Characterization of Tidal Current Turbine Dynamics Using Fluid Structure Interaction (FSI)

Abstract

Global climate change is one of the greatest challenges faced by the humanity. There is a growing awareness among the world population about the need of reducing the greenhouse gas emissions. This in fact, has led to an increase in power generation from renewable sources. The tidal current energy has the potential to play a vital role in a sustainable energy future if the applicable technologies are developed. The main objective of this paper is to investigate the horizontal axis tidal current turbine (HATCT) dynamics using fluid structure interaction (FSI) modeling. Vibration in tidal current turbine is produced due to hydrodynamic forces. The vibration causes resonance and dynamic loads on the structures which leads to failure of the structures. To prevent the TCT from failure and to increase the annual energy production its dynamic analysis is important. In order to achieve this aim a number of key steps were performed. Using computational fluid dynamics (CFD), flow passing through the turbine rotating in a rectangular channel was modelled. The National Renewable Energy Laboratory (NREL) developed code HARP_Opt (Horizontal Axis Rotor Performance Optimization) was used for Blade element momentum (BEM) Design of turbine in support of CFD. The pressure exerted on the turbine blade modelled in CFD was transferred to finite element model (FEM) through Fluid structure interaction (FSI) module in Ansys. Transient structural analysis module of the Ansys work bench was used to investigate the structural response of tidal current turbine. The modal analysis, pre-stressed vibration analysis and forced vibration analysis were performed for the structural response of tidal current turbine. The performance curves obtained from CFD and BEM showed a very good match. The modal analysis showed that neither of the natural frequency is critical and it is expected that the structure of the designed turbine is not prone to resonance. The techniques used in the research provided excellent results that will be crucial in understanding the physics governing the operation of Tidal current turbine (TCT) in tidal currents.