Resonator-Impregnated Monopile-Supported Wind Turbine System: An Experimental Investigation of Dynamic Vibration Control

This research investigated dynamic vibration control in a monopile-supported wind turbine system through strategically placed resonators along its length. Four configurations were analyzed: Case 1 (conventional wind turbine model), Case 2 (resonators in the turbine tower), Case 3 (resonators in the monopile), and Case 4 (resonators in both tower and monopile). Utilizing spectral element formulations, the dynamic stiffness matrix was derived for the wind turbine system, embedded in cohesionless soil with frequency-dependent viscoelastic springs. Analytical responses at the tower top and monopile head under dynamic harmonic excitation were computed, and transmittance was determined as the logarithmic ratio of responses to input excitation. Experimental dynamic tests were conducted on a 3D-printed wind turbine scaled model, yielding displacement responses at the tower top and monopile head. Comparison with analytically determined transmittance values reveals consistent agreement across four configurations. Case 4 demonstrates substantial response reductions, highlighting the efficacy of resonators in both tower and monopile. Transmittance plots indicate notable response reduction near resonant frequencies, showcasing local resonance phenomena. Furthermore, the tower and monopile head responses are substantially reduced when the excitation frequency surpasses the resonator's natural frequencies. This underscores the dynamic vibration control capabilities of periodically positioned resonators within the wind turbine scaled model. The research also explores the influence of parameters such as resonator mass ratio, soil shear modulus, and pile and tower slenderness ratio on transmittance plots.