An experimental fluid evolution observation device in a tank

Abstract

The application discloses a kind of experimental tank fluid evolution observation devices in the technical field of space on-orbit fluid management, comprising: fixed camera, fixedly arranged in the upper of transparent experimental tank;Illumination source, fixedly arranged in the lower of the experimental tank, the illumination source, the fixed camera and the experimental tank are located on a straight line, to observe the real-time evolution of gas-liquid interface in experimental tank using shadow method;Follow-up camera, fixedly installed with the experimental tank, and located in the side of the experimental tank, can move synchronously with the experimental tank;The fixed camera cooperates with the follow-up camera can carry out quasi-three-dimensional observation to gas-liquid interface in the experimental tank, to obtain the video image of gas-liquid interface, gas-liquid two-phase distribution and gas-liquid flow evolution process from two directions of front and side simultaneously.

Description

Technical Field

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

[0002] In space, due to the weakening or even disappearance of Earth's gravity, the behavior of fluids (particularly liquids) differs significantly from that on Earth. In microgravity, the physical properties of fluids, such as surface tension and buoyancy, change, leading to unique patterns in fluid distribution, flow velocity, and stability within containers. Therefore, on-orbit fluid management in space must fully consider these microgravity-induced fluid properties.

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

[0004] 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 through a camera. In the existing technology, observation and recording are generally carried out through a single camera, which is unable to comprehensively observe and record the flow evolution process of the gas-liquid interface. Summary of the Invention

[0005] The purpose of the present invention is to provide a fluid evolution observation device in an experimental tank to solve the technical problem that the existing technology generally uses a single machine to observe and record, and cannot comprehensively observe and record the flow evolution process of the gas-liquid interface.

[0006] In order to solve the above technical problems, a device for observing fluid evolution in an experimental tank is provided, comprising:

[0007] A fixed camera is fixedly set just above the transparent experimental tank;

[0008] An illumination light source is fixedly disposed directly below the experimental tank, wherein 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 using a shadow method;

[0009] 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;

[0010] The fixed camera cooperates with the tracking camera to perform quasi-three-dimensional observation of the gas-liquid interface in the experimental tank, so as to obtain video images of the gas-liquid interface, gas-liquid two-phase distribution and gas-liquid flow evolution process from both the front and side directions.

[0011] As a preferred solution of the present invention, two sets of observation scales are provided on the experimental tank, facing the fixed camera and the follow-up camera respectively.

[0012] Furthermore, the observation scale is arranged along the centrifugal acceleration direction of the variable gravity centrifugal platform so as to observe the current filling ratio of the liquid in the experimental tank when the variable gravity centrifugal platform provides centrifugal acceleration.

[0013] As a preferred embodiment of the present invention, the angle between the two sets of observation scales is 30°-45°.

[0014] As a preferred solution of the present invention, both the fixed camera and the follow-up camera are high-speed cameras to accurately capture the characteristic time points corresponding to each flow evolution moment.

[0015] As a preferred solution of the present invention, the illumination light source is configured as a plurality of evenly distributed white light LED lamp beads to form a relatively uniform background light source.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The fixed phase is combined with a tracking camera, one moving and one static, to provide quasi-three-dimensional observation of the gas-liquid interface within the experimental tank from both the front and side directions. This allows for comprehensive video images of the gas-liquid interface, gas-liquid two-phase distribution, and the evolution of the gas-liquid flow from both the front and side directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0019] Figure 1 Schematic diagram of the structure of the experimental box and the electric control box in the embodiment of the present invention;

[0020] 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;

[0021] Figure 3 Schematic diagram of the structure of the experimental tank and the liquid storage tank in the embodiment of the present invention;

[0022] Figure 4 for Figure 3 Schematic top view of

[0023] Figure 5 for Figure 4 Schematic diagram of the front side perspective;

[0024] Figure 6 Schematic diagram of the structure of the experimental tank, external force applying mechanism, and fluid observation device in an embodiment of the present invention;

[0025] Figure 7 Schematic diagram of the structure of the vibration mechanism in an embodiment of the present invention;

[0026] Figure 8 Schematic diagram of the structure of the mobile platform and the slide rail in an embodiment of the present invention;

[0027] Figure 9 Schematic diagram of the bottom structure of the mobile platform in an embodiment of the present invention;

[0028] Figure 10 Schematic diagram of the top view of the experimental tank in an embodiment of the present invention;

[0029] Figure 11 This is a schematic side view of the experimental tank in an embodiment of the present invention;

[0030] Figure 12 Schematic diagram of the structure of the upper tank in an embodiment of the present invention;

[0031] Figure 13 Schematic diagram of the structure of the lower half tank in an embodiment of the present invention;

[0032] Figure 14 Schematic diagram of the structure of the experimental working fluid storage and charging dual-circuit system in an embodiment of the present invention;

[0033] Figure 15 Schematic diagram of the order of conducting internal and external perturbation experiments in an embodiment of the present invention;

[0034] Figure 16 Schematic diagram of the sequence of conducting the liquid filling experiment in an embodiment of the present invention.

[0035] The numbers in the figure represent the following:

[0036] 1-Experimental box, 2-Electrical control box, 3-Variable gravity centrifuge platform;

[0037] 4-experimental tank, 401-upper tank, 402-lower tank, 403-liquid inlet, 404-liquid outlet;

[0038] 5-Liquid storage tank;

[0039] 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;

[0040] 7-Fluid observation device, 701-Fixed camera, 702-Illumination light source, 703-Moving camera, 704-Observation scale;

[0041] 8-rotating mechanism, 801-stepping motor, 802-connecting shaft;

[0042] 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 switch, 908-right limit switch, 909-main control board, 9010-slide rail. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0044] 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.

[0045] The variable gravity centrifugal platform 3 in the experimental system is equipped with:

[0046] 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;

[0047] 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 components in the experimental box 1 .

[0048] The internal structure of the experimental box 1 is the design focus of the present invention, and mainly includes the following five parts.

[0049] 1. Experimental storage tank

[0050] Experimental tank 4 is a tank used for observing the gas-liquid interface, gas-liquid two-phase distribution, and gas-liquid motion during variable gravity on-orbit fluid experiments in space. The improvements to experimental tank 4 in the present invention are intended to address the technical problem that conventional experimental tank 4 consists of two equally divided tanks, one above the other, connected at the center axis by a flange located at the maximum cross-section of experimental tank 4, making it difficult to obtain quantitative observation images reflecting the maximum gas-liquid interface within the tank.

[0051] The details are as follows:

[0052] 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.

[0053] It includes an upper tank half 401 and a lower tank half 402 that are fixedly connected. A sealing ring is provided between the upper tank half 401 and the lower tank half 402. The edges of the upper tank half 401 and the lower tank half 402 are both provided with lug flanges. The upper and lower lug flanges are sealed and fixed by bolts and built-in O-rings to form a complete transparent and visual experimental tank 4.

[0054] The upper tank 401 and the lower tank 402 are both made of transparent materials so that the gas-liquid interface morphology inside the tank can be observed from outside the tank.

[0055] 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 within the upper tank 401. That is, the maximum cross-section of the experimental tank 4 is located within 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.

[0056] 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.

[0057] The experimental tank 4 is configured to have a typical propellant tank geometry, i.e., the middle portion is a cylindrical shell, and both ends of the experimental tank 4 are symmetrically arranged hemispherical shells, and the diameter of the hemispherical shells is equal to the diameter of the cylindrical shell;

[0058] 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 .

[0059] One advantage of configuring the experimental tank 4 in the above-described shape and radial arrangement is that, when the variable gravity centrifugal platform 3 rotates to provide centrifugal force, the liquid in the experimental tank 4 is 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.

[0060] As the filling rate of the experimental tank 4 increases, the liquid interface gradually moves along the line connecting the sphere centers. Since the ends and the middle of the experimental tank 4 are regular shapes, it is convenient to calculate the filling rate corresponding to each point on the long axis, so that the corresponding observation scale 704 can be marked on the experimental tank 4 as a reference for liquid filling and filling rate adjustment of the experimental tank 4.

[0061] 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.

[0062] 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 .

[0063] An observation scale 704 is provided on the upper tank 401 and arranged along the centrifugal acceleration direction of the variable gravity centrifugal platform 3 to observe the filling ratio of the liquid in the experimental tank 4 when the variable gravity centrifugal platform 3 provides centrifugal acceleration.

[0064] 2. Fluid Observation Device

[0065] 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 existing technology, observation and recording are generally performed through a single camera, which cannot comprehensively observe and record the flow evolution process of the gas-liquid interface.

[0066] 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:

[0067] A fixed camera 701 is fixedly arranged just above the transparent experimental tank 4;

[0068] An illumination light source 702 is fixedly disposed 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 that the real-time evolution of the gas-liquid interface in the experimental tank 4 can be observed using the shadow method.

[0069] 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

[0070] The fixed camera 701 cooperates with the tracking 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.

[0071] The fixed phase, in conjunction with the tracking camera 703, enables quasi-three-dimensional observation of the gas-liquid interface within the experimental tank 4 from both the front and side, capturing comprehensive video images of the gas-liquid interface, the gas-liquid two-phase distribution, and the evolution of the gas-liquid flow from both the front and side directions. Upon powering up the experimental tank 1 and the electrical control box 2, video recording begins immediately and is saved in segments until the storage is full or the power is lost.

[0072] 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 can be used as a reference to more accurately determine the liquid filling rate.

[0073] Therefore, two sets of observation scales 704 are provided on the experimental tank 4 , facing the fixed camera 701 and the follow-up camera 703 respectively.

[0074] 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.

[0075] 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 can be marked at corresponding positions along the centrifugal acceleration direction to indicate the corresponding filling rate.

[0076] In order to facilitate scale marking, 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.

[0077] When the centrifuge rotates and provides a centrifugal acceleration of 1g, the direction of the centrifugal acceleration is perpendicular to the long axis of the experimental tank 4. The gas-liquid interface within the experimental tank 4 remains parallel to the scale lines on the observation scale 704. The center of the long axis of the experimental tank 4 (50% liquid filling ratio) is marked as the center position scale line. Using this as a reference, scale lines for different liquid volume filling ratios are symmetrically scaled along the tank ends (40% and 60% liquid filling ratios correspond to "4", 30% and 70% liquid filling ratios correspond to "3", and so on). A CCD camera is used to observe the gas-liquid interface at the corresponding tank scale lines. The volume filling ratio of the liquid within the tank can be quantitatively determined, allowing real-time optical observation of the gas-liquid interface morphology and position within the tank under different experimental conditions to obtain quantitative scientific experimental results.

[0078] Furthermore, the camera model selected has a resolution of 1080p and a maximum observation field of view of 100mm × 80mm, which can meet the requirements for relatively precise observation and positioning of the gas-liquid interface. For static gas-liquid interface evolution in microgravity, a relatively low acquisition frame rate (25fps) is sufficient. However, for larger tanks requiring variable gravity conditions, external sloshing, and other conditions, the gas-liquid interface undergoes drastic changes. To accurately capture the characteristic time points corresponding to each moment of flow evolution, a high-speed CCD camera acquisition frame rate is required. Considering both downlink bandwidth and storage data volume, we selected an acquisition frame rate of approximately 60fps. During implementation, the acquisition frame rate can be adjusted according to experimental requirements. The lens selected is a fixed-focus lens with a focal length of 115mm and a maximum field of view of approximately 100mm, meeting the scientific requirements of this project.

[0079] There are two sets of observation scales 704, one of which is located in the middle of the top of the experimental tank 4, facing the fixed camera 701, and the other set is set on the side of the experimental tank 4, facing the follow-up camera 703 on the side. In order to obtain a better observation effect, the distance between the two sets of observation scales 704 should not be too close. The observation scale 704 at the middle of the top of the experimental tank 4 is used as the zero degree reference. The angle between the two sets of observation scales 704 is preferably 30°-45°.

[0080] 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.

[0081] The illumination light source 702 is configured as a plurality of evenly distributed white light LED lamp beads to form a relatively uniform background light source.

[0082] 3. Experimental working fluid storage and charging dual-circuit system

[0083] In the space on-orbit fluid management device activity, 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; but due to the mixing of gas-liquid two-phase in the experimental tank 4, the liquid pump 602 will extract gas-liquid two-phase when working, resulting in damage to the liquid pump 602.

[0084] Therefore, the application designs an experimental working medium storage and filling double-loop system 6, so that the liquid pump 602 can only extract liquid phase when working.

[0085] The experimental tank 4, the first electromagnetic valve 601, the liquid pump 602, the liquid storage tank 5 and the second electromagnetic valve 604 are sequentially connected and form a closed loop.

[0086] The ports of the experimental tank 4 and the liquid storage tank 5 connected with the liquid pump 602 are located on the side away from the center of the variable gravity centrifugal platform 3, and the ports of the experimental tank 4 and the liquid storage tank 5 connected with the second electromagnetic valve 604 are located on the side close to the center of the variable gravity centrifugal platform 3, so that the inlet and outlet of the liquid pump 602 are filled with liquid when the variable gravity centrifugal platform 3 provides centrifugal force.

[0087] The liquid pump 602 is connected with a reversing electromagnetic valve 605 on the pipeline at both ends, and the reversing electromagnetic valve 605 can change the direction of the fluid in the loop to select the liquid pump 602 into the experimental tank 4 or the liquid storage tank 5, and can adjust the liquid filling rate of the experimental tank 4 to realize the static equilibrium of the gas-liquid interface under microgravity conditions and the observation of the dynamic behavior of the gas-liquid interface under variable gravity conditions under different liquid filling rates.

[0088] The first electromagnetic valve 601 and the second electromagnetic valve 604 can close the experimental tank 4 after the liquid filling rate adjustment is completed to fix the liquid filling rate of the experimental tank 4.

[0089] The closed loop is provided with a filling hand valve 603 for filling experimental working medium into the closed loop.

[0090] When the variable gravity centrifugal platform 3 provides centrifugal force, under the action of centrifugal force, due to the mass difference of gas-liquid two-phase, the liquid phase in the experimental tank 4 and the liquid storage tank 5 converges on the side away from the center of the variable gravity centrifugal platform 3, and the gas phase is driven to converge on the side close to the center of the variable gravity centrifugal platform 3.

[0091] At this time, the ports of the experimental tank 4 and the liquid storage tank 5 connected with the liquid pump 602 are in the liquid phase, so that the liquid pump 602 will not extract air when extracting liquid, avoiding damage to the liquid pump 602 and prolonging its service life.

[0092] 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 opening of the first solenoid valve 601 ensures the circulation of the liquid phase between the experimental tank 4 and the liquid storage tank 5. The flow of the liquid phase will cause changes in the gas phase in the two tanks. For example, when the liquid phase is injected into the experimental tank 4, the gas phase in the experimental tank 4 will be compressed. In order to prevent the increase of the gas pressure in the experimental tank 4 from affecting the injection of the liquid phase, the experimental tank 4 and the liquid storage tank 5 are connected so that the excess gas in the experimental tank 4 can enter the liquid storage tank 5.

[0093] 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 to lock the liquid phase and the gas phase in the experimental tank 4 to prevent the liquid from escaping.

[0094] 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.

[0095] It can be understood that, in this process, the liquid outlet 404 on the experimental tank 4 is actually a port for the gas phase to pass through.

[0096] The closed loop is further 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 provided close to the ports of the experimental tank 4 and the liquid storage tank 5 away from the second solenoid valve 604.

[0097] 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.

[0098] The steps for liquid filling using the above-mentioned experimental working fluid storage and filling dual-circuit system 6 are as follows:

[0099] Starting the variable gravity centrifugal platform 3 to simulate a microgravity or variable gravity environment and provide centrifugal force for the experimental working fluid storage and charging dual-circuit system 6;

[0100] 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;

[0101] The reversing solenoid valve 605 switches the flow direction of the fluid in the circuit from the liquid storage tank 5 to the experimental tank 4;

[0102] 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 microgravity or variable gravity environment;

[0103] Using the liquid pump 602 and the electromagnetic reversing valve, the experimental tank 4 and the liquid storage tank 5 are bidirectionally filled. The filling ratio of the liquid in the experimental tank 4 is adjusted, and the experiment is repeated 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.

[0104] By adjusting the centrifugal force to simulate the on-orbit rehydration process under different gravity environments, the above experiment was repeated to observe the static equilibrium of the gas-liquid interface under different gravity conditions. The reason for simulating the on-orbit rehydration process under variable gravity rings is that the gravity in the space environment is not fixed. For example, the gravity of the moon and Mars is different.

[0105] That is, the aforementioned design of the experimental fluid storage and filling unit enables constant flow rate injection of the fluid at room temperature, allowing the liquid filling ratio of experimental tank 4 to be varied from 10% to 90%. Since the outer wall of experimental tank 4 is transparent, and the experimental fluid (FC-72, etc.) is also transparent, to facilitate clear observation of the gas-liquid interface distribution and liquid surface movement within the tank, we will dye the experimental fluid and, in conjunction with the selection of a light source, enhance the contrast with the outer wall of the tank, thereby improving the accuracy of gas-liquid interface determination.

[0106] Due to the microgravity in 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 the predetermined flow rate and injection volume through the experimental working fluid storage and filling unit.

[0107] The experimental working fluid storage and filling dual-circuit system consists of 6 components: liquid pump, flow meter 607, reversing valve, solenoid valve, pressure sensor 606, liquid storage tank and filling manual valve 603.

[0108] The pipeline part consists of 316 corrugated pipe, 304 stainless steel pipe and silicone hose.

[0109] The auxiliary sealing materials used are stainless steel ferrules, Loctite magic rope and polytetrafluoroethylene raw tape.

[0110] 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.

[0111] The variable gravity fluid management experimental device, Experimental Box 1, has a narrow interior, a compact layout, and complex fluid transport piping. Using conventional straight-through piping would make installation and maintenance extremely difficult, and most importantly, the outer cover would not fit properly. To address this issue, we chose stainless steel bellows, which offer a smooth inner wall, excellent shock resistance, excellent stretch resistance, flexibility, elasticity, and light weight. These bellows are highly resilient to the vibrations experienced during rocket launch.

[0112] The rocket launch and navigation process will produce severe vibrations. Although the pipes in our box can adapt well to this situation, 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.

[0113] Silicone hoses are suitable for conveying corrosive, high-temperature, or high-pressure media, while pagodas are suitable for conveying gases or liquids. During installation, soak the silicone hose joints in 80-95°C hot water to soften them slightly. The appropriate temperature will give the silicone hose a certain viscosity, making it easier to fit over the pagoda joints and allowing for a tighter bond to the pagoda during cooling and shrinkage.

[0114] Since the experimental tank 4 can rotate and translate, the working fluid delivery hose needs to follow the experimental tank 4. To this end, a coaxial follower cable tray is designed on the opposite side of the motor of the experimental tank 4 to fix the flexible pipe and the heating plate cable in the external heat application mechanism.

[0115] During the experiment, the vibration speed and frequency varied periodically over a wide range, and the test tank rotated 180°. Therefore, the fluid transport pipeline needed to be flexible, resistant to deformation, and visually compliant. This ensured proper coordination with the movement and effective fluid transport during the experiment.

[0116] IV. Experimental device for simulating the on-orbit motion of a space variable gravity fluid tank

[0117] 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.

[0118] The external force applying mechanism includes:

[0119] 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 to simulate the morphological changes of the gas-liquid interface during the rotational motion;

[0120] 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, thereby simulating the changes in gas-liquid interface morphology and instability during the process of gas-liquid interface being disturbed by external forces;

[0121] While the variable gravity centrifugal platform is stationary or moving (primary platform motion), the experimental tank is additionally subjected to on-orbit rotation and translational motion (secondary platform motion) to achieve the dynamic simulation of the gas-liquid two-phase liquid in the above-mentioned primary and secondary motion experimental tanks.

[0122] 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;

[0123] 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.

[0124] The rotating mechanism 8 drives the experimental tank 4 to rotate on track in an angle range of 0 to 180 degrees, and a rotation angular velocity range of 0.1 to 6 rad / s.

[0125] The vibration mechanism 9 applies vibration to the experimental tank 4 at a frequency range of 0.5-1 Hz, and a maximum vibration amplitude of 10 mm.

[0126] The rotating mechanism 8 includes a stepping motor 801, a connecting shaft 802, a tank mounting flange and a rotating bracket;

[0127] The experimental tank 4 is rotatably mounted on the rotating bracket via the tank mounting flange. 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 .

[0128] 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 shells is equal to the diameter of the cylindrical shell;

[0129] The connecting shaft 802 is collinear with the short axis of the experimental tank 4, and the rotating mechanism 8 is capable of driving 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;

[0130] 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 .

[0131] The vibration mechanism 9 includes a linear motor 901, a mobile platform 902 and a slide rail 9010. The experimental tank 4 and the rotating mechanism 8 are both installed on the mobile platform 902.

[0132] The linear motor 901 is used to drive the moving platform 902 to move back and forth linearly along the slide rail 9010 .

[0133] 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 ;

[0134] The reading head 904 is fixedly mounted on the mobile platform 902 to feed back the real-time position of the mobile platform 902 to the linear motor 901;

[0135] The grating ruler 903 is sequentially provided with a left limit switch 906, a zero position 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 mobile platform 902;

[0136] The motor control circuit 905 is connected to the main control board 909 via a 485 interface.

[0137] The steps for simulating the on-orbit motion of a space variable gravity fluid tank using the above-mentioned rotating mechanism 8 and vibrating mechanism 9 are as follows:

[0138] Starting the variable gravity centrifugal platform 3, and making the variable gravity centrifugal platform 3 operate according to the starting speed and target gravity acceleration required by the experimental project;

[0139] The rotating mechanism 8 is activated to drive the experimental tank 4 to rotate at a predetermined angular velocity to a predetermined angle, simulating the dynamic motion characteristics of the fluid inside the tank during the aircraft's on-orbit attitude change. The angle between the long axis of the experimental tank 4 and the centrifugal acceleration is repeatedly changed by the rotating mechanism 8, and the experiment is repeated multiple times.

[0140] The vibration mechanism 9 is started to drive the test tank 4 to vibrate at a predetermined vibration frequency and amplitude, simulating the working condition of the test tank 4 being disturbed by translation and low-frequency vibration. The vibration frequency and amplitude are changed and the experiment is repeated multiple times.

[0141] 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 multiple times.

[0142] 5. External heat application device

[0143] Local temperature changes in the spacecraft tank will affect the increase in phase change pressure 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 pressure changes and gas-liquid interface inside the tank is of great significance for on-orbit fluid management in space.

[0144] The external heat application unit, comprised of a heater and thermocouples, heats the central experimental unit, simulating the effects of localized temperature variations in the spacecraft tank on the phase transition and interface morphology of the liquid within it, as well as the effects of propellant heating and phase transition on pressure changes and the gas-liquid interface within the tank. Thermocouples are also installed at four characteristic points within the experimental tank to monitor temperature changes. For safety reasons and to simulate the boiling point of the working fluid, localized heating is used, with a maximum temperature not exceeding 50°C.

[0145] Heating was performed electrically, using a fixed power input. Thermocouples were locally placed inside the experimental tank 4 for temperature monitoring. Thin-film heating tapes were used, with power ratings of 8 to 10 W, with varying power levels used for the experiments. All thermocouples used were T-type, 125 μm in diameter.

[0146] 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 coordinating the observation and recording of the fluid observation device 7, the impact of tank temperature changes on the gas and gas-liquid interface in the tank can be simulated and explored.

[0147] VI. The simulation method of the variable gravity on-orbit fluid experiment based on the above components is as follows:

[0148] Start the experimental system and conduct preparatory work before simulation;

[0149] Adjust the experimental tank 4 to the predetermined working condition through the variable gravity centrifugal platform, the experimental working medium storage and charging dual-circuit system 6, the external force application mechanism and the external heat application mechanism;

[0150] The fluid observation device 7 is used to observe the changes in the gas-liquid interface morphology of the experimental tank 4 and collect experimental data including temperature and pressure;

[0151] After a single experiment, the experimental conditions were changed, the changes in the gas-liquid interface morphology were observed again, and data were collected.

[0152] Specifically:

[0153] (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, it waits for subsequent program control instructions;

[0154] (2) Startup of the variable gravity centrifugal platform: The variable gravity centrifugal platform 3 of the variable gravity centrifugal 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;

[0155] (3) Adjust the filling ratio: the experimental working fluid storage and filling system drives the experimental working fluid in the reservoir to be added 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;

[0156] (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 achieve the predetermined temperature or predetermined heating rate;

[0157] (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;

[0158] (6) Experimental observation - fixed and follow-up cameras are used with background light to observe the changes in the gas-liquid interface morphology of the experimental object (model tank). The images are compressed in real time and transmitted by the electronic control unit, which is then transferred to the application information system via the variable gravity centrifuge platform controller. Engineering data such as temperature and pressure are collected by sensors and then stored in the space station application information system by the electronic control unit via the variable gravity centrifuge platform controller. Operations control arranges for downloading and analysis at an appropriate time.

[0159] (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, gravity loading mode of the variable gravity centrifugal platform and target gravity acceleration), repeat the above working sequence, and perform experimental image observation and data measurement;

[0160] (8) Standby: After the scheduled experiment is completed, the device is on standby until the ground personnel analyze the data and change the working conditions through the command uplink.

[0161] The control parameters for different experimental conditions: static balance experiment, free interface, external disturbance, repositioning, liquid filling, and other extended experiments are shown in the following table.

[0162]

[0163]

[0164]

[0165] The gravity level refers to the acceleration level at the center of the experimental tank 4, and the heating temperature refers to the temperature controlled by the heating plate.

[0166] 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.

[0167] The typical working process of the external disturbance experiment is shown in the following table.

[0168]

[0169]

[0170] The external perturbation experiment was carried out in the following order: Figure 12 shown.

[0171] 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.

[0172] The typical working process of the liquid filling experiment is shown in the following table.

[0173]

[0174]

[0175]

[0176] The liquid filling experiment is carried out in the following order: Figure 13 shown.

[0177] The above embodiments are merely exemplary embodiments of the present application and are not intended to limit the scope of the present application. The scope of protection 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 scope of protection of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present application.

Claims

1. A device for observing fluid evolution in an experimental tank, characterized in that: include: A fixed camera is fixedly set just above the transparent experimental tank; An illumination light source is fixedly disposed directly below the experimental tank, wherein 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 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 fixed camera cooperates with the tracking camera to perform quasi-three-dimensional observation of the gas-liquid interface in the experimental tank, so as to simultaneously obtain video images of the gas-liquid interface, gas-liquid two-phase distribution, and gas-liquid flow evolution process from both the front and side directions; A rotating mechanism for driving 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, thereby simulating the morphological changes of the gas-liquid interface during the rotational motion; a vibration mechanism for driving the experimental tank and the rotating mechanism to simultaneously perform linear reciprocating motion, so as to apply translational and low-frequency vibration disturbances to the experimental tank, thereby simulating 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 in an experimental box of a variable gravity on-orbit fluid management experimental device, and the experimental box is installed on a variable gravity centrifugal platform to simulate a variable gravity or microgravity space environment; The experimental tank is a box structure composed of a cylindrical shell in the middle and symmetrically arranged hemispherical shells at both ends, and 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, that is, the experimental tank is arranged along the radial direction of the variable gravity centrifugal platform.

2. The device for observing fluid evolution in an experimental tank according to claim 1, characterized in that: The experimental tank is provided with two sets of observation scales facing the fixed camera and the follow-up camera respectively. Furthermore, the observation scale is arranged along the centrifugal acceleration direction of the variable gravity centrifugal platform so as to observe the current filling ratio of the liquid in the experimental tank when the variable gravity centrifugal platform provides centrifugal acceleration.

3. The device for observing fluid evolution in an experimental tank according to claim 2, characterized in that: The included angle between the two sets of observation scales is 30°-45°.

4. The device for observing fluid evolution in an experimental tank according to claim 1, characterized in that: The fixed camera and the follow-up camera are both high-speed cameras, so as to accurately capture the characteristic time points corresponding to each flow evolution moment.

5. The device for observing fluid evolution in an experimental tank according to claim 1, characterized in that: The lighting source is configured as a plurality of evenly distributed white light LED lamp beads to form a relatively uniform background light source.

Images