基于非线性涡激振动的宽频能量采集研究

As a representative of flow-induced vibrations (FIV), vortex-induced vibrations (VIV) for energy harvesting has great potential applications of powering microelectronic devices. The corresponding dynamical issues associated with mechanical-electronic-fluidic coupling are also of theoretical significance. Most previous researches on VIV energy harvesting have clear problems such as narrow resonant flow velocity range and low efficiency. This project creatively introduces the nonlinear magnetic force and investigates the nonlinear VIV energy harvesting, in order to widen the range of resonant flow velocity, arriving at broadband effect and enhancing the efficiency of energy harvesting. The main research work are: 1) According to the magnetic force tests, the nonlinear VIV energy harvesting theoretical model for the piezoelectric beam-cylinder structure is constructed, by taking into account of geometric nonlinearity due to deflection of the piezoelectric beam. 2) By solving eigenvalue problems, variations of the coupling frequency and damping will be analyzed. 3) The effects of magnetic forces with distinct characteristics (bi-stale, hardening and softening) on the vortex-induced vibration responses, transfer of lock-in region and complex dynamic behaviors are investigated in detail, focusing on revealing performance level of the harvester and exploring the optimal parameters and new strategy of VIV energy harvesting. 4) The experimental researches on nonlinear VIV energy harvesting are performed to compare with the theoretical results.

涡激振动作为一种典型的流致振动现象，其振动能量的采集利用在微电子产品的无线供能方面具有很好的应用前景，所涉及的力-电-流体耦合动力学问题的研究也具有重要的理论意义。以往的涡激振动能量采集方案存有明显不足：共振流速范围窄、俘能效率低。本项目拟研究非线性磁铁力作用下的涡激振动能量采集问题，力图寻求宽范围共振流速策略，达到宽频能量采集效果，以提高俘能效率。主要研究工作有：1）基于磁铁力实测数据，考虑压电梁变形引起的几何非线性，建立磁铁力作用下压电梁-圆柱体结构的非线性涡激振动能量采集理论模型；2）求解系统的特征值问题，分析结构的耦合频率和阻尼的变化规律；3）研究不同特性的磁铁力（双稳态、硬特性和软特性）对结构涡激振动强度、锁频区域转迁机制及复杂动力学行为的影响，重点探究磁铁力作用下涡激振动能量采集的优化方案和新策略；4）完成非线性涡激振动能量采集的模型实验，并与理论预测结果进行对比。

随着集成电路及微制造技术的迅速发展，大量的电子产品，如健康监测仪、无线传感器等显示出高精度、小型化和低功耗等特点。本项目提出的以振动能为基础的微能量采集研究可以为以上电子设备供电，实现自供电或零功耗等功能。首先设计了磁铁力下的非线性涡激振动实验，通过自由振动实验得到了系统的固有频率和阻尼系数，为下一步的理论建模做好铺垫，同时也可以很好的解释俘能结构在发生涡激振动行为时其锁频区域发生转迁的原因；其次完成了磁铁力作用下压电梁-圆柱体结构的非线性涡激振动能量采集的理论建模和控制方程的推导，根据磁铁势能特性，得到磁铁力随磁铁间距的变化规律。进一步得到磁铁的势能阱特征，即，单个平衡位置和两个平衡位置表现出来的单稳态和双稳态特性。基于以上相关研究内容，在Applied Energy, Energy, Journal of Sound and Vibration, Applied Physics and Letters等重要期刊上发表论文10余篇，授权发明和实用新型专利4项。研究的成果可以深化对压电梁-圆柱体这类结构非线性涡激振动机理的理解，为流体俘能器件的设计和工程应用提供理论基础和技术储备。