涡街提频振荡水柱驱动压电发电理论分析

海洋波浪能频率低(0.3～1 Hz),海浪进入振荡水柱气室压缩空气形成高速气流。在高速气流通道内放置绕流圆柱钝体,采用卡门涡街效应提高波浪能振荡水柱采集气室气压激振频率,实现高频驱动压电发电,提高海洋能量转换效率。推导波浪进入气室形成振荡的水气动力转换理论,计算了气室初级压强和流速。分析了低频高压气流经钝体形成卡门涡街高频涡流激振提频过程,计算出气压作用于钹型压电发电结构输出的电量。研究气体流速、钝体等系统参数与输出能量的关系。计算结果表明,周期为0.65～1.1 s的海浪进入气室经提频作用于钹型压电发电结构,稳定输出电能可达70～80 mW,为新型波浪能采集技术提供了理论基础。

Theoretical Analysis of Piezoelectric Power Generation Driven by Oscillating Water Column With Vortex Excitation Increasing Frequency

The frequency of ocean wave energy is low (0.3~1 Hz), and the high speed airflow is generated when the ocean waves enter the oscillating water column chamber to compress the air. A cylindrical blunt body is placed in the high speed airflow channel, and the Karman vortex street effect is used to increase the excitation frequency of the wave energy oscillating water column for collecting the air pressure in the air chamber, so as to realize high frequency piezoelectric power generation and improve the efficiency of ocean energy conversion. The water hydrodynamic conversion theory of waves entering into the chamber to form oscillation, and the initial pressure and floe velocity of the chamber are calculated. The frequency increasing process of Karman vortex street high frequency eddy current excitation formed by the low frequency and high pressure air flow passing through the blunt body is analyzed. The output power of the cymbal type piezoelectric generation structure driven by air pressure is calculated. The relationship between the system parameters such as gas velocity and blunt body and the output energy is studied. The calculation results show that the electric energy of 70~80 mW can be output steadily when the ocean wave with a period of 0.65~1.1 s enters into the air chamber and acts on the cymbal piezoelectric power generation structure after increasing the frequency. This study provides a theoretical basis for the new wave energy harvesting technology.