Numerical Optimization of the Blade Profile of a Savonius Type Rotor Using the Response Surface Methodology

The present study aims to numerically determine the geometric proportions that maximize the performance of a Savonius rotor with a split Bach blade profile. For this, the response surface methodology was used through a full factorial experimental design, comprised of four factors corresponding to the width (C) and length (L) of the overlap, and the eccentricity (E) and radius (R) of the blade, which define the geometry of the rotor. The models built from the different treatments of the experimental designs were analyzed using computational simulations in order to obtain the power coefficient (C-P), considered as the response variable. The same parameters and models of computational fluid dynamics were used to analyze each geometry through the ANSYS Fluent software. The analysis of the obtained results showed that there is a great interaction among the evaluated factors, which demonstrates the importance of analyzing them together. The results obtained with the full factorial experiment design were compared with those obtained from a face-centered central composite design, evidencing a difference of only 0.30% in the estimate of the regression model. A C-P of 0.2661 was obtained from the optimized geometry, which represents a 36.50% increase in its performance with respect to the conventional semicircular profile. The optimal dimensions obtained are 4.69, 21.45, 5.52 and 25.15 in percentage values of the rotor diameter, for parameters C, L, E and R parameters, respectively. Experimental data available in the literature were used to contrast the numerical results and a good fit was revealed.