Analyzing the Impact of a Curved Stator on the Performance of a Savonius Wind Turbine using Computational Fluid Dynamics

Wind energy is a prominent renewable energy source, and Vertical Axis Wind Turbines (VAWTs) offer distinct advantages, including adaptability to changing wind directions and reduced noise levels. This paper conducts a numerical investigation into the impact of flat and curved stator blades on VAWTs, specifically the Savonius turbine, under ۲D, viscous, turbulent, and steady flow conditions. Four stator blade configurations were examined, including no stator blades, smooth stator blades, twisted stator blades (Case A), and both blades being concave (Case B). The study reveals that curved stator blades enhance VAWT performance, with Case B exhibiting the most efficient performance. The results show pressure distribution on the turbine blades is non-uniform, with high and low-pressure zones, predominantly on the windward side. The presence of stator blades enhances pressure on all turbine blades, with Case B exhibiting the most optimal pressure distribution. Detailed observation of streamline and velocity distribution reveals improved flow lines for Case B, leading to more effective turbine blade performance. Case B consistently produces the highest turbine torque, with a maximum value of approximately ۲.۱ N·m achieved at Re = ۱۵۷۵۰. The torque demonstrates a positive correlation with increasing Reynolds numbers.  The study further introduces a non-dimensional torque ratio analysis, where Case B attains ۷.۵۹ times higher torque than the reference case at Reynolds number ۱۵۷۵۰. The sensitivity of torque increase with respect to Reynolds number change highlights that Case B (with a slope of torque increase at around ۴.۵e-۰۴)  is the most responsive within the studied Reynolds number range.

Keywords:

Aerodynamics , Savonius , stator , Wind Turbine