Patent Description:
In the related art, a technique to suppress the behavior of a liquid in a liquid container is required.

As an example, in a spacecraft navigating under a microgravitational environment, in order to smoothly supply a liquid propellant containing a liquid fuel and a liquid oxidizer to an engine or a thruster, it is required to suppress the behavior of the liquid propellant, and prevent gas in the liquid container from being supplied to the engine or the thruster.

As the suppression of the behavior of the liquid propellant, for example, a configuration where the liquid propellant is separated from the gas by a partition wall having elasticity is adopted (refer to the following PTL <NUM>).

In addition, for example, a configuration where a structure such as a channel (refer to the following PTL <NUM>) or a vane (refer to the following NPL <NUM>) for holding the liquid propellant by using the surface tension of the liquid propellant is arranged in the liquid container so as to keep the liquid propellant in the vicinity of a pipe leading to the engine or the thruster is adopted.

In addition, for example, a settling method for separating the liquid propellant from the gas by causing an auxiliary thruster to exert microacceleration on the spacecraft is adopted (refer to the following PTL <NUM>).

Moreover, a tank disclosed wherein eEach tank is a solid of revolution and a baffle with a central aperture and a ring of small, spaced apertures is placed halfway along the tank (refer to the following PTL4).

Also, a liquid storage device for a propellant tank in a spacecraft is described including a gas-guide tube, a cover plate, a housing, blades, a supporting column, a base, a passage-window pressing plate, a passage-window mesh piece, a liquid-storage-device mesh piece, a fixing block, and a pressing plate for the liquid-storage-device mesh piece (refer to the following PTL5).

Finally, a surface tension retaining device is disclosed which is mounted within a tank at the outlet opening to prevent the pressurization gas within the tank from entering the outlet while liquid is still flowing from one or more of the tanks within the system (refer to the following PTL6).

As described above, PTL <NUM> to PTL <NUM> and NPL <NUM> are provided as an example of the technique to suppress the behavior of the liquid in the container.

However, in the configuration disclosed in PTL <NUM>, there are difficulties in selecting the material of the partition wall capable of withstanding a cryogenic temperature environment and the installation of the partition wall increases the weight of the liquid container, which is a problem. In addition, in the configurations disclosed in PTL <NUM> and NPL <NUM>, the arrangement of the structure such as a channel or a vane in the liquid container increases the weight of the liquid container, which is a problem.

In addition, in the configuration disclosed in PTL <NUM>, a liquid propellant for exerting microacceleration on the spacecraft is separately required, and in a case where the weight of a body of the spacecraft is large, since a large thrust force is required to exert the microacceleration, a larger amount of the liquid propellant is required; and thereby increasing the weight of the liquid propellant, which is a problem.

The present invention is made in light of the foregoing circumstances, and an object of the present invention is to provide a liquid behavior suppression device that suppresses the behavior of a liquid.

In order to solve the foregoing problems, the present invention is defined by the appended claims.

According to the liquid behavior suppression devices of the present invention, it is possible to suppress the behavior of the liquid.

The embodiments of <FIG> are not part of the invention.

Hereinafter, embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments.

Hereinafter, a liquid behavior suppression device <NUM> according to a first example not covered by the appended claims will be described with reference to <FIG>. In the following description, the liquid behavior suppression device <NUM> which is used in a liquid container <NUM> accommodating a liquid propellant (liquid) <NUM> in a spacecraft navigating under a microgravitational environment will be provided as an example.

As shown in <FIG>, the liquid behavior suppression device <NUM> according to the present example partitions the inside of the liquid container <NUM> in a direction orthogonal to a central axis O, and holds a liquid on a bottom side along an axial direction of the liquid container <NUM> (hereinafter, simply referred to as a bottom side). The liquid behavior suppression device <NUM> is a member that "fractionates a gas-liquid interface in a direction intersecting the direction of acceleration exerted on the liquid container <NUM>" and "generates a surface tension at the fractionated gas-liquid interface".

The liquid behavior suppression device <NUM> is arranged in the liquid container <NUM> having, for example, a cylindrical shape. In the following description, the direction along the central axis O of the liquid container <NUM> is referred as an axial direction, the direction orthogonal to the central axis O is referred to as a radial direction, and the direction around the central axis O is referred to as a circumferential direction.

The liquid behavior suppression device <NUM> has an annular shape in a plan view. An opening <NUM> is formed in a central portion of the liquid behavior suppression device <NUM> in the radial direction. The opening <NUM> communicates with a top portion side in the axial direction of the liquid container <NUM> (side opposite to a bottom, hereinafter simply referred to as a top portion side), and the bottom side. The opening <NUM> is a portion with low pumping resistance in the liquid container <NUM> which is required to supply the liquid propellant <NUM> from the bottom to a thruster or the like.

The position of the liquid behavior suppression device <NUM> in the axial direction is fixed with respect to the liquid container <NUM>. In this state, the liquid behavior suppression device <NUM> is arranged in the liquid propellant <NUM>. In particular, the liquid behavior suppression device <NUM> is positioned closer to the bottom side than the liquid surface (hereinafter, referred to as the gas-liquid interface) of the liquid propellant <NUM>. Incidentally, as the liquid propellant <NUM> is reduced, the liquid behavior suppression device <NUM> becomes positioned closer to the top portion side than the gas-liquid interface.

Then, in the present embodiment, a plurality of holes <NUM> are formed in the liquid behavior suppression device <NUM> to penetrate therethrough in the axial direction. The liquid behavior suppression device <NUM> has a mesh structure where the mesh stretches vertically and horizontally. With this mesh structure, the holes <NUM> which are very small are uniformly formed across the entire region of the liquid behavior suppression device <NUM>. For this reason, the plurality of holes <NUM> are arranged in a mesh pattern in the radial direction in the liquid container <NUM>. It is possible to appropriately change the opening area of the hole <NUM> depending on the properties or the like of the liquid propellant <NUM>.

Subsequently, the operation of the liquid behavior suppression device <NUM> will be described.

Incidentally, the operation when a spacecraft equipped with the liquid container <NUM> navigates under the microgravitational environment will be described.

Under the microgravitational environment, the inertia force exerted on the liquid propellant <NUM> decreases, and thus, the influence of the surface tension on the liquid propellant <NUM> increases. Therefore, as shown in <FIG>, the wettability of an inner surface of the liquid container <NUM> with respect to the liquid propellant <NUM> increases, and the liquid propellant <NUM> moves along the inner surface of the liquid container <NUM> toward the top portion side. At the time, the liquid propellant <NUM> flows toward the top portion side through the plurality of holes <NUM> of the liquid behavior suppression device <NUM>.

As the liquid propellant <NUM> moves toward the top portion side, a space on the bottom side below the liquid behavior suppression device <NUM> in the liquid container <NUM> is depressurized, and a space on the top portion side is relatively pressurized. As shown in <FIG>, when the height of the gas-liquid interface becomes the same as that of the holes <NUM> of the liquid behavior suppression device <NUM>, the holes <NUM> prevent the liquid from passing therethrough. At the time, a surface tension σ which can be obtained by an equation (<NUM>) occurs at the gas-liquid interface positioned in the holes <NUM> (refer to <FIG>). <MAT> Here, P1: pressure of the top portion side (N/mm<NUM>), P2: pressure of the bottom side (N/mm<NUM>), σ: surface tension (N), and A: cross-sectional area (opening area) of the hole <NUM> orthogonal to the central axis O (mm<NUM>).

Then, in a case where the thruster of the spacecraft generates a thrust force when the spacecraft navigates under the microgravitational environment, an inertia force induced by acceleration is exerted toward the top portion side on the liquid container <NUM> and the liquid propellant <NUM>.

In this case, the surface tension σ occurs at the gas-liquid interface positioned in the holes <NUM>, and thus, a force to cause the liquid propellant <NUM> to flow toward the top portion side through the holes <NUM>, the force being generated by the inertia force which is induced by the acceleration of the thrust force generated by the thruster, opposes the surface tension σ occurring at the gas-liquid interface in the holes <NUM>. For this reason, in the liquid container <NUM>, the liquid propellant <NUM> on the bottom side is prevented from passing through the holes <NUM> to flow toward the top portion side, or the gas on the top portion side is prevented from passing through the holes <NUM> toward the bottom side.

As described above, according to the liquid behavior suppression device <NUM> in the present example, the plurality of holes <NUM> are formed in the liquid behavior suppression device <NUM>. For this reason, when the inertia force which is induced by acceleration toward the top portion side is exerted on the liquid propellant <NUM>, the liquid propellant <NUM> flows toward the top portion side through a part of the plurality of holes <NUM> due to the influence of the inertia force or the exertion of the surface tension σ on the wall surface. Therefore, the region on the bottom side below the liquid behavior suppression device <NUM> is depressurized in the liquid container <NUM>.

Then, a pressure difference between the top portion side and the bottom side in the liquid container <NUM> is received by the gas-liquid interface on which the surface tension σ is strongly exerted in the holes <NUM>, and thus, the liquid propellant <NUM> is prevented from moving from the bottom side toward the top portion side in the liquid container <NUM>. Therefore, in addition, the gas is prevented from moving from the top portion side toward the bottom side. As a result, it is possible to suppress the behavior of the liquid propellant <NUM>.

In addition, since the plurality of holes <NUM> are formed in the liquid behavior suppression device <NUM>, it is possible to suppress the weight of the liquid behavior suppression device <NUM>; and thereby, it is possible to suppress an increase in the weight of the liquid container <NUM> which is caused due to the arrangement of the liquid behavior suppression device <NUM> therein.

In addition, the liquid behavior suppression device <NUM> can be made of a material having a predetermined rigidity, and is not required to be made of an elastic material such as a diaphragm. Therefore, the liquid behavior suppression device <NUM> can easily have durability suitable for a cryogenic temperature environment.

In addition, the plurality of holes <NUM> are arranged at different positions in the radial direction. For this reason, when the inertia force which is induced by acceleration straight along the axial direction is exerted on the liquid propellant <NUM>, it is possible to prevent the gas in the liquid container <NUM> from flowing toward the bottom side through the holes <NUM> on the inside in the radial direction while allowing the liquid propellant <NUM> to easily flow along the inner surface of the liquid container <NUM> through the holes <NUM> on the outside in the radial direction.

Subsequently, a second example not covered by the appended claims will be described with reference to <FIG>.

Incidentally, the same reference signs will be assigned to the same portions in the present example as the configuration elements according to the first example, the description thereof will be omitted, and only the points of difference will be described. In addition, the description of the same operation will also be omitted.

<FIG> is a plan view of a liquid behavior suppression device <NUM> according to the second example not covered by the appended claims.

As shown in <FIG>, the liquid behavior suppression device <NUM> includes annular portion (annular member) <NUM> that is arranged in an outer peripheral edge portion to extend along the outer peripheral edge portion, and a grid portion <NUM> that is connected to an inner peripheral edge portion of the annular portion <NUM>.

The annular portion <NUM> extends across the entire periphery. The grid portion <NUM> includes bars that extend orthogonal to each other in a plan view and defines holes <NUM>, each of which has a rectangular shape in a plan view.

The annular portion <NUM> and the grid portion <NUM> are integrally formed. In the shown example, the annular portion <NUM> extends continuously across the entire periphery. Incidentally, a part of the annular portion <NUM> in a circumferential direction may be missing. In the liquid behavior suppression device <NUM>, the weight is reduced by further increasing the opening area of the hole <NUM> compared to that in the configuration having a mesh structure as in the liquid behavior suppression device <NUM> according to the first embodiment. The opening <NUM> according to the first example is not formed in the liquid behavior suppression device <NUM>. In the liquid behavior suppression device <NUM>, since the opening area of the hole <NUM> can be secured, the hole <NUM> serves also as a portion with low pumping resistance in the liquid container <NUM>.

Under the microgravitational environment, when the liquid propellant <NUM> moves toward the top portion side of the liquid container <NUM> along the inner surface of the liquid container <NUM>, the liquid propellant <NUM> interferes with the annular portion <NUM>, and thus, the movement of the liquid propellant <NUM> toward the top portion side is partially blocked. Therefore, it is possible to suppress a large amount of the liquid propellant <NUM> from moving toward the top portion side, and it is possible to suppress the gas on the top portion side from passing through the holes <NUM> toward the bottom side.

In addition, at the time, the gas-liquid interface of the liquid propellant <NUM> may oscillate (sloshing) periodically in the radial direction. In this case, the liquid propellant <NUM> repeatedly collides with a lower surface that faces the bottom side in an outer surface of the annular portion <NUM>; and thereby, it is possible to suppress such oscillation. Namely, the annular portion <NUM> can have the function of a baffle plate for suppressing the sloshing of the liquid propellant <NUM>.

As described above, according to the liquid behavior suppression device <NUM> in the present example, the annular portion <NUM> is arranged in the outer peripheral edge portion of the liquid behavior suppression device <NUM>. For this reason, the flow of the liquid propellant <NUM> from the holes <NUM> on the outside in the radial direction along the inner surface of the liquid container <NUM> is partially blocked by the annular portion <NUM>; and thereby, it is possible to reduce the outflow amount of the liquid propellant <NUM> toward the top portion side, and as a result, it is possible to regulate the amount of the liquid propellant <NUM> passing through the holes <NUM>.

Therefore, in the liquid behavior suppression device <NUM> of which the weight reduction is realized by increasing the opening area of the hole <NUM>, it is possible to effectively suppress an excessive increase in the amount of the liquid propellant <NUM> passing through the holes <NUM> which is caused by the increase in the opening area.

In addition, since the annular portion <NUM> is provided as a baffle plate, it is possible to suppress the gas-liquid interface of the liquid propellant <NUM> from oscillating periodically in the radial direction which is caused by the inertia force induced by acceleration exerted from outside, and it is possible to more effectively suppress the behavior of the liquid propellant <NUM>.

Here, a modified example of the liquid behavior suppression device <NUM> will be described.

<FIG> is a plan view of the modified example of the liquid behavior suppression device <NUM> and not part of the invention.

As shown in <FIG>, a liquid behavior suppression device 2B according to the present modified example does not include the annular portion <NUM>. For this reason, compared to the configuration including the annular portion <NUM>, it is possible to further reduce the weight of the liquid behavior suppression device 2B. Therefore, it is possible to more effectively suppress an increase in the weight of the liquid container <NUM> which is cause by the arrangement of the liquid behavior suppression device 2B.

In addition, since the annular portion <NUM> is not provided, the liquid propellant <NUM> does not interfere with the annular portion <NUM>, and it is possible to increase the outflow amount of the liquid propellant <NUM> flowing along the inner surface of the liquid container <NUM>. As a result, it is possible to regulate the amount of the liquid propellant <NUM> passing through the holes <NUM>.

Subsequently, an embodiment of the present disclosure will be described with reference to <FIG> and <FIG>.

Incidentally, the same reference signs will be assigned to the same portions in the present embodiment as the configuration elements according to the second embodiment, the description thereof will be omitted, and only the points of difference will be described. In addition, the description of the same operation will also be omitted.

<FIG> is a view showing the navigation trajectory of a spacecraft, and <FIG> is a view showing the behavior of the liquid propellant after ta seconds from the start of turning of a lower-stage rocket <NUM>. In addition, <FIG> is a view showing the behavior of the liquid propellant after tb seconds from the start of turning of the lower-stage rocket <NUM>, and <FIG> is a view showing the behavior after tc seconds from the start of turning of the lower-stage rocket <NUM>. Incidentally, it is assumed that time elapses in order of ta seconds, tb seconds, and tc seconds from the start of turning.

In the first example and second example described above, the configurations where the behavior of the liquid propellant <NUM> with respect to the inertia force which is induced by acceleration exerted in the axial direction is suppressed have been described. On the other hand, as shown in <FIG>, for example, the navigating spacecraft separates an upper-stage rocket <NUM> from the lower-stage rocket <NUM> in a multi-stage rocket to turn the lower-stage rocket <NUM>.

In such case, as shown in <FIG>, for example, an inertia force which is induced by acceleration in the direction intersecting the axial direction may be exerted on the liquid propellant <NUM> in the liquid container <NUM> of the lower-stage rocket <NUM>.

For example, as shown in <FIG>, when the behavior of the liquid propellant <NUM> changes significantly, there is a possibility that the center of gravity of the entire spacecraft may become unstable, or the supply of the liquid propellant <NUM> to a thruster may be disrupted.

Then, in the present embodiment, a configuration for effectively suppressing the behavior of the liquid propellant <NUM> with respect to not only the inertia force which is induced by acceleration in the axial direction but also the inertia force which is induced by acceleration in the direction intersecting the axial direction will be described.

<FIG> is a plan view, <FIG> is a cross-sectional view taken along a line B-B, and <FIG> is a cross-sectional view taken along a line C-C for the liquid behavior suppression device according to the embodiment of the present disclosure.

As shown in <FIG>, a liquid behavior suppression device <NUM> includes an annular portion <NUM> that is arranged in an outer peripheral edge portion to extend along the outer peripheral edge portion; a central plate <NUM> that is arranged in a central portion in the radial direction and has a circular shape in a plan view; a coupling portion <NUM> that is connected to the central plate <NUM> and extends in the radial direction; and a partition wall <NUM> that is connected to the coupling portion <NUM> and extends entirely in the circumferential direction.

The annular portion <NUM> includes front and back surfaces facing the axial direction, and has a planar shape extending in the radial direction. The size of the annular portion <NUM> in the radial direction is the same as the size of a portion in the radial direction in which holes <NUM> are arranged in the liquid behavior suppression device <NUM>.

The annular portion <NUM> is connected to the inner surface of the liquid container <NUM>. Incidentally, the size of the annular portion <NUM> in the radial direction can be arbitrary changed. It is possible to improve the function of a baffle plate for suppressing the foregoing sloshing by increasing the size of the annular portion <NUM> in the radial direction.

The central plate <NUM> is coaxially arranged with the central axis O.

A plurality of the coupling portions <NUM> are arranged with a gap therebetween in the circumferential direction. The coupling portion <NUM> couples the annular portion <NUM> to the central plate <NUM> in the radial direction. The plurality of coupling portions <NUM> are arranged in a radial pattern around the central axis O. A plurality of the partition walls <NUM> are arranged with a gap therebetween in the radial direction. A plurality of the holes <NUM> are defined by the plurality of coupling portions <NUM> and the plurality of partition walls <NUM>. The plurality of holes <NUM> are arranged to form a radial pattern around the central axis O.

As shown in <FIG>, the sizes of the plurality of coupling portions <NUM> in the radial direction differ from each other depending on the position thereof in the circumferential direction.

The plurality of coupling portions <NUM> include first coupling portions 33A that couples the central plate <NUM> to an inner peripheral edge portion of the annular portion <NUM> as shown in <FIG>, and second coupling portions 33B that couples the central plate <NUM> to an outer peripheral edge portion of the annular portion <NUM> as shown in <FIG>. The first coupling portions 33A and the second coupling portions 33B are alternately arranged in the circumferential direction. Since the coupling portion <NUM> includes the first coupling portion 33A, it is possible to suppress the weight of the entirety of the liquid behavior suppression device <NUM>.

In addition, the sizes of the plurality of holes <NUM> in the radial direction differ from each other. In the shown example, among the plurality of holes <NUM>, the sizes of the holes <NUM> in the radial direction which are positioned on one side T1 in one direction (hereinafter, referred to as a turning direction T) in the radial direction are smaller than the sizes of the holes <NUM> in the radial direction which are positioned on the other side T2 in the turning direction T.

The liquid behavior suppression device <NUM> includes an auxiliary partition wall <NUM> extending in the circumferential direction. The auxiliary partition wall <NUM> is arranged on one side T1 in the turning direction T. A central angle with respect to the central axis O as a center between both end portions of the auxiliary partition wall <NUM> in the circumferential direction is <NUM>° or less.

A central portion of the auxiliary partition wall <NUM> in the circumferential direction is positioned at the outermost location on one side T1 in the turning direction T. In the shown example, two auxiliary partition walls <NUM> are provided. The two auxiliary partition walls <NUM> are arranged to be biased to one side T1 in the turning direction T.

The two auxiliary partition walls <NUM> are separately arranged between the partition walls <NUM> adjacent to each other in the radial direction and between the partition wall <NUM> and the inner peripheral edge portion of the annular portion <NUM>.

The hole <NUM> which is defined between the partition walls <NUM> adjacent to each other in the radial direction is subdivided by the auxiliary partition wall <NUM>. In particular, the size of the hole <NUM> in the radial direction which is defined between the partition wall <NUM> and the auxiliary partition wall <NUM> is smaller than the size of the hole <NUM> in the radial direction which is defined between the partition walls <NUM> adjacent to each other in the radial direction.

In other words, among the plurality of holes <NUM>, the opening areas of the holes <NUM> which are positioned on one side T1 in the turning direction T are smaller than the opening areas of the holes <NUM> which are positioned on the other side T2 in the turning direction T.

Incidentally, for example, an auxiliary coupling portion extending in the radial direction may be arranged between the coupling portions <NUM> adjacent to each other in the circumferential direction such that the sizes of the plurality of holes <NUM> in the circumferential direction differ from each other and the opening areas of the plurality of holes <NUM> differ from each other.

Firstly, when an inertia force which is induced by acceleration toward the top portion side is exerted on the liquid propellant <NUM>, as described in the first embodiment, the liquid propellant <NUM> can be allowed to pass through and prevented from passing through each of the holes <NUM> that are arranged to form a radial pattern.

Then, when an inertia force which is induced by acceleration in the direction intersecting the axial direction is exerted on the liquid propellant <NUM> from one side T1 toward the other side T2 in the turning direction T, the liquid propellant <NUM> receives the force toward the other side T2 in the turning direction T which makes the liquid propellant <NUM> to attempt to pass through the holes <NUM>, which are positioned on the other side T2 in the turning direction T, toward the top portion side of the liquid container <NUM>.

In this case, among the plurality of holes <NUM>, the opening areas of the holes <NUM> which are positioned on one side T1 in the turning direction T are smaller than the opening areas of the holes <NUM> which are positioned on the other side T2 in the other side T2 in the turning direction T.

For this reason, according to the foregoing equation (<NUM>), it is possible to increase the surface tension σ exerted on the gas-liquid interface in the holes <NUM> which are positioned on one side T1 in the turning direction T; and thereby, it is possible to prevent the gas from passing through the holes <NUM>, which are positioned on one side T1 in the turning direction T, toward the bottom side. Therefore, it is possible to prevent the liquid propellant <NUM> from passing through the holes <NUM>, which are positioned on the other side T2 in the turning direction T, toward the top portion side.

As described above, in the liquid behavior suppression device <NUM> according to the present embodiment, the plurality of holes <NUM> are arranged to form a radial pattern around the central axis O of the liquid container <NUM>. For this reason, regardless of the positions in the circumferential direction, it is possible to uniformly suppress the behavior of the liquid propellant <NUM> with respect to the inertia force which is induced by acceleration in the axial direction. In addition, since the shape of the liquid behavior suppression device <NUM> in the circumferential direction is uniform, it is possible to secure the manufacturability of the liquid behavior suppression device <NUM>.

In addition, the sizes of the plurality of holes <NUM> in the radial direction differ from each other. For this reason, also when the inertia forces which are induced by acceleration not only in the axial direction but also toward the radial direction in addition to the axial direction are exerted on the liquid propellant <NUM>, owing to the surface tension σ described above which occurs in peripheral edge portions of the holes <NUM>, it is possible to effectively prevent the gas in the liquid container <NUM> from flowing toward the bottom side.

In addition, in a case where the sizes of the holes <NUM> in the circumferential direction differ from each other, also when the inertia forces which are induced by acceleration not only in the axial direction but also toward the circumferential direction in addition to the axial direction are exerted on the liquid propellant <NUM>, owing to the surface tension σ described above which occurs in the peripheral edge portions of the holes <NUM>, it is possible to effectively prevent the gas in the liquid container <NUM> from flowing toward the bottom side.

As described above, in the present embodiment, the opening area of the hole <NUM>, which uses the surface tension which is strongly exerted on the liquid propellant <NUM> under the microgravitational environment to allow and prevent the passing of the liquid propellant <NUM> and the gas of which the flow is caused by a pressure difference in the liquid container <NUM>, differs depending on the position in the radial direction or in the circumferential direction. Therefore, the behavior of the liquid propellant <NUM> with respect to the inertia force which is induced by acceleration in the direction intersecting the axial direction is suppressed; and thereby, it is possible to supply the liquid propellant <NUM> to the thruster to restart the thruster, while significantly changing the posture of the spacecraft.

In addition, it is considered that the foregoing effect is more effective when the inertia force which is induced by acceleration generated by a thrust force from the thruster is small, and a transport spacecraft for exploration such as a lunar lander can be also anticipated to adopt this liquid behavior suppression device. Furthermore, from the viewpoint of improving the degree of freedom in changing the posture of the spacecraft, this liquid behavior suppression device can contribute to adopting a navigation route or an operation which is not feasible in the spacecraft until now.

Subsequently, the verification results of the foregoing effects in the first embodiment and the second embodiment will be described.

In verification tests, the liquid container <NUM> in which the liquid behavior suppression device <NUM> according to the first embodiment was arranged was adopted as a first example, and the liquid container <NUM> in which the liquid behavior suppression device <NUM> according to the second embodiment was arranged was adopted as a second example. In addition, the liquid container <NUM> in which the liquid behavior suppression device was not arranged was adopted as a first comparative example.

Then, in a state where each of the liquid containers <NUM> was free-dropped inside a drop tower to be put under the microgravitational environment, the behavior of the liquid propellant <NUM> when an inertia force induced by acceleration toward the top portion side was exerted thereon was observed. In addition, in the liquid containers <NUM> according to the first comparative example and the second example, the behavior of the liquid propellant <NUM> under the same gravitational environments as those in the verification tests and under an inertia force condition induced by acceleration was analyzed by using computational fluid dynamics simulation (CFD simulation).

As a result, in the liquid container <NUM> according to the first comparative example, as shown in <FIG>, in both of the verification test and the computational analysis, it was confirmed that the behavior of the liquid propellant <NUM> changed significantly.

Specifically, it was confirmed that a central portion of the liquid propellant <NUM> in the radial direction rose significantly toward the top portion side and an outer peripheral part of the liquid propellant <NUM> moved toward the top portion side along the inner surface of the liquid container <NUM>. In addition, it was confirmed that the position of the gas-liquid interface of the liquid propellant <NUM> in the axial direction differed significantly depending on the position thereof in the radial direction. Then, it was confirmed that both results of the verification test and the computational analysis were the same.

On the other hand, in the liquid container <NUM> according to the first example, as shown in <FIG>, it was confirmed that the behavior of the liquid propellant <NUM> was suppressed.

Specifically, it was confirmed that the gas-liquid interface of the liquid propellant <NUM> which was positioned at the same position as that of the opening <NUM> of the liquid behavior suppression device <NUM> was recessed toward the bottom side by the surface tension and an outer peripheral part of the liquid propellant <NUM> was raised toward the top portion side by the surface tension.

In addition, also in the liquid container <NUM> according to the second example, as shown in <FIG>, in both of the verification test and the computational analysis, it was confirmed that the behavior of the liquid propellant <NUM> was suppressed.

Specifically, it was confirmed that a central portion of the liquid propellant <NUM> in the radial direction was slightly recessed toward the bottom side and an outer peripheral part of the liquid propellant <NUM> moved toward the top portion side along the inner surface of the liquid container <NUM>.

Incidentally, the central portion of the liquid propellant <NUM> in the radial direction was recessed toward the bottom side, and the gas-liquid interface formed into a curved shape was recessed by the surface tension σ in the holes <NUM>. It can determined that the behavior of the liquid propellant <NUM> is suppressed due to the occurrence of the surface tension σ which is caused by the operation of the present disclosure. Then, it was confirmed that both results of the verification test and the computational analysis were the same.

As described above, in both of the liquid behavior suppression device <NUM> according to the first embodiment and the liquid behavior suppression device <NUM> according to the second embodiment, the effect of suppressing the behavior of the liquid was confirmed.

Subsequently, the verification result of the foregoing effect in the third embodiment will be described.

In this verification test, the liquid container <NUM> in which the liquid behavior suppression device <NUM> according to the third embodiment was arranged was adopted as a third example.

Then, it was assumed that the spacecraft equipped with the liquid container <NUM> turned under the microgravitational environment to receive the inertia force which was induced by acceleration in the direction intersecting the axial direction, and the behavior of the liquid propellant <NUM> when the inertia force which was induced by acceleration from one side T1 toward the other side T2 in the turning direction T was exerted on the liquid container <NUM> was analyzed by using the CFD simulation.

As a result, in the liquid container <NUM> according to the third example, as shown in <FIG>, it was confirmed that the behavior of the liquid propellant <NUM> was suppressed. In the following description, it is assumed that time elapses in order of t<NUM> seconds, t<NUM> seconds, t<NUM> seconds, and t<NUM> seconds from the start of turning.

Specifically, as shown in each of <FIG>, after t<NUM> seconds, after t<NUM> seconds, after t<NUM> seconds, and after t<NUM> seconds from the start [zero second] of the turning operation, the state of the liquid propellant <NUM> which has moved to the top portion side of the liquid container <NUM> changes every moment; however, the liquid propellant <NUM> which is positioned on the bottom side of the liquid container <NUM> maintains a state of being constantly held on the bottom side. In particular, it is recognized that the gas is prevented from flowing to the bottom side due to the surface tension σ which is exerted on the gas-liquid interface positioned in the holes <NUM>, which is the foregoing effect of the holes <NUM>.

As described above, it was confirmed that the liquid behavior suppression device <NUM> according to the embodiment had the effect of suppressing the behavior of the liquid with respect to the inertia forces which were induced by acceleration not only in the axial direction but also in the direction intersecting the axial direction.

Incidentally, the technical scope of the present disclosure is not limited to the foregoing embodiments, and various changes can be made without departing from the concept of the present disclosure.

Claim 1:
A liquid behavior suppression device (<NUM>) configured to partition an inside of a liquid propellant container (<NUM>) of a spacecraft in a direction orthogonal to a central axis and configured to hold a liquid propellant on a bottom side of the liquid propellant container (<NUM>), comprising:
an annular portion ( <NUM>) that is arranged in an outer peripheral edge portion of the liquid behavior suppression device (<NUM>) to extend along the outer peripheral edge portion;
a central plate (<NUM>) arranged in a central portion in a radial direction;
a plurality of coupling portions (<NUM>) couple the annular portion ( <NUM>) to the central plate (<NUM>) in the radial direction; and
a plurality of partition walls (<NUM>, <NUM>) extending in a circumferential direction, wherein a plurality of holes (<NUM>) that are defined by the plurality of coupling portions (<NUM>) and the plurality of partition walls (<NUM>, <NUM>) are formed to penetrate the liquid behavior suppression device (<NUM>) in an axial direction, wherein the plurality of holes (<NUM>) are arranged to form a radial pattern around the central axis,
wherein sizes of the plurality of holes (<NUM>) in the radial direction differ from each other,
wherein sizes of the plurality of holes (<NUM>) in the circumferential direction differ from each other, and
wherein, among the plurality of holes (<NUM>), opening areas of the holes which are positioned on one side (T1) with respect to the central portion and along a turning direction (T), which is one direction in the radial direction, are smaller than opening areas of the holes (<NUM>) which are positioned on the other side (T2) with respect to the central portion and along the turning direction (T).