【作者】 周凯；

【导师】 刘军考；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2017， 博士

【摘要】 自然界中的生物在长达亿万年的进化过程中,经过不断的自然选择,从而形成了在空气或水等流体介质中非凡的运动能力。对游动或飞行生物的研究,可以为水下推进技术的发展产生巨大的推进作用。相对应的仿生学也随之成为机械学科的研究热点,在水下探测、资源开发、国家安全等重要领域具有迫切需求。随着技术的发展,以不同生物为仿生原型的水下推进器也层出不穷,但其推进性能与生物原型相比还有一定的差距,这凸显了对于生物推进机理研究的必要性。生物推进机理研究上的发展将会带动原理样机的研制。为揭示生物高效推进的机理,国内外学者利用多种研究方法进行了大量的工作,包括了数值模拟和原理样机的设计,但其性能参数都无法达到仿生原型的预期效果。本文以研制高性能水下推进器为背景,选取典型的仿生水翼为研究对象,对仿生水翼的推进机理和复杂流场中的能量吸收机制进行研究。以揭示仿生水翼的推进机制为目的,提出一种求解仿生水翼推进的数值方法。首先根据生物观测结果,建立仿生水翼的几何模型和运动学模型。在此基础上,在二维尺度下采用沉浸边界法来模拟边界的作用,流体部分的求解采用格子玻尔兹曼方法和有限差分法;在三维尺度下采用非结构贴体网格来划分流场,通过动网格技术来模拟边界的运动,流体部分采用有限体积法进行离散求解。然后,通过多个算例对数值方法的可靠性进行部分验证。最后设计和搭建了仿生水翼推进实验装置,为数值结果的可靠性验证提供平台。采用提出的数值方法,对NACA型水翼的推进机理进行研究。分别分析了行程角、攻角幅值、升沉幅值和斯特鲁哈尔数四个运动参数对水翼推进性能的影响规律,采用响应曲面法分析了四个运动参数对水翼推进性能的综合影响,建立了运动参数与推进性能之间的数学模型。然后分析了水翼展向柔性对水翼推进性能的影响。通过提取水翼的尾迹流场特征,进一步分析了运动参数和柔性参数对水翼推进性能影响的水动力学机制。最后通过实验验证了数值结果的可靠性。考虑三维形状对水翼推进性能的影响,对新月型水翼的推进机制进行研究。分别对攻角幅值、平动幅值和斯特鲁哈尔数三个运动参数以及展向柔性参数对水翼推进性能的影响进行了分析,采用响应曲面法分析了三个运动参数对水翼推进性能的综合影响,建立了运动参数与推进性能之间的数学模型。通过提取水翼的尾迹流场特征,进一步分析了运动参数和柔性参数对水翼推进性能影响的水动力学机制。最后通过实验验证了数值结果的可靠性。自然界中生物游动所处的流场环境是复杂多变的,其推进过程存在复杂的减阻和能量吸收机制,对复杂流场中水翼推进机理的研究具有重要意义。首先,对柔性板和刚性圆柱在自由来流下的耦合振动进行了数值模拟,探讨了柔性体的能量吸收机制,进一步分析了间距、质量比和雷诺数对耦合振动的影响;对卡门涡街中二维水翼的自由波动进行了数值模拟,分析了不同间距下水翼运动模式和对应的流场特征;为验证鲔科仿生原型几何模型和运动模型的可靠性,首先对鲔科仿生原型的自主推进进行了数值模拟,然后对串列NACA型水翼和串列鲔科仿生原型的推进进行数值模拟,通过提取受力参数和流场特征,分析了其相互作用和能量吸收机制。更多还原

【Abstract】 In the nature,through natural selection over thousands of years,creatures are capable of swimming or flying in fluid medium such as air or water.Study on the propulsion modes of swimming or flying creatures has important significance to underwater propulsion.In the mechanical discipline,biomimetics has become a research focus.Moreover,biomimetics is of vital importance in underwater exploration,ocean exploitation,national security and other important domains.With the developments of technologies,different bionic propulsors have been successfully developed.Unfortunately,propulsion performance of these bionic propulsors can not achieve the same performance as biological prototypes,which highlights the necessity of further study on propulsion mechanism.The mechanism research plays important role,and will boost the developments of principle prototype.In order to reveal the mechanism of high-efficiency propulsion,scholars at home and abroad have devoted lots of efforts with different research methods.However,either the prototype-based experimental results,or numerical results are far from expected performance.Taking high-efficiency propulsor developments as the research background,the paper chooses typical foils as the research object and focuses on the propulsion mechanism of bionic foils and energy absorption mechanisms in complex flow field.To investigate the propulsion mechanism of bionic foils,the paper proposes a numerical method.Firstly,according to the biological observations,geometry model and kinematics model of bionic foils are established.For two-dimensional case,Immersed Boundary Method is adopted to solve the moving boundary problem,Lattice Boltzman Method and Finite Difference Method are adopted to solve the governing equations of fluid domain.For three-dimensional case,dyamic body-fitted mesh is adopted to solve the moving boundary problem,Finite Volume Method are adopted to solve the governing equations of fluid domain.Several numerical examples are carried out to verify the reliability of the numerical method adopted in the paper.Finally,experimental platform is designed and developed to provide further verification of numerical results.The proposed numerical method is used to carry out research on propulsion mechanism of NACA foils.The effects of stroke angle,amplitude of angle of attack,amplitude of heave motion and Strouhal number on the propulsion performance are respectively analyzed.Response Surface Methodology is used to analyze the comprehensive influence of these parameters and set up the mathematic model between motion parameters and propulsive performance.After that,the effect of spanwise flexibility on the propulsion performance is studied.By extracting the flow field characteristics in the wake,the hydrodynamics mechanism of these effects is analyzed further.The numerical results are verified by experiments.Considering the influence of three-dimensional shapes,the propulsion mechanism of crescent-shaped foils is studied.The effects of amplitude of angle of attack,amplitude of heave motion and Strouhal number on the propulsion performance are respectively analyzed.Response Surface Methodology is used to analyze the comprehensive influence of these parameters and set up the mathematic model between motion parameters and propulsive performance.After that,the effect of spanwise flexibility on the propulsion performance is studied.By extracting the flow field characteristics in the wake,the hydrodynamics mechanism of these effects is analyzed further.The numerical results are verified by experiments.In the nature,flow field environment is complex.Complicated drag reduction and energy absorption mechanism exist in animal swimming.Therefore,it is of great significance to study the propulsion mechanism of foils in complex flow field environment.Firstly,the coupling motion between flexible plate and rigid cylinder is numerical simulated,and the energy absorption mechanism is analyzed.In addition,the effects of space,mass ratio and Reynolds number are analyzed further.After that,motion and flow field characteristics of wave foil behind a rigid cylinder are studied.Finally,propulsion modes of NACA foils in tandem arrangement and thunniform bioinspired modes in tandem arrangement are studied respectively.To verify the reliabilities of geometry model and kinematics model adopted in the part,numerical simulations of thunniform bio-inspired mode are carried out,then velocity and flow field characteristics are analyzed.By extracting the flow field characteristics in the wake,the interaction modes and energy absorption mechanism are analyzed further.更多还原