Comparison of computational fluid dynamics and fluid structure interaction models for the performance prediction of tidal current turbines

Abstract

CFD models perform rigid body simulations and ignore the hydroelastic behavior of turbine blades. In reality, the tidal turbine blades deform due to the onset flow. Deformation of the turbine blade alters the angle of attack and pressure difference across the low pressure and high pressure surface of the blade. Therefore, the performance of a Tidal Current Turbine (TCT) is modelled in this study using Computational Fluid Dynamic (CFD) and coupled Fluid Structure Interaction (FSI) simulations to compare the predictions of both models. Results of the performance parameters predicted from both the models are also compared with experimental data. The difference between experimental value of CP and predicted value from the rigid blade CFD and FSI models is less than 10%. The FSI model accounted for the blade deformation and a maximum blade tip deflection of 0.12 mm is observed representing a case of small deformation. The extent of deformation is not enough to alter the angle of attack and flow separation behavior at the blade. The variation in predicted pressure difference across the blade surfaces between the two models resulted in different CP prediction. Almost similar wake predictions are obtained from both the models.

Keywords

• Tidal turbine
• Coupled FSI
• CFD
• Performance
• ANSYS Wokbench
• ANSYS CFX