仿生水空两栖扑翼飞行器研究

水空两栖无人飞行器兼备有空中无人机的机动性与水下潜航器的隐蔽性，在军事及民用领域具有重要的应用价值。但由于空气和水在粘度、密度等物理性质方面存在巨大的差异，传统水空两栖无人飞行器在结构及动力系统水空兼容性方面存在重大的技术难题。为此，本课题从仿生的角度出发，针对空中鸟类扑翼飞行及水下蝠鲼类生物扑翼游动的特点，提出了一种新型仿生水空两栖扑翼飞行器布局形式，采用扑翼运动实现空中及水下的推进，并进行二自由度与三自由度空中及水下扑翼运动流体仿真与水池试验研究，为仿生水空两栖扑翼飞行器的研制提供理论参考。本文主要内容如下： 基于鸟类及蝠鲼类生物的形态特点与运动特点，结合水空两栖扑翼飞行器的设计思路，提出了一种融合有固定翼与三自由度扑翼的新型仿生水空两栖飞行器布局方案，在总体设计任务要求下，进行了机翼、机身、垂尾、平尾等的设计，最终完成了飞行器的总体设计。 建立二维扑翼流体仿真模型，基于动网格技术进行扑翼运动流场动力特性数值模拟。改进柔性变形公式，针对两自由度及三自由度扑翼运动，探究了不同柔性变形对空中及水下扑翼推进性的影响，围绕水下扑翼运动表现大推力特性及空中扑翼运动表现大升力特性，建立了“下正上负”的两自由度水下扑翼柔性变形模型及“下正上正”的二自由度空中扑翼柔性变形模型；建立了“下正上负”的空中及水下三自由度扑翼运动柔性变形模型。在此基础上系统研究了攻角幅值、行程角、斯特劳哈尔数、来流速度等参数对二维扑翼运动流体动力性能的影响。 根据飞行器设计方案及仿生原型扑翼运动特点，设计并制作扑翼验证样机，建立了基于鳍条式的三自由度俯仰运动控制方程，探究了翼面刚性旋转变化与翼面柔性扭转变化的水下扑翼流场特性，发现翼面柔性扭转由于角度变化较为平缓，表现出优异的推力特性。在此基础上进行二自由度与三自由度水下扑翼试验研究，系统分析了机翼形状、上下扑动幅值、攻角幅值、斯特劳哈尔数、来流速度等对扑翼运动水动性能的影响，为仿生水空两栖扑翼飞行器的设计提供了思路。

The water-air amphibious unmanned aerial vehicle has both the maneuverability of air UAV and the concealment of underwater submarine, which has important application value in the military and civil fields. However, due to the huge differences in physical properties such as viscosity and density between air and water, traditional water-air amphibious unmanned aerial vehicles have major technical problems in terms of structure and power system water-air compatibility. To this end, from the perspective of bionics, a new type of bionic water-air amphibious flapping-wing aerial vehicle layout is proposed in this thesis which based on the characteristics of flapping-wing flight of birds and flapping-wing swimming of manta rays, and this layout can help water-air amphibious flapping-wing aerial vehicle achieve air and underwater propulsion through flapping wings. At the same time, the two-degree of freedom and three-degree of freedom air and underwater fluid simulations of flapping wing movement are carried out, and the pool test research is also carried out to provide a theoretical reference for the development of the bionic water-air amphibious flapping-wing aerial vehicle. The main contents of this thesis are as follows: Based on the morphological characteristics and movement characteristics of birds and manta rays, combined with the design ideas of water-air amphibious flapping-wing aerial vehicle, a new type of bionic water-air amphibious aircraft layout scheme combining fixed wings and three-degree-of-freedom flapping wings is proposed. Under the mission requirements, the wing, fuselage, vertical tail, flat tail, etc. are designed, and the overall design of the aircraft is completed. A two-dimensional flapping-wing fluid simulation model is established, and the dynamic characteristics of the flapping-wing motion flow field are numerically simulated based on the dynamic grid technology. A flexible deformation formula is modified, and the influence of different flexible deformations on the propulsion of air and underwater flapping wings is explored for the movement of flapping wings with two degrees of freedom and three degrees of freedom. Focusing on the high-thrust characteristics of underwater flapping wings and the high-lift characteristics of aerial flapping wings, a "down positive and up negative" two-degree-of-freedom underwater flapping wing flexible deformation model and a "down positive and up positive" two-degree-of-freedom aerial flapping wing flexible deformation model are established; The "down positive and up negative" flexible deformation model of flapping wing movement with three-degrees-of-freedom in the air and underwater are established. On this basis, the influence of parameters such as the amplitude of the angle of attack, the angle of travel, the Strouhal number, and the incoming flow velocity on the hydrodynamic performance of the two-dimensional flapping wing is systematically studied. According to the design scheme of the aircraft and the movement characteristics of the bionic prototype flapping wing, the flapping wing verification prototype is designed and produced, and the three-degree-of-freedom pitching motion control equation based on the fin-ray type is established. The flow field characteristics of the underwater flapping wing with the rigid rotation change of the airfoil and the flexible torsion change of the airfoil are explored, and it is found that the flexible torsion of the airfoil exhibits thrust characteristics due to the relatively gentle angle change. On this basis, two-degree-of-freedom and three-degree-of-freedom underwater flapping wing experiments are carried out, and the effects of wing shape, flapping amplitude, angle of attack amplitude, Strouhal number and incoming flow velocity on the hydrodynamic performance of flapping wing are analyzed systematically, which provides ideas for the design of bionic water-air amphibious flapping-wing aerial vehicle.