An immersed boundary-based large-eddy simulation approach to predict the performance of vertical axis tidal turbines. (18th July 2017)

• Record Type: Journal Article
• Authors: Ouro, Pablo; Stoesser, Thorsten
• Is Part Of: Computers & fluids. Volume 152(2017)
• Page Start: 74
• Page End: 87
• Publication Date: 2017-07-18
• Subjects: Vertical axis turbines -- Immersed boundary method -- Large-eddy simulation -- Direct forcing -- Tidal turbines -- Vortex-blade interaction; Fluid dynamics -- Data processing -- Periodicals; 532.050285
• DOI: 10.1016/j.compfluid.2017.04.003
• Languages: English
• ISSNs: 0045-7930

Abstract

Highlights: A LES solver is equipped with an IB method to predict the performance of VATTs. The method is validated with body-fitted models for a VATT in a laminar flow. Simulations of a VATT under turbulent flow confirmed the method's accuracy. LES-IB method results overcome RANS predictions with a closer match with experiments. Blade-vortex interaction visualisations highlight the complex flow around VATTs. Abstract: Vertical axis tidal turbines (VATTs) are perceived to be an attractive alternative to their horizontal axis counterparts in tidal streams due to their omni-directionality. The accurate prediction of VATTs demands a turbulence simulation approach that is able to predict accurately flow separation and vortex shedding and a numerical method that can cope with moving boundaries. Thus, in this study an immersed boundary-based large-eddy simulation (LES-IB) method is refined to allow accurate simulation of the blade vortex interaction of VATTs. The method is first introduced and validated for a VATT subjected to laminar flow. Comparisons with highly-accurate body-fitted numerical models results demonstrate the method's ability of reproducing accurately the performance and fluid mechanics of the chosen VATT. Then, the simulation of a VATT under turbulent flow is performed and comparisons with data from experiments and results from RANS-based models demonstrate the accuracy of the method. The vortex-blade interaction is visualised for various tip speed ratios and together with velocity spectra detailed insights into the fluid mechanics of VATTs are provided.