Low temperature propellant filling method, system and liquid rocket

Abstract

The embodiment of the present application provides a kind of low temperature propellant filling method, system and liquid rocket, comprising: low temperature propellant is from the lower end of vertical pipe to the vertical pipe is filled, when the low temperature propellant that is filled into the vertical pipe reaches the first preset height in the vertical pipe, stop continuing to fill low temperature propellant;The pipe wall surface of the vertical pipe is cooled until the geyser phenomenon disappears;Wherein, during the cooling period, the low temperature propellant in the vertical pipe sequentially occurs violent boiling phenomenon, geyser phenomenon, or, the low temperature propellant in the vertical pipe sequentially occurs geyser phenomenon;Continue to fill low temperature propellant into the vertical pipe until the second preset height in the storage tank connected with the upper end of the vertical pipe is filled.The geyser phenomenon can be inhibited only by the change of filling sequence, without increasing additional structure and weight, low cost and good effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cryogenic propellant filling, in particular to a cryogenic propellant filling method and system and a liquid rocket. BACKGROUND

[0002] Intermittent spring phenomenon (also known as geyser phenomenon) refers to the phenomenon that, in a long vertical pipeline, due to external heat input, the low-temperature liquid in the pipeline is heated to generate bubbles and accumulate, when the bubbles accumulate to form a gas block, the liquid is squeezed out of the pipeline under the action of gravity, and then the low-temperature liquid in the storage tank connected to the upper part of the long vertical pipeline quickly flows back to the long vertical pipeline to fill, thereby causing a pressure fluctuation similar to water hammer. Water hammer (also known as water hammer phenomenon) refers to the dynamic phenomenon that the pressure in the pipeline instantaneously increases or drops sharply due to the rapid change of the flow rate of the liquid in the pipeline (such as rapid opening and closing of a valve, starting and stopping of a pump, etc.).

[0003] For a liquid rocket, the intermittent spring phenomenon mainly occurs during the cryogenic propellant filling and parking stages. The intermittent spring mainly includes three stages: the first stage is the incubation period: due to the external environment heat leakage and the high initial temperature of the pipeline, the low-temperature propellant is continuously heated by the vertical pipe wall; the second stage is the gushing period: after the low-temperature propellant is heated to the boiling point at the current pressure, the liquid rapidly evaporates, and the steam entrains the liquid to gush out of the pipeline; the third stage is the backflow period: due to the action of gravity, the liquid in the storage tank at the upper part of the vertical pipe recharges into the pipeline, the residual gas in the pipeline is condensed by the backflowing low-temperature liquid, the pressure in the pipeline is reduced, the liquid in the storage tank flows back, and the high-speed flowing low-temperature liquid hits the bottom of the vertical pipe and its speed becomes zero, thereby causing a pressure fluctuation similar to water hammer. If the intermittent spring phenomenon often occurs in the system, the water hammer pressure fluctuation generated in the backflow period will cause structural damage to the supply pipeline, valve, pipeline and sensor.

[0004] The existing intermittent spring solving methods and defects are as follows:

[0005] 1. Injecting inert gas (helium): since the partial pressure of the low-temperature propellant vapor in the injected inert gas is 0, injecting inert gas will promote the evaporation of the low-temperature propellant, thereby causing the temperature of the propellant to drop. The demand for inert gas is large, the cost is high, and the intermittent spring may still occur after stopping the injection of inert gas.

[0006] 2. Increasing a circulating pipeline: by connecting the upstream and downstream of the vertical pipeline through an additional pipeline, the heat received by the pipeline is different from that of the original pipeline, so the temperature and density of the propellant in the two pipelines are different, the density of the upper part is small and the density of the lower part is large, thereby forming a circulation between the two pipelines to avoid the intermittent spring phenomenon. The pipeline needs to be modified, the double-pipe structure is complex, the weight is large, and the pipeline structure needs to be reasonably designed, otherwise it will promote the generation of intermittent spring.

[0007] 3. Pipeline insulation / pressurization. Applying a coating to the pipeline increases thermal insulation, reduces heat flow, and reduces evaporation; increasing the filling pipeline pressure increases the boiling point, so it can withstand more heat, suppress bubble generation, and avoid intermittent fountain. Pipeline insulation requires adding a coating to the pipeline, which increases the volume and weight, and the intermittent fountain suppression effect is limited. Pipeline pressurization requires a larger pressure requirement for the filling pipeline, reduces the filling speed, and the intermittent fountain suppression effect is limited.

[0008] Therefore, there is a need for a method or system that can address the structural damage to the supply pipeline, valve, pipeline, and sensor caused by the intermittent fountain phenomenon in a long vertical pipe, which has low cost and good effect. SUMMARY

[0009] The embodiments of the present application provide a low-temperature propellant filling method, system and liquid rocket, which can address the structural damage to the supply pipeline, valve, pipeline and sensor caused by the intermittent fountain phenomenon in a long vertical pipe.

[0010] To achieve the above-mentioned purpose, in a first aspect, the embodiments of the present application provide a low-temperature propellant filling method, comprising:

[0011] Filling low-temperature propellant into the vertical pipe from the lower port of the vertical pipe, and stopping filling low-temperature propellant when the low-temperature propellant filled into the vertical pipe reaches a first preset height in the vertical pipe;

[0012] Cooling the pipe wall surface of the vertical pipe by the low-temperature propellant in the vertical pipe until the intermittent fountain phenomenon of the low-temperature propellant disappears; wherein, during the cooling period, the low-temperature propellant in the vertical pipe successively experiences violent boiling phenomenon and intermittent fountain phenomenon, or the low-temperature propellant in the vertical pipe successively experiences intermittent fountain phenomenon;

[0013] Continuing to fill low-temperature propellant into the vertical pipe until the second preset height in the low-temperature propellant tank connected to the upper port of the vertical pipe is reached.

[0014] In a second aspect, the embodiments of the present application provide a low-temperature propellant filling system, comprising:

[0015] The filling control unit is configured to fill low-temperature propellant into the vertical pipe from the lower port of the vertical pipe, and to stop filling low-temperature propellant when the low-temperature propellant filled into the vertical pipe reaches a first preset height in the vertical pipe;

[0016] The static cooling unit is used for static cooling the wall surface of the vertical pipe filled with the cryogenic propellant in the vertical pipe until the geyser phenomenon of the cryogenic propellant disappears; wherein, during the static cooling, the cryogenic propellant in the vertical pipe sequentially experiences the violent boiling phenomenon and the geyser phenomenon, or the cryogenic propellant in the vertical pipe sequentially experiences the geyser phenomenon.

[0017] The filling control unit is further used for continuing to fill the cryogenic propellant into the vertical pipe until the cryogenic propellant is filled to a second preset height in the cryogenic propellant storage tank connected with the upper end of the vertical pipe.

[0018] In a third aspect, the embodiment of the present application provides a liquid rocket, which comprises the cryogenic propellant filling system.

[0019] The above technical solution has the following beneficial effects: if the filling of the vertical pipe is stopped after the vertical pipe is filled or partially filled, the geyser phenomenon occurs at this time, but at this time, since there is no liquid in the cryogenic propellant storage tank, the backwater surge does not harm the rocket structure. Then, after the wall surface temperature of the vertical pipe is stabilized, the filling of the cryogenic propellant storage tank is continued, at this time, although the cryogenic propellant storage tank is filled with liquid, the geyser does not occur, and thus the rocket structure is not threatened. According to the principle of the geyser, the generation of the geyser is inhibited, and whether the geyser occurs during the static cooling after the first filling is predicted. Only the filling sequence needs to be changed; the rocket structure does not need to be redesigned, no additional structure and weight are added; no inert gas such as helium is needed, and no additional cost is increased. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 is a flow chart of a cryogenic propellant filling method according to an embodiment of the present application;

[0022] Figure 2 is a structural diagram of a cryogenic propellant filling system according to an embodiment of the present application;

[0023] Figure 3 is a structural diagram of a cryogenic propellant storage tank and a vertical pipe according to an embodiment of the present application;

[0024] Figure 4 is a heat flux density curve of the wall surface of the vertical pipe to the cryogenic propellant during the filling process of continuously filling the cryogenic propellant.

[0025] Figure 5 is a timing chart of filling low-temperature propellant by using the low-temperature propellant filling method of the embodiment of the present application.

[0026] The reference signs are shown as follows:

[0027] 1, vertical pipe; 2, low-temperature propellant tank; 3, low-temperature propellant; 4, filling port; 5, air pillow;

[0028] 6, normal-temperature propellant tank; 7, normal-temperature propellant. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] As shown in Figure 1 and Figure 3 , in combination with the embodiments of the present application, a low-temperature propellant filling method is provided, which comprises:

[0031] S101: filling low-temperature propellant 3 into the vertical pipe 1 from the lower port of the vertical pipe 1, and stopping the filling of the low-temperature propellant 3 when the low-temperature propellant 3 filled into the vertical pipe 1 reaches a first preset height in the vertical pipe 1;

[0032] S102: cooling the pipe wall surface of the vertical pipe 1 by the low-temperature propellant 3 in the vertical pipe 1 until the geyser phenomenon of the low-temperature propellant 3 disappears; wherein, during the cooling, the low-temperature propellant 3 in the vertical pipe 1 successively occurs the violent boiling phenomenon and the geyser phenomenon, or the low-temperature propellant 3 in the vertical pipe 1 successively occurs the geyser phenomenon.

[0033] S103: continuing to fill the low-temperature propellant 3 into the vertical pipe 1 until the second preset height in the low-temperature propellant tank 2 connected with the upper port of the vertical pipe 1 is reached.

[0034] If the filling of the vertical pipe 1 is stopped when the vertical pipe 1 is full or partially full, the geyser phenomenon will occur, but at this time, there is no liquid in the low-temperature propellant tank 2, and no backwater will hit the vertical pipe 1 and the arrow structure below the vertical pipe 1. After the temperature of the wall surface of the vertical pipe 1 is stable, the filling of the low-temperature propellant tank 2 is continued, and at this time, although the low-temperature propellant tank 2 will be filled with liquid, the geyser phenomenon will not occur, and thus the arrow structure will not be threatened.

[0035] In the embodiment of the present application, the generation of the geyser is inhibited according to the principle of the generation of the geyser, and only the filling sequence of the low-temperature propellant 3 needs to be changed. The arrow structure does not need to be redesigned, and no additional structure and weight are needed. No inert gas such as helium is needed, and no additional cost is increased.

[0036] Preferably, in S102, the geyser phenomenon of the low-temperature propellant 3 disappears, and the method comprises the following steps.

[0037] When the heat flux density of the wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser, the geyser phenomenon of the low-temperature propellant 3 disappears.

[0038] The end of the static cooling period is determined by judging that the heat flux density of the wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser, and then the filling of the low-temperature propellant 3 can be continued, so that the geyser phenomenon will not occur again.

[0039] Preferably, the low-temperature propellant filling method further comprises the following steps.

[0040] When the heat flux density of the wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser, the heat flux density of the wall surface of the vertical pipe 1 is substantially balanced with the evaporation heat absorption of the low-temperature propellant 3 being continuously filled into the vertical pipe 1.

[0041] Preferably, the heat flux density of the wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser, and the method further comprises the following steps.

[0042] After the low-temperature propellant 3 is filled into the vertical pipe 1 to a first preset height, the temperature of the outer wall of the vertical pipe 1 is monitored by a temperature sensor arranged on the outer wall of the vertical pipe 1; when the temperature of the outer wall of the vertical pipe 1 is stable, it is determined that the heat flux density of the wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser;

[0043] and / or

[0044] After the low-temperature propellant 3 is filled into the vertical pipe 1 to a first preset height, it is determined that the heat flux density of the wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser when the liquid level meter arranged in the low-temperature propellant tank 2 detects no geyser phenomenon.

[0045] The heat flux density of the pipe wall surface of the vertical pipe 1 can be determined by one of the above two methods or simultaneously, and the disappearance of the geyser phenomenon can be accurately determined, so that the low-temperature propellant can be continuously filled without the occurrence of the geyser phenomenon.

[0046] Preferably, the low-temperature propellant filling method further comprises:

[0047] S104: When the temperature change of the outer wall of the vertical pipe 1 is stable, continue to fill the low-temperature propellant 3 into the vertical pipe 1, and if one of the violent boiling phenomenon or the geyser phenomenon in the vertical pipe 1 is detected, it is determined that the heat preservation of the vertical pipe 1 and / or other pipelines before the vertical pipe 1 for transporting the low-temperature propellant 3 has a problem.

[0048] If it is determined that the heat preservation of the vertical pipe 1 and / or other pipelines before the vertical pipe 1 for transporting the low-temperature propellant 3 has a problem, the heat preservation of the pipeline needs to be reprocessed. In the case that the heat preservation effect of the pipeline meets the requirements, the method combining steps S101-S103 can completely avoid the continuous existence of the geyser phenomenon.

[0049] Preferably, the first preset height is 50% to 100% of the height of the vertical pipe 1, and the specific filling height is related to the structure of the rocket, the external environment, the type of low-temperature propellant, etc.

[0050] During the filling of the low-temperature propellant, one of the important conditions for the occurrence of the geyser phenomenon and the formation of the water hammer in the vertical pipe 1 is that there is enough low-temperature propellant in the low-temperature propellant tank 2 at the upper end of the vertical pipe 1; but if the total amount of low-temperature propellant in the low-temperature propellant tank 2 is insufficient, even if the reflux liquid in the vertical pipe 1 is squeezed out to the low-temperature propellant tank 2, it cannot form a reflux water hammer or the pressure of the reflux water hammer is small, which will not cause damage to the pipeline structure of the rocket, etc. Therefore, in the implementation of the present application, only the low-temperature propellant 3 is filled into the vertical pipe 1, and only to 50% to 100% of the height of the vertical pipe 1, after the static cooling period, the low-temperature propellant in the vertical pipe 1 occurs the geyser phenomenon, which cannot form a reflux water hammer or the pressure of the reflux water hammer is small, which will not cause damage to the pipeline structure of the rocket, etc.

[0051] Preferably, the temperature change of the outer wall of the vertical pipe 1 is stable, which comprises:

[0052] During the set time, the temperature change value of the outer wall of the vertical pipe 1 does not exceed the preset temperature difference.

[0053] When the temperature change value of the outer wall of the vertical pipe 1 does not exceed the preset temperature difference, it indicates that the heat flux density change value of the pipe wall surface of the vertical pipe 1 is stable, that is, the heat exchange between the low-temperature propellant 3 in the vertical pipe 1 and the pipe wall surface of the vertical pipe 1 is basically balanced.

[0054] As Figure 2 shown in the embodiments of the present application, a low-temperature propellant filling system is provided, comprising:

[0055] A filling control unit 100 is configured to fill the low-temperature propellant 3 into the vertical pipe 1 from the lower port of the vertical pipe 1, and stop filling the low-temperature propellant 3 when the low-temperature propellant 3 filled into the vertical pipe 1 reaches a first preset height in the vertical pipe 1.

[0056] A standing cooling unit 200 is configured to standing cool the pipe wall surface of the vertical pipe 1 by the low-temperature propellant 3 in the vertical pipe 1 until the geyser phenomenon of the low-temperature propellant 3 disappears; wherein, during the standing cooling, the low-temperature propellant 3 in the vertical pipe 1 sequentially experiences the violent boiling phenomenon and the geyser phenomenon, or the low-temperature propellant 3 in the vertical pipe 1 sequentially experiences the geyser phenomenon.

[0057] The filling control unit 100 is further configured to continue filling the low-temperature propellant 3 into the vertical pipe 1 until the low-temperature propellant 3 reaches a second preset height in the low-temperature propellant storage tank 2 connected to the upper port of the vertical pipe 1.

[0058] In the embodiments of the present application, the generation of the geyser is inhibited according to the principle of the geyser generation, and only the filling timing of the low-temperature propellant 3 needs to be changed; without the need to redesign the structure of the rocket body, additional structures and weights are not needed; without the need of inert gas such as helium, additional costs are not increased.

[0059] Preferably, the standing cooling unit 200 comprises:

[0060] A determination sub-unit is configured to determine that the geyser phenomenon of the low-temperature propellant 3 disappears when the heat flux density of the pipe wall surface of the vertical pipe 1 is less than the geyser occurrence heat threshold.

[0061] The end of the standing cooling period is determined by judging that the heat flux density of the pipe wall surface of the vertical pipe 1 is less than the geyser occurrence heat threshold, and then the low-temperature propellant 3 can be continuously filled, so that the geyser phenomenon does not occur again.

[0062] Preferably, the filling control unit 100 is specifically configured to:

[0063] When the heat flux density of the pipe wall surface of the vertical pipe 1 is less than the geyser occurrence heat threshold, the heat flux density of the pipe wall surface of the vertical pipe 1 is substantially balanced with the evaporation heat absorption of the low-temperature propellant 3 continuously filled into the vertical pipe 1.

[0064] Preferably, the determination sub-unit is specifically configured to:

[0065] After the low-temperature propellant 3 is filled to a first preset height in the vertical pipe 1, the temperature of the outer wall of the vertical pipe 1 is monitored by a temperature sensor arranged on the outer wall of the vertical pipe 1; when the temperature of the outer wall of the vertical pipe 1 changes stably, it is determined that the heat flux density of the pipe wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser occurrence.

[0066] and / or

[0067] After the low-temperature propellant 3 is filled to a first preset height in the vertical pipe 1, the temperature of the outer wall of the vertical pipe 1 is monitored by a temperature sensor arranged on the outer wall of the vertical pipe 1; when the temperature of the outer wall of the vertical pipe 1 changes stably, it is determined that the heat flux density of the pipe wall surface of the vertical pipe 1 is less than the heat threshold value of the geyser occurrence.

[0068] The heat flux density of the pipe wall surface of the vertical pipe 1 can be determined by one of the above two methods or simultaneously, and the disappearance of the geyser phenomenon can be accurately determined, so that the low-temperature propellant can be continuously filled without the occurrence of the geyser phenomenon.

[0069] Preferably, the determination subunit is further configured to continue filling the low-temperature propellant 3 into the vertical pipe 1 when the temperature of the outer wall of the vertical pipe 1 changes stably, and if one of the violent boiling phenomenon or the geyser phenomenon is detected in the vertical pipe 1, it is determined that the heat preservation of the vertical pipe 1 and / or other pipelines for conveying the low-temperature propellant 3 before the vertical pipe 1 is problematic.

[0070] If it is determined that the heat preservation of the vertical pipe 1 and / or other pipelines for conveying the low-temperature propellant 3 before the vertical pipe 1 is problematic, the heat preservation of the pipeline needs to be reprocessed. In the case that the heat preservation effect of the pipeline meets the requirements, the continuous existence of the geyser phenomenon can be completely avoided by combining the filling control unit and the standing cooling unit.

[0071] Preferably, the first preset height is 50% to 100% of the height of the vertical pipe 1, and the specific filling height is related to the structure of the rocket, the external environment, the type of low-temperature propellant, etc.

[0072] An important condition for the intermittent fountain phenomenon and water hammer to occur in the vertical pipe 1 during the low-temperature propellant filling process is that there is enough low-temperature propellant in the low-temperature propellant tank 2 at the upper end of the vertical pipe 1. However, if the total amount of low-temperature propellant in the low-temperature propellant tank 2 is insufficient, even if the reflux liquid in the vertical pipe 1 is squeezed out to the low-temperature propellant tank 2, the reflux water hammer cannot be formed or the reflux water hammer pressure is small, and the rocket pipeline structure and the like will not be damaged. Therefore, in the implementation of the present application, only low-temperature propellant 3 is filled in the vertical pipe 1, and only 50% to 100% of the height of the vertical pipe 1 is filled. After the standing cooling period, the low-temperature propellant in the vertical pipe 1 occurs intermittent fountain, which cannot form reflux water hammer or the reflux water hammer pressure is small, and the rocket pipeline structure and the like will not be damaged.

[0073] Preferably, the determining subunit is specifically used for:

[0074] When the temperature change value of the outer wall of the vertical pipe 1 does not exceed the preset temperature difference within the set time length, it is determined that the temperature change of the outer wall of the vertical pipe 1 is stable.

[0075] When the temperature change value of the outer wall of the vertical pipe 1 does not exceed the preset temperature difference, it indicates that the heat flux density change value of the pipe wall surface of the vertical pipe 1 is stable, that is, the heat exchange between the low-temperature propellant 3 in the vertical pipe 1 and the pipe wall surface of the vertical pipe 1 is basically balanced.

[0076] Preferably, in combination with the embodiments of the present application, a liquid rocket comprises the low-temperature propellant filling system described above.

[0077] The above technical solutions of the embodiments of the present application will be described in detail below in combination with specific application examples. Technical details not introduced in the implementation process can be referred to the related descriptions in the foregoing.

[0078] The embodiments of the present application are low-temperature propellant filling methods, which are used for low-temperature propellant filling in the field of rockets. The propellant includes an oxidizer and a fuel. The oxidizer includes liquid oxygen, hydrogen peroxide, etc. The fuel includes kerosene, methane, liquid hydrogen, etc. The low-temperature propellant refers to a chemical propellant that needs to be stored in a liquid form at an extremely low temperature under a standard pressure, for example, liquid oxygen, methane, liquid hydrogen, etc. The conventional filling sequence is to first fill the normal-temperature propellant tank 6 with normal-temperature propellant 7, for example, kerosene, and then fill the low-temperature propellant tank 2 with low-temperature propellant 3. The low-temperature propellant tank 2 is located above the normal-temperature propellant tank 6, and the vertical pipe 1 penetrates the normal-temperature propellant tank 6 from the bottom to communicate with the low-temperature propellant tank 2 above the normal-temperature propellant tank 6.

[0079] When the cryogenic propellant 3 is filled, the cryogenic propellant 3 enters into the vertical pipe 1 from the horizontal filling port 4 connected with the lower port of the vertical pipe 1, and then enters into the cryogenic propellant tank 2 through the vertical pipe 1, and generally does not need to be filled to the top, so there is a gas pillow 5 above the cryogenic propellant 3, as shown in Figure 3 .

[0080] If the cryogenic propellant continues to be filled into the cryogenic propellant tank 2, the curve of the heat flow of the pipe wall surface of the vertical pipe 1 facing the propellant over time is as shown in Figure 4 .

[0081] 1. In the early stage of filling, the pipe is boiling

[0082] In the early stage of filling (0~t1), because the temperature of the vertical pipe 1 and the cryogenic propellant tank 2 is high, the temperature difference with the cryogenic propellant 3 is large, the heat flow density (heat flow) Q of the pipe wall surface of the vertical pipe 1 facing the cryogenic propellant input is large, that is, Q>Q2, so the cryogenic propellant 3 will boil and evaporate a large amount, and the geyser phenomenon will not occur.

[0083] 2. In the middle stage of filling, the geyser occurs

[0084] With the progress of the filling process, in the middle stage of filling (t1~t2), the temperature of the pipe wall surface of the vertical pipe 1 gradually decreases, and the heat flow density Q of the pipe wall surface of the vertical pipe 1 facing the cryogenic propellant 3 reaches a suitable interval (Q1<Q<Q2), in this stage, the bubble generation rate is greater than the overflow rate, and is aggregated into large bubbles, so that the vertical pipe 1 is filled, and then a part of the liquid originally in the vertical pipe 1 and a part of the liquid squeezed into the cryogenic propellant tank 2 will flow back into the vertical pipe 1, and the geyser phenomenon occurs.

[0085] 3. In the late stage of filling, the bubbles are uniformly generated

[0086] In the late stage of filling (t>t2), the heat flow density Q of the pipe wall surface of the vertical pipe 1 facing the cryogenic propellant 3 is less than a certain value Q1, that is, Q<Q1, at this time, the heat flow density of the pipe wall surface of the vertical pipe 1 is basically balanced with the heat absorption of the evaporation of the cryogenic propellant 3, the cryogenic propellant 3 slowly generates bubbles and overflows, but the geyser phenomenon will not occur.

[0087] As shown in Figure 5 , the sequential steps of the embodiment of the present application are:

[0088] 1. Partial filling

[0089] In the early stage of filling, only the cryogenic propellant 3 is filled in the vertical pipe 1, and only filled to 50%~100% of the height of the vertical pipe 1, and the cryogenic propellant 3 is not filled into the cryogenic propellant tank 2. The specific filling height is related to the rocket structure, external environment, cryogenic propellant type, etc.

[0090] Intermittent fountain usually occurs in the first time period, for example, three to five minutes, after the vertical pipe 1 is filled, and generally does not occur after the pipe is filled for a longer time, for example, one hour or more than one hour. Meanwhile, the heat flux density transferred by the pipe wall surface to the low-temperature propellant 3 is too large or too small, and the intermittent fountain phenomenon does not occur. Therefore, at the beginning of filling, only the low-temperature propellant 3 is filled in the vertical pipe 1 to 50% to 100% of the height of the vertical pipe 1, and the low-temperature propellant 3 is not filled in the low-temperature propellant tank 2.

[0091] 2, Static cooling

[0092] Subsequently, the static cooling is performed for a long enough time, and the temperature of the pipe wall surface of the vertical pipe 1 and the liquid level meter parameter in the low-temperature propellant tank 2 are detected. During the static cooling, even if the evaporation boiling or gushing phenomenon occurs in the vertical pipe 1, the backflow phenomenon does not occur because there is not enough supercooled low-temperature propellant 3 in the low-temperature propellant tank 2, and therefore the backflow water hammer does not cause damage to the structure of the rocket and the safety of the sensor. Wherein, the enough refers to the height of 100 mm to 300 mm of the low-temperature propellant, and the intermittent fountain water hammer pressure is relatively small and can be ignored. However, it is still preferred that there is no liquid in the low-temperature propellant tank 2.

[0093] Wherein, the main hazard of the intermittent fountain is that the backflow water hammer causes damage to the pipe, the valve, the structure of the rocket, and the sensor. An important condition for the intermittent fountain phenomenon to occur in the vertical pipe 1 and form a water hammer during the low-temperature propellant filling process is that there is enough low-temperature propellant in the low-temperature propellant tank 2 at the upper end of the vertical pipe 1. However, if the total amount of the low-temperature propellant in the low-temperature propellant tank 2 is insufficient, even if the backflow liquid in the vertical pipe 1 is squeezed out to the low-temperature propellant tank 2, the backflow water hammer cannot be formed or the backflow water hammer pressure is small, and therefore the damage to the structure of the rocket pipe and the like does not occur. Therefore, in the implementation of the present application, only the low-temperature propellant 3 is filled in the vertical pipe 1, and only filled to 50% to 100% of the height of the vertical pipe 1, and after the static cooling period, the intermittent fountain occurs in the low-temperature propellant in the vertical pipe 1, which cannot form a backflow water hammer or the backflow water hammer pressure is small, and therefore the damage to the structure of the rocket pipe and the like does not occur.

[0094] By static cooling for a long enough time, the heat flux density Q of the pipe wall surface of the vertical pipe 1 is less than a certain value Q1, and then the low-temperature propellant is filled, and the intermittent fountain does not occur.

[0095] 3, Continue to fill

[0096] After the temperature change of the pipe wall surface of the vertical pipe 1 reaches stability or the liquid level meter in the low-temperature propellant tank 2 no longer detects the gushing phenomenon, the filling of the low-temperature propellant tank 2 is continued. Wherein, the temperature change reaches stability is exemplified as: the temperature change is not more than 5K within 10 minutes.

[0097] The initial temperature of the tube wall of vertical tube 1 is room temperature. After the cryogenic propellant is added, the tube wall transfers heat to the cryogenic propellant, and the tube wall temperature drops. After a sufficiently long time, the tube wall temperature reaches a stable state, and cryogenic propellant can continue to be added without the occurrence of geyser phenomenon.

[0098] 4. After allowing the tube wall temperature to stabilize through static cooling, continue adding cryogenic propellant 3. If violent boiling or gushing still occurs in the vertical tube 1, it indicates that the rocket's piping design cannot avoid geyser phenomena, and the piping insulation and other aspects need to be redesigned. Otherwise, it indicates that the piping will not experience geyser phenomena after sufficient cooling.

[0099] As can be seen in this embodiment of the invention, during the initial t0~t1 time period of the initial loading stage, only a portion of the vertical tube 1 is filled with cryogenic propellant. Subsequently, a static cooling period of t1~t2 is performed to fully pre-cool the tube wall, the outer coating layer, and the room-temperature propellant of the vertical tube 1. During this time, geysers may occur within the vertical tube 1, but because there is no cryogenic propellant in the cryogenic propellant tank 2, backflow cannot occur or the backflow water hammer pressure is low, thus avoiding damage to the rocket body from backflow water hammer. Until the tube wall of the vertical tube 1 is cooled to a heat flux density less than Q1, cryogenic propellant loading continues. Geysers will not occur in the vertical tube 1, allowing cryogenic propellant to be continuously added to the designated liquid level in the cryogenic propellant tank 2.

[0100] The beneficial technical effects achieved by the embodiments of the present invention are as follows:

[0101] If refueling is stopped after vertical tube 1 is fully or partially filled, a geyser-like eruption will occur. However, since there is no liquid in cryogenic propellant tank 2 at this time, backflow water will not form in vertical tube 1 or the rocket structure below it. Once the temperature of the tube wall of vertical tube 1 stabilizes, refueling of cryogenic propellant tank 2 will continue. Although cryogenic propellant tank 2 will be filled with liquid at this time, a geyser will not occur, and therefore it will not pose a threat to vertical tube 1 or the rocket structure below it.

[0102] In this embodiment of the invention, the generation of geysers is suppressed based on the principle of geyser generation, requiring only a change in the timing of cryogenic propellant 3 loading; there is no need to redesign the rocket body structure, nor to add additional structure and weight; and there is no need for inert gases such as helium, thus avoiding additional costs.

[0103] It is to be understood that the foregoing description is that of certain embodiments of the disclosure only, and that modifications or alterations can be made thereto without departing from the scope and spirit of the inventive concepts disclosed. Although the disclosure has been described with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and changes can be made thereto without departing from the scope of the disclosure. The disclosure is not intended to be limited to the embodiments described but is to be accorded the full scope of the claims, and various embodiments thereof, and equivalents thereof. Therefore, to the extent the embodiments coming within the scope of the claims attached hereto, applicable by law, such embodiments fully reside in the scope of the disclosure.

[0104] The foregoing description of the exemplary embodiments of this disclosure has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

[0105] The above description includes one or more examples of the embodiments. Of course, not all possible combinations of components or methods described above will be described, but one of ordinary skill in the art will recognize that further combinations and permutations of the embodiments described herein are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations going to the scope of the claims, including full equivalents thereof. In addition, no limitation is intended to the terms "comprising," "including," "containing," or "having" together with their derivatives, as such terms are interpreted when used in the specification and / or claims. Furthermore, one or more terms are used herein which shall not be interpreted under the doctrine of equivalents, as that doctrine is interpreted under 35 U.S.C. § 112(6), unless otherwise specifically stated herein.

[0106] The above description is in detail only for specific embodiments of the present application, and should not be used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.​​​

Claims

1. A method of filling a cryogenic propellant characterized in that, The method comprises: filling low-temperature propellant (3) into the vertical pipe (1) from the lower port of the vertical pipe (1), and stopping the filling of the low-temperature propellant (3) when the low-temperature propellant (3) filled into the vertical pipe (1) reaches a first preset height in the vertical pipe (1); cooling the pipe wall surface of the vertical pipe (1) by the low-temperature propellant (3) in the vertical pipe (1) until the geyser phenomenon of the low-temperature propellant (3) disappears; wherein, during the cooling, the low-temperature propellant (3) in the vertical pipe (1) successively experiences the violent boiling phenomenon and the geyser phenomenon, or the low-temperature propellant (3) in the vertical pipe (1) experiences the geyser phenomenon; continuing to fill the low-temperature propellant (3) into the vertical pipe (1) until a second preset height in a low-temperature propellant storage tank (2) connected to the upper port of the vertical pipe (1) is reached.

2. The cryogenic propellant filling method of claim 1, wherein, The geyser phenomenon of the low-temperature propellant (3) disappears, comprising: when the heat flux density of the pipe wall surface of the vertical pipe (1) is less than the heat threshold value of the geyser, the geyser phenomenon of the low-temperature propellant (3) disappears.

3. The low-temperature propellant filling method according to claim 2, wherein the continuing to fill the low-temperature propellant (3) into the vertical pipe (1) until the second preset height in the low-temperature propellant storage tank (2) connected to the upper port of the vertical pipe (1) is reached, comprises: when the heat flux density of the pipe wall surface of the vertical pipe (1) is less than the heat threshold value of the geyser, the heat flux density of the pipe wall surface of the vertical pipe (1) is substantially balanced with the evaporation heat absorption of the low-temperature propellant (3) being continuously filled into the vertical pipe (1).

4. The cryogenic propellant filling method of claim 2, wherein, The heat flux density of the pipe wall surface of the vertical pipe (1) being less than the heat threshold value of the geyser further comprises: after the low-temperature propellant (3) is filled into the vertical pipe (1) to the first preset height, the temperature of the outer wall of the vertical pipe (1) is monitored by a temperature sensor arranged on the outer wall of the vertical pipe (1); when the temperature of the outer wall of the vertical pipe (1) is stable, it is determined that the heat flux density of the pipe wall surface of the vertical pipe (1) is less than the heat threshold value of the geyser; and / or after the low-temperature propellant (3) is filled into the vertical pipe (1) to the first preset height, it is determined that the heat flux density of the pipe wall surface of the vertical pipe (1) is less than the heat threshold value of the geyser when the geyser phenomenon is not detected by a liquid level meter arranged in the low-temperature propellant storage tank (2).

5. The cryogenic propellant filling method of claim 4, wherein, Further comprising: after the temperature of the outer wall of the vertical pipe (1) is stable, the low-temperature propellant (3) is continuously filled into the vertical pipe (1), and if the violent boiling phenomenon or the geyser phenomenon in the vertical pipe (1) is detected, it is determined that there is a problem with the heat preservation of the vertical pipe (1).

6. The cryogenic propellant filling method of claim 1, wherein, The first preset height is 50% to 100% of the height of the vertical pipe (1).

7. The cryogenic propellant filling method of claim 1, wherein, The temperature of the outer wall of the vertical pipe (1) being stable, comprises: within a set time, the temperature variation of the outer wall of the vertical pipe (1) does not exceed a preset temperature difference.

8. A cryogenic propellant filling system characterized by, ​ The filling control unit is configured to fill the cryogenic propellant (3) into the vertical pipe (1) from the lower port of the vertical pipe (1), and stop filling the cryogenic propellant (3) into the vertical pipe (1) when the cryogenic propellant (3) reaches a first preset height in the vertical pipe (1). The static cooling unit is configured to perform static cooling on the pipe wall surface of the vertical pipe (1) by the cryogenic propellant (3) in the vertical pipe (1) until the geyser phenomenon of the cryogenic propellant (3) disappears; and during the static cooling, the cryogenic propellant (3) in the vertical pipe (1) sequentially experiences the violent boiling phenomenon and the geyser phenomenon, or the cryogenic propellant (3) in the vertical pipe (1) only experiences the geyser phenomenon. The filling control unit is further configured to continue filling the cryogenic propellant (3) into the vertical pipe (1) until a second preset height in a cryogenic propellant storage tank (2) connected to the upper port of the vertical pipe (1) is reached.

9. A liquid rocket, characterized in that, The cryogenic propellant filling system comprises the cryogenic propellant filling system according to claim 8.

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