【作者】 刘芳芳；

【导师】 杨灿军； Kok-Meng Lee；

【作者基本信息】 浙江大学 ， 机械电子工程， 2012， 博士

【摘要】 水下推进器在海洋资源的勘探技术装备开发中起着越来越重要的作用,传统的水下推进器多采用螺旋桨推进,在效率、机动能力、能耗、噪音等方面存在不足,因此,设计高性能水下推进器已成为各国关注的热点和核心问题之一。鱼类作为海洋的主要“居民”经过上亿年的进化和自然选择,形成了适合海洋环境的独特形态和运动方式。其中柔性鳍波动推进模式与传统的鱼类身体／尾鳍(body and/or caudal fin,简称BCF)推进模式相比,属于中央鳍／对鳍(median and/or paired fin,简称MPF)推进模式,具有低速下高效、高机动性和低流体扰动等显著优点,为未来水下推进器的仿生设计提供了新的选择,采用此种推进模式的仿生推进器不仅适用于远距离航行,还具有小范围机动灵活、抗扰动能力强的特点,对海洋资源的勘探技术装备开发甚至军事方面具有重要的理论研究价值和广阔的应用前景。论文主要围绕柔性鳍波动推进仿生系统的结构设计、水动力学建模及数值计算和实验验证三方面展开：首先,基于动量守恒定律对柔性鳍波动推进模型进行水动力分析,提出基于三维非定常流体控制方程组和基于流固耦合控制方程组的柔性鳍波动系统动力学建模方法,并对两种建模方法进行了分析与比较。其次,以刀鱼长背鳍为研究对象,提出一种新型柔性长背鳍波动模型并通过波动性能实验对柔性长鳍进行优化,采用基于三维非定常流体控制方程组的建模方法对柔性长鳍进行动力学建模并采用计算流体动力学(computational fluid dynamics,简称CFD)方法对柔性长鳍波动推进运动实现三维数值计算,揭示了柔性鳍波动时周围流体的压力场、速度场分布特征,同时揭示了柔性鳍波动推进力的变化周期是鳍波动周期的一半。然后,仿生设计并研制了一套基于柔性长鳍波动的仿生推进装置,该装置采用单电机驱动,依靠柔性鳍自身与流体的相互作用传递行波实现推进。同时开展水下推进性能实验,验证系统设计的可行性和可靠性。通过数值计算结果与实验结果的对比,验证了动力学模型及数值计算方法的合理性与准确性,为进一步分析柔性鳍波动的推进机理及提高推进性能的研究提供理论指导及实验基础。为了进一步提高柔性鳍波动推进性能,以枪乌贼为研究对象提出柔性双鳍波动推进方式,并基于流固耦合建模的数值计算方法对柔性双鳍波动推进性能进行优化评估,实现三维流固耦合数值计算,在此基础上完成柔性双鳍波动推进仿生系统的样机研制并开展了水下推进性能实验,验证双鳍波动系统设计的可行性和可靠性。基于流固耦合建模的数值计算方法是一种有效的柔性鳍波动推进设计优化方法,为开发新型的基于柔性鳍波动的仿生推进系统提供新的思路及分析方法。本研究工作在柔性鳍波动推进动力学模型及仿生装置研制等方面积累的成果为柔性鳍波动推进仿生智能机器人的深入研究积累了很好的经验,为今后更为深入的理论研究和开发实践奠定了坚实基础。更多还原

【Abstract】 Propellers have been playing an increasingly important role in underwater devices for resources exploration. As traditional propulsions (such as jets and axial propellers) have little advantages of propulsive efficiency at low speed, maneuverability, power consumption and acoustic noise, designing of alternative high-performance underwater propulsion becomes one of most interested research topics. Fish owes their unique morphological characteristics and movement modes for living in deep sea environment after billions of years of evolution and natural selection. In comparison against body/caudal fin (BCF) modes, the flexible undulating fin-based propulsion mode (as one of median/paired fin modes) offers several advantages including good propulsive efficiency, great maneuverability, and low underwater acoustic noise at low speeds; as a result, it is a source of biologically inspiration for future propeller designs.This dissertation presents the design and modeling of a flexible undulating fin-based propulsion system and findings of computational and experimental investigations.Firstly, a new design of a long flexible undulating fin inspired by the knifefish has been developed with the aid of an experimental investigation. Secondly, the hydrodynamics of a flexible undulating fin has been numerically modeled based on the conservation equations of mass and momentum. The three dimensional unsteady fluid controlled equations take into account the effects of fluid-solid interaction and have been numerically solved using computational fluid dynamics (CFD) method for the pressure and velocity distributions and the forces acting on the undulating fin in the neighborhood of the undulating fin. Thirdly, a fin-based robotic fish (driven by a single DC-motor) has been designed and developed for forward propulsion using the undulating fin which propagates the wave in the opposite direction of the swim. The feasibility and reliability of the design have been examined experimentally, which also provides a basis for validating the computed thrust. The theoretical predication, which agrees well with the measured data validating the numerical model, offers guidance for performances improvements of future designs.To improve the propulsion performances, the undulating lateral fin has been numerically solved using a three-dimensional unsteady method based on fluid-solid interaction effect, for optimizing the design of the robotic fish based on flexible lateral fins, which method is experimentally validated previously by comparing the computed thrust against data measured on the prototype long flexible-fin mechanism. Thus a prototype paired lateral-fin mechanism has been developed and experiments have been done validating for feasibility and reliability of the system. The results show that this analysis method is feasible and reasonable for analyzing and optimizing the propulsion performance.In summary, the hydrodynamic model and numerical results of the flexible undulating fin provide a good foundation for research and development of a flexible undulating fin based system.更多还原