Analysis and optimization of single and tandem bluff body configurations for enhanced flow-induced vibrations and energy harvesting potential

This study presents a comprehensive experimental investigation into the influence of bluff body geometry and spatial arrangement on flow-induced vibrations and their application for piezoelectric energy harvesting. Wind tunnel tests were performed on both single and tandem bluff body configurations, where unsteady aerodynamic forces excite a flexible cantilever beam integrated with a piezoelectric transducer. Utilizing a full factorial Design of Experiments (DOE) approach, the effects of bluff body shape—from sharp-edged cubes to fully rounded spheres—and longitudinal spacing on vibration amplitude and electrical output were systematically analysed. Results reveal that rounded geometries, particularly the spherical bluff body (C6), positioned at an optimal tandem spacing of 1.25 times the characteristic diameter (1.25D) upstream of the flexible beam, generate the highest root mean square (RMS) displacement and voltage output, reaching up to 25.12 V RMS. Statistical analyses quantify the significant contributions of both geometric configuration and spacing distance to the dynamic and electrical responses, highlighting the critical interplay between wake dynamics and structural vibrations. These findings offer practical insights for optimizing flow-induced energy harvesting systems, advancing the development of self-powered devices for applications in environmental monitoring and fluid-structure interaction-based technologies. This study, by integrating experimental validation with energy harvesting assessment and systematic analysis, aims to deliver a more holistic and practically relevant contribution. • DOE was used to study effects of bluff body shape and spacing on vibrations. • Rounded body (C6) at 1.25D spacing gave highest beam displacement and voltage. • Tandem bluff bodies boosted vortex-induced excitation and energy harvesting. • Geometry had major impact; spacing was key within similar configurations.