A space variable gravity fluid tank on-orbit motion simulation experimental device and method

Abstract

The invention discloses an on-orbit motion simulation experimental device of a space variable gravity fluid tank in the field of space on-orbit fluid management technology, comprising: an experimental tank for storing experimental fluid; the experimental tank is transparently arranged so that the gas-liquid interface in the tank can be observed from outside the experimental tank; a rotating mechanism is used to drive the experimental tank to rotate so as to adjust the angle between the experimental tank and the centrifugal acceleration direction of a variable gravity centrifugal platform so as to simulate the morphological change of the gas-liquid interface during the rotational motion; a vibrating mechanism is used to drive the experimental tank and the rotating mechanism to perform linear reciprocating motion simultaneously so as to apply translation and low-frequency vibration disturbances to the experimental tank so as to simulate the morphological change and instability of the gas-liquid interface during the process of the gas-liquid interface being disturbed by external force; the experimental tank, the rotating mechanism and the vibrating mechanism are all installed on the variable gravity centrifugal platform.

Description

Technical Field

[0001] The present invention relates to the technical field of space on-orbit fluid management, and in particular to an on-orbit motion simulation experimental device and method for a space variable gravity fluid tank. Background Art

[0002] In the space environment, due to the weakening or disappearance of the earth's gravity, the behavior of fluids (especially liquids) is significantly different from that on the ground. In a microgravity environment, the physical properties of the fluid, such as surface tension and buoyancy, will change, resulting in the fluid's distribution in the container, flow velocity, stability, etc. showing unique laws. Therefore, on-orbit fluid management in space needs to fully consider the fluid characteristics under these microgravity conditions.

[0003] On-orbit fluid management in space, also known as microgravity fluid management or space fluid management, refers to a series of operations and management activities for fluids (including liquids, gases or two-phase flows) in a space environment (such as inside a spacecraft) to ensure that fluid-related systems can operate normally and perform specific functions. These activities usually include the storage, transmission, control of fluids, and related scientific research and technical verification.

[0004] The space experiment plan involves different experimental conditions. According to the actual working conditions of the spacecraft tank, there is a situation where the gas-liquid interface is disturbed and unstable. It is of great significance to explore the oscillation law and recovery period of the free liquid surface in the tank caused by gravity changes and external disturbances. Summary of the invention

[0005] In order to solve the above technical problems, the present invention specifically provides an on-orbit motion simulation experimental device for a space variable gravity fluid tank, comprising:

[0006] Experimental tank, used to store experimental fluid;

[0007] The experimental tank is transparent so that the gas-liquid interface in the tank can be observed from outside the experimental tank;

[0008] A rotating mechanism, used to drive the experimental tank to rotate, so as to adjust the angle between the experimental tank and the centrifugal acceleration direction of the variable gravity centrifugal platform, so as to simulate the morphological change of the gas-liquid interface during the rotational motion;

[0009] A vibration mechanism, used to drive the experimental tank and the rotating mechanism to perform linear reciprocating motion simultaneously, so as to apply translational and low-frequency vibration disturbances to the experimental tank, and simulate the morphological changes and instability of the gas-liquid interface during the process of the gas-liquid interface being disturbed by external forces;

[0010] The experimental tank, the rotating mechanism and the vibrating mechanism are all installed on a variable gravity centrifugal platform;

[0011] The rotating mechanism and the vibrating mechanism cooperate with each other to simulate the on-orbit motion of a space variable gravity fluid tank that combines rotation and translation motion.

[0012] As a preferred solution of the present invention, the rotation mechanism drives the experimental tank to rotate on-orbit at an angle range of 0 to 180° and a rotation angular velocity range of 0.1 to 6 rad / s.

[0013] As a preferred solution of the present invention, the vibration mechanism applies vibration to the test tank at a frequency interval of 0.5-1 Hz, and a maximum vibration amplitude of 10 mm.

[0014] As a preferred solution of the present invention, the rotating mechanism comprises a stepping motor, a connecting shaft, a tank mounting fixing flange and a rotating bracket;

[0015] The experimental tank is rotatably mounted on the rotating bracket via the tank mounting fixing flange, and the stepper motor is connected to the experimental tank via a connecting shaft to drive the experimental tank to rotate around the connecting shaft.

[0016] As a preferred solution of the present invention, the middle of the experimental tank is a cylindrical shell, and the two ends of the experimental tank are symmetrically arranged hemispherical shells, and the diameter of the hemispherical shell is equal to the diameter of the cylindrical shell;

[0017] The connecting shaft is colinear with the short axis of the experimental tank, and the rotating mechanism can drive the experimental tank to rotate around its short axis to adjust the angle between the long axis of the experimental tank and the centrifugal acceleration direction of the variable gravity centrifugal platform;

[0018] The major axis is the longest centerline passing through the center of the test tank, and the minor axis is the shortest centerline passing through the center of the test tank.

[0019] As a preferred solution of the present invention, the vibration mechanism includes a linear motor, a mobile platform and a slide rail, and the experimental tank and the rotating mechanism are both installed on the mobile platform;

[0020] The linear motor is used to drive the moving platform to reciprocate linearly along the slide rail.

[0021] As a preferred solution of the present invention, the vibration mechanism further includes a grating ruler and a reading head, and the moving platform can move along the grating ruler under the drive of the linear motor;

[0022] The reading head is fixedly mounted on the mobile platform to feed back the real-time position of the mobile platform to the linear motor;

[0023] The grating ruler is sequentially provided with a left limit switch, a zero switch and a right limit switch connected to the motor control circuit of the linear motor to control the moving range of the moving platform;

[0024] The motor control circuit is connected to the driver via a 485 interface.

[0025] The present invention also provides a space variable gravity fluid tank on-orbit motion simulation experiment method, using the space variable gravity fluid tank on-orbit motion simulation experiment device, comprising the following steps:

[0026] Start the variable gravity centrifugal platform and make the turntable of the variable gravity centrifugal platform operate according to the start-up speed and target gravity acceleration required by the experimental project;

[0027] The rotating mechanism is started to drive the experimental tank to rotate to a predetermined angle at a predetermined angular velocity, simulating the dynamic motion characteristics of the fluid inside the tank during the on-orbit attitude change of the aircraft, and the angle between the long axis of the experimental tank and the centrifugal acceleration is changed multiple times by the rotating mechanism, and the experiment is repeated multiple times;

[0028] Start the vibration mechanism to drive the test tank to vibrate according to the predetermined vibration frequency and vibration amplitude, simulate the working condition of the test tank being disturbed by translation and low-frequency vibration, change the vibration frequency and vibration amplitude, and repeat the experiment for multiple times;

[0029] The rotating mechanism and the vibrating mechanism are started simultaneously to simulate the on-orbit motion of a space variable gravity fluid tank that combines rotation and translation motion, and the rotation and / or vibration parameters are changed, and the experiment is repeated multiple times.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The rotating mechanism can simulate the working condition of the change of the direction of gravity acceleration alone, so as to simulate the morphological change of the gas-liquid interface during the rotational motion; the vibration mechanism can simulate the working condition of the experimental tank being subjected to low-frequency disturbance alone, and simulate the morphological change and instability of the gas-liquid interface during the disturbance of the gas-liquid interface by external force; through the coordination of the rotating mechanism and the vibration mechanism, the composite working condition of the change of the direction of gravity acceleration of the experimental tank and the low-frequency disturbance can be simulated at the same time, and the situation of the disturbed and unstable gas-liquid interface can be realistically simulated, which is helpful to study the oscillation law and recovery period of the free liquid surface in the tank caused by gravity changes and external disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0033] Figure 1 It is a structural schematic diagram of the experimental box and the electric control box in the embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the internal structure of the experimental box after cross-section in an embodiment of the present invention;

[0035] Figure 3 It is a schematic diagram of the structure of the experimental tank and the liquid storage tank in the embodiment of the present invention;

[0036] Figure 4 for Figure 3 A top view schematic diagram of

[0037] Figure 5 for Figure 4 A schematic diagram of a front side view;

[0038] Figure 6 It is a schematic diagram of the structure of the experimental tank, the external force applying mechanism, and the fluid observation device in the embodiment of the present invention;

[0039] Figure 7 It is a structural schematic diagram of a vibration mechanism in an embodiment of the present invention;

[0040] Figure 8 It is a structural schematic diagram of a mobile platform and a slide rail in an embodiment of the present invention;

[0041] Fig. 9 Schematic diagram of the bottom structure of the mobile platform in an embodiment of the present invention;

[0042] Fig.10 It is a schematic diagram of the top view of the experimental storage tank in the embodiment of the present invention;

[0043] Fig.11 It is a schematic diagram of the side structure of the experimental tank in the embodiment of the present invention;

[0044] Fig.12 It is a schematic diagram of the structure of the upper tank in an embodiment of the present invention;

[0045] Fig.13 This is a schematic diagram of the structure of the lower half tank in an embodiment of the present invention;

[0046] Fig.14 It is a structural schematic diagram of the experimental working fluid storage and charging dual-circuit system in an embodiment of the present invention;

[0047] Fig.15 A schematic diagram of the sequence of conducting internal and external disturbance experiments in an embodiment of the present invention;

[0048] Fig.16 Schematic diagram of the sequence of conducting a liquid filling experiment in an embodiment of the present invention.

[0049] The numbers in the figure represent the following:

[0050] 1-experimental box, 2-electrical control box, 3-variable gravity centrifugal platform;

[0051] 4-experimental tank, 401-upper tank, 402-lower tank, 403-liquid inlet, 404-liquid outlet;

[0052] 5-Liquid storage tank;

[0053] 6-experimental working fluid storage and charging dual circuit system, 601-first solenoid valve, 602-liquid pump, 603-charging hand valve, 604-second solenoid valve, 605-reversing solenoid valve, 606-pressure sensor, 607-flow meter;

[0054] 7-fluid observation device, 701-fixed camera, 702-illumination light source, 703-follow-up camera, 704-observation scale;

[0055] 8-rotating mechanism, 801-stepping motor, 802-connecting shaft;

[0056] 9-vibration mechanism, 901-linear motor, 902-moving platform, 903-grating ruler, 904-reading head, 905-motor control circuit, 906-left limit switch, 907-zero position switch, 908-right limit switch, 909-main control board, 9010-slide rail. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] The present invention specifically provides a space variable gravity on-orbit fluid experiment system and method. It should be emphasized that the experimental system and method are adapted to the microgravity or variable gravity environment provided by the variable gravity centrifugal platform 3, that is, the variable gravity or microgravity space environment simulated by the variable gravity centrifugal platform 3. All experimental components and experimental methods in the present invention are constructed based on this.

[0059] The variable gravity centrifugal platform 3 in the experimental system is equipped with:

[0060] The experimental box 1 is installed on the variable gravity centrifugal platform 3 of the variable gravity centrifugal platform 3, and is provided with an experimental storage tank 4 and a liquid storage tank 5;

[0061] The electric control box 2 is installed on the variable gravity centrifugal platform 3 of the variable gravity centrifugal platform 3 and is connected to the electronic devices in the experimental box 1 .

[0062] The internal structure of the experimental box 1 is the design focus of the present invention, and mainly includes the following five parts.

[0063] 1. Experimental storage tank

[0064] The experimental tank 4 is a box used for observing the gas-liquid interface, gas-liquid two-phase distribution and gas-liquid movement in the variable gravity on-orbit fluid experiment in space. The improvement of the experimental tank 4 in the present invention is used to solve the technical problem that the existing experimental tank 4 is composed of two equally divided boxes, the two boxes are connected by a flange at the middle axis, and the flange is located at the maximum cross-section of the experimental tank 4, which is not convenient for obtaining a quantitative observation image reflecting the maximum gas-liquid interface in the tank.

[0065] The details are as follows:

[0066] The off-axis visualization quantitative observation of the sealed tank is used to observe the maximum cross section of the liquid in the experimental tank 4.

[0067] It includes an upper tank 401 and a lower tank 402 that are fixedly connected, a sealing ring is provided between the upper tank 401 and the lower tank 402, and lug flanges are provided on the edges of the upper tank 401 and the lower tank 402. The upper and lower lug flanges are sealed and fixed by bolts and built-in O-rings to form a complete transparent and visualized experimental tank 4.

[0068] The upper tank 401 and the lower tank 402 are both made of transparent materials so that the gas-liquid interface morphology in the tank can be observed outside the tank.

[0069] The volume of the upper tank 401 is greater than that of the lower tank 402, so that the center of the experimental tank 4 is located in the upper tank 401, that is, the maximum cross-section of the experimental tank 4 is located in the upper tank 401, so that the gas-liquid interface morphology at the maximum axial cross-section in the center of the experimental tank 4 can be observed from above the experimental tank 4.

[0070] When observing the gas and liquid in the experimental tank 4, the line of sight is from top to bottom, so the liquid inlet 403 and the liquid outlet 404 of the experimental tank 4 are both arranged on the lower half tank 402 to avoid blocking the observation line of sight.

[0071] The experimental tank 4 is set to a typical propellant tank geometry, that is, the middle is a cylindrical shell, and the two ends of the experimental tank 4 are symmetrically arranged hemispherical shells, and the diameter of the hemispherical shell is equal to the diameter of the cylindrical shell;

[0072] The line connecting the centers of the two hemispherical shells is consistent with the direction of the centrifugal acceleration of the variable gravity centrifugal platform 3 , that is, the experimental tank 4 is arranged along the radial direction of the variable gravity centrifugal platform 3 .

[0073] One of the advantages of setting the experimental tank 4 to the above-mentioned shape and arranging it radially is that when the variable gravity centrifugal platform 3 rotates to provide centrifugal force, the liquid in the experimental tank 4 will be concentrated on one side of the experimental tank 4 under the action of the centrifugal force, and the liquid interface is perpendicular to the line connecting the two sphere centers, that is, the liquid interface is perpendicular to the long axis of the experimental tank 4.

[0074] As the filling rate of the experimental tank 4 increases, the liquid interface gradually moves along the line connecting the sphere centers. Since both ends and the middle of the experimental tank 4 are of regular shapes, it is convenient to calculate the filling rate corresponding to each point on the long axis, so as to mark the corresponding observation scale 704 on the experimental tank 4 as a reference for the liquid filling and filling rate adjustment of the experimental tank 4.

[0075] That is, the filling rate observation in the present invention needs to be carried out under the condition that the centrifugal force provided by the variable gravity centrifugal platform 3 is small, that is, it is carried out under the variable gravity centrifugal platform 3 simulating microgravity or variable gravity conditions, which conforms to the real space gravity environment, not under the normal gravity of the earth.

[0076] The liquid inlet 403 and the liquid outlet 404 are symmetrically arranged on both sides of the lower tank 402 along the centrifugal acceleration direction of the variable gravity centrifugal platform 3 .

[0077] An observation scale 704 is provided on the upper tank 401, and the observation scale 704 is arranged along the centrifugal acceleration direction of the variable gravity centrifugal platform 3, so as to observe the filling ratio of the liquid in the experimental tank 4 when the variable gravity centrifugal platform 3 provides centrifugal acceleration.

[0078] 2. Fluid Observation Device

[0079] In the on-orbit fluid management simulation experiment in space, it is necessary to observe and record the gas and liquid in the experimental tank 44 through a camera. In the prior art, observation and recording are generally performed through a single camera, which is unable to comprehensively observe and record the flow evolution process of the gas-liquid interface.

[0080] The fluid observation device 7 of the present invention realizes the morphology observation of the gas-liquid interface of the experimental liquid in the experimental tank 4 by the shadow method, including:

[0081] A fixed camera 701 is fixedly arranged just above the transparent experimental tank 4;

[0082] An illumination light source 702 is fixedly arranged directly below the experimental tank 4. The illumination light source 702, the fixed camera 701 and the experimental tank 4 are located in a straight line so as to observe the real-time evolution of the gas-liquid interface in the experimental tank 4 by using the shadow method;

[0083] The follow-up camera 703 is fixedly installed with the experimental tank 4 and is located on the side of the experimental tank 4, and can move synchronously with the experimental tank 4; specifically, the follow-up camera 703 is installed on the lug flange of the upper tank 401

[0084] The fixed camera 701 cooperates with the follow-up camera 703 to perform quasi-three-dimensional observation of the gas-liquid interface in the experimental tank 4, so as to determine the flow evolution process of the gas-liquid interface from both the front and side directions.

[0085] The fixed phase cooperates with the follow-up camera 703, which can perform quasi-three-dimensional observation of the gas-liquid interface in the experimental tank 4 from the front and side, one moving and one static, and at the same time, comprehensively obtain video images of the gas-liquid interface, gas-liquid two-phase distribution, and gas-liquid flow evolution process from the front and side directions. After the experimental box 1 and the electric control box 2 are powered on, they start shooting and save in segments until the storage is full or the power is cut off.

[0086] If a scale is marked on the experimental tank 4, when observing the gas and liquid in the experimental tank 4, the observation scale 704 is used as a reference, so that the liquid filling rate can be judged more accurately.

[0087] Therefore, two groups of observation scales 704 are provided on the experimental tank 4, facing the fixed camera 701 and the follow-up camera 703 respectively.

[0088] Furthermore, the observation scale 704 is arranged along the centrifugal acceleration direction of the variable gravity centrifugal platform 3 so as to observe the current filling ratio of the liquid in the experimental tank 4 when the variable gravity centrifugal platform 3 provides centrifugal acceleration.

[0089] The observation scale 704 is arranged along the centrifugal acceleration direction of the variable gravity centrifugal platform 3. According to the previous volume measurement of the experimental tank 4, corresponding scales are marked at corresponding positions along the centrifugal acceleration direction to indicate the corresponding filling rate.

[0090] In order to facilitate the marking of scales, the experimental tank 4 can be set to the above-mentioned typical propellant tank geometry, and the experimental tank 4 can be arranged along the radial direction of the variable gravity centrifuge platform 3, that is, along the direction of centrifugal acceleration, so that the observation scale 704 is arranged along the long axis of the experimental tank 4.

[0091] When the centrifuge rotates and provides 1g centrifugal acceleration, the direction of the centrifugal acceleration is perpendicular to the long axis of the experimental tank 4, and the gas-liquid interface in the experimental tank 4 is parallel to each scale line in the observation scale 704. The center of the long axis direction of the experimental tank 4 (50% liquid filling ratio) is marked as the central position scale line, and based on this, the scale lines of different liquid volume filling ratios are symmetrically scaled along the two ends of the tank (40%, 60% liquid filling ratio corresponds to "4", 30%, 70% liquid filling ratio corresponds to "3", and so on). By using a CCD camera to observe the gas-liquid interface at the corresponding position of the tank scale line, the volume filling ratio of the liquid in the tank can be quantitatively obtained, and the real-time optical observation of the gas-liquid interface morphology and position in the tank under different experimental conditions can be completed to obtain quantitative scientific experimental results.

[0092] Furthermore, the camera model selected has a resolution of 1080p and a maximum observation field of 100mm×80mm, which can meet the requirements of relatively accurate observation and positioning of the gas-liquid interface. For the evolution of the static gas-liquid interface under microgravity, a relatively low acquisition frame rate (25fps) can meet the requirements. However, for the application of variable gravity conditions, external force shaking, etc., for larger tanks, the gas-liquid interface changes dramatically. If the characteristic time points corresponding to each flow evolution moment are to be accurately captured, a relatively high-speed CCD camera acquisition frame rate is necessary. Considering the downlink bandwidth and the amount of stored data, we choose an acquisition frame rate of about 60fps. In specific implementation, the acquisition frame rate can be adjusted according to the experimental requirements. The selected lens is a fixed-focus lens with a focal length of 115mm and a maximum field of view of about 100mm, which meets the scientific needs of this project.

[0093] There are two groups of observation scales 704, one of which is opposite to the fixed camera 701, namely, located at the middle position of the top of the experimental tank 4, and the other is arranged on the side of the experimental tank 4, opposite to the follow-up camera 703 on the side. In order to obtain a better observation effect, the distance between the two groups of observation scales 704 should not be too close. The observation scale 704 at the middle position of the top of the experimental tank 4 is taken as the zero degree reference, and the angle between the two groups of observation scales 704 is preferably 30°-45°.

[0094] The fixed camera 701 and the follow-up camera 703 are both high-speed cameras, so as to accurately capture the characteristic time points corresponding to each flow evolution moment.

[0095] The illumination light source 702 is configured as a plurality of evenly distributed white light LED lamp beads to form a relatively even background light source.

[0096] 3. Experimental working fluid storage and filling dual circuit system

[0097] During the activities of the on-orbit fluid management device in space, the liquid in the liquid storage tank 5 is pumped into the experimental tank 4 by the liquid pump 602, and the liquid filling rate in the experimental tank 4 is adjusted by the liquid pump 602; however, since the gas-liquid two-phases in the experimental tank 4 are mixed, the liquid pump 602 will extract the gas-liquid two-phases when working, causing damage to the liquid pump 602.

[0098] For this purpose, the present invention designs a dual-circuit system 6 for storing and filling experimental working fluids, so that the liquid pump 602 can only extract the liquid phase when working.

[0099] It includes an experimental tank 4, a first electromagnetic valve 601, a liquid pump 602, a liquid storage tank 5 and a second electromagnetic valve 604 which are connected in sequence to form a closed loop;

[0100] The ports on the experimental tank 4 and the liquid storage tank 5 connected to the liquid pump 602 are both located on a side thereof away from the center of the variable gravity centrifugal platform 3, and the ports on the experimental tank 4 and the liquid storage tank 5 connected to the second electromagnetic valve 604 are both located on a side thereof close to the center of the variable gravity centrifugal platform 3, so that when the variable gravity centrifugal platform 3 provides centrifugal force, the inlet and outlet of the liquid pump 602 are filled with liquid;

[0101] The pipelines on both sides of the head and tail of the liquid pump 602 are connected with a reversing solenoid valve 605, and the reversing solenoid valve 605 can change the direction of the fluid in the circuit to select the liquid pump 602 to enter the experimental tank 4 or the liquid storage tank 5, and can adjust the filling rate of the experimental tank 4 to achieve static balance of the gas-liquid interface under microgravity conditions and dynamic behavior observation under variable gravity conditions under different filling rates;

[0102] The first solenoid valve 601 and the second solenoid valve 604 can close the experimental tank 4 after the filling rate is adjusted to fix the filling rate of the experimental tank 4;

[0103] A filling manual valve 603 is installed in the closed loop for filling the closed loop with experimental working fluid.

[0104] When the variable gravity centrifugal platform 3 provides centrifugal force, under the action of centrifugal force, due to the mass difference between the gas and liquid phases, the liquid phases in the experimental tank 4 and the liquid storage tank 5 converge on the side away from the center of the variable gravity centrifugal platform 3, while the gas phase is driven to converge on the side close to the center of the variable gravity centrifugal platform 3.

[0105] At this time, the ports on the experimental tank 4 and the liquid storage tank 5 connected to the liquid pump 602 are both in the liquid phase, so that the liquid pump 602 will not draw air when extracting liquid, thereby avoiding damage to the liquid pump 602 and extending its service life.

[0106] It should be noted that when the liquid pump 602 is working, the first solenoid valve 601 and the second solenoid valve 604 are both in the open state. The first solenoid valve 601 is opened to ensure the circulation of liquid between the experimental tank 4 and the liquid storage tank 5. The flow of liquid will cause changes in the gas phase in the two tanks. For example, when liquid is injected into the experimental tank 4, the gas phase in the experimental tank 4 will be compressed. In order to avoid the increase of air pressure in the experimental tank 4 affecting the injection of liquid, the experimental tank 4 is connected to the liquid storage tank 5 so that excess gas in the experimental tank 4 can enter the liquid storage tank 5.

[0107] When the filling rate in the experimental tank 4 reaches a predetermined value, the first solenoid valve 601 and the second solenoid valve 604 are closed, so that the liquid phase and the gas phase can be locked in the experimental tank 4 to prevent the liquid from escaping.

[0108] The above-mentioned filling system can also simulate the on-orbit filling of liquids, that is, simulate the on-orbit liquid replenishment process in space, and is widely used.

[0109] It can be understood that, in this process, the liquid outlet 404 on the experimental tank 4 is essentially a port for the gas phase to pass through.

[0110] The closed loop is also provided with a pressure sensor 606 for detecting the hydraulic pressure of the experimental tank 4 and the liquid storage tank 5, and the pressure sensor 606 is respectively arranged close to the ports of the experimental tank 4 and the liquid storage tank 5 away from the second solenoid valve 604.

[0111] A flow meter 607 is connected to the pipeline at the liquid outlet of the liquid pump 602. The flow meter 607 can not only calculate the amount of liquid filled per unit time, but also be used to measure the total amount of liquid filled.

[0112] The steps of liquid filling using the above-mentioned experimental working fluid storage and filling dual-circuit system 6 are as follows:

[0113] Starting the variable gravity centrifugal platform 3 to simulate a microgravity or variable gravity environment, and providing centrifugal force for the experimental working fluid storage and charging dual-circuit system 6;

[0114] Open the first and second solenoid valves 604 to allow the liquid in the closed loop to converge on the side close to the liquid pump 602, so that the liquid pump 602 is in the liquid phase;

[0115] The flow direction of the fluid in the circuit is switched to flow from the liquid storage tank 5 to the experimental tank 4 through the reversing solenoid valve 605;

[0116] Turn on the liquid pump 602, and inject liquid into the experimental tank 4 at a set flow rate within a filling ratio range of 10% to 90%, and observe the changes in the shape and position of the gas-liquid interface under the microgravity or variable gravity environment;

[0117] By using the liquid pump 602 and the electromagnetic reversing valve, the experimental tank 4 and the liquid storage tank 5 are filled in both directions, the filling ratio of the liquid in the experimental tank 4 is adjusted, and the experiment is repeated for multiple times to observe the changes in the shape and position of the gas-liquid interface under the conditions of different filling ratios in the microgravity or variable gravity environment;

[0118] Adjust the centrifugal force to simulate the on-orbit rehydration process under different gravity environments, repeat the above experiment, and observe the static equilibrium of the gas-liquid interface under different gravity conditions. The reason for simulating the on-orbit rehydration process under a variable gravity ring is that the gravity of the space environment is not fixed. For example, the gravity of the moon and Mars is different.

[0119] That is, through the above design of the experimental working fluid storage and filling unit, the flow rate of normal temperature working fluid injection can be achieved, and the liquid filling ratio of the experimental tank 4 can be changed from 10% to 90%. Since the outer wall of the experimental tank 4 is transparent, the experimental working fluid (FC-72, etc.) is also transparent. In order to facilitate the clear observation of the gas-liquid interface distribution and liquid surface movement of the liquid in the tank, we will adopt the method of dyeing the experimental working fluid, cooperate with the selection of light source, and improve the contrast with the outer wall of the tank to improve the judgment accuracy of the gas-liquid interface.

[0120] Due to the microgravity of space, the gas-liquid interface of the liquid in the tank is not necessarily concentrated at the liquid inlet 403 of the experimental tank 4 under external disturbance. Therefore, when we carry out scientific experiments, the liquid filling ratio is adjusted unidirectionally from small to large, that is, a small filling ratio test is first performed on orbit, and then the liquid is filled into the tank according to a predetermined flow rate and injection volume through the experimental working fluid storage and filling unit.

[0121] The experimental working fluid storage and filling dual-circuit system 6 components include: liquid pump, flow meter 607, reversing valve, solenoid valve, pressure sensor 606, liquid storage tank and filling manual valve 603.

[0122] The pipeline part consists of 316 corrugated pipe, 304 stainless steel pipe and silicone hose.

[0123] The auxiliary sealing materials include stainless steel ferrules, Loctite magic rope and polytetrafluoroethylene raw tape.

[0124] The above components have been well verified in the aerospace field, and all indicators meet our usage requirements; the selection of pipelines is also strictly verified according to our indicators, and has been verified for compatibility, pressure resistance, sealing, corrosion resistance, strength, etc.; the sealing auxiliary materials are also extremely mature products, and meet the compatibility of our working fluids.

[0125] The space inside the experimental box 1 of the variable gravity fluid management experimental device is small, the layout is compact, and the fluid transportation pipeline is complicated. If conventional straight-through pipelines are used for installation, the installation and maintenance of the pipelines will become extremely difficult, and the most important thing is that the outer sealing plate will not be installed in place. In order to solve this problem, we use stainless steel bellows, which have the advantages of smooth inner wall, shock resistance, tensile resistance, flexibility, elasticity, and light weight. The bellows have a high adaptability to the vibration during the rocket launch process.

[0126] The launch and navigation of the rocket will produce severe vibrations. Although the pipes in our box can adapt to this situation well, if the bellows resonate, it may cause unnecessary damage to the surrounding components or boxes. Therefore, we protect the places where there is a risk of collision between the bellows and other locations. The protective material is a polytetrafluoroethylene film wrapped around the outer layer of the bellows, and the adjacent long pipes are fixed with polytetrafluoroethylene ties to reduce the vibration amplitude.

[0127] Silicone hoses are suitable for conveying some corrosive, high-temperature or high-pressure media, while pagodas are suitable for conveying gas or liquid. When installing, soak the silicone hose at the silicone joint with 80-95℃ hot water to make it slightly soft. The appropriate temperature can make the silicone hose have a certain viscosity, so that the silicone hose can be easily put on the pagoda joint, and it can be more tightly bonded to the pagoda during the cooling and shrinking process.

[0128] Since the experimental tank 4 has rotation and translation operations, the working fluid delivery hose must form a follow-up mode with the experimental tank 4. For this reason, a coaxial follow-up wire tray is designed on the opposite side of the motor of the experimental tank 4, and the wire tray is used to fix the flexible pipeline and the heating plate cable in the external heat application mechanism.

[0129] During the experiment, the vibration speed and frequency are constantly changing in stages over a wide range, and the test tank rotates at an angle of 180°. Therefore, the fluid transport pipeline needs to have a certain degree of flexibility, deformation resistance, and visualization. In this way, it can cooperate well with the movement during the experiment and complete a good working fluid transport function.

[0130] IV. Experimental device for simulating the on-orbit motion of a space variable gravity fluid tank

[0131] The space experiment plan involves different experimental conditions. According to the actual working conditions of the spacecraft tank, there is a situation where the gas-liquid interface is disturbed and unstable. It is of great significance to explore the oscillation law and recovery period of the free liquid surface in the tank caused by gravity changes and external disturbances.

[0132] The external force applying mechanism includes:

[0133] The rotating mechanism 8 is used to drive the experimental tank 4 to rotate so as to adjust the angle between the experimental tank 4 and the centrifugal acceleration direction of the variable gravity centrifugal platform 3 so as to simulate the morphological change of the gas-liquid interface during the rotational motion;

[0134] The vibration mechanism 9 is used to drive the experimental tank 4 and the rotating mechanism 8 to perform linear reciprocating motion simultaneously, so as to apply translational and low-frequency vibration disturbances to the experimental tank 4, so as to simulate the morphological changes and instability of the gas-liquid interface during the process of the gas-liquid interface being disturbed by external forces;

[0135] While the variable gravity centrifuge platform is stationary or moving (primary platform movement), the experimental tank is additionally subjected to on-orbit rotation and translational motion (secondary platform movement) to achieve dynamic simulation of gas-liquid two-phase liquid in the primary and secondary motion experimental tanks.

[0136] The experimental tank 4, the rotating mechanism 8 and the vibrating mechanism 9 are all installed in the experimental tank 1 of the variable gravity on-orbit fluid management experimental device;

[0137] The rotating mechanism 8 and the vibrating mechanism 9 cooperate with each other to simulate the on-orbit motion of a space variable gravity fluid tank that combines rotation and translation motion.

[0138] The rotating mechanism 8 drives the experimental tank 4 to rotate on track at an angle range of 0 to 180 degrees and a rotation angular velocity range of 0.1 to 6 rad / s.

[0139] The vibration mechanism 9 applies vibration to the experimental tank 4 at a frequency interval of 0.5-1 Hz, and a maximum vibration amplitude of 10 mm.

[0140] The rotating mechanism 8 includes a stepping motor 801, a connecting shaft 802, a tank mounting fixing flange and a rotating bracket;

[0141] The experimental tank 4 is rotatably mounted on the rotating bracket via the tank mounting fixing flange, and the stepper motor 801 is connected to the experimental tank 4 via a connecting shaft 802 to drive the experimental tank 4 to rotate around the connecting shaft 802 .

[0142] The middle of the experimental tank 4 is a cylindrical shell, and the two ends of the experimental tank 4 are symmetrically arranged hemispherical shells, and the diameter of the hemispherical shell is equal to the diameter of the cylindrical shell;

[0143] The connecting shaft 802 is colinear with the short axis of the experimental tank 4, and the rotating mechanism 8 can drive the experimental tank 4 to rotate around its short axis to adjust the angle between the long axis of the experimental tank 4 and the centrifugal acceleration direction of the variable gravity centrifugal platform 3;

[0144] The major axis is the longest center line passing through the center of the experimental tank 4 , and the minor axis is the shortest center line passing through the center of the experimental tank 4 .

[0145] The vibration mechanism 9 includes a linear motor 901, a mobile platform 902 and a slide rail 9010, and the experimental tank 4 and the rotating mechanism 8 are both installed on the mobile platform 902;

[0146] The linear motor 901 is used to drive the moving platform 902 to move back and forth linearly along the slide rail 9010 .

[0147] The vibration mechanism 9 further includes a grating ruler 903 and a reading head 904, and the moving platform 902 can move along the grating ruler 903 under the drive of the linear motor 901;

[0148] The reading head 904 is fixedly mounted on the moving platform 902 to feed back the real-time position of the moving platform 902 to the linear motor 901;

[0149] The grating ruler 903 is sequentially provided with a left limit switch 906, a zero switch 907 and a right limit switch 908 connected to the motor control circuit 905 of the linear motor 901 to control the moving range of the moving platform 902;

[0150] The motor control circuit 905 is connected to the main control board 909 via a 485 interface.

[0151] The steps of using the above-mentioned rotating mechanism 8 and vibrating mechanism 9 to simulate the on-orbit motion of a space variable gravity fluid tank are as follows:

[0152] Starting the variable gravity centrifugal platform 3, so that the variable gravity centrifugal platform 3 operates according to the starting speed and target gravity acceleration required by the experimental project;

[0153] The rotating mechanism 8 is started to drive the experimental tank 4 to rotate to a predetermined angle at a predetermined angular velocity, so as to simulate the dynamic motion characteristics of the fluid inside the tank during the on-orbit attitude change of the aircraft, and the angle between the long axis of the experimental tank 4 and the centrifugal acceleration is changed multiple times by the rotating mechanism 8, and the experiment is repeated multiple times;

[0154] Start the vibration mechanism 9 to drive the experimental tank 4 to vibrate according to the predetermined vibration frequency and vibration amplitude, simulate the working condition of the experimental tank 4 being disturbed by translation and low-frequency vibration, change the vibration frequency and vibration amplitude, and repeat the experiment for multiple times;

[0155] The rotating mechanism 8 and the vibrating mechanism 9 are started simultaneously to simulate the on-orbit motion of a space variable gravity fluid tank that combines rotation and translation motion, and the rotation and / or vibration parameters are changed, and the experiment is repeated for multiple times.

[0156] 5. External heat application device

[0157] Local temperature changes in the spacecraft tank will affect the phase change pressure increase of the liquid inside it, and the heated gas-liquid interface of the propellant will also be affected. Simulating and exploring the impact of tank temperature changes on the pressure changes and gas-liquid interface inside the tank is of great significance for on-orbit fluid management in space.

[0158] The external heat application unit is composed of a heater, a thermocouple, etc. The central experimental unit is heated by the heater to simulate the influence of the local temperature change of the spacecraft tank on the phase change interface morphology of the liquid inside it, as well as the influence of the propellant heating and phase change effect on the pressure change and gas-liquid interface inside the tank. At the same time, thermocouples are also installed at the internal characteristic points of the experimental tank 4 to monitor temperature changes. Considering safety and the boiling point of the simulated working fluid, we choose the local heating method with a maximum temperature not exceeding 50°C.

[0159] The heating method is electric heating, and the external heat input is carried out by using a fixed power input method. Thermocouples are arranged locally inside the experimental tank 4 for temperature monitoring. A thin film heating belt is used, and the electric power is 8 to 10W. Different electric powers will be selected for experiments; the thermocouples used are all T-type thermocouples with a diameter of 125μm.

[0160] By setting a heater and a thermocouple in the experimental tank 4, the experimental tank 4 is locally heated and the temperature is monitored; by adjusting the heating temperature and cooperating with the observation and recording of the fluid observation device 7, the influence of the tank temperature change on the gas and the gas-liquid interface in the tank can be simulated and explored.

[0161] 6. The simulation method of the variable gravity on-orbit fluid experiment in space after integrating the above components is as follows:

[0162] Start the experimental system and carry out preparations before simulation;

[0163] Adjust the experimental tank 4 to a predetermined working condition through a variable gravity centrifugal platform, a dual circuit system 6 for storing and filling experimental working fluid, an external force applying mechanism and an external heat applying mechanism;

[0164] The fluid observation device 7 is used to observe the changes in the gas-liquid interface morphology of the experimental tank 4, and to collect experimental data including temperature and pressure;

[0165] After a single experiment, change the experimental conditions, observe the changes in the gas-liquid interface morphology again, and collect data.

[0166] Specifically:

[0167] (1) Power on and preheat: The electric control box 2 is turned on, the control components (sensors, observation equipment, light source, etc.) are turned on, data collection begins, and after preheating, the subsequent program control instructions are waited for;

[0168] (2) Startup of the variable gravity centrifuge platform: The variable gravity centrifuge platform 3 of the variable gravity centrifuge platform operates according to the startup rate and target gravity acceleration required by the experimental project, and the internal components of the "Space Variable Gravity On-Orbit Fluid Management Experimental Device" perform corresponding actions according to the stabilized target gravity acceleration or the instantaneous switching of gravity acceleration;

[0169] (3) Adjusting the filling ratio: The experimental working fluid storage and filling system drives the experimental working fluid in the reservoir to be filled with liquid according to the preset filling rate and filling volume to complete the target filling rate of the model tank. After stabilization, the initial working condition is formed before the experiment;

[0170] (4) Temperature control: The electronic control unit feedback controls the heating plate in the experimental object (sets the heating duty cycle) based on the temperature measurement value to make it reach the predetermined temperature or predetermined heating rate;

[0171] (5) External force application unit action: the vibration mechanism or rotation mechanism inside the experimental device rotates or vibrates the model tank according to the set action time, working mode and working content to achieve the predetermined experimental background working conditions;

[0172] (6) Experimental observation: fixed and follow-up cameras with background light are used to observe the changes in the gas-liquid interface morphology of the experimental object (model tank), and the images are compressed in real time and transmitted by the electronic control unit, and then transmitted to the application information system through the variable gravity centrifuge platform controller. For engineering data such as temperature and pressure, after being collected by sensors, they are also stored in the space station application information system by the electronic control unit through the variable gravity centrifuge platform controller, and the operation control arranges for downlink analysis at an appropriate time;

[0173] (7) Working condition change: After a single experiment, change the experimental working conditions (temperature, heating rate, flow rate, filling rate, shaking loading, rotation angle and angular velocity, variable gravity centrifugal platform gravity loading method and target gravity acceleration), repeat the above working sequence, and perform experimental image observation and data measurement;

[0174] (8) Standby: After the scheduled experiment is completed, the device is on standby until the ground personnel analyze the data and then change the operating conditions by sending commands uplink.

[0175] For different experimental conditions: static balance experiment, free interface, external disturbance, repositioning, liquid filling, and other extended experimental control parameters are shown in the following table.

[0176]

[0177]

[0178]

[0179] Among them, the gravity level refers to the acceleration level at the center point of the experimental tank 4, and the heating temperature refers to the temperature control temperature of the heating plate.

[0180] Take the external disturbance experiment as an example: mainly by changing the control parameters such as the filling ratio of the experimental tank 4, the rotation angle of the rotating mechanism 3, the rotation speed of the rotating mechanism 3, the vibration frequency of the horizontal vibration mechanism, and the amplitude of the horizontal vibration mechanism.

[0181] The typical working process of external disturbance experiment is shown in the following table.

[0182]

[0183]

[0184] The external perturbation experiment was carried out in the following order: Fig.12 shown.

[0185] Liquid filling experiment: mainly by changing the filling ratio of the experimental tank 4, the rotation angle of the rotating mechanism 3, the rotation speed of the rotating mechanism 3, the liquid filling rate and other control parameters.

[0186] The typical working process of liquid filling experiment is shown in the following table.

[0187]

[0188]

[0189] The liquid filling experiment is carried out in the following order: Fig.13 shown.

[0190] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A space variable gravity fluid tank on-orbit motion simulation experimental device, characterized in that: include: Experimental tank, used to store experimental fluid; The experimental tank is transparent so that the gas-liquid interface in the tank can be observed from outside the experimental tank; A rotating mechanism, used to drive the experimental tank to rotate, so as to adjust the angle between the experimental tank and the centrifugal acceleration direction of the variable gravity centrifugal platform, so as to simulate the morphological change of the gas-liquid interface during the rotational motion; A vibration mechanism, used to drive the experimental tank and the rotating mechanism to perform linear reciprocating motion simultaneously, so as to apply translational and low-frequency vibration disturbances to the experimental tank, and simulate the morphological changes and instability of the gas-liquid interface during the process of the gas-liquid interface being disturbed by external forces; The experimental tank, the rotating mechanism and the vibrating mechanism are all installed on a variable gravity centrifugal platform; The rotating mechanism and the vibrating mechanism cooperate with each other to simulate the on-orbit motion of a space variable gravity fluid tank that combines rotation and translation motion; A fixed camera is fixedly set just above the transparent experimental tank; An illumination light source is fixedly arranged directly below the experimental tank, and the illumination light source, the fixed camera and the experimental tank are located in a straight line, so as to observe the real-time evolution of the gas-liquid interface in the experimental tank by using a shadow method; A follow-up camera is fixedly installed with the experimental tank and is located on the side of the experimental tank, and can move synchronously with the experimental tank; The rotation mechanism drives the experimental tank to rotate on-orbit at an angle range of 0 to 180 degrees and a rotation angular velocity range of 0.1 to 6 rad / s; The vibration mechanism applies vibration to the test tank at a frequency interval of 0.5-1 Hz, with a maximum vibration amplitude of 10 mm; The rotating mechanism comprises a stepping motor, a connecting shaft, a tank mounting fixing flange and a rotating bracket; The experimental tank is rotatably mounted on the rotating bracket via the tank mounting fixing flange, and the stepper motor is connected to the experimental tank via a connecting shaft to drive the experimental tank to rotate around the connecting shaft.

2. The on-orbit motion simulation experimental device of a space variable gravity fluid tank according to claim 1 is characterized in that: The middle of the experimental tank is a cylindrical shell, and the two ends of the experimental tank are symmetrically arranged hemispherical shells, and the diameter of the hemispherical shell is equal to the diameter of the cylindrical shell; The connecting shaft is colinear with the short axis of the experimental tank, and the rotating mechanism can drive the experimental tank to rotate around its short axis to adjust the angle between the long axis of the experimental tank and the centrifugal acceleration direction of the variable gravity centrifugal platform; The major axis is the longest centerline passing through the center of the test tank, and the minor axis is the shortest centerline passing through the center of the test tank.

3. A space variable gravity fluid tank on-orbit motion simulation experimental device according to claim 1 or 2, characterized in that: The vibration mechanism includes a linear motor, a mobile platform and a slide rail, and the experimental tank and the rotating mechanism are both installed on the mobile platform; The linear motor is used to drive the moving platform to reciprocate linearly along the slide rail.

4. The on-orbit motion simulation experimental device of a space variable gravity fluid tank according to claim 3 is characterized in that: The vibration mechanism also includes a grating ruler and a reading head, and the moving platform can move along the grating ruler under the drive of the linear motor; The reading head is fixedly mounted on the mobile platform to feed back the real-time position of the mobile platform to the linear motor; The grating ruler is sequentially provided with a left limit switch, a zero switch and a right limit switch connected to the motor control circuit of the linear motor to control the moving range of the moving platform; The motor control circuit is connected to the driver via a 485 interface.

5. A space variable gravity fluid tank on-orbit motion simulation experimental method, characterized in that: The on-orbit motion simulation experimental device for a space variable gravity fluid tank according to any one of claims 1 to 4 comprises the following steps: Start the variable gravity centrifugal platform and make the turntable of the variable gravity centrifugal platform operate according to the start-up speed and target gravity acceleration required by the experimental project; The rotating mechanism is started to drive the experimental tank to rotate to a predetermined angle at a predetermined angular velocity, simulating the dynamic motion characteristics of the fluid inside the tank during the on-orbit attitude change of the aircraft, and the angle between the long axis of the experimental tank and the centrifugal acceleration is changed multiple times by the rotating mechanism, and the experiment is repeated multiple times; Start the vibration mechanism to drive the test tank to vibrate according to the predetermined vibration frequency and vibration amplitude, simulate the working condition of the test tank being disturbed by translation and low-frequency vibration, change the vibration frequency and vibration amplitude, and repeat the experiment for multiple times; The rotating mechanism and the vibrating mechanism are started simultaneously to simulate the on-orbit motion of a space variable gravity fluid tank that combines rotation and translation motion, and the rotation and / or vibration parameters are changed, and the experiment is repeated multiple times.

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