Experimental and numerical investigation of the impact of turbulence on a small-scale double-stage Savonius vertical axis wind turbine in an open environment application

Abstract

This paper presents an experimental and numerical investigation of the impact of turbulence on a small-scale double-stage modified Savonius vertical axis wind turbine (VAWT) operating in an open environment. The study utilized wind tunnel experiments with free stream velocities of 4 ms⁻¹, 6 ms⁻¹, 7 ms⁻¹, 8 ms⁻¹, and 11 ms⁻¹. The power and torque coefficients were measured for various wind speeds, with significant observations noted at 7 ms⁻¹. Specifically, the maximum power coefficient (Cp) of 23 % was achieved for the modified Savonius turbine was at 7 ms⁻¹, which was found to be higher compared other wind speeds, demonstrating optimal aerodynamic performance. Controlled turbulence was introduced using a turbulence-generating mechanism, with turbulence intensities ranging from 10 % to 14 %. Numerical simulations were performed to validate the experimental results, and the findings revealed that turbulence intensity influenced the aerodynamic efficiency of the turbine blades, enhancing their performance in certain conditions. Notably, under turbulent conditions at lower wind speeds 4 ms^-1to 7 ms⁻¹, the torque coefficient increased from 0.24 and 0.15 under uniform flow to 0.40 and 0.44, respectively. At higher wind speeds 8 ms^-1and 11 ms⁻¹, a slight decrease in torque coefficient was observed due to the onset of turbulent flow effects. The study advances the understanding of the turbine’s performance in turbulent environments, particularly highlighting the importance of turbulence intensity for optimizing turbine design and efficiency in urban and complex wind conditions. These results provide valuable insights for designing wind turbines capable of operating efficiently in varied and dynamic wind environments.