Abstract
Oscillating water column (OWC) axial impulse turbines permit the conversion of wave energy into electrical power. Unlike other hydropower units with a mature and well established technology, such turbines have been recently developed, there are still few prototypes operating and therefore there is a large space for optimizing its design. Many recent studies focus on the improvement of the efficiency and transient characteristics by means of experimentation and also simulation techniques. In the present paper we use a 3D numerical simulation model (computational fluid dynamics model with ANSYS-Fluent 18) to analyze the influence of different geometrical parameters on the efficiency of the turbine, which have been less discussed yet. A reference configuration case has been used to validate our simulation model by comparing it with previous experimental results. Then, parametric variations in the guide vane number and type, gaps between the rotating and stationary part and hub to tip ratio have been introduced in the model to discuss the influence of these effects. It is found that some of these parameters have an important influence on the efficiency of the turbine and therefore, the results presented in this paper can help to optimize future designs of OWC impulse turbines.
Highlights
Oscillating water column (OWC) is a method to transform wave energy of the seas and oceans [1,2]into useful energy, such as electricity
In this paper we determine the influence of relevant design parameters on the steady flow efficiency of an impulse turbine for OWC, whose performance has been experimentally analyzed in the past
While computational fluid dynamics (CFD) simulation models combined with the genetic algorithm have been recently used for a multiple optimization of several parameters at the same time [20], the analysis of every single parameter separately gives another perspective to the optimization problem, closer to the physical point of view
Summary
Oscillating water column (OWC) is a method to transform wave energy of the seas and oceans [1,2]. In the work of Maeda et al [7] and Setoguchi et al [5] the effect of the guide vane angle θ on the efficiency of the turbine is discussed, showing that this parameter that greatly affects the performance. In the work of Thakker and Dhanasekaran [16] the turbulence model k − ε is used to analyze the same effect In this case they found that for smaller tip clearances the efficiency is higher for values of T/lr smaller than 0.25% no improvement of the performance is observed. In this paper we determine the influence of relevant design parameters on the steady flow efficiency of an impulse turbine for OWC, whose performance has been experimentally analyzed in the past. We evaluate the influence of the guide vane number, which has not been previously discussed
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