Navegando por Autor "Maciel, Rafael Pereira"

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Constructal design applied to an oscillating water column wave energy converter device subjected to a realistic sea state
(2022) Maciel, Rafael Pereira; Isoldi, Liércio André; Gomes, Mateus das Neves
This work presents a numerical analysis of an Oscillating Water Column (OWC) converter device, an ocean Wave Energy Converter (WEC) into electrical energy, using realistic sea state data. The main goal of this work is to perform a geometric evaluation of this device in order to define an optimal geometry to maximize its available hydrody- namic power. To do so, the WaveMIMO methodology was employed, which converts sea data from spectral wave model Tomawac into time series of free surface elevation, which is, then, appropriately treated and transformed into orbital velocity compo- nents of water particles. Tomawac obtained realistic sea state data from the coastal region of the city of Rio Grande, in the state of Rio Grande do Sul, Brazil, for the year 2014, which was used for the study case. In the numerical simulations, it was also em- ployed a methodology which uses transient velocity data as a means to impose velocity boundary condition for the generation of numerical waves. This methodology was validated reproducing a laboratory experiment with regular waves, which consisted of laboratory-scale OWC device inserted in a wave channel. To perform the geometrical evaluation of the device, the Constructal Design method is employed. The objective function is to maximize the available hydropneumatic power. The hydropneumatic chamber volume (VHC) and the total volume of the OWC device (VT ) are adopted as geometric constraints of the problem and were kept constant. Three degrees of freedom (DOF) are chosen for this study: H1 /L (ratio between height and length of the hydropneumatic chamber), whose values are varied, H2/l (ratio between height and length of the turbine duct) and H3 (submergence depth of hydropneumatic chamber), whose values were kept constant. Finally, the best device performance happened with geometry of H1 /L value of 0.1985 and presented a hydropneumatic power Phyd of 29.63 W. That is 4.34 times higher than the power obtained with the worst geometry performance, which was 6.83 W, obtained with the degree of freedom H1 /L value of 2.2789; and 2.49 times higher than the power obtained by the device with the same dimensions as those from the one in Pico island, which was 11.89 W. The contribu- tion of this study is to perform a geometric evaluation, with the Constructal Design method, of an OWC device subjected to realistic irregular waves from the wave climate of the coastal region of the city of Rio Grande, in the state of Rio Grande do Sul, Brazil, which is unprecedented in the literature.