engines to flow back into the tank. This multi-port pipe needs to be fixed to the engine compartment wall, i.e., located on one side of the multiple engines. When there are a large number of engines, the design of this multi-port pipe needs to consider the internal fluid flow characteristics, and if necessary, internal flow guiding devices are required. This results in a large multi-port pipe volume, significantly occupying engine compartment space, and poor precooling effect for engines farther from the main return pipe. Taking the precooling 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 via an eight-port pipe. The eight-port pipe is large, causing significant space occupation and poor precooling effect.

[0046] The precooling system for a multi-engine cryogenic liquid launch vehicle provided in this embodiment of the invention comprises a reflux ring pipe 24, a first main reflux pipe 21, and a second main reflux pipe 22. The reflux ring pipe 24 has a first outlet 241, a second outlet 242, and multiple inlets 243. Inlets 243 are located on both sides of the first outlet 241 and both sides of the second outlet 242. The first main reflux pipe 21 connects the first outlet 241 to the storage tank 1, and the second main reflux pipe 22 connects the second outlet 242 to the storage tank 1. Multiple... Each engine 3 is connected to multiple branch return pipes 23 and multiple inlets 243 in a one-to-one correspondence. This allows a portion of the propellant flowing into the return ring pipe 24 to converge from both sides of the first outlet 241 to the first main return pipe 21, while another portion of the propellant flows from both sides of the second outlet 242 to the second main return pipe 22. This achieves good flow characteristics without the need for a large multi-port pipe, avoiding the space occupation of large multi-port pipes in the engine compartment and ensuring good pre-cooling for each engine. Furthermore, the return ring pipe 24 can be installed close to the engine compartment wall along its circumference, and its multiple inlets 243 can be positioned as close as possible to the corresponding engine 3, shortening the length of the branch return pipes 23, simplifying the piping layout, and further reducing the space occupied in the engine compartment.

[0047] It should be noted that, in addition to flowing through the engine, the cryogenic propellant also flows through the turbopump and other components related to the engine supply system, such as pipes, valves, and cavities, to ensure that the rocket engine and its delivery system reach a suitable operating temperature before ignition. Therefore, engine 3 can be directly or indirectly connected to the delivery pipe and branch return pipe.

[0048] In some embodiments of the present invention, the plurality of engines 3 include a plurality of circumferential engines, which are arranged around the center of the engine compartment. The plurality of inlets 243 include a plurality of circumferential inlets 2432. A plurality of branch return pipes 23 connected to the plurality of circumferential engines are connected one-to-one with the plurality of circumferential inlets 2432. Specifically, the two pipe sections on the return ring pipe 24 located between the first outlet 241 and the second outlet 242 are of equal length, and the number of circumferential inlets 2432 on the two pipe sections is the same.

[0049] Among them, see Figure 2 The multiple branch return pipes 23 include multiple circumferential return pipes 232. Multiple circumferential engines are connected to multiple circumferential return ports through the multiple circumferential return pipes 232. Multiple circumferential inlets 243 are configured to correspond to the multiple circumferential engines, ensuring that the lengths of the multiple circumferential return pipes 232 are equal.

[0050] It is understandable that the two pipe sections on the return ring pipe 24 located between the first outlet 241 and the second outlet 242 are respectively the first pipe section 24a and the second pipe section 24b. The first outlet 241 is located at the position where one end of the first pipe section 24a is connected to one end of the second pipe section 24b, and the second outlet 242 is located at the position where the other end of the first pipe section 24a is connected to the other end of the second pipe section 24b. The first pipe section 24a and the second pipe section 24b are of equal length, and the number of circumferential inlets 2432 on the first pipe section 24a and the second pipe section 24b is the same. In this way, the propellant flow rate entering the first pipe section 24a and the second pipe section 24b can be the same, which is beneficial to balancing the precooling effect of multiple circumferential engines.

[0051] When the number of circumferential engines is even, the number of circumferential inlets 2432 is also even, and they can be evenly distributed on the two pipe sections. When the number of circumferential engines is odd, the number of circumferential inlets 2432 is also odd. In this case, one circumferential inlet 2432 can be located at the connection between the first pipe section 24a and the second pipe section 24b, and the other multiple circumferential inlets 2432 can be evenly distributed on the two pipe sections.

[0052] Optionally, the return ring pipe 24 has a circular ring structure, with the first outlet 241 and the second outlet 24b located on opposite sides of the circular ring structure. The first pipe section 24a and the second pipe section 24b are both semi-circular ring pipe sections, and the two semi-circular ring pipe sections are provided with the same number of circumferential inlets 2432.

[0053] Furthermore, the plurality of engines 3 also includes a central engine, and a plurality of circumferential engines are arranged around the central engine. The plurality of inlets 243 also includes a central inlet 2431, and the branch return pipe 23 connected to the central engine is connected to the central inlet 2431. The central inlet 2431 and the first outlet 241 are located at the same position in the return ring pipe 24.

[0054] Understandably, the multiple branch return pipes 23 also include a central return pipe 231, through which the central engine is connected to the central inlet 2431. The central inlet 2431 and the first outlet 241 are located at the same position in the return ring pipe 24, meaning they are both located at the same position in the annular direction of the return ring pipe 24, i.e., at the point where one end of the first pipe section 24a is connected to one end of the second pipe section 24b.

[0055] For example, the precooling system of the seven-engine cryogenic liquid launch vehicle includes one central engine and six circumferential engines, with the return annular pipe 24 having a circular structure. Each of the two semi-circular pipe sections has three circumferential inlets 2432, used for propellant return from the three circumferential engines. The propellant flowing from the central engine returns directly to the first main return pipe 21 via the central inlet 2431 and the first outlet 241. The propellant from the six circumferential engines is evenly distributed into the two pipe sections, and the propellant within these sections is further distributed to the first main return pipe 21 and the second main return pipe 22.

[0056] The central inlet 2431 and the first outlet 241 can be arranged opposite each other in the diameter direction of the return ring pipe 24. For example, the central inlet 2431 is located on the lower side of the return ring pipe 24, and the first outlet 241 is located on the upper side of the return ring pipe 24, so as to facilitate the installation of the central return pipe 231 and the first main return pipe 21.

[0057] In some embodiments of the present invention, a plurality of circumferential inlets 2432 are symmetrically distributed about the center of the pipe section. Specifically, the plurality of circumferential inlets 2432 includes a plurality of first circumferential inlets and a plurality of second circumferential inlets. The plurality of first circumferential inlets are located in the first pipe section 24a and are symmetrically distributed about the center of the first pipe section 24a. The plurality of second circumferential inlets are located in the second pipe section 24b and are symmetrically distributed about the center point of the second pipe section 24b.

[0058] For example, there are six circumferential engines. The first tube 24a has three first circumferential inlets, one of which is located in the center of the first tube 24a, and the other two are symmetrically located on both sides. Similarly, the second tube 24b has three second circumferential inlets, one of which is located in the center of the second tube 24b, and the other two are symmetrically located on both sides. In this way, the propellant flowing into the first tube 24a and the second tube 24b can be distributed more evenly to the first outlet 241 and the second outlet 242, which can further balance the precooling effect of multiple circumferential engines.

[0059] like Figure 3 As shown, in some embodiments of the present invention, the return ring pipe 24 has a circular structure, and the first outlet 241, the second outlet 242 and a plurality of circumferential inlets 2432 are evenly spaced in the circumferential direction of the return ring pipe 24.

[0060] Specifically, the first outlet 241, multiple second circumferential inlets, the second outlet 242, and multiple first circumferential inlets are arranged at equal intervals along the annular direction of the return loop pipe 24. This further balances the precooling effect of the multiple circumferential engines. For example, there are six circumferential engines, see [reference needed]. Figure 3 The first outlet 241, three second circumferential inlets, the second outlet 242, and the three first circumferential inlets are distributed at a 45° angle in the return loop pipe 24.

[0061] It should be noted that the return annular pipe 24 in this embodiment is not limited to a circular annular structure. Its specific shape is determined according to the shape of the inner wall of the engine compartment. For example, the return annular pipe 24 can be a rectangular or elliptical annular structure. This embodiment does not impose any restrictions on this. The circular annular structure of the return annular pipe 24 described in the above embodiments means that the return annular pipe 24 can be a regular circular annular structure or a structure close to a circular annular structure. This embodiment does not impose any restrictions.

[0062] Based on the above embodiments, such as Figure 1 As shown, the reflux pipe group 2 also includes a blind pipe 25. The ends of the first main reflux pipe 21 and the second main reflux pipe 22 away from the storage tank 1 are both connected to the blind pipe 25, and the ends of the blind pipe 25 away from the storage tank 1 are closed.

[0063] See Figure 4 and Figure 5 Both the bottom end of the first main return pipe 21 and the bottom end of the second main return pipe 22 are connected to blind pipes 25. The first main return pipe 21 and the second main return pipe 22 can be integrally formed with the corresponding blind pipes 25, or they can be connected by pipe fittings.

[0064] During the natural circulation precooling process, the cryogenic propellant entering the blind tube 25 does not flow. The 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.

[0065] Based on the above embodiments, such as Figure 1 and Figure 2 As shown, the precooling system for a multi-engine cryogenic liquid launch vehicle provided in this embodiment of the invention also includes a helium ejector device, and both the first main return pipe 21 and the second main return pipe 22 are connected to the helium ejector device.

[0066] Specifically, the helium ejection device includes a helium ejector 51 and a helium source 52. Both the first main return pipe 21 and the second main return pipe 22 are equipped with helium ejectors 51, which are connected to the helium source 52.

[0067] The helium ejector 51 is located inside the corresponding return main pipe. Its inlet is connected to the helium supply pipe 55, and its outlet faces the storage tank 1, in the same direction as the rocket body's flight path.

[0068] The helium ejector device also includes a filter 53 and a one-way valve 54, which are located on the connecting pipeline between the helium source 52 and the helium ejector 51. When helium ejection precooling needs to be started, the one-way valve 54 is opened, and helium gas flows sequentially through the filter 53, the one-way valve 54, and the helium ejector 51 into the main return pipe, enhancing the propellant circulation driving force, strengthening the precooling effect, and improving the reliability of the precooling system.

[0069] In some embodiments of the present invention, the reflux pipe assembly 2 further includes a two-position three-way valve 26 and a discharge pipe 27. See also Figure 4 and Figure 5 Both the first outlet 241 and the second outlet 242 are connected to a two-position three-way valve 26. The first outlet of the two-position 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-position three-way valve 26 corresponding to the second outlet 242 is connected to the second main return pipe 22. The second outlets of both two-position three-way valves 26 are connected to a discharge pipe 27, the end of the discharge pipe 27 away from the two-position three-way valve 26 being connected to the atmosphere.

[0070] Specifically, the inlets of the first pipe section 24a, the second pipe section 24b, and the two-position three-way valve 26 can be connected by a three-way pipe. The first outlet of the two-position three-way valve 26, the blind pipe 25, and the corresponding main return pipe are connected by a three-way pipe. The second outlet of the two-position three-way valve 26 is connected to the corresponding discharge pipe 27 by a right-angle pipe.

[0071] The first outlet of the two-position three-way valve 26 is normally open, and the second outlet is normally closed. When natural circulation precooling cannot meet the precooling requirements, or when both natural circulation precooling and helium ejection precooling cannot meet the precooling requirements, the second outlet of the two-position three-way valve 26 can be opened to start discharge precooling. The cryogenic propellant is discharged through the discharge pipe 27, further enhancing the precooling effect.

[0072] The precooling system for a multi-engine cryogenic liquid launch vehicle provided in some embodiments of the present invention further includes a first temperature sensor, a second temperature sensor, and a control unit. Each engine 3 has a first temperature sensor at its inlet for collecting the temperature of the propellant flowing into the engine 3. Each engine 3 has a second temperature sensor at its outlet for collecting the temperature of the propellant flowing out of the engine 3. The first temperature sensor, the second temperature sensor, the helium ejector, and the two-position three-way valve 26 are all communicatively connected to the control unit.

[0073] Specifically, the first temperature sensor collects the inlet propellant temperature of the engine, and the second temperature sensor collects the outlet propellant temperature. The first and second temperature sensors send the collected temperature data to the control unit, which determines whether helium ejector precooling and exhaust precooling need to be initiated based on the collected temperature data. When helium ejector precooling needs to be initiated, the control unit controls the one-way valve 54 and the helium ejector 51 to open. When exhaust precooling needs to be initiated, the control unit controls the second outlet of the two-position three-way valve 26 to open. Precooling is considered complete when both the inlet and outlet propellant temperatures of the engine 3 are below the set temperatures.

[0074] The precooling system for a multi-engine cryogenic liquid launch vehicle provided in this embodiment of the invention achieves natural circulation precooling by setting up a reflux loop pipe 24, a first main reflux pipe 21, a second main reflux pipe 22, and multiple branch reflux pipes 23; furthermore, it achieves enhanced natural circulation precooling by setting up a blind pipe 25; furthermore, it achieves helium ejection precooling by adding helium ejection precooling on the first main reflux pipe 21 and the second main reflux pipe 22; furthermore, it achieves emission precooling by connecting an exhaust pipe 27 to the first main reflux pipe 21 and the second main reflux pipe 22.

[0075] During rocket precooling, enhanced natural circulation precooling can be performed first. If enhanced natural circulation precooling cannot meet the precooling requirements, helium ejection precooling and / or emission precooling can be initiated. By employing multiple redundancy methods to address the impact of various uncertainties during precooling, the reliability of the precooling scheme before ignition is improved, and direct emission precooling, which would waste propellant, is avoided. The structural layout of the return pipe assembly 2, using a return ring pipe 24 plus a first main return pipe 21 and a second main return pipe 22, solves the problem of limited space within the engine compartment, improves the precooling effect, and meets the precooling balance requirements of multiple engines. This approach is applicable to new high-thrust reusable launch vehicles with a large number of engines and complex piping distribution, and has significant engineering application value, especially for seven-engine cryogenic liquid launch vehicles with multiple engines and complex piping distribution.

[0076] This invention also provides a pre-cooling method for a multi-rocket cryogenic liquid launch vehicle, which is applied to the pre-cooling system for a multi-rocket cryogenic liquid launch vehicle described in any of the above embodiments. The pre-cooling method includes the following steps:

[0077] Step S1: Start natural circulation precooling.

[0078] 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.

[0079] Step S3: After the natural circulation precooling has lasted for a first set time, if it is determined that either the first temperature or the second temperature is greater than the set temperature, then helium ejection precooling is started.

[0080] Step S4: After the helium ejection precooling has lasted for a second set time, if it is determined that either the first temperature or the second temperature is greater than the set temperature, then emission precooling is initiated.

[0081] Specifically, valves are installed on the delivery pipe assembly. By controlling the opening of the corresponding valves, natural circulation precooling is initiated. During the natural circulation precooling process, the first temperature of the propellant at the inlet and the second temperature of the propellant at the outlet of each engine 3 are acquired in real time. For example, if the set temperature is 92K, during the precooling process, when both the first and second temperatures are below 92K, it indicates that the precooling requirement has been met.

[0082] If, after natural circulation precooling has continued for a first set time, such as 2 minutes, neither the first temperature nor the second temperature has dropped to or below the set temperature, it indicates that natural circulation precooling cannot meet the precooling requirements. At this time, the helium ejector device is activated to initiate helium ejection precooling.

[0083] If, after a second set duration of helium ejection precooling (e.g., 2 minutes), neither the first nor the second temperature drops to or below the set temperature, it indicates that natural circulation precooling combined with helium ejection precooling is insufficient to meet the precooling requirements. At this point, 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 opened to initiate discharge precooling, allowing the propellant to be discharged through the two discharge pipes 27. This precooling method for multi-engine cryogenic liquid launch vehicles addresses the impact of various uncertainties during precooling through multiple redundancy measures. This improves the reliability of the precooling scheme before ignition and avoids direct discharge precooling, which would otherwise waste propellant.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A precooling system for a multi-engine cryogenic liquid launch vehicle, characterized in that, include: The tank is used to store cryogenic propellant; Multiple engines, each of which is connected to the storage tank via a delivery pipe; The reflux pipe assembly includes: a reflux ring pipe, a first main reflux pipe, a second main reflux pipe, and multiple branch reflux pipes. The reflux ring pipe is adapted to be installed along the bulkhead of the engine compartment and is provided with a first outlet, a second outlet, and multiple inlets. The first main reflux pipe is connected between the first outlet and the tank, and the second main reflux pipe is connected between the second outlet and the tank. One end of each of the multiple branch return pipes is connected to one of the multiple engines, and the other end of each of the multiple branch return pipes is connected to one of the multiple inlets; the multiple inlets are spaced apart 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 precooling system for a multi-engine cryogenic liquid launch vehicle according to claim 1, characterized in that, The plurality of engines includes: a plurality of circumferential engines, wherein the plurality of circumferential engines are arranged around the center of the engine compartment; The plurality of inlets includes: a plurality of circumferential inlets, and a plurality of branch return pipes connected to the plurality of circumferential engines are connected one-to-one with the plurality of circumferential inlets; The two pipe sections located between the first outlet and the second outlet on the return loop pipe are of equal length, and the number of circumferential inlets on the two pipe sections is the same.

3. The precooling system for a multi-engine cryogenic liquid launch vehicle according to claim 2, characterized in that, The pipe section has multiple circumferential inlets symmetrically distributed about the center of the pipe section.

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

5. The precooling system for a multi-engine cryogenic liquid launch vehicle according to claim 2, characterized in that, The plurality of engines further includes: a central engine, and the plurality of circumferential engines are arranged around the central engine; the plurality of inlets further includes: 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 on the return ring pipe.

6. The precooling system for a multi-engine cryogenic liquid launch vehicle according to claim 1, characterized in that, The reflux pipe assembly further includes a blind pipe, wherein the ends of the first main reflux pipe and the second main reflux pipe away from the storage tank are both connected to the blind pipe, and the ends of the blind pipe away from the storage tank are closed.

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

8. The precooling system for a multi-engine cryogenic liquid launch vehicle according to claim 7, characterized in that, The reflux pipe assembly further includes: a two-position three-way valve and a discharge pipe, wherein 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 precooling system for a multi-engine cryogenic liquid launch vehicle according to claim 8, characterized in that, Also includes: A first temperature sensor is provided at the inlet of each of the engines to collect the temperature of the propellant flowing into the engine. A second temperature sensor is provided at the outlet of each of the engines to collect the temperature of the propellant flowing out of the engine. The control unit is connected in communication with the first temperature sensor, the second temperature sensor, the helium ejector, and the two-position three-way valve.

10. A precooling method for a multi-engine cryogenic liquid launch vehicle, applied to the precooling system of a multi-engine cryogenic liquid launch vehicle as described in any one of claims 7-9, characterized in that, include: Initiate natural circulation precooling; A first temperature of the propellant at the inlet of each engine and a second temperature of the propellant at the outlet of each engine are obtained. After the natural circulation precooling has continued for a first set time, if it is determined that either the first temperature or the second temperature is greater than the set temperature, then helium ejection precooling is initiated. After the helium ejection precooling has continued for a second set duration, if it is determined that either the first temperature or the second temperature is greater than the set temperature, then emission precooling is initiated.

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