Energy Harvesting from the Vortex-Induced Vibrations of Bluff Body Oscillators

<p>Vortex-induced vibration (VIV) of bluff bodies provides an effective mechanism for harvesting energy from fluid flows. Yet, the complex fluid-structure interactions governing vibration amplitude, synchronization, and energy transfer in single and coupled oscillators remain only partially understood, limiting the optimization of such systems for energy generation. This study presents a comprehensive experimental investigation into how bluff-body geometry, array configuration, and structural parameters influence the VIV response of elastically mounted oscillators. The goal was to identify the governing parameters that maximize vibration amplitude and improve energy-harvesting efficiency. For a single circular cylinder, vibration amplitude and lock-in bandwidth were found to depend primarily on the mass ratio, stiffness, and cylinder diameter. Increasing mass reduced both peak amplitude and resonance velocity, whereas larger diameters – corresponding to lower mass ratios – produced stronger vibrations and broader lock-in ranges. End conditions were also crucial: endplates roughly three times the cylinder diameter suppressed spanwise flow and stabilized the wake, while endplates twice the diameter yielded the largest amplitudes by balancing aerodynamic enhancement with added mass effects. A predictive framework was developed to estimate the peak amplitude and corresponding reduced velocity. The critical-angle-of-attack model and Skop-Griffin correlation both showed strong predictive accuracy. A neural network model successfully captured the relationship between structural parameters and peak response velocity, revealing that end-confined configurations consistently reached similar peak reduced velocities, regardless of mass or damping, while open-end cylinders exhibited strong aspect-ratio sensitivity. Experiments on side-by-side cylinder arrays demonstrated that decreasing the gap ratio profoundly alters wake coupling and vibration behavior. Two interaction regimes were observed: weak and strong. In the strong-interaction regime, multiple coupled vibration modes – such as in-phase, opposite-phase, and phase-wandering – emerged, leading to up to a fourfold increase in amplitude and a threefold expansion of lock-in bandwidth, corresponding to roughly sixteen times greater energy potential. Tests with D-shaped cylinders revealed that bluff-body geometry strongly affects VIV behavior. Larger D-shapes exhibited significantly higher amplitudes and broader lock-in ranges, with the largest configuration reaching five times the amplitude of its circular counterpart. Overall, this work establishes a predictive and experimental foundation for the design of efficient, scalable VIV energy harvesters and provides insight into how geometry and coupling can be tuned for optimal flow-energy conversion.</p>

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Year dc:date.available

2026

Author dc:creator

• Fershalov, Andrei Y

Contributors dc:contributor

• Niell Elvin

• Vortex induced vibrations
• Energy Harvesting
• Flow-Structure interaction
• Bluff Body Oscillator
• Aerodynamic coupling
• Cylinder-oscillator arrays
• Coupled vibration modes.
• Aerodynamics and Fluid Mechanics
• Applied Mechanics
• Other Mechanical Engineering

Repository record dc:identifier

https://academicworks.cuny.edu/cc_etds_theses/1245

OAI identifier oai:identifier

oai:academicworks.cuny.edu:cc_etds_theses-2390