The effects of blade twist and nacelle shape on the performance of horizontal axis tidal current turbines
Purimitla, Srinivasa Rao
Mohan Dass, E.T.
Date of Issue2017
Energy Research Institute @NTU
The paper presents the effects of blade twist and nacelle shape on the performance of horizontal axis tidal current turbines using both analytical and numerical methods. Firstly, in the hydrodynamic design procedure, the optimal profiles of untwisted and twisted blades and their predicted theoretical turbine performance are obtained using the genetic algorithm method. Although both blade profiles produce desired rated rotational speed, the twisted blade achieves higher power and thrust performance. Secondly, numerical simulation is performed using sliding mesh technique to mimic rotating turbine in ANSYS FLUENT to validate the analytical results. The Reynolds-Averaged Navier-Stokes (RANS) approximation of the turbulence parameters is applied to obtain the flow field around the turbine. It is found that power and axial thrust force from BEMT (Blade Element Momentum Theory) method are under-predicted by 2% and 8% respectively, compared with numerical results. Afterwards, the downstream wake field of the turbine is investigated with two different nacelle shapes. It is found that the rotor performance is not significantly affected by the different nacelle shapes. However, the structural turbulence caused by the conventional nacelle is stronger than that by the NACA-profiled shape, and the former can cause detrimental effect on the performance of the downstream turbines in tidal farms.
Tidal current turbine
Applied Ocean Research
© 2017 Elsevier Ltd. This is the author created version of a work that has been peer reviewed and accepted for publication by Applied Ocean Research, Elsevier. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [https://doi.org/10.1016/j.apor.2017.02.003].