CFD-Based Numerical Analysis of a Vertical Axis Wind Turbine
This research is a numerical investigation into the two-dimensional configuration of a Savonius vertical axis wind turbine (VAWT) using computational fluid dynamics (CFD). Transient analysis has been performed on this turbine using rotatable domains in COMSOL Multiphysics to capture the unsteady aerodynamic characteristics. A transient analysis was also performed using the incompressible Navier-Stokes equations to determine the following performance characteristics: velocity distribution; pressure distribution; torque generated by turbine; and acceleration of rotor. The results showcase how blade flow asymmetry between advancing and returning blades creates periodic vortex shedding patterns, and how the torque generated is also fluctuating. For the purpose of this analysis, the torque increases from near zero torque to approximately 0.45 N·m., while the angular velocity grows from 0 rad/sec (initially) to roughly 37 rad/sec (maximum velocity achieved) during the transient analysis. During the simulation, the rotor speed achieved during transient analysis is approximately 350 rpm, with a corresponding mechanical power value ranging from approximately 16 to 17 W. The results obtained from the transient analysis suggest that the flow separation and wake behaviour associated with unsteady states are critical to determining the overall turbine performance. Furthermore, the CFD model created through this investigation establishes a solid methodology for determining the performance of Savonius vertical axis wind turbines relative to predicted aerodynamic characteristics and design optimization criteria.