Interaction of side-by-side piezoelectric beams in quiescent flow and grid turbulence

The interaction between two piezoelectric cantilever beams in quiescent flow under impact loading and in grid-generated turbulent flow has been studied in this paper. In our experiments, two identical PVDF beams were placed side-by-side and parallel to each other along the vertical plane. The voltages of both beams were measured in a ring-down test setting for different gap-to-beam width ratios. Subsequently, the setup was placed in a wind tunnel equipped with a passive grid and voltage measurements were recorded for different gap-to-beam width ratios at various distances from the grid in three flow cases. For the impact loading in a quiescent flow case, a pulse forcing model was used to capture the output of the transmitting and receiving beams for the smallest beam gap case using a combination of experimental observations and trial and error. The forcing model was subsequently applied to larger gap cases through a force ratio r. The force ratio results for different gap widths indicate that the aerodynamic coupling between two beams in quiescent flow is highly sensitive to change in the gap-to-beam width ratio, especially when the gap width is less than the beam width. For the grid turbulence case, the average plot contours indicate that, for the three flow cases considered, the presence of one beam next to another enhances the energy harvesting process by up to 2000% per beam compared to the case where a single beam is placed in the flow, potentially improving the viability of employing these non-resonant harvesters in real-world applications.