Simulation and 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 capabilities applied to its blades. It also explores the feasibility of applying moving mesh to model the morphing capability inside the software package STAR CCM+© in order to use Computational Fluid Dynamics (CFD) to analyze the flow’s behavior. Particularly it is important to capture the presence of dynamic stall and vortex shedding at certain regions over the blade’s path, which are associated with a decreased in the overall power coefficient. This work developed a methodology to analyze these morphing capabilities when applied over airfoils in 2D simulations, by using a combination of overset meshes and the morphing approach. The accuracy is verified by creating a baseline scenario and compare it against a benchmark case, while also testing for grid and time step sensitivity. The use of Reynold Averaged Navier Stokes equations was chosen, with Menter’s SST k-omega as the turbulence model. Afterward, a maximum power coefficient curve was plotted by testing three airfoil’s shapes as references, one forming the baseline case, while the other two delimiting the maximum deformation, marked as outward and inward cases. A final optimized case was tested, where the morphing was applied to strategic regions where the dynamic stall was highest, and where the shapes could ensure the maximum possible power output. This resulted in an improvement of 46.2% of the overall power coefficient.