Simulation based analysis of morphing blades applied to a vertical axis wind turbine

Abstract

This study compares the performance of a Vertical Axis Wind Turbine with and without using morphing blades. It also presents a Computational Fluid Dynamics (CFD) modeling methodology to morph a blade while performing a rotational movement by using a combination of overset meshes and deforming meshes. The flow is simulated by solving the Unsteady Reynold Averaged Navier Stokes equations with Menter’s SST k-omega as the turbulence model. Proper care is taken to capture the presence of dynamic stall and vortex shedding that appears during the blade’s rotation, which is associated with a reduction in power output. The accuracy is verified and validated by comparing simulation results with experimental data, as well as testing for grid and time step sensitivity. The power coefficient curves obtained from simulating three different airfoils, a NACA0012 and two cases delimiting the maximum deformations of the trailing edge, are analyzed. A final proposed morphing scenario is tested, where the blade morphing is applied during a portion of the rotation to prevent dynamic stall. The morphing approach resulted in an improvement of 46.2% of the overall power output.