Performance of galloping piezoelectric energy harvesters

A galloping piezoelectric energy harvester is composed of a cantilevered piezoelectric beam and a tip bluff body. Self-excited vibration is induced when the tip bluff body is subjected to airflow. Then, the piezoelectric materials can convert the mechanical energy into electrical energy. In this article, a coupled aero-electro-mechanical model is developed to analyze a galloping piezoelectric energy harvester. A dimensionless formulation is adopted so that it is very convenient to conduct scaling and performance comparison of different galloping piezoelectric devices. Analytical approximate solution approach is employed to solve these coupled nonlinear equations using the Krylov-Bogoliubov method. Tip bluff body is assumed to have either rectangular or square section. System parameters such as galloping velocity, limit cycle oscillation amplitude, and harvested energy are determined accordingly and presented in an explicit form. Performances of galloping piezoelectric energy harvesters with different tip bluff bodies and electrical loads are characterized. In addition, experimental data are used to validate our predictions with good agreement. The galloping piezoelectric energy harvester having square section shows better performance compared to the one with rectangular section. Furthermore, the performance can be substantially improved by exploring the inherent jump phenomenon as observed in the limit cycle oscillation hysteresis response of a galloping piezoelectric energy harvester with square bluff body.