基于共振声学放大原理的涡激振动自发电装置设计与试验

为实现从自然环境中自动获取清洁能源,并给无线传感器和通讯模块供电,基于涡激振动及共振声学放大原理,设计了一种压电自发电装置。首先对位于该自发电装置内的压电悬臂梁复合结构进行力学分析;其次基于计算流体力学数值方法,对绕流圆柱后附加不同板长条件下的流场动力学特性进行分析,以明确悬臂梁长度对脱涡频率和升力、阻力系数的影响规律。利用有限元软件ANSYS对压电悬臂梁复合结构的横向往复振动进行数值模拟,确定了复合结构的横向振动频率随板长L的变化规律。最后对位于该装置两侧的亥姆霍兹共振器的结构尺寸进行优化设计,以使流场的脱涡频率、压电悬臂梁复合结构的一阶横向振动频率和共振器的谐振频率达到一致,从而使压电发电装置产生共振并输出最大的电能。试验结果表明,涡激振动自发电装置在5 m/s的风速下可产生两相峰峰值为6.0 V的开路电压,且上述3个频率达到一致。4~6.25 m/s为该自发电装置的自锁风速区间,在此风速范围内,自发电装置均能产生较大的电压。

Design and Experiment of Vortex-induced Vibration Self-generating Device Based on Principle of Resonant Acoustic Amplification

In order to acquire clean energy from the natural environment and supply power to the wireless sensors and communication modules, a vortex-induced vibration self-generating device was designed based on the principle of vortex-induced vibration and resonant acoustic amplification. The device mainly consisted of a cavity, a cylinder, a piezoelectric cantilever composite structure, a base and two Helmholtz resonators. Firstly, mechanical analysis of the piezoelectric cantilever composite structure in the self-generating device was carried out. Secondly, based on the computational fluid dynamics method, the dynamic characteristics of the flow field of self-generating device under different plate lengths were analyzed. And the influence of length of cantilever beam on vortex frequency, lift and drag coefficient was clarified. The finite element software ANSYS was used to simulate the transverse reciprocating vibration of piezoelectric cantilever composite structure to finish the structural design. Finally, the structural dimensions of the Helmholtz resonator on both sides of the device were optimized to make the flow field vortex shedding frequency. And the first-order transverse vibration frequency of piezoelectric cantilever composite structure and the resonant frequency of the resonator was consistent. The experimental results demonstrated that the self-generating device can produce an open-circuit voltage with a peak-to-phase voltage of 6.0V at wind speed of 5m/s, and the above three frequencies were consistent. The experimental results also showed that the speed of 4~6.25m/s was the self-locking wind speed range of the self-generating device. Within the wind speed range, the self-generating device can produce the maximum voltage amplitude. The results of the study provided a reference for the structural design of the vortex-induced vibration self-generating device.