Performance improvement of the Savonius turbine using a novel augmentation device with the Taguchi optimization method

This paper proposes a new augmentation device to improve the coefficient of power (Cp) of a Savonius turbine using a computational fluid dynamics method. The device is a rotating cylinder synchronized with a rotating turbine using a timing belt mechanism without needing any external power source. Unlike conventional flow deflectors, the device is not placed in front of the turbine. Instead, it is placed parallel to the turbine position. The optimum device diameter and position are determined using the Taguchi optimization method. The device diameter and its position (lateral distance, longitudinal distance, and location; left and right) are selected as controllable process parameters and the Cp as the performance output. The Taguchi L-16 orthogonal array is selected as the design of experiment. From the Taguchi analysis, the optimum device parameter improves the Cp by up to 0.3877 at a tip speed ratio (TSR) of 0.9, a 55.64% improvement relative to the case without the device. The highest Cp achieved is 0.4450 at TSR 1.1 with an 83.73% improvement relative to the case without the device. Analysis of variance results suggest that the Cp is greatly influenced by both the device diameter and lateral distance. The proposed device improves the overall performance of the Savonius turbine over a wide range of TSR.