Projeto de uma turbina eólica de eixo vertical tipo H para teste em túnel de vento

Abstract

The present work develops a complete design of a H-type vertical axis wind turbine, based on the hydrodynamic model of multiple stream tubes in association with an optimization algorithm, to determine rotor geometries that operate in the optimal energy production condition. The main objective is to design an optimized scaled rotor to be tested in a wind tunnel, capable of withstanding the loads it will be subjected to in its maximum power coefficient condition. The project was carried out for a historical series of wind data (40 years) obtained from the meteorological station OMM:08798 (Latitude: -7.1°; Longitude: -34.86°), located in the Solar Energy Laboratory (LES/ UFPB), João Pessoa/PB, Brazil. Since the dimensions and operational conditions of the wind tunnel where the rotor will be tested are limited (Hydraulics Laboratory - CT/UFPB), similarity analyzes have restricted the dimensions/operating conditions to a free stream velocity in the tunnel of 15.89 m/s and 25 W of wind power extraction. Under these conditions, adopting a NACA 0025 aerodynamic profile for the blade profile, a 3-blade rotor with aspect ratio 2, a reduced-scale rotor was obtained, with the following characteristics: solidity = 0.45, rotor radius = 0.159 m, rotor height = 0.318 m, airfoil chord = 23.9 mm and rotation speed = 3,243.8 rpm. For this geometry, the maximum power coefficient achieved was Cpmax = 0.29 at the tip speed ratio λmax = 3.4. For tests in the wind tunnel, the rotor blades were constructed from 3D printing using PLA (Polylactic Acid). In a simplified, considering the rotor's inertial efforts and the forces acting on the blades, its structural elements (shaft, blade-shaft connection rods and fasteners) were designed in 6351-T6 aluminum alloy. A 3D static structural computational analysis was performed using Mechanical APDL®/ANSYS software to verify if the projected structure would be able to withstand the efforts to which it would be subjected. Additionally, modal analyzes were performed in the same software to verify if the structure's natural frequencies would not coincide to the rotor operating frequency.