【作者】 丁浩；

【导师】 宋保维；

【作者基本信息】 西北工业大学 ， 兵器科学与技术， 2015， 博士

【摘要】 无人水下航行器在海洋开发和科学考察中发挥着重要作用。海龟、企鹅等大型海洋生物独特的形体结构及运动方式,使其在低速运动状态下具有灵活性好、噪声低、能量利用率高等优点,深入研究此类海洋生物的肢体运动模式,探索水下扑翼推进机理,并将其应用到水下航行器中,对于丰富水下推进技术,提高低速下航行器的运动性能具有重要的意义。目前,水下扑翼推进技术研究刚刚起步,推进机理尚不明晰,尤其是扑翼推进技术在水下航行器上的应用仍处于探索阶段,采用扑翼推进方式的水下航行器其运动性能及操纵机理需要进行深入的研究。本文采用数值模拟、理论计算以及实验研究相结合的方法,围绕扑翼推进力学机理、推进性能与扑翼结构参数及运动规律的关系、扑翼航行器流体动力特性、扑翼航行器操纵机理及运动性能等方面展开研究工作,主要研究内容及成果表现在以下几个方面：1.水下仿生扑翼推进水动力性能数值模拟研究(1)根据海龟前肢运动特性,建立了扑翼平面三自由度运动数学模型；(2)将滑移网格技术和动网格技术相结合,采用CFD方法对单自由度、二自由度、三自由度扑翼运动的二维非定常流场进行了数值模拟,阐释了扑翼推力产生机理；(3)针对单自由度扑翼运动方式研究了翼型厚度、翼型弯度、旋转轴位置、时间非对称运动方式对扑翼水动力性能的影响,给出了推进效果最优的翼型厚度及旋转轴位置,并分析了扑翼升力特性和推力特性随影响因素的变化规律；(4)针对三自由度扑翼运动方式研究了扑翼推力及推进效率与运动参数的关系,并对单自由度、二自由度和三自由度三种扑翼运动方式的推进效率进行了对比分析。2.扑翼水下航行器外形设计及流体动力特性研究(1)在分析海龟外部形态及肢体功能的基础上,设计了单自由度扑翼航行器的外形及布局；(2)基于滑移网格技术对单自由度扑翼推进器的水动力性能进行仿真计算,给出了最佳推进效率所对应的展弦比；通过全因子实验模拟,拟合了静水中扑翼推力与运动参数之间的函数关系,并对其进行了响应面分析；在此基础上,计算分析了扑翼推进性能与进速比及平衡偏角的关系；(3)将扑翼推进器和航行体作为一个整体考虑,研究了二者之间的非定常流体动力干扰,重点分析了来流速度以及扑翼推进器与航行体轴向间距对二者流体动力干扰的影响；(4)针对扑翼航行器扁平型主体在大攻角和大侧滑角下的流体动力特性进行了数值计算分析,给出了阻力、升力及力矩系数随攻角和侧滑角变化的水动力学表达式,并通过模拟悬臂水池实验计算了其旋转导数。3.扑翼水下航行器动力学建模及运动性能仿真研究(1)对扑翼水下航行器运动过程的受力情况进行分析,并通过理论推导建立扑翼推进器推力数学模型,在此基础上,基于Newton-Euler法建立了扑翼航行器空间六自由度运动数学模型；(2)基于Matlab-Simulink平台建立扑翼航行器的运动仿真系统,对扑翼航行器在纵平面和水平面内的运动性能进行了仿真研究,分析了扑翼航行器运动参数的变化特性,重点研究了推进器数量及推进器运动参数对航行器运动性能的影响。4.扑翼推进水动力性能实验研究(1)根据扑翼运动过程水动力交变和非定常的特点,搭建了测量扑翼水动力性能的实验平台；(2)针对NACA0012翼型做单自由度扑翼运动的水动力性能进行实验研究,明确了扑翼推力及推进效率与运动参数(频率和幅值)的关系；(3)针对7组翼板的水动力性能实验结果探讨了截面形状、弦长、展长的变化对扑翼水动力性能的影响;(4)选取特定工况将实验结果和CFD仿真结果进行对比,验证扑翼水动力性能仿真计算方法的正确性及结果的可信性。5.扑翼水下航行器样机研制及实验(1)研制了扑翼航行器实验样机,根据实验样机多运动执行单元协同运动的特点及空间多自由度运动的要求,设计了实验样机总体控制软硬件系统；(2)在敞水中对扑翼航行器实验样机进行了航行性能实验。通过实验结果重点分析：扑翼推进器频率和幅值对航行器直航速度和加速度的影响;三种差动转弯模式下航行器转向能力和转弯效率的优劣；控制扑翼推进器平衡偏角实现航行器升沉运动的可行性及不同平衡偏角下样机的下潜能力。选取特定工况,通过对比仿真计算结果与实验结果,验证了扑翼航行器动力学模型的正确性。更多还原

【Abstract】 Unmanned underwater vehicles (UUVs) have played an important role in the ocean exploitation and scientific investigation. Large marine animals, such as turtles and penguins, have evolved with unique physical structure and motion pattern after billions of years of evolution. Owing to these gifts, they can move freely in water with good flexibility, low noise and high efficiency. The significance obviously is there for the improvement of the motion performance of UUVs if we can study the flapping-foil propulsion mechanism of the marine animals and apply it to the UUVs.Currently, underwater flapping-foil propulsion research is in the start-up stage and the propulsion mechanism is unclear. It’s challenging for us to use this new propulsion mode on the UUVs. The motion character and manipulation mechanism of flapping-foil propelled UUVs remains to be investigated. In this paper, the flapping-foil propulsion mechanism, the relationship between the flapping motion and the propulsion performance, the fluid dynamics and the maneuverability of the flapping-foil propelled UUV are investigated with a combined method including numerical simulations, theoretical predictions and experimental studies.The main research contents and innovative works can be summarized as follows:1. Computational fluid dynamics (CFD) simulations of underwater biomimetic flapping-foil.(1) A3degrees of freedom (DOF) motion model is established according to turtle forelimb movement characteristics.(2) With the sliding mesh method and dynamic mesh method, two-dimensional CFD studies are performed on the1DOF,2DOF and3DOF flapping foils, respectively. The thrust generation mechanism is illustrated.(3) For1DOF flapping-foil movement pattern, the influence of foil thickness, foil camber, rotation axis position, and the time-asymmetric movement pattern on the hydrodynamics performance of the flapping-foil is studied. The optimal foil thickness and the rotation axis position are given. The variation of flapping-foil lift and thrust characteristics with the influencing factors is studied.(4) For3DOF flapping-foil movement pattern, the relationship between motion parameters, thrust and propulsion efficiency is studied. The propulsion efficiency of1DOF,2DOF, and3DOF motions are compared quantitatively.2. Shape design and hydrodynamic characteristics of the flapping-foil UUV. (1) A new flapping-foil UUV shape is designed after the biomimetic research of sea turtle morphology.(2) Using sliding mesh technique, the thesis calculates hydrodynamic performance of the1DOF flapping-foil thruster. The aspect ratio corresponding to optimum propulsive efficiency is given. The fitting functions of average thrust coefficient, average thrust and flapping-foil motion parameters are given by full factorial experimental simulation. Through the response surface analysis, this paper gives the size of the main effects and interaction effects which affecting the flapping-foil propulsion performance. On this basis, respectively, the relationship between advance ratio, bias angle and propulsion performance of the thruster is analyzed.(3) The thesis considers flapping-foil thruster and UUV’s body as a whole to study the unsteady hydrodynamic interference with each other, and focuses on the hydrodynamic interference with different inflow velocity and dimensionless gap between the thruster and UUV’body.(4) Respectively, the thesis calculates hydrodynamic characteristics of the flapping-foil UUV’s tri-axial ellipsoid body at high angles of attack and sideslip, and the hydrodynamic expression of drag, lift and moment coefficients change with the two are given. By simulating the cantilever pool experiments, rotary derivatives are calculated.3. Dynamic modeling and motion characteristics simulation of the flapping-foil UUV.(1) A6DOF mathematical model of the UUV motion is developed based on the Newton-Euler equations. An accurate model for the hydrodynamic forces of the flapping foil is established. The flapping foil model is validated with the CFD results.A motion simulation platform is established in the Matlab-Simulink environment. The motion characteristics of the flapping-foil UUV in the longitudinal and the horizontal planes are simulated respectively. The influence of numbers of thrusters and other thruster motion parameters on the motion characteristics of the UUV is studied.4. Experimental study on the hydrodynamics performance of flapping-foil(1). An experiment platform for the measurement of flapping-foil unsteady hydrodynamic forces is build.(2). An experiment on the1DOF motion of a NACA0012foil is performed. The relationship between the motion parameters, thrust and propulsion efficiency is given.(3). The influence of section shape, chord length and span length of the foils on the hydrodynamics performance of flapping foils is studied.(4) Chosen specific situations, the CFD simulation result is validated by comparing it with the experiment data.5. Flapping-foil UUV prototype development and experiment(1) A prototype of flapping-foil UUV is developed. The overall control hardware and software systems of experimental prototype is designed according to collaborative movement characteristics of experimental prototype and the requirement of multi degree of freedom movement in space.(2). The navigation performance experiments of the prototype is conducted in open water.The influence of flapping-foil frequency and amplitude on the UUV velocity and acceleration is studied. The maneuverability of three different motion modes is compared. The feasibility of heave motion is validated by controlling the bias angle of flapping-foil thrusters. Chosen specific situations, the dynamic model and simulation method of the flapping-foil UUV motion is validated by comparing the result with the experiment data.更多还原