Banca de DEFESA: Reginaldo Nunes da Silva

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Reginaldo Nunes da Silva
DATE: 30/08/2023
TIME: 14:30
LOCAL: Plataforma Microsoft Teams
TITLE:

Conversion of turbulence kinetic energy by horizontal-axis turbines

KEY WORDS:

turbulence, wind turbines, hydrokinetic turbines, wind tunnel, large-eddy simulation

PAGES: 120
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

Wind and hydrokinetic energy sources have great potential to meet global energy needs while helping to mitigate environmental problems. Among technologies for converting renewable energy, horizontal axis turbines are the most advanced. However, there are still gaps in knowledge when it comes to the influence of turbulence kinetic energy on energy conversion by horizontal axis turbines. This thesis aims to advance scientific knowledge regarding the mechanisms of conversion of kinetic energy of turbulence into mechanical energy, in horizontal axis rotors subjected to flows with high levels of turbulence intensity. Experimental studies were carried out in a wind tunnel and numerical simulations using Computational Fluid Dynamics (CFD). In the experiments, a cylinder was used upstream of the turbine to maintain average speed and change speed fluctuations in the rotor plane. The power of the wind tunnel fan was adjusted so that the average speed of the rotor plane with the cylinder was the same as in the experiments without the cylinder. The vortices generated by the cylinder concentrated kinetic energy from the turbulence at a specific frequency. In the numerical modeling, the Large Eddy Simulation (LES) technique was used and the same configurations of the experiments were computationally replicated. The average flow and the spectral of points upstream and downstream of the turbine with and without the cylinder were analyzed. In addition, a spectral analysis of the torque was performed and the entire power curve was determined with and without the upstream cylinder. An analysis of the kinetic energy transport of turbulence in the turbine control volume was also carried out. The results showed that the turbine converts kinetic energy from turbulence when it is transported by turbulent structures with a frequency equal to the turbine rotation frequency. When the frequencies are the same, there is a peak in the power curve (Cp), indicating the existence of a mechanism for converting turbulence kinetic energy into shaft power. The numerical analysis identified that this occurs due to pressure diffusion in the control volume during the interaction of the rotor with the large-scale structures that have the same turbine rotation frequency.

COMMITTEE MEMBERS:
Interno - 2126286 - ADRIANO TODOROVIC FABRO
Interno - 404142 - ANTONIO CESAR PINHO BRASIL JUNIOR
Externo à Instituição - CLAUDIO JOSE CAVALCANTE BLANCO
Externo à Instituição - JERSON ROGERIO PINHEIRO VAZ - UFPA
Presidente - 3375759 - TAYGOARA FELAMINGO DE OLIVEIRA