典型仿生水翼的推进及能量吸收机制研究

发布时间：2018-09-12 18:15

【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。
[Abstract]:In the course of evolution for hundreds of millions of years, organisms in nature have undergone constant natural selection, thus forming extraordinary mobility in fluid media such as air or water. The study of swimming or flying organisms can greatly promote the development of underwater propulsion technology. With the development of technology, underwater thrusters with different bionic prototypes emerge in endlessly, but their propulsion performance is still lagging behind that of biological prototypes, which highlights the necessity of studying the mechanism of biological propulsion. In order to reveal the mechanism of bio-efficient propulsion, scholars at home and abroad have done a lot of work by using a variety of research methods, including numerical simulation and prototype design, but its performance parameters can not achieve the expected results of bionic prototype. In order to reveal the propulsion mechanism of bionic hydrofoil, a numerical method for solving the propulsion of bionic hydrofoil is proposed. Firstly, bionic hydrofoil is established according to the results of biological observation. On this basis, immersion boundary method is used to simulate the action of the boundary in two-dimensional scale, lattice Boltzmann method and finite difference method are used to solve the fluid part, unstructured body-fitted grid is used to divide the flow field in three-dimensional scale, and moving grid technology is used to simulate the movement of the boundary, fluid. Finally, a bionic hydrofoil propulsion experimental device is designed and built to provide a platform for the reliability verification of numerical results. The propulsion mechanism of NACA hydrofoil is studied by using the proposed numerical method. The influence of stroke angle, angle of attack amplitude, heave amplitude and Strouhal number on hydrofoil propulsion performance is analyzed. The comprehensive influence of four motion parameters on hydrofoil propulsion performance is analyzed by response surface method. The mathematical model between motion parameters and propulsion performance is established. Then the hydrofoil flexibility is analyzed. The influence of motion parameters and flexible parameters on hydrofoil propulsion performance is further analyzed by extracting hydrofoil wake flow field characteristics. Finally, the reliability of numerical results is verified by experiments. The effects of three motion parameters, i.e. attack angle amplitude, translational amplitude, Strouhal number, and spread flexibility on hydrofoil propulsion performance are analyzed. The comprehensive effects of the three motion parameters on hydrofoil propulsion performance are analyzed by response surface method, and the mathematical model between motion parameters and propulsion performance is established. The characteristics of wake flow field of hydrofoil are extracted, and the hydrodynamic mechanism of the influence of motion parameters and flexible parameters on hydrofoil propulsion performance is further analyzed. Finally, the reliability of numerical results is verified by experiments. Firstly, the coupled vibration of a flexible plate and a rigid cylinder in free flow is numerically simulated, the energy absorption mechanism of the flexible body is discussed, and the effects of spacing, mass ratio and Reynolds number on the coupled vibration are further analyzed. In order to verify the reliability of the geometric model and the motion model of the bionic prototype of the tuna family, the self-propulsion of the bionic prototype of the tuna family was numerically simulated, and then the tandem NACA hydrofoil and the tandem bionic prototype of the tuna family were advanced. The interaction and energy absorption mechanism were analyzed by extracting force parameters and flow field characteristics.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：Q811

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