An experimental working fluid storage and filling dual-loop system and method

Abstract

The present invention discloses an experimental working medium storage and filling dual-loop system and method in the technical field of space on-orbit fluid management. The ports on the experimental storage tank and the liquid storage tank connected to the liquid pump are both located on the side far from the center of the variable gravity centrifuge platform, and the ports on the experimental storage tank and the liquid storage tank connected to the second solenoid valve are both located on the side close to the center of the variable gravity centrifuge platform, so that when the variable gravity centrifuge platform provides centrifugal force, the inlet and outlet of the liquid pump are filled with liquid; a reversing solenoid valve is connected to the pipelines on both the head and tail sides of the liquid pump, and the reversing solenoid valve can change the fluid direction in the loop to select to pump the liquid into the experimental storage tank or the liquid storage tank. A flowmeter is connected to the pipeline at the liquid outlet end of the liquid pump, which is used to measure the current flow rate during the liquid injection process and measure the liquid filling amount transported into the experimental storage tank after the liquid injection ends, and can reciprocally adjust the liquid filling rate of the experimental storage tank.

Description

Technical Field

[0001] The present invention relates to the technical field of in-orbit fluid management in space, and particularly to an experimental working medium storage and filling dual-loop system and method. 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, physical properties such as the surface tension and buoyancy of fluids will change, resulting in unique laws in aspects such as the distribution, flow velocity, and stability of fluids in containers. Therefore, in-orbit fluid management in space needs to fully consider these fluid characteristics under microgravity conditions.

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

[0004] In the activities of in-orbit fluid management devices, a liquid pump is used to pump the liquid in the liquid storage tank into the experimental tank, and the liquid filling rate in the experimental tank is adjusted by the liquid pump; however, due to the mixing of gas and liquid phases in the experimental tank, the liquid pump will pump gas-liquid two-phase when working, resulting in damage to the liquid pump. Summary of the Invention

[0005] The purpose of the present invention is to provide an experimental working medium storage and filling dual-loop system to solve the technical problem in the prior art that the gas-liquid two-phase is mixed in the experimental tank, and the liquid pump will pump gas-liquid two-phase when working, resulting in damage to the liquid pump.

[0006] To solve the above technical problem, the present invention provides an experimental working medium storage and filling dual-loop system, including an experimental tank, a first solenoid valve, a liquid pump, a liquid storage tank, and a second solenoid valve that are sequentially connected to form a closed loop;

[0007] The ports on the experimental tank and the liquid storage tank connected to the liquid pump are both located on the side far from the center of the variable gravity centrifuge platform, and the ports on the experimental tank and the liquid storage tank connected to the second solenoid valve are both located on the side close to the center of the variable gravity centrifuge platform, so that when the variable gravity centrifuge platform provides centrifugal force, the inlet and outlet of the liquid pump are filled with liquid;

[0008] On the pipelines on both the head and the tail sides of the liquid pump, a reversing solenoid valve is connected. The reversing solenoid valve can change the fluid direction in the loop to select to pump the liquid into the experimental storage tank or the liquid storage tank, and can adjust the liquid filling rate of the experimental storage tank to observe the static balance of the gas-liquid interface under microgravity conditions and the dynamic behavior under variable gravity conditions under different liquid filling rate conditions;

[0009] After the liquid filling rate is adjusted, the first solenoid valve and the second solenoid valve can close the experimental storage tank to fix the liquid filling rate of the experimental storage tank;

[0010] A filling manual valve is installed in the closed loop for filling the experimental working medium into the closed loop.

[0011] As a preferred solution of the present invention, a pressure sensor for detecting the hydraulic pressures of the experimental storage tank and the liquid storage tank is further provided on the closed loop, and the pressure sensor is respectively arranged close to the ports on the sides of the experimental storage tank and the liquid storage tank away from the second solenoid valve.

[0012] As a preferred solution of the present invention, a flowmeter is connected to the pipeline at the liquid outlet end of the liquid pump for measuring the current flow rate during the liquid injection process and the liquid filling amount transported into the experimental storage tank after the liquid injection ends.

[0013] As a preferred solution of the present invention, observation scales are provided on the experimental storage tank, and the observation scales are arranged along the centrifugal acceleration direction of the variable gravity centrifuge platform to observe the filling ratio of the liquid in the experimental storage tank when the variable gravity centrifuge platform provides centrifugal acceleration.

[0014] The present invention also provides an experimental working medium storage and filling method, using the above-mentioned experimental working medium storage and filling dual-loop system, including the following steps:

[0015] Start the variable gravity centrifuge platform to simulate a microgravity or variable gravity environment and provide centrifugal force for the experimental working medium storage and filling dual-loop system;

[0016] Open the first and second solenoid valves to make the liquid in the closed loop converge on the side close to the liquid pump, so that the liquid pump is in the liquid phase;

[0017] Switch the flowable direction of the fluid in the loop through the reversing solenoid valve to flow from the liquid storage tank to the experimental storage tank;

[0018] Start the liquid pump and inject liquid into the experimental storage tank at a set flow rate within the filling ratio range of 10% to 90%, and observe the shape and position changes of the gas-liquid interface in the microgravity or variable gravity environment;

[0019] Using a liquid pump and an electromagnetic directional valve, two-way filling of the experimental storage tank and the liquid storage tank is achieved, the filling ratio of the liquid in the experimental storage tank is adjusted, and multiple experiments are repeated. The shape and position changes of the gas-liquid interface under the observed microgravity or variable gravity environment under different liquid filling rates are observed.

[0020] Adjust the magnitude of the centrifugal force, simulate the in-orbit liquid replenishment process under different gravity environments, repeat the above experiments, and observe the static equilibrium of the gas-liquid interface under different gravity conditions.

[0021] The present invention has the following beneficial effects compared with the prior art:

[0022] The ports on the experimental storage tank and the liquid storage tank connected to the liquid pump are both located on the side away from the center of the variable gravity centrifugal platform, and the ports on the experimental storage tank and the liquid storage tank connected to the second solenoid valve are both located on the side close to the center of the variable gravity centrifugal platform.

[0023] When the variable gravity centrifugal platform provides centrifugal force, under the action of the centrifugal force, due to the mass difference between the gas-liquid two phases, the liquid phase in the experimental storage tank and the liquid storage tank converges on the side away from the center of the variable gravity centrifugal platform, while the gas phase is driven to converge on the side close to the center of the variable gravity centrifugal platform. At this time, the ports on the experimental storage tank and the liquid storage tank connected to the liquid pump are both in the liquid phase, so that when the liquid pump pumps liquid, it will not draw air, avoiding damage to the liquid pump and prolonging its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained according to the provided drawings.

[0025] Figure 1 It is a schematic structural diagram of the experimental box and the electronic control box in the embodiment of the present invention;

[0026] Figure 2 It is a schematic internal structural diagram after the experimental box in the embodiment of the present invention is sectioned;

[0027] Figure 3 It is a schematic structural diagram of the experimental storage tank and the liquid storage tank in the embodiment of the present invention;

[0028] Figure 4 For Figure 3 The top view schematic diagram;

[0029] Figure 5 For Figure 4 The front view schematic diagram of the perspective;

[0030] Figure 6 Structural schematic diagrams of the experimental storage tank, external force application mechanism, and fluid observation device in the embodiments of the present invention;

[0031] Figure 7 Structural schematic diagram of the vibration mechanism in the embodiments of the present invention;

[0032] Figure 8 Structural schematic diagrams of the moving platform and slide rail in the embodiments of the present invention;

[0033] Figure 9 Structural schematic diagram of the bottom of the moving platform in the embodiments of the present invention;

[0034] Figure 10 Top view structural schematic diagram of the experimental storage tank in the embodiments of the present invention;

[0035] Figure 11 Side view structural schematic diagram of the experimental storage tank in the embodiments of the present invention;

[0036] Figure 12 Structural schematic diagram of the upper half storage tank in the embodiments of the present invention;

[0037] Figure 13 Structural schematic diagram of the lower half storage tank in the embodiments of the present invention;

[0038] Figure 14 Structural schematic diagram of the experimental working fluid storage and filling dual-loop system in the embodiments of the present invention;

[0039] Figure 15 Schematic diagram of the sequence for conducting external disturbance experiments in the embodiments of the present invention;

[0040] Figure 16 Schematic diagram of the sequence for conducting liquid filling experiments in the embodiments of the present invention.

[0041] The reference numerals in the figures are respectively represented as follows:

[0042] 1 - experimental box, 2 - electronic control box, 3 - variable gravity centrifugal platform;

[0043] 4 - experimental storage tank, 401 - upper half storage tank, 402 - lower half storage tank, 403 - liquid inlet, 404 - liquid outlet;

[0044] 5 - liquid storage tank;

[0045] 6 - experimental working fluid storage and filling dual-loop system, 601 - first solenoid valve, 602 - liquid pump, 603 - filling hand valve, 604 - second solenoid valve, 605 - reversing solenoid valve, 606 - pressure sensor, 607 - flow meter;

[0046] 7 - Fluid observation device, 701 - Fixed camera, 702 - Lighting source, 703 - Follow - up camera, 704 - Observation scale;

[0047] 8 - Rotation mechanism, 801 - Stepper motor, 802 - Connecting shaft;

[0048] 9 - Vibration mechanism, 901 - Linear motor, 902 - Moving platform, 903 - Grating scale, 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 implementation mode

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0050] The present invention specifically provides a space variable - gravity on - orbit fluid experiment system and method. It should be emphasized that this experiment system and method are adapted to the microgravity or variable - gravity environment provided by the variable - gravity centrifuge platform 3, that is, based on the variable - gravity or microgravity space environment simulated by the variable - gravity centrifuge platform 3. All the experimental components and experimental methods in the present invention are constructed based on this.

[0051] On the variable - gravity centrifuge platform 3 in this experiment system, there are installed:

[0052] Experiment box 1, installed on the variable - gravity centrifuge platform 3 of the variable - gravity centrifuge platform 3, and an experimental storage tank 4 and a liquid storage tank 5 are arranged therein;

[0053] Electric control box 2, installed on the variable - gravity centrifuge platform 3 of the variable - gravity centrifuge platform 3, and connected to the electronic devices in the experiment box 1.

[0054] The internal structure of the experiment box 1 is the design focus of the present invention, mainly including the following five parts.

[0055] I. Experimental storage tank

[0056] The experimental storage tank 4 is a box body used to observe the gas - liquid interface, gas - liquid two - phase distribution and gas - liquid movement in the space variable - gravity on - orbit fluid experiment. In the present invention, the improvement of the experimental storage tank 4 is to solve the technical problem that the existing experimental storage tank 4 is composed of two equal - part box bodies up and down, and the two box bodies are connected by a flange at the middle axis, and the flange is located at the maximum cross - section of the experimental storage tank 4, which is not convenient for obtaining quantitative observation images reflecting the maximum gas - liquid interface in the storage tank.

[0057] The specific details are as follows:

[0058] An off-axis visualization and quantitative observation sealed storage tank is adopted to observe the maximum cross-section of the liquid in the experimental storage tank 4.

[0059] It includes an upper half storage tank 401 and a lower half storage tank 402 that are fixedly connected. A sealing ring is arranged between the upper half storage tank 401 and the lower half storage tank 402. Lobe flanges are arranged at the edges of both the upper half storage tank 401 and the lower half storage tank 402. The upper and lower lobe flanges are sealed and fixed by bolts and an internal O-ring to form a complete transparent and visible experimental storage tank 4.

[0060] The boxes of both the upper half storage tank 401 and the lower half storage tank 402 are made of transparent materials so as to be able to observe the gas-liquid interface morphology inside the box from the outside of the box.

[0061] The volume of the upper half storage tank 401 is larger than that of the lower half storage tank 402, so that the center of the experimental storage tank 4 is located inside the upper half storage tank 401, that is, the maximum cross-section of the experimental storage tank 4 is located inside the upper half storage tank 401, so as to be able to observe the gas-liquid interface morphology at the maximum axial cross-section at the center inside the experimental storage tank 4 from above the experimental storage tank 4.

[0062] When observing the gas-liquid in the experimental storage tank 4, the line of sight is from top to bottom. Therefore, the liquid inlet 403 and the liquid outlet 404 of the experimental storage tank 4 are both arranged on the lower half storage tank 402 to avoid blocking the observation line of sight.

[0063] The experimental storage tank 4 is set to the geometric morphology of a typical propellant storage tank, that is, the middle is a cylindrical shell as a whole, and both ends of the experimental storage tank 4 are hemispherical shells symmetrically arranged, and the diameter of the hemispherical shell is equal to the diameter of the cylindrical shell;

[0064] 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 storage tank 4 is arranged radially along the variable gravity centrifugal platform 3.

[0065] One of the advantages of setting the experimental storage tank 4 to the above shape and arranging it radially is that when the variable gravity centrifugal platform 3 rotates to provide centrifugal force, the liquid in the experimental storage tank 4 will be concentrated on one side of the experimental storage tank 4 under the action of the centrifugal force, and the liquid interface is perpendicular to the line connecting the two centers of the spheres, that is, the liquid interface is perpendicular to the long axis of the experimental storage tank 4.

[0066] As the filling rate of the experimental storage tank 4 increases, the liquid interface gradually moves along the line connecting the centers of the spheres. Since both ends and the middle of the experimental storage tank 4 are regular shapes, it is convenient to calculate the filling rate corresponding to each point on the long axis, so as to facilitate marking the corresponding observation scale 704 on the experimental storage tank 4 as a reference for the liquid filling and filling rate adjustment of the experimental storage tank 4.

[0067] That is, to observe the filling rate in the present invention, it needs to be carried out under the condition that the variable gravity centrifuge platform 3 provides centrifugal force, that is, under the condition of simulating microgravity or variable gravity on the variable gravity centrifuge platform 3, which conforms to the real space gravity environment and is not under the normal gravity of the earth.

[0068] The liquid inlet 403 and the liquid outlet 404 are symmetrically arranged on both sides of the lower half storage tank 402 along the direction of the centrifugal acceleration of the variable gravity centrifuge platform 3.

[0069] Observation scales 704 are arranged on the upper half storage tank 401, and the observation scales 704 are arranged along the direction of the centrifugal acceleration of the variable gravity centrifuge platform 3 to observe the filling ratio of the liquid in the experimental storage tank 4 when the variable gravity centrifuge platform 3 provides centrifugal acceleration.

[0070] II. Fluid Observation Device

[0071] In the space on-orbit fluid management simulation experiment, it is necessary to observe and record the gas-liquid in the experimental storage tank 44 through a camera. In the prior art, the observation and recording are generally carried out through a single camera position, and the flow evolution process of the gas-liquid interface cannot be comprehensively observed and recorded.

[0072] In the present invention, the fluid observation device 7 realizes the morphology observation of the gas-liquid interface of the experimental liquid in the experimental storage tank 4 through the shadow method, including:

[0073] A fixed camera 701, fixedly arranged directly above the transparent experimental storage tank 4;

[0074] A lighting source 702, fixedly arranged directly below the experimental storage tank 4. The lighting source 702, the fixed camera 701 and the experimental storage tank 4 are located on a straight line to observe the real-time evolution of the gas-liquid interface in the experimental storage tank 4 by using the shadow method;

[0075] A follow-up camera 703, fixedly installed together with the experimental storage tank 4 and located on the side of the experimental storage tank 4, capable of moving synchronously with the experimental storage tank 4; specifically, the follow-up camera 703 is installed on the lug flange of the upper half storage tank 401

[0076] The fixed camera 701 cooperates with the follow-up camera 703 to be able to perform quasi-three-dimensional observation on the gas-liquid interface in the experimental storage tank 4 to determine the flow evolution process of the gas-liquid interface from two directions, the front and the side, at the same time.

[0077] The fixed-phase cooperating with the follow-up camera 703 can perform quasi-three-dimensional observations on the gas-liquid interface in the experimental storage tank 4 from the front and side respectively, one static and one moving, and can comprehensively obtain video images of the gas-liquid interface, the gas-liquid two-phase distribution, and the gas-liquid flow evolution process from both the front and side directions. After the experimental tank 1 and the electronic control box 2 are powered on, the camera starts shooting directly and saves the footage in segments until the storage is full or the power is cut off.

[0078] If scales are marked on the experimental storage tank 4, when observing the gas-liquid in the experimental storage tank 4, with the observation scale 704 as a reference, the liquid filling rate can be judged more accurately.

[0079] Therefore, two groups of observation scales 704 are respectively arranged on the experimental storage tank 4 opposite to the fixed camera 701 and the follow-up camera 703.

[0080] And the observation scale 704 is arranged along the centrifugal acceleration direction of the variable-gravity centrifugal platform 3 to observe the current liquid filling ratio in the experimental storage tank 4 when the variable-gravity centrifugal platform 3 provides centrifugal acceleration.

[0081] Arranging the observation scale 704 along the centrifugal acceleration direction of the variable-gravity centrifugal platform 3, according to the previous volume measurement of the experimental storage tank 4, corresponding scales can be marked at corresponding positions along the centrifugal acceleration direction to represent the corresponding filling rates.

[0082] To facilitate scale marking, the experimental storage tank 4 can be set to the above-mentioned typical propellant storage tank geometric shape, and the experimental storage tank 4 is arranged along the radial direction of the variable-gravity centrifugal platform 3, that is, along the centrifugal acceleration direction, so that the observation scale 704 is arranged along the long axis of the experimental storage tank 4.

[0083] When the centrifuge rotates and provides a 1g centrifugal acceleration, the centrifugal acceleration direction is perpendicular to the long axis of the experimental storage tank 4, and the gas-liquid interface in the experimental storage tank 4 is parallel to each scale line in the observation scale 704. The central position scale line is marked at the center of the long axis direction of the experimental storage tank 4 (50% liquid filling ratio), and based on this, scale lines corresponding to different liquid volume filling ratios are symmetrically scaled along both ends of the storage tank (the 40% and 60% liquid filling ratios correspond to "4", the 30% and 70% liquid filling ratios correspond to "3", and so on). Using a CCD camera to observe the gas-liquid interface at the corresponding positions of the storage tank scale lines, the size of the liquid volume filling ratio in the storage tank can be quantitatively obtained, and the real-time optical observation of the gas-liquid interface morphology and its position in the storage tank under different experimental conditions can be completed, obtaining quantitative scientific experimental results.

[0084] Furthermore, for the selected camera model with a resolution of 1080p and a maximum observation field of view of 100mm × 80mm, it can meet the relatively precise 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 need to apply variable gravity conditions, external force shaking, etc., for larger-sized storage tanks, the gas-liquid interface changes violently. If it is necessary to accurately capture the characteristic time points corresponding to each flow evolution moment, a relatively high-speed CCD camera acquisition frame rate is required. Considering the downstream bandwidth and the amount of stored data comprehensively, the acquisition frame rate we selected is about 60fps. During 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, meeting the scientific requirements of this project.

[0085] There are two groups of observation scales 704. One group is directly opposite to the fixed camera 701, that is, located at the middle position of the top of the experimental storage tank 4, and the other group is arranged on the side of the experimental storage tank 4, directly 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 the observation scales 704 should not be too close. Taking the observation scale 704 at the middle position of the top of the experimental storage tank 4 as the zero-degree reference, the included angle between the two groups of observation scales 704 is preferably 30° - 45°.

[0086] Both the fixed camera 701 and the follow-up camera 703 are high-speed cameras to accurately capture the characteristic time points corresponding to each flow evolution moment.

[0087] The lighting source 702 is set as multiple white LED lamp beads with a uniform distribution to form a relatively uniform background light source.

[0088] III. Experimental Working Fluid Storage and Filling Double-Loop System

[0089] During the activities of the in-space on-orbit fluid management device, the liquid pump 602 is used to pump the liquid in the liquid storage tank 5 into the experimental storage tank 4 and to adjust the liquid filling rate in the experimental storage tank 4 through the liquid pump 602. However, due to the mixing of gas and liquid phases in the experimental storage tank 4, the liquid pump 602 will extract both gas and liquid phases when working, resulting in damage to the liquid pump 602.

[0090] Therefore, the present invention designs an experimental working fluid storage and filling double-loop system 6 to enable the liquid pump 602 to extract only the liquid phase when working.

[0091] It includes an experimental storage tank 4, a first solenoid valve 601, a liquid pump 602, a liquid storage tank 5, and a second solenoid valve 604 that are sequentially connected to form a closed loop;

[0092] The ports on the experimental storage tank 4 and the liquid storage tank 5 connected to the liquid pump 602 are both located on the side away from the center of the variable gravity centrifuge platform 3, and the ports on the experimental storage tank 4 and the liquid storage tank 5 connected to the second solenoid valve 604 are both located on the side close to the center of the variable gravity centrifuge platform 3, so that when the variable gravity centrifuge platform 3 provides centrifugal force, the inlet and outlet of the liquid pump 602 are filled with liquid;

[0093] A reversing solenoid valve 605 is connected to the pipelines on both the head and tail sides of the liquid pump 602. The reversing solenoid valve 605 can change the direction of the fluid in the loop to select to pump the liquid from the liquid pump 602 into the experimental storage tank 4 or the liquid storage tank 5, and can adjust the liquid filling rate of the experimental storage tank 4 to observe the static equilibrium of the gas-liquid interface under microgravity conditions and the dynamic behavior under variable gravity conditions under different liquid filling rate conditions;

[0094] The first solenoid valve 601 and the second solenoid valve 604 can close the experimental storage tank 4 after the liquid filling rate is adjusted to fix the liquid filling rate of the experimental storage tank 4;

[0095] A filling manual valve 603 is installed in the closed loop for filling the experimental working medium into the closed loop.

[0096] When the variable gravity centrifuge platform 3 provides centrifugal force, under the action of the centrifugal force, due to the mass difference between the gas and liquid phases, the liquid phases in the experimental storage tank 4 and the liquid storage tank 5 converge on the side away from the center of the variable gravity centrifuge platform 3, while the gas phase is driven to converge on the side close to the center of the variable gravity centrifuge platform 3.

[0097] At this time, the ports on the experimental storage tank 4 and the liquid storage tank 5 connected to the liquid pump 602 are both in the liquid phase, so that when the liquid pump 602 pumps liquid, it will not draw air, avoiding damage to the liquid pump 602 and prolonging its service life.

[0098] It should be noted that when the liquid pump 602 is working, both the first solenoid valve 601 and the second solenoid valve 604 are in the open state. The opening of the first solenoid valve 601 ensures the circulation of the liquid phase between the experimental storage tank 4 and the liquid storage tank 5. Since the flow of the liquid phase will cause changes in the gas phase in the two tanks, for example, when injecting the liquid phase into the experimental storage tank 4, the gas phase in the experimental storage tank 4 will be compressed. To avoid the increase in the air pressure in the experimental storage tank 4 affecting the injection of the liquid phase, the experimental storage tank 4 is connected to the liquid storage tank 5 so that the excess gas in the experimental storage tank 4 can enter the liquid storage tank 5.

[0099] When the filling rate in the experimental storage tank 4 reaches the predetermined value, the first solenoid valve 601 and the second solenoid valve 604 are closed, and the liquid phase and the gas phase can be locked in the experimental storage tank 4 to avoid liquid escape.

[0100] The above-mentioned filling system can also simulate the in-orbit refueling of liquids, that is, simulate the in-orbit liquid replenishment process in space, and has a wide range of applications.

[0101] It can be understood that during this process, the liquid outlet 404 on the experimental storage tank 4 is essentially the diameter for the passage of gas phase.

[0102] A pressure sensor 606 for detecting the hydraulic pressures of the experimental storage tank 4 and the liquid storage tank 5 is also provided on the closed loop, and the pressure sensor 606 is respectively arranged close to the ports of the experimental storage tank 4 and the liquid storage tank 5 on the side away from the second solenoid valve 604.

[0103] A flowmeter 607 is connected to the pipeline at the liquid outlet end of the liquid pump 602. This flowmeter 607 can not only calculate the liquid filling amount per unit time, but also be used to measure the total liquid filling amount.

[0104] The steps of using the above-mentioned experimental working fluid storage and filling dual-loop system 6 for liquid filling are as follows:

[0105] Start the variable gravity centrifuge platform 3 to simulate a microgravity or variable gravity environment and provide centrifugal force for the experimental working fluid storage and filling dual-loop system 6;

[0106] Open the first and second solenoid valves 604 to make the liquid in the closed loop converge on the side close to the liquid pump 602, so that the liquid pump 602 is in the liquid phase;

[0107] Switch the flowable direction of the fluid in the loop through the reversing solenoid valve 605 to flow from the liquid storage tank 5 to the experimental storage tank 4;

[0108] Open the liquid pump 602 and inject liquid into the experimental storage tank 4 at a set flow rate within the filling ratio range of 10% - 90%, and observe the shape and position changes of the gas-liquid interface in the microgravity or variable gravity environment;

[0109] Utilize the liquid pump 602 and the electromagnetic reversing valve to achieve two-way filling of the experimental storage tank 4 and the liquid storage tank 5, adjust the filling ratio of the liquid in the experimental storage tank 4, repeat the experiment multiple times, and observe the shape and position changes of the gas-liquid interface in the microgravity or variable gravity environment under different liquid filling rates;

[0110] Adjust the magnitude of the centrifugal force to simulate the in-orbit liquid replenishment 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 in-orbit liquid replenishment process under variable gravity is that the gravity in the space environment is not fixed either. For example, the gravitational forces on the Moon and Mars are different.

[0111] That is, through the above design of the experimental working fluid storage and filling unit, it is possible to inject the room-temperature working fluid with a certain flow rate, and change the liquid filling ratio of the experimental storage tank 4 from 10% to 90%. Since the outer wall of the experimental storage tank 4 is transparent and the experimental working fluid (such as FC-72) is also transparent, in order to clearly observe the distribution of the gas-liquid interface and the movement of the liquid level in the storage tank, we will adopt the method of dyeing the experimental working fluid, and cooperate with the selection of the light source to increase the contrast with the outer wall of the storage tank, so as to improve the judgment accuracy of the gas-liquid interface.

[0112] Under the condition of space microgravity, the gas-liquid interface of the liquid in the storage tank may not be concentrated at the liquid inlet 403 of the experimental storage tank 4 under external disturbances. Therefore, when we carry out scientific experiments, the liquid filling ratio is adjusted unidirectionally from small to large, that is, we first conduct small filling ratio tests in orbit, and then fill the liquid into the storage tank at a predetermined flow rate and injection volume through the experimental working fluid storage and filling unit.

[0113] The components of the experimental working fluid storage and filling dual-loop system 6 include: liquid pump, flowmeter 607, reversing valve, solenoid valve, pressure sensor 606, liquid storage tank and filling manual valve 603.

[0114] The pipeline part is composed of 316 bellows, 304 stainless steel pipes and silicone hoses.

[0115] The sealing auxiliary materials used are stainless steel ferrule, Loctite magic rope and polytetrafluoroethylene raw tape.

[0116] 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 passed verifications such as compatibility, pressure resistance, sealing, anti-corrosion and strength; the sealing auxiliary materials are also extremely mature products and meet the compatibility of our working fluids.

[0117] The protruding space inside the experimental box 1 of the variable gravity fluid management experimental device is narrow, the layout is compact, and the fluid transport pipelines are complicated. If conventional straight pipelines are used for installation, the installation and maintenance of the pipelines will become extremely difficult. Most importantly, the outer sealing plate will not be able to be installed in place. To solve this problem, we choose stainless steel bellows, which have the advantages of smooth inner wall, earthquake resistance, tensile resistance, flexibility, elasticity and light weight. The bellows have extremely high adaptability to the vibration during the rocket's liftoff.

[0118] Vigorous vibrations will occur during the rocket's startup and flight. Although the pipelines in our box can well adapt to this situation, if the bellows resonate, it may cause unnecessary losses to the surrounding components or the box body. Therefore, we protect the places where there is a risk of the bellows colliding with other positions. The protection material is to wrap the outer layer of the bellows with polytetrafluoroethylene film, and the adjacent long pipelines are fixed with polytetrafluoroethylene tie straps to reduce the vibration amplitude.

[0119] The silicone hose is suitable for transporting some corrosive, high-temperature or high-pressure media, while the flare fitting is suitable for transporting gases or liquids. When installing, soak the silicone hose at 80 - 95 °C in hot water at the silicone joint 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 sleeved on the flare fitting, and it can bond more tightly with the flare fitting during the cooling and shrinking process.

[0120] Due to the rotational and translational operations of the experimental storage tank 4, the working fluid delivery hose needs to form a follow-up mode with the experimental storage tank 4. Therefore, a coaxial follow-up wire carrier disc is designed on the opposite side of the motor of the experimental storage tank 4, and the wire carrier disc is used to fix the flexible pipeline and the heating sheet cable in the external heat application mechanism.

[0121] During the experiment, its vibration speed and frequency change continuously in stages within a wide range, and the rotation angle of the test tank is 180°. Therefore, the fluid transport pipeline needs to have a certain flexibility, anti-deformation, and visualization. Only in this way can it cooperate well with the movement during the experiment and complete a good working fluid transport function.

[0122] IV. On-orbit motion simulation experimental device for a space variable-gravity fluid storage tank

[0123] The space experiment plan involves different experimental conditions. According to the actual working conditions of the spacecraft storage tank, there is a situation where the gas-liquid interface is disturbed and becomes unstable. It is of great significance to explore the oscillation law and recovery period of the free liquid surface in the storage tank caused by gravity changes and external disturbances.

[0124] The external force application mechanism includes:

[0125] A rotation mechanism 8, used to drive the experimental storage tank 4 to rotate, so as to adjust the angle between the experimental storage tank 4 and the centrifugal acceleration direction of the variable-gravity centrifugal platform 3, in order to simulate the morphological changes of the gas-liquid interface during rotational motion;

[0126] A vibration mechanism 9, used to drive the experimental storage tank 4 and the rotation mechanism 8 to perform linear reciprocating motion simultaneously, so as to apply translational and low-frequency vibration disturbances to the experimental storage tank 4, and simulate the morphological changes and instability phenomena of the gas-liquid interface during the process of the gas-liquid interface being disturbed by external forces;

[0127] At the same moment when the variable-gravity centrifugal platform is stationary or moving (primary platform movement), the on-orbit rotation and translation movements of the experimental storage tank are externally applied (secondary platform movement), so as to realize the dynamic simulation of the gas-liquid two-phase liquid in the experimental storage tank for the above primary and secondary movements.

[0128] The experimental storage tank 4, the rotation mechanism 8 and the vibration mechanism 9 are all installed in the experimental box 1 body of the variable-gravity on-orbit fluid management experimental device;

[0129] The rotation mechanism 8 and the vibration mechanism 9 cooperate to simulate the in-orbit motion of a space variable gravity fluid storage tank that combines rotation and translational motion.

[0130] The rotation angle range of the experimental storage tank 4 driven by the rotation mechanism 8 in orbit is 0 to 180°, and the rotation angular velocity range is 0.1 to 6 rad / s.

[0131] The vibration frequency range of the vibration applied by the vibration mechanism 9 to the experimental storage tank 4 is 0.5 - 1 Hz, and the maximum vibration amplitude is 10 mm.

[0132] The rotation mechanism 8 includes a stepping motor 801, a connecting shaft 802, a storage tank mounting and fixing flange, and a rotating bracket;

[0133] The experimental storage tank 4 is rotatably mounted on the rotating bracket through the storage tank mounting and fixing flange, and the stepping motor 801 is connected to the experimental storage tank 4 through the connecting shaft 802 for driving the experimental storage tank 4 to rotate around the connecting shaft 802.

[0134] The middle of the experimental storage tank 4 is a cylindrical shell, and both ends of the experimental storage tank 4 are hemispherical shells symmetrically arranged, and the diameter of the hemispherical shell is equal to the diameter of the cylindrical shell;

[0135] The connecting shaft 802 is collinear with the short axis of the experimental storage tank 4, and the rotation mechanism 8 can drive the experimental storage tank 4 to rotate around its short axis to adjust the angle between the long axis of the experimental storage tank 4 and the direction of the centrifugal acceleration of the variable gravity centrifuge platform 3;

[0136] The long axis is the longest center line passing through the center of the experimental storage tank 4, and the short axis is the shortest center line passing through the center of the experimental storage tank 4.

[0137] The vibration mechanism 9 includes a linear motor 901, a moving platform 902, and a slide rail 9010. The experimental storage tank 4 and the rotation mechanism 8 are both mounted on the moving platform 902;

[0138] The linear motor 901 is used to drive the moving platform 902 to move linearly back and forth along the slide rail 9010.

[0139] The vibration mechanism 9 further includes a grating ruler 903 and a reading head 904. The moving platform 902 can move along the grating ruler 903 under the drive of the linear motor 901;

[0140] The reading head 904 is fixedly mounted on the moving platform 902 to feedback the real-time position of the moving platform 902 to the linear motor 901;

[0141] On the grating scale 903, a left limit switch 906, a zero position switch 907, and a right limit switch 908 are sequentially arranged and connected to the motor control circuit 905 of the linear motor 901 to control the moving range of the moving platform 902;

[0142] The motor control circuit 905 is connected to the main control board 909 through a 485 interface.

[0143] The steps of using the above-mentioned rotating mechanism 8 and vibrating mechanism 9 to simulate the on-orbit movement of the space variable gravity fluid storage tank are as follows:

[0144] Start the variable gravity centrifuge platform 3, and make the variable gravity centrifuge platform 3 operate at the starting rate and target gravitational acceleration required by the experimental project;

[0145] Start the rotating mechanism 8, drive the experimental storage tank 4 to rotate to a predetermined angle at a predetermined angular velocity, simulate the dynamic motion characteristics of the fluid inside the storage tank during the on-orbit attitude change of the spacecraft, and change the angle between the long axis of the experimental storage tank 4 and the centrifugal acceleration through the rotating mechanism 8 multiple times, and repeat the experiment multiple times;

[0146] Start the vibrating mechanism 9, drive the experimental storage tank 4 to vibrate at a predetermined vibration frequency and vibration amplitude, simulate the working conditions of the experimental storage tank 4 being disturbed by translational motion and low-frequency vibration, change the vibration frequency and vibration amplitude, and repeat the experiment multiple times;

[0147] Start the rotating mechanism 8 and the vibrating mechanism 9 simultaneously, simulate the on-orbit movement of the space variable gravity fluid storage tank with combined rotational and translational motion, change the rotational and / or vibration parameters, and repeat the experiment multiple times.

[0148] V. External Heat Application Device

[0149] The local temperature change of the spacecraft storage tank will affect the increase in the liquid phase change pressure inside it, and the hot gas-liquid interface of the propellant will also be affected. Simulating and exploring the influence of the storage tank temperature change on the pressure change and gas-liquid interface inside the storage tank is of great significance for space on-orbit fluid management.

[0150] The external heat application unit consists 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 storage tank on the morphology of the liquid phase change interface inside it, as well as the influence of the heat generation and phase change effect of the propellant on the pressure change and gas-liquid interface inside the storage tank. At the same time, thermocouples are also installed at the internal characteristic points of the experimental storage tank 4 to monitor the temperature change. Considering safety and the boiling point of the simulated working fluid, we choose the method of local heating, and the maximum temperature does not exceed 50°C.

[0151] The heating method is electric heating. External heat input is carried out by means of a fixed power input. Thermocouples are locally arranged inside the experimental storage tank 4 for temperature monitoring. A thin-film heating tape with an electric power of 8 - 10 W is used, and different electric powers will be selected for experiments; the thermocouples used are all T-type thermocouples with a diameter of 125 μm.

[0152] By setting heaters and thermocouples inside the experimental storage tank 4, local temperature heating and temperature monitoring of the experimental storage tank 4 are carried out; by adjusting the heating temperature and cooperating with the observation records of the fluid observation device 7, the influence of the temperature change of the storage tank on the gas and gas-liquid interface inside the storage tank can be simulated and explored.

[0153] VI. The space variable gravity on-orbit fluid experiment simulation method after integrating the above components is as follows:

[0154] Start the experimental system and carry out the preparatory work before the simulation;

[0155] Adjust the experimental storage tank 4 to the predetermined working conditions through the variable gravity centrifuge platform, the dual-loop system 6 for experimental working fluid storage and filling, the external force application mechanism and the external heat application mechanism;

[0156] Through the fluid observation device 7, observe the morphological changes of the gas-liquid interface of the experimental storage tank 4, and collect experimental data including temperature, pressure, etc.;

[0157] After a single experiment, change the experimental working conditions, observe the morphological changes of the gas-liquid interface again, and collect data.

[0158] Specifically:

[0159] (1) Power on and warm up - Turn on the electronic control box 2, turn on the control components (sensors, observation equipment, light sources, etc.), start data collection, and wait for subsequent program control instructions after warming up;

[0160] (2) Start the variable gravity centrifuge platform - The variable gravity centrifuge platform 3 of the variable gravity centrifuge platform operates at the start-up rate and target gravitational acceleration required by the experimental project. The internal components of the "Space Variable Gravity On-orbit Fluid Management Experimental Device" either act according to the stabilized target gravitational acceleration or according to the instantaneous switching of the gravitational acceleration.

[0161] (3) Adjust the filling ratio - Drive the experimental working fluid in the liquid storage tank by the experimental working fluid storage and filling system, and complete the supplementary liquid of the target filling rate of the model storage tank according to the preset liquid injection rate and liquid injection volume. After stabilization, form the initial working conditions before the experiment;

[0162] (4) Temperature control - The electronic control unit feedback-controls the heating sheet inside the experimental object (sets the heating duty cycle) according to the temperature measurement value to make it reach the predetermined temperature or predetermined heating rate;

[0163] (5) External force application unit operation - The vibration mechanism or rotation mechanism inside the experimental device rotates or vibrates the model storage tank according to the set action time, working mode, and working content to reach the predetermined experimental background conditions;

[0164] (6) Experimental observation - The morphology change of the gas-liquid interface of the experimental object (model storage tank) is observed by the fixed and follow-up cameras with the background light, and the images are compressed in real time and transmitted by the electronic control unit, and then entered into the application information system through the variable gravity centrifuge platform controller. For engineering data such as temperature and pressure, after being collected by the sensors, they also enter the space station application information system for storage through the electronic control unit via the variable gravity centrifuge platform controller, and are analyzed after being downloaded and parsed by the operation control as scheduled;

[0165] (7) Working condition change - After a single experiment, change the experimental working conditions (temperature, heating rate, flow rate, liquid filling rate, sloshing load, rotation angle and angular velocity, variable gravity centrifuge platform gravity loading mode and target gravitational acceleration), repeat the above working sequence, and conduct experimental image observation and data measurement;

[0166] (8) Standby - After the scheduled experiment is completed, the device stands by. After the ground personnel conduct data analysis, the working conditions are changed through uplink commands.

[0167] For different experimental working conditions: static balance experiment, free interface, external disturbance, repositioning, liquid filling, and other extended experimental control parameters are shown in the following table.

[0168]

[0169]

[0170] Among them, the gravity level refers to the acceleration level at the center point of the experimental storage tank 4, and the heating temperature refers to the temperature controlled by the heating sheet.

[0171] Taking the external disturbance experiment as an example: The control parameters are mainly changed by changing the filling ratio of the experimental storage tank 4, the rotation angle of the rotation mechanism 3, the rotation rate of the rotation mechanism 3, the vibration frequency of the horizontal vibration mechanism, the amplitude of the horizontal vibration mechanism, etc.

[0172] The typical working condition process of the external disturbance experiment is shown in the following table.

[0173]

[0174]

[0175] The sequence of conducting the external disturbance experiment is as Figure 12 shown.

[0176] Liquid filling experiment: mainly control parameters such as the filling ratio of the experimental storage tank 4, the rotation angle of the rotating mechanism 3, the rotation speed of the rotating mechanism 3, and the liquid injection rate are changed.

[0177] The typical working condition process of the liquid filling experiment is shown in the following table.

[0178]

[0179]

[0180]

[0181] The sequence of conducting the liquid filling experiment is as Figure 13 shown.

[0182] The above embodiments are only exemplary embodiments of the present application and are not used to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions within the essence and protection scope of the present application, and such modifications or equivalent substitutions should also be regarded as falling within the protection scope of the present application.

Claims

1. A dual-circuit system for storing and filling experimental working fluids, characterized in that: It includes an experimental tank, a first electromagnetic valve, a liquid pump, a liquid storage tank and a second electromagnetic valve which are connected in sequence to form a closed loop; The ports on the experimental tank and the liquid storage tank connected to the liquid pump are both located on a side thereof away from the center of the variable gravity centrifugal platform, and the ports on the experimental tank and the liquid storage tank connected to the second solenoid valve are both located on a side thereof close to the center of the variable gravity centrifugal platform, so that when the variable gravity centrifugal platform provides centrifugal force, the inlet and outlet of the liquid pump are filled with liquid; A reversing solenoid valve is connected to the pipelines on both sides of the head and tail of the liquid pump, and the reversing solenoid valve can change the direction of the fluid in the circuit to select to pump the liquid into the experimental tank or the liquid storage tank, and can adjust the filling rate of the experimental tank to achieve static balance of the gas-liquid interface under microgravity conditions and dynamic behavior observation under variable gravity conditions under different filling rates; The first solenoid valve and the second solenoid valve can close the experimental tank after the filling rate is adjusted to fix the filling rate of the experimental tank; A filling hand valve is installed in the closed circuit for filling the closed circuit with experimental working fluid.

2. A dual-circuit system for storing and filling experimental working fluids according to claim 1, characterized in that: The closed loop is also provided with pressure sensors for detecting the hydraulic pressure of the experimental tank and the liquid storage tank, and the pressure sensors are respectively arranged close to the ports of the experimental tank and the liquid storage tank away from the second solenoid valve.

3. A dual-circuit system for storing and filling experimental working fluid according to claim 2, characterized in that: A flow meter is connected to the pipeline at the liquid outlet of the liquid pump to measure the current flow rate during the liquid injection process and the amount of liquid delivered to the experimental tank after the liquid injection is completed.

4. A dual-circuit system for storing and filling experimental working fluids according to claim 1, characterized in that: The experimental tank is provided with an observation scale, and the observation scale is arranged along the centrifugal acceleration direction of the variable gravity centrifugal platform, so as to observe the filling ratio of the liquid in the experimental tank when the variable gravity centrifugal platform provides centrifugal acceleration.

5. A method for storing and filling experimental working fluid, characterized in that: The experimental working fluid storage and charging dual-circuit system according to any one of claims 1 to 4 comprises the following steps: Starting the variable gravity centrifugal platform to simulate a microgravity or variable gravity environment and provide centrifugal force for the experimental working fluid storage and charging dual-circuit system; Open the first and second solenoid valves to make the liquid in the closed loop gather on the side close to the liquid pump, so that the liquid pump is in the liquid phase; The flow direction of the fluid in the circuit is switched to flow from the liquid storage tank to the experimental tank by means of a reversing solenoid valve; Turn on the liquid pump, inject liquid into the experimental tank 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; Use a liquid pump and an electromagnetic reversing valve to achieve bidirectional filling of the experimental tank and the liquid storage tank, adjust the filling ratio of the liquid in the experimental tank, repeat the experiment multiple times, and observe the changes in the shape and position of the gas-liquid interface under different filling ratios in microgravity or variable gravity environments; The centrifugal force was adjusted to simulate the on-orbit rehydration process under different gravity environments, and the above experiments were repeated to observe the static balance of the gas-liquid interface under different gravity conditions.

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