In the quest of an appropriate turbulence model for analyzing the aerodynamics of a conventional Savonius (S-type) wind rotor

For over two decades, the quest for decentralized electric power generation has stimulated much research interest into the Savonius (or S-type) wind turbine rotors. To enhance their efficiency, the operating parameters have already been examined by various numerical and experimental techniques. While most researchers have focused on using selected turbulence models to arrive at some meaningful conclusions and recommendations, no study analyzing a range of turbulence models in a systematic and comprehensive manner is reported. This study thus aims at conducting 2-D unsteady numerical simulations of a conventional semicircular-bladed Savonius rotor using six different turbulence models, viz., standard k-epsilon, realizable k-epsilon, RNG k-epsilon models, standard k-omega and shear stress transport (SST) k-omega, and transition SST (TSST) turbulence models. The simulations are performed by commercial finite-volume method solver ANSYS Fluent 17.1 at a fixed Reynolds number (Re) of 1.23 x 10(5) based on the rotor overall diameter. This study demonstrates the prediction capabilities of realizable k-epsilon, RNG k-epsilon, SST k-omega, and TSST models more accurately than those of other models. However, due to higher computational cost associated with TSST model, the use of realizable k-epsilon, RNG k-epsilon, and SST k-omega models for predicting the aerodynamic performance of other developed and to-be-developed profiles of Savonius rotor is recommended.