Three-dimensional effects on the performance of a vertical axis tidal turbine

In this paper, 3-D effects on the performance of the Hunter turbine have been investigated by means of numerical simulations. It was observed that there is always a performance gap between results from 2-D and 3-D models. However, with increasing aspect ratio, the uniformity of the turbine performance along the entire span was effectively improved. Moreover, at higher flow coefficients, the pressure distributions of all turbines had similar profiles. A correction factor is defined that is related to the turbine height as well as the diameter. With the aid of this definition, the performance results for all Hunter turbines equipped with six blades could be collapsed into a single relationship with flow coefficient. It was also found that the overall level of torque fluctuation in the 2-D model is far less than those in 3-D models, while the 3-D torque fluctuation decreases with increasing aspect ratio.

► We investigate 3-D effects on the performance of the Hunter Turbine.
► There is difference between results from 2-D and 3-D models.
► Combined characteristic length is proposed to account for the effects of aspect ratio.
► The torque fluctuation in 2-D model is far less than those in 3-D models.