CONSTRUCTAL DESIGN OF AN ONSHORE OVERTOPPING DEVICE IN REAL SCALE FOR TWO DIFFERENT OCEAN WAVE PERIODS AND DIFFERENT AREAS OF THE RAMP
Jaifer Corrêa Martins1; Dante Vinícius Eloy Barbosa1; Marcelo Moraes Goulart1; Jeferson Avila Souza1; Luiz Alberto Oliveira Rocha2; Mateus das Neves Gomes3; Liércio André Isoldi1; Elizaldo Domingues dos Santos1
1 Universidade Federal do Rio Grande; 2 Universidade Federal do Rio Grande do Sul; 3 Instituto Federal do Paraná
doi:10.20906/CPS/CILAMCE2015-0197
Resumo
The study about technologies and operational principles of devices to convert wave energy into electrical one (WEC) has increased significantly. Among the studied WECs it is possible to mention the overtopping device. Its main operational principle consists on a ramp which guides the incoming waves into a reservoir raised slightly above the sea level. The accumulated water in the reservoir flows through a low head turbine generating electricity. In the present work it is performed a numerical study concerned with the effect of ramp geometry over the performance of an onshore overtopping device in real scale by means of Constructal Design. The purpose of this study is to evaluate the effect of the ramp volume fraction (fi) and the ratio between the height and length of the ramp (H1/L1) over the amount of water that enters into device reservoir for two different ocean wave periods (T = 5.0 s and 7.5 s). All cases are performed for one specific distance from the bottom of the tank to the bottom of device of S = 5.0 m. Moreover, three different ramp volume fractions are investigated: fi = 0.006, fi = 0.012 and fi = 0.024. For all studied cases the conservation equations of mass, momentum and one equation for the transport of volumetric fraction are solved with the finite volume method (FVM). To tackle with water-air mixture, the multiphase model Volume of Fluid (VOF) is used. Preliminary results showed that Constructal Design allowed an improvement of the shape of ramp. In general, the optimal shapes performed several times better than the worst ones. Results also depicted that the mass of water stored in the reservoir increased with the increases of wave period from T = 5.0 s to T = 7.5 s.
Palavras-chave: Constructal Design; Overtopping Device; WEC