Experimental and numerical study on 2-DOF wind-induced vibration and energy harvesting of triangular prism

Abstract

The two-degrees of freedom (2-DOF) wind-induced vibration (WIV) response and energy harvesting performance of an equilateral triangular prism were conducted by numerical and experimental studies under different attack angles. The piezoelectric patch is applied in this work to extract power. To enhance the output power of the prism, an omnidirectional piezoelectric system is used to harvest energy in flow and cross flow directions simultaneously. It's found that the attack angle (α0) is a key factor influencing the power extraction performance of the system. The output power of the prism almost keeps around zero when 0° ≤ α0 ≤ 30° and increases monotonously with the increase of wind velocity for 30° < α0 ≤ 60°. Especially for α0 ≥ 55°, the power output experiences a rapid increase. The highest output power of 1.30 mW can be obtained when α0 = 60°. The WIV responses show that the amplitude in the direction perpendicular to incoming flow can reach 3.00b (b is the side length of the triangular cross section for the prism) when α0 = 60°. And the lock-in region can be observed in high reduced velocity range when 30° ≤ α0 ≤ 60°. In addition, due to the transition of vortex pattern from 2S to P + S for high attack angles, the unsteady aerodynamic loading acting on the prism results in strong WIV responses with high vibration amplitude, which then leads to the improvement of energy harvesting performance from WIV.