JP4660966B2 - Liquid tank - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid tank, and more particularly to a liquid tank that contains a cryogenic liquid under microgravity or weightlessness.
[0002]
[Prior art]
In space infrastructure construction, a cryogenic liquid such as liquid oxygen or liquid hydrogen is transported between spacecrafts in orbit around the earth, and tanks provided in satellites are used as fuel for attitude control thrusters for artificial satellites. It is envisaged to be housed.
[0003]
In order to fill a tank, which is a sealed container, with a liquid, it is necessary to discharge a gas having a volume equal to the volume of the liquid flowing into the tank from the tank. On the ground, gas and liquid are separated into two layers by gravity, so that it is easy to discharge only the gas from the tank. However, since the earth orbit is a zero gravity environment, the gas and the liquid in the tank are not separated into two layers under such an environment, and the gas and the liquid are mixed. Therefore, it is difficult to discharge only the gas from the tank on the earth orbit, and only the gas cannot be discharged unless the tank is capable of gas-liquid separation and liquid capture in a weightless environment. In other words, since the liquid is discharged when the gas is discharged, the tank cannot be efficiently filled with the liquid.
[0004]
In order to solve this problem, a tank that has a mechanism for adhering liquid to the inner wall of the tank using centrifugal force and a mechanism for capturing liquid by surface tension can perform gas-liquid separation without using gravity Has been proposed.
[0005]
[Problems to be solved by the invention]
However, since the mechanism using centrifugal force rotates the tank itself or stirs the liquid in the tank to cause the liquid to adhere to the inner wall of the tank, a rotation drive mechanism is required. It is unsuitable for spacecrafts such as artificial satellites that require severe airtightness and light weight. In addition, due to the inertial force generated by the rotational force of the rotational drive mechanism, there are problems such as making it difficult to control the attitude of the spacecraft.
[0006]
According to the liquid capturing mechanism using the surface tension, such a problem does not occur because there is no drive mechanism. However, since the cryogenic liquid such as liquid oxygen and liquid hydrogen that is the main transfer target has a very low surface tension, it is inefficient to use a liquid trapping mechanism by surface tension for such a cryogenic liquid, Not appropriate.
[0007]
In addition, the cryogenic liquid is extremely volatile, and when it is supplied to the tank, it volatilizes instantly and raises the internal pressure of the tank. Since the liquid cannot be filled, there is a problem that the accommodation efficiency is poor. In addition, as described above, in a tank that cannot perform gas-liquid separation, it is difficult to discharge only gas, and since liquid is discharged together with gas, there is a problem that the storage efficiency is further deteriorated.
[0008]
In order to supply the liquid to the tank without discharging the gas, a method of filling the liquid while suppressing the volatilization of the liquid by increasing the pressure in the tank can be considered. However, it is very difficult and unrealistic to provide a tank and a feeder that can withstand a high pressure state that suppresses the volatilization of the cryogenic liquid.
[0009]
The present invention has been made in view of such problems, and an object of the present invention is to efficiently and easily accommodate a cryogenic liquid in a tank in a weightless or microgravity environment.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is a liquid tank disposed in a zero-gravity or microgravity environment, and is a cylindrical or spherical tank body, and a circumferential direction of an inner wall surface of the tank body a liquid supply means for flowing so as to pivot the liquid along the jet pipe the liquid toward the center of the tank body is ejected from the opened spout, the opening that is open toward the center of the tank body An exhaust pipe that communicates the inside of the tank main body with the outside of the tank; and a liquid jet ejected from the jet outlet is provided between a jet outlet of the jet pipe and an opening of the exhaust pipe. And a baffle that prevents direct discharge from the opening. Further, the present invention is characterized in that the ejection port of the ejection pipe and the opening of the exhaust pipe are arranged to face each other in the axial direction of the tank body. Further, the present invention is characterized in that the ejection pipe is provided so as to protrude from the inner wall surface of the tank body toward the center of the tank body. In the liquid tank according to the present invention, the liquid flowing into the tank main body flows along the cylindrical or spherical inner wall surface by centrifugal force, so that the tank inner wall surface side is in a liquid phase even in a zero gravity or microgravity environment. Gas-liquid separation can be performed so that the center side of the tank is in the vapor phase. Further, since the liquid phase flows along the inner wall surface of the tank when the liquid is supplied, the tank body is pre-cooled by the heat of vaporization caused by the evaporation of the liquid phase, and the liquid can be efficiently supplied to the tank.
[0011]
Further, the present invention is characterized in that the liquid tank includes liquid ejecting means for ejecting the liquid toward the center of the tank body. The liquid tank according to the present invention can condense the vapor phase by ejecting the liquid toward the center of the tank body which is separated into gas and liquid by centrifugal force and becomes a vapor phase.
[0012]
Further, the present invention is characterized in that the liquid tank includes a gas passage for communicating the inside of the tank body and the outside of the tank. In the liquid tank according to the present invention, only the gas can be discharged from the tank by communicating the inside of the tank main body, which is separated into a vapor phase by the centrifugal force, into the vapor phase, and the outside of the tank.
[0013]
The present invention, in the liquid tank, the tank body is characterized in that which is set to a vacuum prior to the supply of the liquid. In the liquid tank according to the present invention, since the pressure difference can be utilized for supplying the liquid by keeping the inside of the tank body in a vacuum, the liquid can be supplied with small power.
[0014]
The present invention, in the liquid tank, inside the tank body, and further comprising a liquid acquisition mechanism that captures the supplied liquid. When the liquid tank according to the present invention is used as, for example, a fuel tank for an attitude control thruster of an artificial satellite, it is captured by the liquid capturing mechanism even when the thruster is stationary in which liquid and gas are mixed in the tank. The liquid can be discharged.
[0015]
The present invention, in the liquid tank, wherein the tank body is characterized by having a heat insulating material covering the outer wall. In the liquid tank according to the present invention, solar heat, heat radiation from peripheral devices, and the like are blocked by a heat insulating material, so that an increase in temperature of the tank body can be suppressed and volatilization of the supplied liquid can be suppressed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a liquid tank 100 that is disposed in a weightless or microgravity environment and stores a liquid according to an embodiment of the present invention. As shown in FIG. 2, the liquid tank 100 is a propellant tank 100 that contains the propellant of the thruster 110 of the satellite, and is supplied from the supply side tank 120 with a cryogenic liquid (propellant such as liquid oxygen or liquid hydrogen). ) L can be filled and this propellant L can be supplied to the thruster 110. The thruster 110 is an engine that controls the attitude of the artificial satellite, and is operated using the propellant L as fuel.
[0017]
As shown in FIGS. 1 and 2, the tank body 10 of the propellant tank 100 is connected to the thruster 110 via the propellant supply pipe 25. Connected to the tank body 10 are a supply pipe 20 as a liquid supply means having a valve 20A, an ejection pipe 21 as a liquid ejection means having a valve 21A, and an exhaust pipe 22 as a gas passage having a valve 22A. .
[0018]
The supply-side tank 120 is mounted on the orbit return vehicle, connected to the propellant tank 100 for the thruster 110 of the artificial satellite, and can be supplied with the propellant L. A supply pipe 122 having a valve 122A is connected to the tank body 121 of the supply side tank 120. In addition, a pump 124 for pumping the propellant L from the tank body 121 is connected to the supply pipe 122.
[0019]
As shown in FIG. 2, the propellant L is supplied to the propellant tank 100 configured as described above through the supply pipe 20, the ejection pipe 21, and the supply pipe 122, as shown in FIG. And the valves 20A, 21A and 122A are opened and the pump 124 is driven, whereby the propellant L is pumped from the supply-side tank 120.
[0020]
The tank body 10 of the propellant tank 100 is formed in a substantially cylindrical shape by a material (for example, an aluminum alloy) suitable for housing a cryogenic liquid. As shown in FIG. 1, the outside of the tank body 10 is covered with a heat insulating material S to prevent the tank body 10 from being heated by solar heat or peripheral equipment. Inside the tank body 10, a supply pipe 20 that allows the propellant L to flow in along the circumferential direction of the inner wall surface, an ejection pipe 21 that ejects the propellant L toward the approximate center of the tank body 10, and a tank An exhaust pipe 22 that allows communication between the substantial center of the main body 10 and the outside of the tank main body 10 and a liquid trapping mechanism (liquid trap) 24 that traps the propellant L in the tank main body 10 are disposed. Prior to the supply of the propellant L, the tank body 10 is precooled by spraying the propellant L from the supply pipe 20 and set to a vacuum.
[0021]
The supply pipe 20 is formed in a tubular shape substantially parallel to the axis of the tank body 10, and in this embodiment, two places are provided as shown in FIGS. As shown in FIG. 1, the supply ports 20 a of the supply pipe 20 are arranged in the axial direction in the tank main body 10, and open at right angles to the axis of the tank main body 10 and in a cylindrical tangential direction. .
[0022]
The propellant L that has flowed in from the supply port 20a in the circumferential tangential direction flows along the inner wall surface of the tank body 10, and due to the momentum of this outflow, as shown in FIGS. 1 and 3A, the tank body 10 A flow in the circumferential direction of the inner wall surface is formed. Since the tank body 10 is in a weightless environment, the propellant L tries to keep turning according to the centrifugal force. The flow of the propellant L is hindered by collision with the supply pipe 20 provided on the inner wall surface of the tank body 10 or friction with the inner wall surface of the tank body 10. It is necessary that the propellant L be introduced from the supply port 20a at a pressure that can continue to swivel.
[0023]
The inside of the tank body 10 is set to a vacuum prior to the supply of the propellant L, and when the propellant L is supplied, the liquid phase LL of the propellant L and the vapor phase (alge) LS of the volatilized propellant L are generated. It exists. In a state where the propellant L is swiveling in the tank body 10, the liquid phase LL always adheres to the inner wall surface of the tank body 10 due to centrifugal force as shown in FIG. The ledge LS is displaced by the liquid phase LL and is located near the axis of the tank body 10. When the amount of the propellant L in the tank body 10 increases due to the inflow of the propellant L, the liquid phase LL increases in thickness as shown in FIG. It is energized in the circumferential direction, adheres to the inner wall surface, and continues to turn. When the propellant L further flows in and the amount of the propellant L in the tank body 10 increases, the liquid phase LL becomes thicker as shown in FIG. Adheres to the wall. On the other hand, the ledge LS decreases as the propellant L increases, but the position does not change and is approximately in the vicinity of the center of the tank body 10.
[0024]
When the propellant L is supplied to the tank body 10, the propellant L volatilizes and increases the internal pressure of the tank body 10. The increase in the internal pressure can be suppressed by condensing the ledge LS by making the propellant L having a temperature lower than that in the tank main body 10 into a mist and bringing it into contact with the ledge LS.
[0025]
The ejection pipe 21 is formed in a tubular shape that communicates the inside and outside of the tank body 10 and is supplied with the propellant L from the supply-side tank 120 in order to make the propellant L into a mist and contact the ledge LS. As shown in FIG. 1, the ejection pipe 21 arranged on the axis of the tank body 10 has an ejection port 21 a that opens toward the vicinity of the approximate center of the tank body 10, and from the ejection port 21 a to the tank body 10. By spraying the propellant L in the form of a mist toward the vicinity of the center of the ledge, that is, the ledge LS described above, the temperature of the ledge LS can be lowered and condensed to reduce the volume. Note that the propellant L ejected to condense the ledge LS is preferably at a lower temperature than at least the inside of the tank body 10.
[0026]
Although an increase in internal pressure due to the volatilization of the propellant L is suppressed as described above, when the internal pressure increases excessively, it is necessary to discharge the gas from the tank body 10. As shown in FIG. 1, the exhaust pipe 22 is formed in a tubular shape that communicates between the inside and outside of the tank body 10, and is disposed on the axis of the tank body 10. The opening 22a of the exhaust pipe 22 is opened in the vicinity of the approximate center of the tank body 10, that is, in the above-described ledge LS portion, and the valve 22A is opened, as shown in FIGS. 3 (a) to 3 (c). In addition, gas can be discharged from the tank body 10 from here. The baffle 23 provided between the opening 22a and the ejection port 21a is a baffle plate that prevents the propellant L ejected from the ejection port 21a from being directly discharged from the opening 22a.
[0027]
In order to supply the propellant L filled in the tank main body 10 to the thruster 110 as described above, it is necessary to extract only the liquid phase LL. However, when the outflow of the propellant L from the supply pipe 20 is stopped, the swirling flow of the liquid phase LL is gradually disturbed due to collision with the supply pipe 20 or friction with the inner wall surface of the tank body 10 and finally. Since there is no flow, the liquid phase LL and the ledge LS are mixed in the tank body 10, so that only the liquid phase LL from the tank body 10 in which the ledge LS is mixed unless gas-liquid separation or liquid capture is performed. Cannot be extracted. In order to supply only the liquid phase LL of the propellant L to the thruster 110, a liquid trap 24 that captures the liquid phase LL is provided in the tank body 10.
[0028]
The liquid trap 24 is a mechanism that captures the propellant L in the tank body 10 by capillary action using surface tension, and is connected to a propellant supply pipe 25 for supplying the captured propellant L to the thruster 110. ing.
[0029]
By supplying the propellant L captured in the liquid trap 24 to the thruster 110 via the propellant supply pipe 25, the thruster 110 is operated and an acceleration force is applied to the tank body 10 in either direction, The propellant L (liquid phase LL) moves in any direction in the tank body 10 according to inertia and adheres to the inner wall surface. For example, as shown in FIG. 1, when an acceleration force F directed downward in the figure is applied to the tank body 10, the liquid phase LL moves upward in the figure in the tank body 10 in accordance with inertia. The propellant L can be supplied to the thruster 110 via the supply pipe 26. The propellant supply pipe 26 is installed at a location suitable for discharging the liquid phase LL depending on the operating direction of the thruster 110.
[0030]
The shapes, combinations, and the like of the constituent members shown in the embodiment are merely examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention. In the illustrated example, the tank body is formed in a cylindrical shape, but it may be formed in a spherical shape so that the liquid is swung on the spherical surface by centrifugal force.
[0031]
【The invention's effect】
As described above, according to the liquid tank of the present embodiment, the liquid that has flowed into the tank body flows along the cylindrical or spherical inner wall surface by centrifugal force, so that even in a zero gravity or microgravity environment. Since the gas-liquid separation can be performed so that the tank inner wall surface is in the liquid phase and the tank center side is in the vapor phase (alignment), it is easy to discharge only gas or liquid from the tank, and at the same time, the liquid Since the tank can be precooled by the heat of vaporization, efficient liquid supply and discharge can be realized.
[0032]
In addition, according to the liquid tank of the present embodiment, the ledge can be efficiently cooled and condensed by ejecting the liquid toward the center of the tank body which is gas-liquid separated by centrifugal force and becomes the ledge. Thus, it becomes possible to allow a lot of liquid to flow into the tank body more easily.
[0033]
In addition, according to the liquid tank of the present embodiment, it is possible to easily discharge only the gas from the tank by communicating the inside of the tank main body that is separated into gas and liquid by centrifugal force and the outside of the tank. This makes it possible to supply liquid more efficiently.
[0034]
Further , according to the liquid tank of the present embodiment , the tank main body is kept in a vacuum, so that the pressure difference with the supply side tank can be increased, less power is required for the liquid supply means, and more efficient. Liquid supply becomes possible.
[0035]
Further , according to the liquid tank of the present embodiment , for example, when used as a fuel tank for an attitude control thruster of an artificial satellite, the liquid is captured by capturing the initial driving amount for driving the stationary thruster by the liquid capturing mechanism. Since only the liquid can be discharged even when the supply is in the gas-liquid separation state, the liquid can be supplied more efficiently.
[0036]
Further , according to the liquid tank of the present embodiment , the heat input such as solar heat is blocked by the heat insulating material to suppress the temperature rise of the tank body, and by suppressing the volatilization of the supplied liquid, the tank internal pressure is increased. As a result, more efficient liquid supply can be achieved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a liquid tank according to the present invention.
FIG. 2 is a conceptual diagram showing a connection between a thruster to which a liquid tank according to the present invention is applied and a supply-side tank.
FIG. 3 is a cross-sectional view showing the beginning of supply (a), the middle of supply (b), and before the end of supply (c) in the process of supplying the liquid to the liquid tank according to the present invention.
[Explanation of symbols]
100 Propellant tank (tank for liquid)
10 Tank body 20 Supply pipe (liquid supply means)
21 Jet pipe (liquid jet means)
22 Exhaust pipe (gas passage)
24 Liquid trap (liquid trapping mechanism)
S Insulation material L Liquid (propellant)
LL Liquid phase LS Alleged (vapor phase)

Claims (6)

A liquid tank placed in a zero-gravity or microgravity environment,
A tank body formed in a cylindrical or spherical shape;
Liquid supply means for flowing the liquid so as to swirl along the circumferential direction of the inner wall surface of the tank body;
An ejection pipe for ejecting liquid from an ejection opening opened toward the center of the tank body;
An exhaust pipe having an opening opened toward the center of the tank body, and communicating the inside of the tank body and the outside of the tank;
A baffle provided between the outlet of the ejection pipe and the opening of the exhaust pipe to prevent the liquid ejected from the ejection outlet from being directly discharged from the opening;
A liquid tank characterized by comprising:   The liquid tank according to claim 1, wherein the outlet of the ejection pipe and the opening of the exhaust pipe are arranged to face each other in the axial direction of the tank body. 3. The liquid tank according to claim 1, wherein the ejection pipe is provided so as to protrude from an inner wall surface of the tank body toward a center of the tank body.   The liquid tank according to any one of claims 1 to 3, wherein the tank body is set to a vacuum prior to supply of the liquid.   5. The liquid tank according to claim 1, further comprising a liquid capturing mechanism that captures the supplied liquid inside the tank main body.   The liquid tank according to claim 1, wherein the tank body includes a heat insulating material that covers an outer wall.

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