多稳态涡激振动能量收集系统高能轨道调控及宽频响应机理研究

Vortex-induced vibration energy harvesting is considered as an effective way to retrieve the kinetic energy of wind and water flow. However, there is still room for improvement in energy conversion efficiency of flow fields with low and variable speed. Converting the kinetic energy of flow field into electrical energy efficiently is a practical subject in urgent need of study. This project proposes a new multistable vortex-induced vibration energy harvesting structure and focuses on the application of nonlinear dynamics method in high energy orbit control and broadband response mechanism. An efficient and broadband vortex-induced vibration energy harvesting strategy is proposed and will be studied by means of dynamic modeling, theoretical analysis, numerical simulation and experimental verification. The chaos dynamics research method of multistable vortex-induced vibration energy harvesting system is developed and the mechanism of chaotic response is revealed by Melnikov theory. The parameter threshold of homoclinic bifurcation is predicted and the chaotic response above the parameter threshold is controlled to attain the high energy orbit so as to improve the energy conversion efficiency. The broadband response mechanism of the multistable vortex-induced vibration energy harvesting system is explained based on the theory of internal resonance and stochastic coherence resonance. The method of broadening the range of lock-in velocity will be presented and the influence law of structure parameters on the effect of broadband energy harvesting will be investigated to obtain the optimal structure parameters. The results of the project will not only provide a theoretical basis for understanding the dynamics of the multistable vortex-induced vibration energy harvesting system, but also provide theoretic foundations and experimental evidence for the efficient conversion of the kinetic energy of the low speed and variable speed fluid.

涡激振动能量收集可以实现风、水流等流体动能的有效回收，但是在锁频范围和收集效率方面仍然存在改善空间，将宽频的环境流场动能高效地转化为电能是实际应用中亟待研究的课题。本项目提出新型的多稳态涡激振动能量收集结构，聚焦于非线性动力学方法在高能轨道调控以及拓宽锁频范围的应用，通过动力学建模、理论分析、数值仿真和实验验证综合研究高效的涡激振动宽频能量收集策略。将发展多稳态涡激振动能量收集系统的混沌动力学研究方法，基于Melnikov理论揭示混沌发生机理，预测发生同宿分岔的参数阈值并调控参数阈值内的混沌响应至高能轨道，提高能量转化效率；还将阐明多稳态涡激振动能量收集系统的宽频响应机理，基于内共振以及随机相干共振理论提出拓宽锁频范围的方法，明确结构参数对能量收集效果的影响规律，获得优化的结构参数。项目成果不仅为多稳态涡激振动能量收集系统提供动力学理论基础，还为实现低速、变速流体动能的高效转化提供理论与实验依据。

环境振动，包括风、海浪以及机械振动等，都蕴含着大量动能。通过能量收集技术可以将环境中能量存储起来，从而解决一些低功耗传感器件的供能需求。为了克服常规能量收集装置频带较窄的不足，本项目聚焦于将多稳态非线性引入到能量采集结构，实现宽频、高效的能量输出。研究内容涉及结构的创新设计、非线性动力学定性与定量分析方法、随机振动和流固耦合实验方法。主要贡献包括：考虑磁铁的几何非对称性，设计并建立带有阶梯状势能函数的三稳态能量收集模型，提高了宽频环境激励下的收集性能；基于Padé逼近函数和Melnikov理论发展了多稳态能量收集系统的同宿分岔预测方法；利用磁力耦合软化结构刚度，降低了结构阻尼以及诱发驰振的切入风速；基于有限元方法，分析了钝头体对气动力以及流致振动能量收集的影响规律；结合理论和风洞实验探究了基础激励和驰振共同作用下双稳态能量收集系统的非线性动力学特性。以上研究完善了多稳态振动能量采集系统的非线性动力学建模、分析以及控制方法，优化了钝头体形状并揭示内在性能提升机理，相关成果将为提高流致振动能量转化效率提供一定的参考和借鉴。