深腔流激振荡特性研究及能量采集初步分析

针对深腔流激振荡现象的内部声场特性及其流体动能利用方法进行了研究,通过对谐振空腔内部的流场和声场进行数值模拟,探究腔体结构尺寸和流速对内部声振荡响应特性的影响,选用合适的空腔结构安装压电换能器初步实现声电能量转换过程,并进行实验验证。结果表明,当谐振腔开口尺寸H_(R)=30 mm,长度L_(R)=230 mm时,可在相当于高压输气管道的流速范围内获得属于第一水力模态和第一声学模态的稳定声振荡;当气体流速为32.26 m·s^(-1)时,声场压力振幅可达4.62 kPa;选用压电陶瓷厚度hp=1.0 mm的压电片进行实验测试,可得开路电压为1.99 V;实验结果与模型预测结果趋势一致。该方法丰富了环境流体动能的利用方式,且有望在低功耗、远距离、低维护等特殊场合的微型无线电子设备中实现无源供电。

Characteristics of flow-induced oscillation in deep cavity and preliminary analysis of energy harvesting

The acoustic characteristics of flow induced oscillation in deep cavity and the utilization method of fluid kinetic energy are studied. Through the numerical simulation of the flow field and sound field characteristics inside the resonant cavity, the effects of cavity structure size and flow rate on the internal acoustic oscillation response characteristics are explored. The appropriate deep cavity structure is selected to realize energy harvesting through the piezoelectric transducer. The effectiveness of the numerical model and calculation method is verified by experiments. The results show that the high acoustic pressure output of the first acoustic mode and the first hydraulic mode can be obtained in the flow rate range of the high-pressure gas transmission pipeline, by using a resonator with an opening diameter of 30 mm and a length of 230 mm. At a mean flow rate of 32.26 m·s^-1, a maximum pressure amplitude reaches 4.62 kPa. Under this model, the piezoelectric patch with h_p=1.0 mm is selected for test experiments, and the maximum open-circuit voltage is 1.99 V. The experimental results are consistent with the predicted results of the model, which fully shows the potential of flow induced oscillation in energy supply. This method not only enriches the utilization of environmental fluid kinetic energy, but also is expected to realize passive power supply in micro wireless electronic equipment on special occasions such as low power consumption, long distance and low maintenance.