翼型颤振压电俘能器的输出特性研究

压电俘能器能够为自然界中低功率的微机电系统持续供能. 为了模拟机翼的沉浮?俯仰二自由度运动和有效俘获气动弹性振动能量, 本文提出一种新颖的翼型颤振压电俘能器. 基于非定常气动力模型, 推导翼型颤振压电俘能器流?固?电耦合场的数学模型. 建立有限元模型, 模拟机翼的沉浮?俯仰二自由度运动, 获得机翼附近的涡旋脱落和流场特性. 搭建风洞实验系统, 制作压电俘能器样机. 利用实验验证理论和仿真模型的正确性, 仿真分析压电俘能器结构参数对其气动弹性振动响应和俘获性能的影响. 结果表明: 理论分析、仿真模拟和实验研究获得的输出电压具有较好的一致性, 验证建立数学和仿真模型的正确性. 仿真分析获得机翼附近的压力场变化云图, 表明交替的压力差驱动机翼发生二自由度沉浮?俯仰运动. 当风速超过颤振起始速度时, 压电俘能器发生颤振, 并表现为极限环振荡. 当偏心距为0.3和风速为16 m/s时, 可获得最大输出电压为17.88 V和输出功率为1.278 mW. 功率密度为7.99 mW/cm3, 相比较于其他压电俘能器, 能实现优越的俘获性能. 研究结果对设计更高效的翼型颤振压电俘能器提供重要的指导意义. 

OUTPUT CHARACTERISTICS INVESTIGATION OF AIRFOIL-BASED FLUTTER PIEZOELECTRIC ENERGY HARVESTER

Piezoelectric energy harvesters can persistently drive the low-power micro-electromechanical systems in the natural environment. For simulating two degrees of freedom plunge-pitch motions of the airfoil and harvesting effectively the aeroelastic vibration energy, this paper proposes a novel airfoil-based flutter piezoelectric energy harvester. Based on the unsteady aerodynamic model, the mathematical model of the fluid-structure-electric coupling fields of the airfoil-based flutter piezoelectric energy harvester is derived. The finite element model is established to simulate the two degrees of freedom plunge-pitch motions of the airfoil and obtain the vortex shedding and flow field characteristics around the airfoil. A wind tunnel experimental system is designed and the prototype of the piezoelectric energy harvester is fabricated. The correctness of the mathematical and simulation models is verified by using the experimental method, and the determined effects of structural parameters of the piezoelectric energy harvester on its aeroelastic vibration response and harvesting performance are analyzed numerically. The obtained results show that the output voltage obtained from theoretical analyses, simulation analyses and experimental investigation demonstrate the good consistency, which verifies the correctness of the mathematical and simulation models. The simulation analyses demonstrate that the changed pressure fields around the airfoil can be obtained, which indicate that the alternated pressure difference drives the airfoil to take place two degrees of freedom plunge-pitch motions. When the airflow velocity exceeds the flutter onset of one, the piezoelectric energy harvester takes place the flutter and occurs the limit cycle oscillations. When the eccentricity is 0.3 and the airflow velocity is 16 m/s, the maximum output voltage is up to 17.88 V and the corresponding output power is 1.278 mW. The power density is up to 7.99 mW/cm3, which achieves the superior harvesting performance over other. The research results provide an important guidance for further designing more efficient airfoil-based flutter piezoelectric energy harvesters.