Performance improvement of Savonius rotor using multiple quarter blades - A CFD investigation

Savonius rotor is preferred for many power generation applications like tidal, wind and hydro, especially on a small scale by virtue of its simple and inexpensive construction, installation and maintenance. Present study is focussed on the estimation and comparison of the performance in terms of Coefficient of Performance (COP) of a new configuration of Savonius rotor with the conventional one, using numerical simulation approach. New configuration comprises multiple quarter blades added to conventional configuration. A methodology for the numerical simulation of Savonius rotor is developed and validated, that can be employed for comparative study of different design configurations for design based optimization of Savonius rotor. Accuracy of the simulation results, despite of correct methodology, is dependent on accurate estimation of turbulence and meshing parameters. Present work employs Shear Stress Transport (SST) model for modelling turbulence which incorporates the near wall fluctuation capturing capability of k-ω model and robust k-ɛ model for modelling the bulk domain. Meshing parameters include correct estimation of first layer thickness for boundary layer on the blades based on the desired y+ value. An improvement in Coefficient of Performance ranging between 8.89% and 13.69% for different inlet velocities is observed for new configuration over the conventional configuration.