基于尾流驰振的低速水流压电能量采集器分岔机理及性能研究

The galloping phenomenon in flow-induced vibration is used to convert the low-velocity fluid energy into vibration energy. Through galloping piezoelectric energy harvesting, the clean energy of low-velocity water flows in oceans and rivers is exploited to meet the wireless sensor powering demand for remote control. Compared with the galloping, wake galloping can further reduce the onset flow velocity and improve the energy harvesting efficiency since the disturbance of incoming vortices enhances the structural vibration. Aiming at high-efficient low-velocity flow energy harvesting, a new water flow energy harvester is designed by utilizing wake galloping and piezoelectric effect in this project. Combining the theory of nonlinear dynamics and the circulating water channel experimental study, the nonlinear fluid-solid-electric coupled modeling, stability analysis and energy harvesting performance of the low-velocity water flow piezoelectric energy harvester based on wake galloping are investigated. The bifurcation mechanism of the low-velocity water flow piezoelectric energy harvester based on the wake galloping is explored, and the stability criterion is proposed to reduce the onset velocity of energy harvesting. The effects of wake disturbance, fluid-structural coupling and electromechanical coupling on the system's nonlinear dynamic characteristics and energy harvesting performances are revealed. The conversion efficiencies from the low-velocity fluid energy to the vibration energy and the vibration energy to the electric energy are enhanced. This project will provide theoretical basis for the design of high-efficient low-velocity water flow energy harvester, and is of great significance for promoting the development of new hydroelectric technology.

利用流致振动中的结构驰振现象将低速流体能转化为振动能，通过驰振能量采集，开发海流和江河流等低速水流清洁能源，满足远程控制领域的无线传感供能需求。相比恒流驰振，尾流驰振由于来流涡扰动对结构振动的增强作用，能进一步降低起始流速，提高低速水流能量采集效率。本项目以高效低速水流能量采集为目标，利用尾流驰振和压电效应，设计新型低速水流能量采集器。结合非线性动力学理论和循环水槽试验研究，开展基于尾流驰振的低速水流压电能量采集器非线性流固电耦合建模、动力学稳定性分析和能量采集性能研究。探索基于尾流驰振的低速水流压电能量采集器分岔机理，提出稳定性判断准则，降低能量采集起始流速。揭示尾流干扰、流固耦合和力电耦合对系统非线性动力学特性和能量采集性能的影响规律，提高低速流体能到振动能以及振动能到电能的转化效率。本项目研究将为高效低速水流能量采集器设计提供理论依据，对促进新型水能发电技术的发展具有重要意义。

利用流致振动中的结构驰振现象将低速流体能转化为振动能，通过驰振能量采集，开发海流和江河流等低速水流清洁能源，满足远程控制领域的无线传感供能需求。相比恒流驰振，尾流驰振由于来流涡扰动对结构振动的增强作用，能进一步降低起始流速，提高低速水流能量采集效率。本项目以宽速高效流致振动能量采集为目标，在悬臂梁式压电能量采集器结构优化方面取得创新，主要包括上游障碍尾流驰振下的能量采集，上下游障碍共同作用下的能量采集，上下游障碍刚性配置和弹性配置下的能量采集。同时，通过拓扑等效优化提升了传统钝体的动力学性能，还受到自然界中鱼尾流体动力学和导线覆冰振动增强现象提出新型截面钝体已降低提高采集效率并降低起振流速。基于所设计的新型能量采集器，项目中通过Hamilton原理和Gauss定律建立了采集系统的机械控制方程和电控制方程。针对驰振和尾流驰振效应，分别建立了水流介质和气体介质作用下钝体的动力学公式。引入Galerkin离散对控制方程降阶，利用等效结构的思想得到机电力耦合的系统控制方程。基于实验现象和验证模型，探索了障碍物尾流驰振作用下能量采集器的振动特性，包括系统共振和霍普夫分岔等。借助数值模拟，分析了驰振和尾流驰振作用下流场涡态、流速和压力变化情况，有效的发掘系统振动的优化机理。在此基础上，本项目还探讨了两种应力均匀分布的变截面悬臂梁、外接电路中配置大电容实现系统电阻尼、压电电磁协同和环境温度对能量采集器的影响，并通过相应的数学模型分析了系统参数对采集性能的影响。

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