Numerical Investigation of Wake Phenomenon for 2-bladed and3-bladed Tidal Current Turbines

In this paper, the effect of wake phenomenon on the performance of 2 and 3 bladed tidal current turbines have been investigated. Computational fluid dynamics analysis using ANSYS-FLUENT has been conducted. Initially, turbines were evaluated at the different values of the tip speed ratio and the maximum power coefficient was estimated. Then, the wake distance was evaluated for this maximum power coefficient. Results showed that at the tip speed ratio of 5, the maximum power coefficient for both turbines was achievable which were 0.35 and 0.28 for a 3 and 2-bladed turbines, respectively. Also, the wake phenomenon in 2-bladed turbine terminated earlier than 3-balded, so that; at a distance after the turbine which was equal to the thirteen times more than the turbine diameter, the flow velocity returned to 87% and 81% of initial flow velocity for 2 and 3-bladed turbines, sequentially. Considering the results, 3-bladed turbines are justified to use when there is no restriction for the area of the tidal farm while the maximum power extraction is the main objective. Conversely, 2-bladed turbines seem to be more appropriate where the tidal farm area is the particular of importance.