Banca de QUALIFICAÇÃO: Maurício Vitali Mendes

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Maurício Vitali Mendes
DATE: 25/08/2023
TIME: 14:00
LOCAL: Plataforma Teams
TITLE:

TLCD Passive and Semi-active Vibration Control of Offshore Wind Turbines Monopile under Random Hazards.

KEY WORDS:

Random Vibrations; Vibration Control; TLCD; Offshore Wind Turbines; Soil-Structure Interaction.

PAGES: 79
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

This work presents a study of passive and semi-active control for t structural vibrations of an offshore wind turbine in a monopile subject to random wind and wave forces. For passive control is considered the TLCD (Tuned Liquid Column Damper) with water in the U-shaped reservoir, while the semi-active device considered is the MR-TLCD. TLCD with the magnetorheological fluid contained in the reservoir. The study of the random vibration control problem explored in the thesis begins by considering the passive TLCD with water in the reservoir, with the numerical model of the structure by beam finite element from EulerBernoulli theory, the fluid-structure interaction between the monopile and the seawater by the additional mass, and the soil-structure interaction through the simplified model of coupled springs model. Before evaluating the damper performance, a parametric study of the optimal TLCD is conducted. The genetic algorithm method is employed, where the passive TLCD positioned in the nacelle has its parameters optimized to reduce the wind turbine response in terms of fore-aft displacements at the top of the tower. The results of the optimal parameters of the device are compared to the parameters computed by numerical search methods through response maps. From the stochastic analysis of the structure response the optimum tuning ratio and the equivalent proportional damping ratio are determined so that the tuned liquid column damper has the highest efficiency, that is, the smallest displacement at the top of the tower. The parameters of the attenuator obtained by both optimization methods show differences of less than 0.5%. Subsequently, with the use of the genetic algorithm a parametric study of the optimal passive TLCD installed in the OWT is performed considering the random excitation of the wind and wave forces in the structure and the wind forces in the rotor (Kaimal, JONSWAP and rotationally sampled PSD, respectively). The optimal parameters of passive TLDC have a direct relationship with the considered spectrum and the FRF (frequency response function) of the turbine with the attached damper. Both (force and FRF) should be considered for the passive liquid column optimization process. With the optimal parameters of passive TLCD determined by the parametric study, the control of displacements at the top of the standard OWT is presented. The fore-aft oscillation at the top of the tower with a passive TLCD coupled to the nacelle presents a significant reduction for the different dynamic actions.

COMMITTEE MEMBERS:
Externo à Instituição - GINO BERTOLLUCCI COLHERINHAS - UFG
Externo à Instituição - GUILHERME ROSA FRANZINI - USP
Interno - ***.843.298-** - JOSE LUIS VITAL DE BRITO - UnB
Presidente - 404485 - LINEU JOSE PEDROSO