Force measuring device for sphere near-ice-surface movement

Abstract

The invention discloses a force measuring device for sphere near-ice-surface movement, and the device comprises a sphere module which comprises a front half spherical shell and a hole-containing rear half spherical shell; the supporting module comprises a supporting rod, a trailer and a flange; the driving module comprises a motor arranged on the trailer and a frequency converter for controlling the speed of the trailer; the force measuring module comprises a six-component sensor and a data acquisition instrument; and the PIV module comprises a laser, a first high-speed camera and a second high-speed camera. Real-time stress data of the sphere can be acquired in a complex boundary environment, important physical information such as a velocity field of a flow field under sphere movement can be acquired by combining a flow field visualization means, a formation mechanism of hydrodynamic characteristics of the self-propelled sphere is revealed by modules, and the self-propelled sphere hydrodynamic characteristic can be obtained. The research blank that the evolution of the vortex structure after the sphere and the stress of the sphere cannot be compared and analyzed is filled, and an accurate test verification basis is provided for relevant numerical simulation.

Description

Technical Field

[0001] The invention relates to the technical field of experimental fluid mechanics, in particular to a force measuring device for a sphere moving near an ice surface. Background Art

[0002] The phenomenon of flow around convex bodies is widespread in natural environments and engineering systems, involving a variety of single-phase and two-phase flow problems, such as particle transport in haze and dust storms, heat dissipation design in nuclear power plants and thermal power plants, gas mixing in combustion systems, the movement of small underwater vehicles, and the flow organization inside equipment such as chemical reactors and storage tanks. Because flow around convex bodies is often accompanied by significant vortex structures, its study is of great significance for understanding complex flow characteristics and optimizing related engineering designs. Given that a sphere is a typical convex body structure, systematically studying the coupling mechanism between its hydrodynamic characteristics during flow field motion and the evolution of vortex structures in its wake can provide guidance for theoretical and numerical studies of such problems. This problem is one of the core issues in the field of fluid mechanics, and its key lies in revealing the complex interaction between the moving body and the fluid. Traditional research often uses experimental methods involving a stationary sphere and moving fluid to analyze the hydrodynamic response of the sphere. Although this method has certain feasibility and reliability under standard working conditions (unbounded flow field), it has significant limitations when studying the hydrodynamic behavior of the sphere near the ice surface or near the free liquid surface environment. For example, it is difficult to simulate the unsteadiness of the flow field with a fixed sphere, and the effect of the sphere's motion on the surrounding flow field is ignored, while the boundary layer of the fluid motion on the boundary also has a significant impact on the flow field. Traditional experiments are mostly conducted far away from the boundary, making it difficult to simulate the effects of ice surface interference and water surface fluctuations on the flow field and forces.

[0003] Specifically, existing experimental schemes generally use relative motion theory, which makes it difficult to reproduce the unsteady flow field experienced by a sphere under actual self-propulsion. In particular, it is difficult to understand its hydrodynamic characteristics and the evolution mechanism of vortices in the complex flow fields of free liquid and near ice. Furthermore, in such environments, traditional force measurement methods lack the ability to simultaneously observe the instantaneous flow field structure, making it difficult to clearly establish the force-flow field coupling relationship. Summary of the Invention

[0004] The present invention aims to provide a force measuring device for a ball moving near an ice surface to solve the problems mentioned in the background art. To solve the above technical problems, the present invention is implemented through the following technical solutions: The present invention is a force measuring device for a ball moving near an ice surface, comprising: A spherical module, comprising a front half spherical shell and a rear half spherical shell containing a hole, wherein the front half spherical shell and the rear half spherical shell containing a hole are provided with threads on the outer sides of the maximum diameters and are threadedly connected to a connecting disk, a fixing block is fixed at the center of the connecting disk, and a screw is passed through the end of the fixing block; A support module, comprising a support rod, a trailer, and a flange. One end of the support rod is connected to an opening on the rear half of the spherical shell containing the hole through a tail shaft rod adapter plate. The flange is fixedly connected to the other end of the support rod and the docking end of the trailer. A set of flanges are docked with each other by bolts. The trailer is located above the water pool arranged outside. A drive module, the drive module including a motor placed on the trailer and a frequency converter for controlling the speed of the trailer; A force measuring module, comprising a six-component force sensor and a data acquisition instrument, wherein the six-component force sensor is fixed to the center of the connection disk inside the sphere by the screws, the six-component force sensor has a built-in sensor DC power supply, and the data acquisition instrument is mounted on the outer surface of the six-component force sensor; The PIV module includes a laser, a first high-speed camera and a second high-speed camera. The laser penetrates and is sealed at a corner below the front of the pool. The first high-speed camera is located on one side above the pool, and the second high-speed camera is located directly above the pool.

[0005] Furthermore, the middle part of the support rod is hollow and is provided with cables, which are electrically connected to the sensor DC power supply and the data acquisition instrument respectively.

[0006] Furthermore, the support rod is made of a hollow steel pipe, the diameter of which is smaller than the diameter of the sphere, and a counterweight is installed in the hollow space in the middle of the support rod.

[0007] Furthermore, a false bottom simulating an ice surface is provided in the water pool, and a slide rail is fixed to the upper outer edge of the water pool and is threadedly fixed to the trailer.

[0008] Furthermore, the data acquisition instrument, the frequency converter, the laser and the output end of the second high-speed camera are all electrically connected to the input end of the external computer through a transmission cable.

[0009] Furthermore, the PIV module also includes tracer particles, which are uniformly injected into the fluid of the shooting section and are used to track material movement, transfer process or medium flow through physical, chemical or biological property marking.

[0010] The present invention has the following beneficial effects: The biggest difference between this invention and the traditional "spherical static-fluid motion" test mode based on the theory of relative motion is that it truly restores the scene of an underwater vehicle sailing in water, especially when the sphere moves near the wall and near the free liquid surface, which has great advantages over traditional test methods.

[0011] The present invention is based on the structural design of a hollow sphere and uses a built-in six-component force sensor to achieve high-precision measurement of the lift, drag and torque exerted on the sphere during underwater movement.

[0012] The present invention cleverly integrates the synchronous data acquisition of the PIV module and the force measurement module through a high-precision joint measurement platform based on time-series synchronous acquisition technology, realizing synchronous, high-frequency and accurate recording of wake evolution and force response in complex flow environments.

[0013] By adjusting the distance between the false bottom and the sphere, the present invention can realize the control of test working conditions at different distances between the sphere and the ice surface; by adjusting the flange connection between the trailer and the supporting structure, the center height of the sphere can be adjusted in real time before or during the test, thereby accurately controlling its vertical distance from the free liquid surface.

[0014] The present invention achieves the simultaneous acquisition of sphere force data and the structural evolution of its wake flow field. By matching and comparing flow field images with hydrodynamic measurement results at the same time point, a modular study of the coupling relationship between the flow field structure evolution process and the hydrodynamic response of the sphere can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the connection between the sphere and the support rod of the present invention; Figure 3 This is a schematic diagram of unified time control and recording for multiple devices according to the present invention.

[0017] In the accompanying drawings, the components represented by the reference numerals are as follows: 1. Front half of the spherical shell; 2. Connecting plate; 3. Support rod; 4. Six-component force sensor; 5. False bottom; 7. Slide rail; 8. Trailer; 9. Laser; 10. First high-speed camera; 11. Flange; 12. Water tank; 13. Tail shaft adapter plate; 14. Fixing block; 15. Cable; 16. Screw; 17. Second high-speed camera; 18. Back half of the spherical shell with hole; 19. External computer; 20. Data acquisition instrument; 21. Frequency converter. DETAILED DESCRIPTION

[0018] 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.

[0019] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0020] See also Figure 1-3 As shown, the present invention is a force measuring device for a ball moving near an ice surface, comprising: The spherical module includes a front half spherical shell 1 and a rear half spherical shell 18 with a hole. The outer sides of the maximum diameters of the front half spherical shell 1 and the rear half spherical shell 18 with a hole are provided with threads and are threadedly connected to a connecting disk 2. A fixing block 14 is fixed to the center of the connecting disk 2, and a screw 16 is passed through the end of the fixing block 14. The threaded connection between the thread and the connecting plate 2 connects the front half of the spherical shell 1 with the rear half of the spherical shell 18 containing the hole to form the entire spherical structure. The fixing block 14 uses screws 16 to install and fix the six-component force sensor 4.

[0021] The support module includes a support rod 3, a trailer 8, and a flange 11. One end of the support rod 3 is connected to the opening on the rear half of the spherical shell 18 with a hole through the tail shaft rod adapter plate 13. The flange 11 is fixedly connected to the other end of the support rod 3 and the docking end of the trailer 8. A set of flanges 11 are docked by bolts. The trailer 8 is located above the water pool 12 set outside. The support rod 3 and the sphere are docked and installed using the tail shaft adapter plate 13, and the support rod 3 is connected to the trailer 8 with the help of the flange 11. The sphere is dragged in multiple positions by moving the position of the trailer 8 to achieve the test requirements of multiple positions.

[0022] The middle of the support rod 3 is hollow and is provided with a cable 15, which is electrically connected to the sensor DC power supply and the data acquisition device 20 respectively; The support rod 3 is made of a hollow steel pipe, the diameter of which is smaller than the diameter of the sphere, and a counterweight is installed in the hollow space in the middle of the support rod 3; The middle part of the support rod 3 is hollow, and its diameter is smaller than that of the sphere, so that the influence of the support rod 3 on the fluid is as small as possible. At the same time, the space inside the hollow is sufficient for the layout of the cable 15, and the remaining space can be equipped with a weight block, so that the support rod 3 is close to zero buoyancy, thereby reducing the influence on force measurement. The laid cables 15 are power supply and signal cables 15, and are respectively electrically connected to the DC power supply of the sensor and the data acquisition instrument 20 described below to provide power and meet data transmission. The support rod 3 is an L-shaped rod with a length of 1300mm and 420mm respectively; it adopts a cavity structure design with an outer diameter of 15mm and a thickness of 2mm.

[0023] A drive module, which includes a motor placed on the trailer 8 and a frequency converter 21 for controlling the speed of the trailer 8; The motor provides the power required for the trailer 8 to move, and the frequency converter 21 controls the moving speed of the trailer 8. The drive module and the above-mentioned support module can make the sphere move in still water, thereby realistically simulating the movement of the sphere. In particular, when simulating the sphere near the ice surface and the free liquid surface, the method of using the relative motion theory is quite different from the actual sphere movement. Through the modular design of the sphere and the hollow design of the support module, the six-component force sensor 4 is placed inside the sphere, and the cable 15 for powering the sensor and transmitting the signal is placed inside the support rod 3, which greatly reduces the interference of the test device on the flow field. Combined with PIV The simultaneous triggering of the module and the force measurement module makes the obtained flow field information and the hydrodynamics of the sphere simultaneous, reducing the error caused by artificial time reconstruction, greatly reducing the workload of post-processing, and being able to fundamentally reveal the changes in the hydrodynamics of the sphere from the perspective of flow field evolution. The driving module is composed of a track module horizontally arranged on the ice surface on both sides of the test pool 12, a trailer 8 carrying a test model, and a power device. The track module provides linear motion guidance for the trailer 8, and the power device drives the trailer 8 to move in a uniform straight line along the track through a transmission mechanism. The maximum towing speed of the trailer 8 can reach 4 m / s, and the speed control accuracy is as high as 0.005 m / s.

[0024] The force measurement module includes a six-component force sensor 4 and a data acquisition device 20. The six-component force sensor 4 is fixed to the center of the connection disk 2 inside the sphere by screws 16. The six-component force sensor 4 has a built-in sensor DC power supply. The data acquisition device 20 is installed on the outer surface of the six-component force sensor 4. The six-component force sensor 4 is used to measure the hydrodynamic force during the movement of the sphere.

[0025] PIV module, the PIV module includes a laser 9, a first high-speed camera 10 and a second high-speed camera 17. The laser 9 is sealed and connected to a corner below the front of the pool 12. The first high-speed camera 10 is located on one side above the pool 12, and the second high-speed camera 17 is located directly above the pool 12. The laser 9 generates laser light and uses the missing particles, which are then captured by the first high-speed camera 10 and the second high-speed camera 17 .

[0026] The PIV module also includes tracer particles, which are uniformly injected into the fluid of the imaging section and are used to track material movement, transfer process or medium flow through physical, chemical or biological property markers.

[0027] A false bottom 5 simulating an ice surface is provided in the pool 12, and a slide rail 7 is fixed to the upper outer edge of the pool 12 and is screwed to the trailer 8; The slide rail 7 provides guidance for the position movement of the trailer 8, and the maximum towing speed of the trailer 8 can reach 4 m / s, with a speed control accuracy of up to 0.005 m / s. The power device of the trailer 8 drives the trailer 8 to move in a uniform straight line along the track through a transmission mechanism.

[0028] The data acquisition device 20 , the frequency converter 21 , the laser 9 and the output end of the second high-speed camera 17 are all electrically connected to the input end of the external computer 19 via the transmission cable 15 .

[0029] Working principle: Step 1: Drive the trailer 8 to a specific position according to the test plan and the specific working conditions in the test outline, and adjust the flange 11 so that the ball is in the required position.

[0030] Step 2: Place the laser 9, the first high-speed camera 10, and the second high-speed camera 17 in the pre-calculated stable section of the sphere's motion, adjust the laser optical path and the shooting angles of the first high-speed camera 10 and the second high-speed camera 17; and evenly inject the tracer particles into the fluid in the shooting section.

[0031] Step 3: Place the laser 9, the first high-speed camera 10, and the second high-speed camera 17 at the pre-calculated stable section of the sphere's motion, and adjust the shooting angle.

[0032] Step 4: Through the software that is triggered simultaneously in computation, the driving module, force measurement module and PIV module are controlled to start simultaneously to obtain synchronized flow field and sphere hydrodynamic time history data.

[0033] Specifically, in order to solve the problem that (1) the fixed sphere test ignores the mutual coupling between the sphere and the flow field and cannot accurately reflect the dynamic response in the real self-propelled motion, the present invention provides a hydrodynamic simulation test device based on a track-type high-precision trailer 8 drive. The trailer 8 installed on the special guide rail at the top of the test tank can drive the test sphere to perform stable uniform linear motion along the direction of the tank through the support module, thereby realizing the equivalent simulation of the hydrodynamic response under the self-propelled state. Specifically, the trailer 8 module has the following key features: high motion control accuracy, the trailer 8 is driven by a motor and controlled by a frequency converter 21, and can achieve a maximum towing speed of 4 m / s, and has a high speed control accuracy of 0.005 m / s, significantly improving the motion consistency and repeatability; the sphere connection structure is adjustable, and the sphere is connected to the flange 11 on the trailer 8 through the sphere support module, which can not only transmit the motion load, but also change the distance of the sphere entering the water surface, thereby realizing test measurements with different spacing ratios. Through the above-mentioned structural design, the test device described in the present invention can not only move in a variety of scenarios, but also synchronously measure the hydrodynamic loads and flow field visualization during its movement, and fully reproduce the relationship between the hydrodynamic force and the evolution of the wake vortex structure under actual self-propelled motion.

[0034] To solve the problem (2) that the arrangement of the force measuring device inside the sphere is limited due to the small space layout; the present invention adopts a hollow sphere structure design and realizes a non-invasive sensor layout by building in a six-component force sensor 4. A hole is opened on the sphere so that the support rod 3 can be inserted into the sphere and connected to the six-component force sensor 4. Therefore, the support rod 3 is connected to the sphere through the six-component force sensor 4 as a medium, and then the sphere is driven to move in a uniform linear motion by the trailer 8, thereby realizing the test of the sphere sailing straight in the water. In addition to supporting the sphere, the support rod 3 has a cavity inside, and the signal transmission cable 15 and the sensor power supply cable 15 of the six-component force sensor 4 can be passed from the support rod 3 to the free liquid surface and connected to the data acquisition module and the power supply. The sphere model includes two parts: a sphere shell and a connection plate 2; the sphere shell is divided into two modules: two half spherical shells. Both hemispheres are internally threaded, connecting to the connecting plate 2 to form a complete sphere. A circular hole is machined into the stern shell to ensure the connecting rod can smoothly extend into the sphere and accurately connect to the six-component force sensor 4. The connecting plate 2 is composed of a circular disk with a diameter that matches the inner diameter of the sphere. The disk is threaded around its perimeter to ensure precise docking with the shell. A threaded hole is also located in the center of the disk for securing the six-component force sensor 4.

[0035] To solve the problem (3) of being unable to simultaneously obtain information on the synchronous evolution of the hydrodynamic forces acting on the sphere and the surrounding flow field structure, and lacking a modular understanding of the correlation mechanism between the two, the present invention integrates image acquisition, hydrodynamic acquisition, and motion control into the same software environment, thereby achieving synchronous startup and synchronous data storage. This allows for synchronous, high-frequency, and precise recording of wake evolution and force response in complex flow environments.

[0036] To solve the problem (4) that existing devices are difficult to simulate actual navigation conditions in near-ice and near-free-surface environments; the present invention proposes and designs a multi-scenario liquid surface boundary control method that can flexibly switch between the two typical boundary conditions of near-free-surface and near-ice surface to support experimental research in complex hydrodynamic environments. The core innovation of this module lies in the introduction of a modular false bottom structure and a high-precision vertical adjustment mechanism. Among them, the false bottom is used to simulate the rigid boundary conditions under the ice sheet and is made of PMMA (organic glass). This material has extremely high deformation resistance and high transparency and has good surface flatness to approximate the rigid boundary characteristics of a natural ice sheet. A support structure is added under the false bottom to make it perpendicular to the pool bottom. In order to achieve continuous adjustment and high-precision positioning control of the distance between the sphere and the liquid surface, a flange 11 is used to connect the trailer 8 and the support structure. The center height of the sphere can be adjusted in real time before or during the test, thereby accurately controlling its vertical distance from the free liquid surface. Furthermore, this module is highly integrated with the PIV flow field visualization module and the six-component force measurement module, enabling simultaneous acquisition of data on the hydrodynamic forces acting on the sphere and the evolution of its wake structure under various boundary conditions. Combined with the aforementioned time-series synchronization mechanism, experimenters can modularly study the quantitative coupling between the flow characteristics around the sphere, its force response, and its unsteady wake behavior near ice and free surface conditions, and at varying spacings.

[0037] To solve the problem (5), it is difficult to conduct an effective coupling analysis of the evolution process of the complex vortex structure at the tail of the sphere with its hydrodynamic change process. The reason is (3), which affects the in-depth study of the wake-force interaction mechanism. After successfully overcoming limitation (3), the experiment can achieve the synchronous acquisition of the sphere force data and the evolution of its wake flow field structure. By matching and comparing the flow field images and hydrodynamic measurement results at the same time node, it is possible to study the coupling relationship between the flow field structure evolution process and the hydrodynamic response of the sphere. This joint analysis method provides strong support for revealing the interaction mechanism between wake characteristics and force changes, and lays an experimental foundation for a deep understanding of unsteady hydrodynamic behavior.

[0038] This solution adopts a modular design and integrates the six-component force sensor 4 inside the sphere to achieve real-time high-precision measurement of the three component forces and three component moments. In addition, when designing the sphere support module, this patent cleverly extends the power cable 15 and the signal transmission cable 15 out of the water through the cavity inside the sphere support rod 3, thereby greatly reducing the disturbance of the flow field by the transmission cable 15. It can achieve efficient and stable collection and recording of force data during the self-propulsion movement of the sphere, and improve the test flexibility and data integrity under free navigation conditions in water. In order to further study the dynamic coupling relationship between the sphere and the flow field, particle image velocimetry (PIV) technology is introduced, and the flow field visualization and force measurement are synchronized in time during the experiment, effectively revealing the interaction mechanism between the sphere movement and the surrounding fluid vortex structure, filling the research gap that the evolution of the vortex structure after studying the sphere and the force on the sphere cannot be compared and analyzed. At the same time, in order to simulate the interference effect between the sphere and the ice surface or liquid surface in a real environment, this patent designs a false bottom (5) to achieve rapid regulation of different spacing ratios.

[0039] In summary, this patented test module can not only obtain real-time force data of the sphere in a complex boundary environment, but also combine flow field visualization methods to obtain important physical information such as the velocity field of the flow field under the movement of the sphere. The module reveals the formation mechanism of the hydrodynamic characteristics of the self-propelled sphere, fills the research gap of studying the evolution of the vortex structure behind the sphere and the inability to conduct comparative analysis of the force on the sphere, and provides an accurate experimental verification basis for related numerical simulations.

[0040] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A force measuring device for a ball moving near an ice surface, characterized in that: include: A spherical module, comprising a front half spherical shell (1) and a rear half spherical shell (18) containing a hole, wherein threads are provided on the outer sides of the maximum diameters of the front half spherical shell (1) and the rear half spherical shell (18) containing a hole, and are threadedly connected to a connecting disk (2), a fixing block (14) is fixed at the center of the connecting disk (2), and a screw (16) is passed through the end of the fixing block (14); A support module, the support module comprises a support rod (3), a trailer (8) and a flange (11), one end of the support rod (3) is connected to the opening on the rear half of the spherical shell (18) containing the hole through the tail shaft rod adapter plate (13), the flange (11) is fixedly connected to the other end of the support rod (3) and the docking end of the trailer (8), a group of the flanges (11) are docked by bolts, and the trailer (8) is located above the water pool (12) arranged outside; A drive module, the drive module comprising a motor placed on the trailer (8) and a frequency converter (21) for controlling the speed of the trailer (8); A force measuring module, the force measuring module comprising a six-component force sensor (4) and a data acquisition instrument (20), the six-component force sensor (4) being fixed to the center of the connection disk (2) inside the sphere by the screw (16), the six-component force sensor (4) having a built-in sensor direct current power supply, and the data acquisition instrument (20) being mounted on the outer surface of the six-component force sensor (4); A PIV module comprises a laser (9), a first high-speed camera (10) and a second high-speed camera (17); the laser (9) is sealed and connected to a corner below the front of a pool (12); the first high-speed camera (10) is located on one side above the pool (12); and the second high-speed camera (17) is located directly above the pool (12).

2. A force measuring device for ball motion near ice surface according to claim 1, characterized in that: The middle part of the support rod (3) is hollow and is provided with a cable (15) which is electrically connected to the sensor DC power supply and the data acquisition device (20) respectively.

3. The force measuring device for ball motion near ice surface according to claim 1, characterized in that: The support rod (3) is made of a hollow steel pipe, the diameter of which is smaller than the diameter of the sphere, and a counterweight is installed in the hollow space in the middle of the support rod (3).

4. The force measuring device for ball motion near ice surface according to claim 1, characterized in that: The water pool (12) is provided with a false bottom (5) simulating an ice surface, and a slide rail (7) is fixed to the upper outer edge of the water pool (12) and is threadedly fixed to the trailer (8).

5. The force measuring device for ball motion near ice surface according to claim 1, characterized in that: The output ends of the data acquisition instrument (20), the frequency converter (21), the laser (9) and the second high-speed camera (17) are all electrically connected to the input end of the external computer (19) via a transmission cable (15).

6. The force measuring device for ball motion near ice surface according to claim 1, characterized in that: The PIV module further includes tracer particles, which are uniformly injected into the fluid of the shooting section and are used to track material movement, transfer process or medium flow through physical, chemical or biological property marking.

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