An experimental device for underwater super-high Reynolds number flow field

Abstract

The application discloses an underwater super-high Reynolds number flow field experimental device, which comprises a spherical structure, a fixing device and a measuring device; the spherical structure comprises a surface flexible skin and an internal rigid framework; the internal rigid framework comprises a circular tube structure arranged along a diameter and a rigid reinforcing ring arranged along a circumference of an inner surface of the spherical structure; rigid end portions are arranged at upper and lower ends of the vertically arranged circular tube; two valves are arranged at the two end portions respectively; an inspection well is connected to the lower end of the vertical circular tube; the measuring device comprises pressure sensors arranged uniformly on an outer surface of the spherical structure, three-dimensional space position sensors arranged on an inner surface of the spherical structure and tension sensors arranged at ends of traction ropes; the surface skin is attached to the internal rigid framework, internal pressure is added, and the spherical shape is maintained underwater, so that the research on flow field characteristics under super-high Reynolds number is realized at a low cost, and the application has important guiding significance for the research on the structural design of underwater hydrogen storage tanks in real marine engineering.

Description

Technical Field

[0001] This invention relates to the fields of fluid mechanics and fluid engineering experiments, and in particular to an underwater ultra-high Reynolds number flow field experimental device. Background Technology

[0002] With the collection and on-site storage of marine renewable energy, large-scale seabed energy storage devices are being extensively studied. These large devices are mostly spherical or cylindrical, with diameters exceeding 5 meters. Research has found that the hydrodynamic characteristics of these large marine structures in ocean currents exhibit ultra-high Reynolds numbers (greater than 1 x 10⁻⁶). 7 Within the scope of current research, the flow field characteristics around a sphere at ultra-high Reynolds numbers are analyzed using computational fluid dynamics numerical simulations. However, different turbulence models yield significantly different calculation results, lacking experimental verification. Furthermore, conventional wind tunnel experiments often fail to meet the practical needs of marine engineering. Therefore, to enhance understanding of ultra-high Reynolds number flow field characteristics and optimize the design of underwater structures in marine engineering, a novel underwater ultra-high Reynolds number flow field testing device and method are urgently needed.

[0003] Tiwari (Tiwari SS, Pal E, Bale S. Flow past a single stationary sphere, 1. Experimental and numerical techniques[J]. Powder Technology, 2020, 365: 115–148.) reviews the latest advances and discoveries in flow around a stationary sphere from both experimental and numerical simulation perspectives. The research and application of statistical methods and flow field information processing techniques are discussed; these techniques are the main methods for characterizing such complex wake turbulence. Previous related research is summarized and analyzed, and suggestions for future development are proposed. This review reveals that current research methods for flow around a sphere mainly include theoretical analysis, experimental research, and numerical simulation. Since the flow around a sphere is a complex nonlinear fluid mechanics problem, existing theoretical methods cannot obtain analytical solutions. Therefore, experimental research and numerical simulation remain important research methods. Most publicly available experiments at high Reynolds numbers are wind tunnel experiments. Achenbach used wind tunnel experiments in the 1970s to study Reynolds numbers in the range of 5 × 10⁻⁶. 4 <Re<6X10 6The problem of flow past spheres (Achenbach E. Experiments on the flow past spheres at very high Reynolds numbers[J]. Journal of Fluid Mechanics,1972,54(3):565–575.) was studied, measuring the surface conditions of a smooth sphere at approximately 0.45% turbulence, including total drag, local static pressure, and local surface friction distribution. At such high Reynolds numbers, wind tunnel experiments using gas as the flow medium inevitably encounter problems such as compressibility and blockage rate, resulting in significant errors compared to the actual underwater structure environment in marine engineering.

[0004] No literature has been found on spherical flow experiments directly utilizing the marine environment at high Reynolds numbers; the highest Reynolds number found in existing spherical flow experiments is 6 x 10⁻⁶. 6 Direct numerical simulation (DNS) is currently limited by the Reynolds number to 1 x 10^6 times due to the limitations of computing power. 5 Numerical simulation using turbulence models can reduce computational effort, but there is a lack of experimental data to verify simulations at higher Reynolds numbers, making it difficult to apply in practical engineering.

[0005] Extremely high Reynolds number flows present a series of challenges. Existing model experiments are limited by Reynolds number less than 1 x 10⁻⁶. 7 The scope is limited. Numerical simulations, due to the high Reynolds number, extremely small scale of turbulent flow structures, and massive computational grids, are difficult to model, inaccurate to measure, and computationally inefficient. Therefore, there is a need to innovate and invent an underwater experimental device for ultra-high Reynolds number flow fields to advance related research. Summary of the Invention

[0006] To address the current limitations of experimental research and equipment for ultra-high Reynolds numbers, this invention proposes an underwater ultra-high Reynolds number flow field testing device and method. The device comprises a spherical structure, a fixing device, and a measuring device. The spherical structure includes a flexible surface skin and an internal rigid frame. The internal rigid frame includes a circular tube structure arranged along the diameter and rigid reinforcing rings arranged circumferentially along the inner surface of the sphere. The vertically arranged circular tubes have rigid ends at their upper and lower ends. Two valves are installed at each end. An inspection well is connected to the lower end of the vertical circular tube. The measuring device includes pressure sensors uniformly distributed on the outer surface of the spherical structure, a three-dimensional spatial position sensor on the inner surface of the spherical structure, and a tension sensor at the end of the traction rope. This invention maintains the spherical shape underwater by applying pressure to the internal rigid frame through the surface skin, achieving the study of flow field characteristics at ultra-high Reynolds numbers at a relatively low cost. This has significant guiding significance for the structural design of underwater hydrogen storage tanks in practical marine engineering. The device and method of this invention can measure Reynolds numbers up to 10 x 10 at a relatively low cost. 7The flow field characteristics around a sphere are shown. This has guiding significance for research on underwater hydrogen storage tanks and other applications in real-world marine engineering.

[0007] The present invention is achieved by at least one of the following technical solutions.

[0008] An underwater ultra-high Reynolds number flow field experimental device includes a spherical structure, a fixing device, and a measuring device;

[0009] The spherical structure includes a flexible surface skin and a rigid skeleton inside the sphere.

[0010] The rigid frame includes vertically arranged circular tubes, circular tubes on a horizontal diameter plane, and rigid reinforcing rings arranged circumferentially along the inner surface of the sphere.

[0011] The vertically arranged circular tube has rigid ends at both the upper and lower ends; two valves are installed in the rigid upper end, which are the air inlet and the air outlet respectively, and two valves are installed in the rigid lower end, which are the water inlet and the water outlet respectively;

[0012] The rigid lower end is connected to the inspection well;

[0013] The fixing device is located below the spherical structure and includes a counterweight and a traction rope. The counterweight is connected to the spherical structure through the traction rope.

[0014] The measuring device includes a pressure sensor arranged on the outer surface of the spherical structure, a three-dimensional spatial position sensor inside the spherical structure, and a tension sensor at the end of the traction rope.

[0015] Furthermore, the surface skin is fixed by being fitted around an internal rigid skeleton.

[0016] Furthermore, water is introduced through the inlet to provide gravity within the spherical structure.

[0017] Furthermore, by filling the air inlet with gas to increase the internal pressure of the spherical structure, the internal pressure of the spherical structure becomes greater than the external pressure, thereby causing the flexible skin on the surface to be stretched into a sphere.

[0018] Furthermore, the pressure sensor on the outer surface of the spherical structure is arranged on the outer side of the surface skin to measure surface pressure data.

[0019] Furthermore, the three-dimensional spatial position sensor is arranged near the intersection of the reinforcing rings inside the spherical structure to record the underwater attitude of the spherical structure during the experiment.

[0020] Furthermore, the tension sensor is positioned at the upper end of the traction rope to measure the tension at the end of the traction rope in real time.

[0021] Furthermore, the diameter of the spherical structure is not less than 5m.

[0022] Furthermore, the air inlet is connected to an external air pump to pressurize the interior of the spherical structure.

[0023] Furthermore, the inlet is connected to an external water pump to fill the interior of the spherical structure with water.

[0024] Compared with the prior art, the present invention has the following effects and advantages:

[0025] In this invention, the underwater ultra-high Reynolds number flow field experimental device includes a spherical structure, a fixing device, and a measuring device. The spherical structure has a water inlet / outlet and an air inlet / outlet. The water inlet / outlet allows water to flow in and out, and the air inlet / outlet is connected to a gas supply device. Water is injected into the spherical structure and air is added to make the internal air pressure higher than the external pressure, thereby maintaining the spherical shape of the device underwater. The volume ratio of water to air inside the spherical structure varies depending on the experimental conditions, and the entire spherical structure maintains positive buoyancy in the water. The fixing device is connected to the spherical structure, sinks to the seabed, and the spherical structure is suspended in the water.

[0026] This invention ingeniously utilizes an internal rigid framework and a flexible surface skin to simulate large-scale underwater spherical structures at a relatively low cost, and uses internal water and air pressure to maintain the shape of the experimental sphere. Under normal ocean current velocities, the Reynolds number of the flow field in this experimental device can reach 10 x 10⁻⁶. 7 The study on the flow field characteristics at ultra-high Reynolds numbers has important guiding significance for the structural design of underwater hydrogen storage tanks in real marine engineering. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of an underwater ultra-high Reynolds number flow field experimental device and method according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the internal skeleton of the experimental device in the embodiment.

[0029] Figure 3 This is a schematic cross-sectional view of the experimental setup used in the example.

[0030] Figure 4 for Figure 2 A magnified view of part A in the middle;

[0031] Figure 5 for Figure 1 Enlarge the image of part B in the middle. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0037] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0038] The present invention will now be described in further detail with reference to specific embodiments.

[0039] like Figure 1-5 As shown, the present invention discloses an underwater ultra-high Reynolds number flow field experimental device, comprising: a spherical structure 1, a fixing device 2, and a measuring device 3;

[0040] The spherical structure includes a flexible surface skin 4 and an internal rigid skeleton 5;

[0041] The flexible surface skin is made of waterproof and seawater corrosion resistant material, and is segmented and bonded to the internal rigid frame, which can withstand a certain amount of internal pressure.

[0042] The internal rigid frame 5 includes a circular tube 6 arranged along the vertical diameter direction, a circular tube 7 on the horizontal diameter plane, and a rigid reinforcing ring 8 arranged circumferentially along the inner surface of the sphere. The rigid frame is made of steel and can withstand internal pressure underwater to prevent excessive deformation of the sphere structure.

[0043] The vertically arranged circular tube 6 extends to a rigid upper end 10. The structure is made of steel to strengthen the connection with other components and the overall structural strength. Two valves are installed inside the rigid upper end 10, namely an air inlet 11 and an exhaust outlet 12. Two valves are installed inside the rigid lower end 10, namely a water inlet 13 and a water outlet 14.

[0044] As one embodiment, the air inlet 11 can be connected to an external air pump to inflate and pressurize the inside of the sphere. The water inlet 13 can be connected to an external water pump to fill the inside of the sphere with water.

[0045] The rigid lower end 9 is connected to an inspection well 15. The inspection well is closed and sealed during the experiment. During the preparation or maintenance of the experiment, personnel and equipment can enter and exit the interior of the sphere, and it also provides a passage for the replacement of the skeleton structure and the entry and exit of experimental equipment.

[0046] The fixing device 2 is located below the spherical structure 1 and includes a counterweight 16 and a traction rope 17. The counterweight is connected to the spherical structure via the traction rope 17. The counterweight 16 can be filled with high-density, low-cost materials such as scrap steel or concrete, so that the upper spherical structure is filled with water and pressurized to form a sphere, overcoming buoyancy and submerging below the sea surface with the counterweight. The counterweight can be rectangular or cylindrical, etc., and has a certain degree of stability on the seabed, so that it will not move under its own weight due to ocean currents or the tension of the traction rope.

[0047] The surface skin 4, fixed to the internal rigid frame 5, possesses both watertight and airtight properties and can withstand a certain internal pressure. Sensors are evenly arranged on the outer side of the surface skin to measure the water pressure at various points in real time. Water is introduced through the inlet 13 to provide partial gravity, and gas is injected through the air inlet 11 to increase the internal pressure, making the internal pressure of the structure greater than the external pressure, thus tauting the flexible surface skin into a sphere. Since the surface of the sphere is a flexible material, when the spherical structure is simultaneously subjected to the buoyancy of water and the tension of the fixing structure, the surface of the sphere tends to deform into a teardrop shape. At this time, the outer flexible skin maintains the spherical shape by being fixed to the internal rigid frame and reinforcing ring.

[0048] As one embodiment, the diameter of the spherical structure is not less than 5m.

[0049] The measuring device 3 includes a pressure sensor 18 arranged on the outer surface of the spherical structure 1, a three-dimensional spatial position sensor 19 inside the spherical structure 1, and a tension sensor 20 located at the end of the traction rope 17. The tension sensor 20 is used to measure the tension at the end of the traction rope in real time.

[0050] The pressure sensor 18 on the outer surface of the spherical structure 1 is arranged on the outside of the surface skin 4, and can obtain the surface pressure data of the device. The specific sensor distribution density and number are determined according to the actual application.

[0051] A three-dimensional spatial position sensor 20 inside the spherical structure 1 is arranged near the intersection of the three reinforcing rings 8 to record the underwater attitude of the spherical structure 1 during the experiment.

[0052] During the experiment, the device of this invention will be placed on the seabed. The spherical structure 1, due to its positive buoyancy, can float in the water. Ocean currents flowing around the spherical structure generate a flow field with ultra-high Reynolds numbers. Sensors on the surface of the spherical structure 1 record the water pressure at various locations in real time, thereby obtaining experimental values ​​of the flow around the sphere exceeding the Reynolds number. The device of this invention can be placed on the seabed for continuous experiments for an extended period and can then be recovered and reused. This invention maintains the spherical shape underwater by attaching a surface skin around an internal rigid skeleton and applying pressure to the interior, achieving the study of flow field characteristics at ultra-high Reynolds numbers at a relatively low cost. This has significant guiding significance for research on the structural design of underwater hydrogen storage tanks in practical marine engineering.

[0053] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, enabling those skilled in the art to better understand and utilize the invention.

Claims

1. An underwater ultra-high Reynolds number flow field experimental device, characterized in that, It includes a spherical structure (1), a fixing device (2), and a measuring device (3); the diameter of the spherical structure (1) is not less than 5m; The spherical structure includes a flexible surface skin (4) and a rigid skeleton (5) inside the sphere, wherein the flexible surface skin (4) is fixed by being attached to the internal rigid skeleton (5); The rigid frame (5) includes a vertically arranged circular tube (6), a circular tube (7) on a horizontal diameter plane, and a rigid reinforcing ring (8) arranged circumferentially along the inner surface of the sphere. The vertically arranged circular tube (6) has two rigid ends at its upper and lower ends; the upper rigid end (10) has two valves, namely an air inlet (11) and an air outlet (12), and the lower rigid end (9) has two valves, namely a water inlet (13) and a water outlet (14); gas is filled in through the air inlet (11) to increase the internal pressure of the spherical structure (1), so that the internal pressure of the spherical structure (1) is greater than the external pressure of the structure, thereby making the flexible skin on the surface taut into a sphere; The rigid lower end (9) is connected to the inspection well (15); The fixing device (2) is located below the spherical structure (1) and includes a counterweight (16) and a traction rope (17). The counterweight (16) is connected to the spherical structure (1) through the traction rope (17). The measuring device (3) includes a pressure sensor (18) arranged on the outer surface of the spherical structure (1), a three-dimensional spatial position sensor (19) inside the spherical structure (1), and a tension sensor (20) at the end of the traction rope (17); the three-dimensional spatial position sensor (19) is arranged near the intersection of the reinforcing rings (8) inside the spherical structure (1) to record the underwater posture of the spherical structure (1) during the experiment; The pressure sensor (18) on the outer surface of the spherical structure (1) is arranged on the outside of the flexible skin (4) to measure the surface pressure data; The spherical structure (1) is suspended in water. The water flow around the spherical structure (1) generates a flow field with ultra-high Reynolds number. The pressure sensor on the surface of the spherical structure (1) records the water pressure at each position in real time, thereby obtaining the experimental value of the ultra-high Reynolds number of the spherical flow.

2. The underwater ultra-high Reynolds number flow field experimental device according to claim 1, characterized in that, Water is introduced through the inlet (13) to increase the weight of the spherical structure (1).

3. The underwater ultra-high Reynolds number flow field experimental device according to claim 1, characterized in that, The tension sensor (20) is arranged at the upper end of the traction rope (17) to measure the tension at the end of the traction rope in real time.

4. The underwater ultra-high Reynolds number flow field experimental device according to claim 1, characterized in that, The air inlet (11) is connected to an external air pump to pressurize the inside of the spherical structure (1).

5. The underwater ultra-high Reynolds number flow field experimental device according to claim 1, characterized in that, The inlet (13) is connected to an external water pump to fill the interior of the spherical structure (1) with water.

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