Experimental study of an oscillating water column converter to optimize nonlinear PTO using genetic algorithm

The characteristics of incident waves, draft depth, and orifice diameter significantly affects the performance of the OWC. This paper evaluated the hydrodynamic response of an OWC with nonlinear PTO imposed on the Caspian Sea wave conditions experimentally. Experimental tests have been done in two stages; first, considering the incident wave frequency constant in 0.4 Hz, two main variables, area ratio, and depth ratio, have considered optimizing the performance by genetic algorithm. The experiments for three area ratios of the orifice equal to 0.5%, 0.75%, and 2%, and the three depth ratio equal to 0.05, 0.14 0.33 have been done. The optimal values of the area and depth ratios are equal to 1% and 0.24, respectively. In the next step, the tests were carried out for a wide range of conditions of the Caspian Sea, and four area ratios and depth ratios, including the optimal values, repeated in the form of 800 tests. The results showed that the converter performance would be optimum for the other frequencies considering the optimal values. The optimal converter can generate 191W, while before the optimization, the highest recorded power was 132W, an increase of 45%. After optimization, the converter pneumatic efficiency has increased to 53.74%.