Flexible webbed wing structure capable of improving dynamic characteristics

Abstract

The invention discloses a flexible webbed wing structure capable of improving dynamic characteristics, which comprises a body, an isosceles trapezoid of the cross section of the body is called as a cross section trapezoid, and the bottom edge of the cross section trapezoid is longer than the top edge of the cross section trapezoid; the included angle of the two side edges of the section trapezoid is called as the taper angle, the height of the section trapezoid is called as the height of the flexible webbed wing, the surface hardness of the body is 60 HB, the taper angle is 4.7-5.2 degrees, the top edge is 2 mm, the bottom edge is 5 mm, and the height of the flexible webbed wing is 110 mm. The body is made of SBR rubber. Optimized object parameters of the dynamic characteristics of the flexible webbed wing are determined, a geometric model of the flexible webbed wing and a fluid-solid coupling 2.5 D model of the flexible webbed wing are established, numerical simulation is carried out on the dynamic characteristics of the flexible webbed wing by using an ANSYS Workbench simulation platform, and finally a relative optimal result of each optimized object parameter is obtained. The flexible webbed wing prepared according to the invention can improve the energy conversion efficiency of the wave glider and increase the voyage and speed of the wave glider; the maneuverability and controllability of the wave glider can be enhanced, the environmental adaptability of the wave glider is enhanced, the comprehensive performance of the wave glider is improved, the performance of the flexible web wing of the wave glider is remarkably improved, the application range of the flexible web wing of the wave glider is remarkably widened, and powerful technical support is provided for development of ocean science and technology and effective utilization of ocean resources.

Description

Technical Field

[0001] The present invention relates to the field of underwater robots, and in particular to a flexible webbed wing propulsion technology for underwater robots (wave gliders). Background Art

[0002] Traditional underwater robots are mostly propeller-driven, which has problems such as low efficiency, high energy consumption, and high noise. In the field of ocean exploration and monitoring, flexible paddles are key components of wave gliders. The design and material selection of flexible paddles have a direct impact on their power performance in the water. Especially in the face of complex and changeable marine environments, how to improve the power conversion efficiency by optimizing the shape, materials, and control strategies of the paddles has become a research focus. Improving the power characteristics of flexible paddles is of great significance for enhancing the ocean observation capabilities of wave gliders, extending their operating cycles, and reducing maintenance costs. It has a far-reaching impact on promoting the development of marine science and technology and the effective use of marine resources.

[0003] The research object of the present invention is the flexible fins for wave gliders (wave gliders are underwater robots). Wave gliders can perform long-term tasks in the ocean without external energy supply. They have been widely used in marine science, seawater engineering and even military fields. They can carry various scientific instruments and sensors for marine environment observation, data collection and transmission. They can realize large-scale and long-distance observation of sea surface meteorological parameters, monitoring of sea surface hydrodynamic environmental parameters and underwater target detection. They can also be used as water communication nodes in fishery production, offshore drilling, ocean freight, ocean surveys, marine military, etc., and of course they can also perform other personalized tasks.

[0004] Unlike traditional wave gliders, which convert wave energy into driving force, the essence of traditional wave gliders is to convert the heave motion of the floating body caused by wave energy into forward driving force. On the basis of converting heave motion into driving force, the flipper wave glider can also equally convert the heel, pitch and other unstable motions of the floating body caused by waves into forward driving force.

[0005] Improving the dynamic characteristics of the flexible fins can improve the energy conversion efficiency of the wave glider, increase the range and speed of the wave glider, and enhance the maneuverability and controllability of the wave glider and the environmental adaptability of the wave glider. In order to improve the performance of the wave glider, it is necessary to improve the flexible fins.

[0006] The basic structure of the flexible fin is: comprising a body, the isosceles trapezoid presented by the cross section of the body is called a cross-sectional trapezoid, the bottom side of the cross-sectional trapezoid is longer than the top side of the cross-sectional trapezoid. In the present invention, the angle between the two sides of the cross-sectional trapezoid is called a cone angle.

[0007] When optimizing and improving the flexible paddle, the selectable numerical space of each parameter is almost infinite, and the numerical selection space of the combination of each parameter is even larger. In traditional research, it is not feasible to make a physical flexible paddle with different parameter combinations for actual testing to explore the method of the best parameter combination, and the financial cost and time cost are unbearable. If simulation is to be performed, it is necessary to determine a suitable basic model, and it is also necessary to establish a geometric model of the flexible paddle itself and a motion model of the flexible paddle, and determine various details of the simulation. There is no suitable motion model of the flexible paddle in the prior art, and there is no solution to various details of the dynamic characteristics of the flexible paddle, so it is impossible to carry out simulation. Therefore, in the prior art, it is difficult to effectively design the optimization parameters of the flexible paddle. Summary of the invention

[0008] The purpose of the present invention is to provide a flexible webbed wing structure with improved dynamic characteristics, and to improve the dynamic characteristics of the flexible webbed wing by optimizing the structure and surface hardness and other characteristics, thereby optimizing and improving the performance of a wave glider.

[0009] To achieve the above-mentioned purpose, the flexible wing structure with improved dynamic characteristics of the present invention comprises a body, an isosceles trapezoid presented by the cross section of the body is called a cross-sectional trapezoid, the bottom side of the cross-sectional trapezoid is longer than the top side of the cross-sectional trapezoid; the angle between the two sides of the cross-sectional trapezoid is called a cone angle, and the height of the cross-sectional trapezoid is called the height of the flexible wing, and is characterized in that: The surface hardness of the body is 60HB, the cone angle is 4.7°-5.2°, the top edge is 2 mm, the bottom edge is 5 mm, and the height of the flexible fin is 110 mm.

[0010] The material of the body is SBR rubber.

[0011] The cone angle is 4.7°.

[0012] The present invention has the following advantages: The present invention determines that the optimization object parameters of the dynamic characteristics of the flexible web wing are material, surface hardness, cone angle, top edge length and bottom edge length. On the basis of adopting the Mooney-Rivlin model, a geometric model of the flexible web wing itself is established, and a 2.5D fluid-solid coupling model of the flexible web wing is established. The ANSYS Workbench simulation platform is used to carry out numerical simulation on the dynamic characteristics of the flexible web wing, and finally the optimal results of each optimization object parameter are obtained. The flexible web wing prepared according to the optimal result of the present invention can improve the energy conversion efficiency of the wave glider, increase the range and speed of the wave glider; it can also enhance the maneuverability and controllability of the wave glider, enhance the environmental adaptability of the wave glider, and improve the comprehensive performance of the wave glider, significantly improve the performance and application range of the flexible web wing of the wave glider, provide strong technical support for the development of marine science and technology and the effective utilization of marine resources, and have good promotion and application value.

[0013] The research and development results of the present invention are inseparable from the flexible flipper fluid-solid coupling 2.5D model, and the research and development process also includes the following advantages: 1. Double improvement of simulation accuracy and efficiency: The present invention effectively simulates the fluid-solid coupling dynamic performance of flexible paddles under large deformation through numerical simulation and optimization methods. The simulation process also considers the periodic changes of waves, the non-uniformity of flow velocity, and the dynamic changes of underwater pressure in detail, ensuring that the simulation results can fully reflect the complex situation in the actual marine environment. The present invention successfully introduces simulation technology into the research and development of flexible paddles, significantly improving the propulsion efficiency and stability of the flexible paddles of underwater robots. At the same time, the use of optimization algorithms also greatly improves the efficiency of the design process.

[0014] 2. Multi-parameter optimization design: The optimization analysis method of the present invention optimizes the material parameters and geometric dimensions of the flexible flipper in detail, and takes into account multiple performance indicators such as propulsion efficiency, structural strength, and durability, ensuring that the underwater robot has good structural stability and durability while improving propulsion efficiency. This multi-parameter optimization design enables the underwater robot to better adapt to the changing marine environment.

[0015] 3. Significant enhancement of durability and reliability: The present invention has conducted long-term performance tests on the optimized flexible paddles, including fatigue tests, aging tests, and environmental adaptability tests. These tests simulate various situations that the flexible paddles may encounter in long-term operation, evaluate their durability and reliability in actual marine environments, and provide important references for the design of flexible paddles for underwater robots, significantly enhancing their survivability and stability in harsh marine environments.

[0016] 4. Comprehensive improvement of environmental adaptability: The present invention significantly improves the environmental adaptability of the underwater robot's flexible fins. The different sea conditions considered in the simulation process and the careful consideration of materials and dimensions in the optimization analysis enable the underwater robot to maintain efficient and stable operation in various marine environments, and expand its application scope, enabling it to better serve key areas such as marine observation, resource exploration, ecological research and climate observation.

[0017] 5. Promote the innovation and development of marine science and technology: The implementation and optimization of the present invention improve the performance of the flexible paddles of underwater robots, and also enhance their adaptability and reliability in complex marine environments, providing new impetus for the development of marine science and technology. Through precise simulation and optimized design, the present invention makes it possible to realize long-term, low-energy, large-scale, multi-field, fast-communication, and low-cost marine observation equipment, which is of great strategic significance for the development and utilization of marine resources, the monitoring and protection of the marine environment, and the formulation of relevant policies. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a 2.5D geometric model diagram of the flexible web after parameter optimization of the present invention.

[0019] Figure 1 In the figure, the 2 mm side is the top side of the flexible wing, the 5 mm side is the bottom side of the flexible wing, and the 110 mm height (also the length) of the flexible wing.

[0020] Figure 2 This is a diagram of the 2.5D model of the flexible paddle wing fluid-structure interaction.

[0021] Figure 3 It is a simulation diagram of the driving force evaluation of flexible fins using different materials.

[0022] Figure 4 It is the ae part of the simulated pressure cloud diagram of the five key nodes of 0T, 0.25T, 0.5T, 0.75T and 1T in the stable cycle of different materials. T refers to the stable cycle.

[0023] Figure 5 It is the fg part of the simulated pressure cloud diagram of the five key nodes of 0T, 0.25T, 0.5T, 0.75T and 1T for different materials in the stable cycle.

[0024] Figure 4 and Figure 5In the figure, the materials represented by a-g are: a refers to styrene-butadiene rubber; b refers to natural rubber; c refers to carbon black filled natural rubber; d refers to EPDM rubber; e refers to nitrile rubber; f refers to soft polyurethane; g refers to hard polyurethane. Each figure a-g consists of five rectangular blocks, and each rectangular block represents the five key time nodes of 0T, 0.25T, 0.5T, 0.75T and 1T from left to right.

[0025] Figure 6 This is a simulation result diagram of the dynamic characteristics of flexible paddles with different surface hardness.

[0026] Figure 7 This is a simulation diagram of the average driving force of flexible paddles with the same top edge size and different bottom edge sizes.

[0027] Figure 8 This is a simulation diagram of the average driving force of flexible paddles with the same bottom edge size and different top edge sizes. DETAILED DESCRIPTION

[0028] like Figures 1 to 8 As shown, the flexible wing structure for improving dynamic characteristics of the present invention includes a body, the isosceles trapezoid presented by the cross section of the body is called a cross-sectional trapezoid, the bottom side of the cross-sectional trapezoid is longer than the top side of the cross-sectional trapezoid; the angle between the two sides of the cross-sectional trapezoid is called a cone angle, the height of the cross-sectional trapezoid is called the height of the flexible wing, the surface hardness of the body is 60HB (Brinell hardness), the cone angle is 4.7°-5.2° (including both end values), preferably 4.7°. The top side is 2 mm, the bottom side is 5 mm, and the height of the flexible wing is 110 mm.

[0029] The material of the body is preferably SBR rubber, and other rubber materials such as carbon black filled natural rubber may also be used.

[0030] The following is an introduction to the research and development ideas of the present invention. The research and development ideas do not belong to the prior art. They are the overall technical ideas created by the applicant in combination with the prior art when faced with the problem of "how to optimize the dynamic characteristics of flexible flippers": The applicant has found that the following parameters have a significant impact on the dynamic characteristics of the flexible fin: 1. Surface hardness.

[0031] 2. Cone angle.

[0032] 3. Top edge length.

[0033] 4. Length of the bottom side. The cone angle has a functional relationship with the length of the top side and the length of the bottom side.

[0034] When optimizing and improving the flexible paddle, these parameters need to be optimized. The selectable numerical space of each parameter is almost infinite, and the numerical selection space of the combination of each parameter is even larger. In traditional research, the method of making physical flexible paddles with different parameter combinations for actual testing to explore the best parameter combination is not feasible, and the financial and time costs are unbearable.

[0035] Therefore, the applicant decided to explore the optimal parameter combination through simulation, but many problems need to be solved when moving in this direction.

[0036] The first step is to find a suitable base model.

[0037] Because the flexible webbed wing undergoes elastic deformation under the action of waves, thereby generating a forward driving force, the applicant classifies it as a fluid-solid coupling problem. Fluid-solid coupling problems can be divided into unidirectional fluid-solid coupling and bidirectional fluid-solid coupling. The flexible webbed wing can convert the energy of ocean waves into the driving force of the wave glider. The wave glider includes an above-water floating body, an underwater gliding body, and a cable connecting the above-water floating body and the underwater gliding body, and the flexible webbed wing is installed on the underwater gliding body. The above-water floating body moves with the waves under the action of waves, and the flexible webbed wing moves relative to the surrounding water flow under the drive of the floating body, and produces elastic deformation under the pressure of the water flow, and a pressure difference occurs between its upper and lower surfaces, thereby generating a propulsion force. In this interaction process, the dynamic behavior of the fluid will cause the deformation of the flexible webbed wing, and the deformation of the flexible webbed wing will in turn affect the surrounding fluid flow. Based on this understanding, the applicant classifies the study of the dynamic characteristics of the flexible webbed wing into a bidirectional fluid-solid coupling problem.

[0038] Flexible flippers are made of rubber. To predict the mechanical behavior of rubber, the Mooney-Rivlin model, Ogden model, Neo-Hookean model and Yeoh model are generally used to describe the stress-strain relationship of rubber.

[0039] The Mooney-Rivlin model is particularly suitable for describing nonlinear elastic behavior at moderate deformation levels.

[0040] The Ogden model is a more advanced nonlinear model. Although it can theoretically provide more accurate results, it has more parameters and requires more complex data fitting.

[0041] The applicant believes that for some particularly complex material behaviors, such as extreme stretching, the Ogden model is a better choice, but for the application of flexible paddles in wave gliders, this accuracy is redundant, because in the application of flexible paddles in wave gliders, unless a collision occurs, the flexible paddles will not be extremely deformed. The Ogden model that takes extreme deformation into consideration is used for the simulation of the dynamic characteristics of flexible paddles. It is inevitable that redundant calculations will be performed due to the consideration of extreme deformation. Although the results produced are more accurate, they do not help substantially in solving the problem. Instead, they greatly increase the amount of calculations, increase the computing energy consumption, and prolong the simulation time. Therefore, the applicant excluded the Ogden model.

[0042] The Neo-Hookean model is the simplest nonlinear elastic material model, suitable for describing small to medium deformations. Due to its simple form, it is very useful in analyzing and simulating the behavior of isotropic, incompressible, highly elastic materials. The applicant believes that in the application scenario of flexible fins in wave gliders, although extreme deformations such as extreme stretching will not occur, large deformations may also occur, so the applicant also excludes the Neo-Hookean model.

[0043] The Yeoh model is designed to handle large strain problems, especially when the material behavior shows significant compression or hardening. The applicant believes that the Yeoh model is more accurate when dealing with very large deformations. The main deformation of the flexible wing of the wave glider is the medium deformation of the tangential deformation, so the applicant also excludes the Yeoh model.

[0044] In summary, after comprehensive consideration, the applicant believes that the Mooney-Rivlin model is the most suitable basic model for the application scenario of flexible fin wings in wave gliders.

[0045] After selecting the basic model, it is necessary to simplify the motion principle of the webbed wing wave glider, establish its geometric model and analyze its motion model in detail before using the Mooney-Rivlin model to simulate the dynamic characteristics of the flexible webbed wing.

[0046] The applicant first established a geometric model of the flexible fin itself, such as Figure 1As shown. The three-dimensional model can analyze the interaction between the structure and the fluid in detail, and is suitable for complex situations that require precise simulation, but the computational cost is high. The two-dimensional model simplifies the structure and fluid flow, has a low computational cost, and is suitable for situations where the structural response and flow direction are single. The applicant combined the characteristics of the two-dimensional model and the three-dimensional model, and established a 2.5D model of the flexible paddle, retaining the spatial characteristics of the three-dimensional model. By setting the symmetry plane, the numerical simulation of the three-dimensional space model is converted into a two-dimensional plane numerical value, thus combining the advantages of the three-dimensional model that can accurately model and the advantages of the two-dimensional model with low computational cost.

[0047] The applicant then established a 2.5D model of fluid-solid coupling of a flexible paddle as a motion model, as shown in Figure 2. The watershed is 800 mm high and 300 mm wide; the flexible paddle is 150 mm from the bottom of the watershed. In order to simplify the calculation model and increase the calculation speed, the motion form is that the flexible paddle moves in the vertical direction in the watershed.

[0048] When simulating, it is necessary to determine the sea state level to be simulated. Table 1 is a sea state level table.

[0049] Table 1

[0050] According to the predetermined working environment of the wave glider, the simulated sea condition level is determined to be the second-level sea condition. The waves under the second-level sea condition can be regarded as sine waves, with a wave height between 0.1 and 0.5 meters and a wavelength of about 15 meters. The second-level sea condition is selected as the main external working condition for numerical simulation for the following reasons: ① The second-level sea condition is common in vast ocean areas and is a typical environment for the routine operation of wave gliders; ② The surface waves of the second-level sea condition are mild and can be regarded as a sine function; ③ When conducting wave tank experiments to verify the numerical simulation results, the characteristic conditions of the second-level sea condition are easy to achieve and the data collection is more accurate.

[0051] by Figure 2 The coordinate origin is established at 150 mm from the bottom of the basin, the horizontal direction is the x-axis, and the numerical direction is the y-axis. The motion model of the flexible paddle in the fax simulation is established as: y=0.5A×sin{2×π / T×t-0.5π}+0.5A. Among them, A is the wave height in meters; T is the wave period in seconds; t is the time in seconds.

[0052] The simulation platform uses ANSYS Workbench. The simulation results are as follows Figure 2 - Figure 8 The most relevant simulation results are presented below.

[0053] The present invention uses four indicators, namely driving force, resistance, combined force and efficiency, to characterize the dynamic characteristics of the flexible paddle. The time period during which the dynamic characteristics of the flexible paddle remain relatively stable during the movement is called a stable period.

[0054] like Figure 3 As shown in the figure, the SBR rubber material has the best dynamic properties, followed by the two NR materials, then the EPDM and NBR materials, and the two PU materials have the worst performance. The reason why the SBR rubber material has the best dynamic properties is that after combining Figure 4 and Figure 5 Analysis shows that the main reason is that the SBR rubber material has suitable rigidity in addition to suitable elasticity, so that when used as the flexible wing of the wave glider in the present invention, its deformation and rebound characteristics under secondary sea conditions make its transient driving force almost all in the positive direction, thereby improving the propulsion efficiency.

[0055] Figure 4 and Figure 5 It can be seen that the SBR rubber material with the best driving force effect has almost no deformation at 0T, 0.5T and 1T, and reaches the maximum deformation at 0.25T and 0.75T, indicating that for the purpose of driving force optimization, SBR rubber is the most suitable material for flexible webs.

[0056] Figure 6 The following is a simulation result of the dynamic characteristics of flexible paddles with different surface hardness. Since the flexible paddles will produce periodic power output during movement, Figure 6 The characteristic values ​​of each index in the graph are wavy over time. Figure 6 It can be seen that the flexible paddles with different surface hardness are very close in terms of resistance and resultant force, with no obvious difference. However, in terms of driving force and efficiency, the flexible paddle with a surface hardness of 60HB is significantly better than the flexible paddles with other surface hardness.

[0057] Research Figure 7 The bottom edge size directly affects the mechanical properties of the flexible paddle, especially its elasticity and rigidity. Although increasing the bottom edge size reduces the elastic deformation capacity of the flexible paddle, the rigidity of the flexible paddle is also enhanced, and the rebound speed becomes faster, which greatly reduces the number of negative driving forces in the transient response of the flexible paddle. When the top edge size is constant, there must be an optimal bottom edge size to make the dynamic characteristics of the flexible paddle the best. Therefore, when designing a flexible paddle, the thickness selection of the bottom edge is a key consideration. It is necessary to maintain sufficient rigidity to provide stability and durability while maintaining appropriate elasticity to ensure efficient energy conversion and good dynamic response. By accurately balancing these factors, effective optimization of the wave glider paddle can be achieved and its overall performance in the marine environment can be improved.

[0058] Research Figure 8 The top edge size has a certain influence on the dynamic characteristics of the flexible paddle. Within a certain range, the top edge size can significantly affect the elasticity of the flexible paddle. In addition, by comparing the influence of the bottom edge size on the dynamic characteristics of the flexible paddle, it is found that its influence on the dynamic characteristics of the flexible paddle is relatively small. The top edge size affects the dynamic characteristics of the flexible paddle by affecting other parameters of the flexible paddle. Figure 7 and Figure 8 When the top edge size is 2 mm and the bottom edge size is 5 mm, the dynamic characteristics of the flexible fin are relatively optimal.

[0059] After the top and bottom dimensions are determined, the cone angle is also determined. The calculation formula for the cone angle is: ψ = 2arctan{(b-a) / 110}×180° / π. Among them, ψ is the cone angle in degrees; b is the top dimension, and a is the bottom dimension.

[0060] Depend on Figure 7 In the data sets with fixed top dimensions and different bottom dimensions, it is shown that a certain size combination in the middle has the best effect on the dynamic characteristics of the flexible paddle. Observing the data points of these characteristics, the sizes are: 5-0.1 mm, 5-0.5 mm, 6-1 mm, 6-1.5 mm, 7-2 mm. The bottom dimensions of the paddles at these specific points are not all the same. The cone angles of these specific turning points are all between 4.7° and 5.2°. Among them, the driving force performance is relatively best when the cone angle is 4.7°.

[0061] Depend on Figure 8 Unlike the bottom edge size which directly affects the driving force of the flexible paddle, the top edge size does not have a direct impact on the driving force of the flexible paddle, but indirectly affects the dynamic characteristics of the flexible paddle by affecting the cone angle.

[0062] In summary, the optimized flexible wing parameters supported by the simulation structure are made of SBR rubber material, the surface hardness of the body is 60HB (Brinell hardness), the cone angle is 4.7°-5.2°, the top edge is 2 mm, the bottom edge is 5 mm, and the height of the flexible wing is 110 mm.

[0063] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A flexible wing structure with improved dynamic characteristics, comprising a body, wherein the isosceles trapezoid presented by the cross section of the body is called a cross-sectional trapezoid, the bottom side of the cross-sectional trapezoid is longer than the top side of the cross-sectional trapezoid; the angle between the two sides of the cross-sectional trapezoid is called a cone angle, and the height of the cross-sectional trapezoid is called the height of the flexible wing, characterized in that: The surface hardness of the body is 60HB, the cone angle is 4.7°-5.2°, the top edge is 2 mm, the bottom edge is 5 mm, and the height of the flexible fin is 110 mm.

2. The flexible paddle structure for improving dynamic characteristics according to claim 1, characterized in that: The material of the body is SBR rubber.

3. The flexible wing structure for improving dynamic characteristics according to claim 1, characterized in that: The cone angle is 4.7°.

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