Estudo numérico de um conversor Coluna de Água Oscilante através do método Design Construtal

Abstract

Wave energy converting devices take advantage of the movement of water to generate electricity, converting potential and kinetic energy into electrical. The present work focuses on the study of an Oscillating Water Column (OWC) converter, which uses the vertical movement of the waves inside a semi-submerged chamber to obtain high speed air through a chimney, in which an electrical generator must be connected. A three-dimensional model of the OWC device, with a rectangular chamber and a cylindrical chimney, in a 1:15 scale, was investigated with the objective of maximizing the hydrodynamic efficiency from geometric variations, using the Constructal Design method. The problem was solved numerically with the Fluent software, which uses the Finite Volume Method, along with the Volume of Fluid model for multiphase flow. The parameters analyzed were the chamber submersion level (H3/h), ratio between the width of the chamber and the width of the computational wave tank (w/Z) and ratio between the height and the diameter of the chimney (H2/d). For the studied cases, the highest efficiency values were obtained when H3 ≈ h, W ≈ Z and H2 d. However, the pressure fields inside the device showed a symmetrical behavior along the width w, suggesting that, for the cases studied, the parameter w/Z had a low influence on the efficiency values. In contrast, geometric variations in the chimney (H2/d) showed more significant efficiency gains, a decrease in internal air recirculations and more uniform velocity and pressure fields. Among all the cases analyzed, the worst and the best efficiency values obtained were 0.14% and 49.85%, respectively.