Two-dimensional fluid-structure interaction analysis of a vertical axis tidal turbine blade using periodic inflow equivalence model

Fluid structure response of vertical axis tidal turbine blades using NACA 0012 and periodic inflow equivalence model are predicted in this work. The response is investigated numerically by developing a two-dimensional computational fluid dynamics model at high Reynolds number (3.07x10(6)). The Periodic Inflow Equivalence Model is conducted by modeling the rotation of the turbine as a time-dependent incoming fluid velocity magnitude and angle of attack current entering the two-dimensional computational fluid dynamics domain. The blade response is modeled by a vibrational system with spring damper components which are attached at the blade fluid dynamic center point. The aim of this study is to predict a resonant condition or a lock-in frequency induced by wake generation at a vertical axis turbine blade during the turbine operation. The model is generated using a dynamic mesh construction in OpenFOAM 2.2, and the mesh is refined using snappyHexMesh utility. The mesh has seven added boundary layers around the blade surface and simulated using k- shear stress transport turbulence model. Drag, lift, and moment force coefficient are observed during 12s, which is equal to 3.3 revolutions, and extracted using fast Fourier transform method to obtain its predominant frequency. The predominant frequency determines the dynamic condition of the blade and is used for predicting a resonance based on the turbine's natural frequency. The result shows that the vertical axis tidal turbine which is manufactured from a composite material with pitch stiffness of 200(Nm)/rad, heave stiffness of 1000N/s, and operates at tidal velocity of 0.656m/s is found to experience a resonance or lock-in phenomena induced by wake generation in the pitch mode response.