Asymmetric Wind Turbine Blades: Numerical Investigation of Wake Interactions for Rotors With Non-Identical Blade Loadings

The inner and outer regions of a wind turbine blade, known as the root and tip, produce powerful vortex structures in the helical vortex system that form the near wake region. Over time and space, these large vortex structures break down to smaller-scale turbulence, which characterizes the far-wake region. The presence of perturbation is one of the means to trigger a faster breakdown of the vortex structures. A faster breakdown of the vortices is considered favorable due to the so-called momentum entrainment from the boundary layer that in turn energizes the flow for the downstream turbines to extract more energy. In this research, we will demonstrate the effects of introducing rotor asymmetries in wake development and dynamics of tip vortex interactions in a cluster of two wind in-line turbines. Simulations are performed by representing wind turbine blades using the blade element method (BEM) based actuator line modeling and large eddy simulation (LES) technique is employed to solve the governing Navier-Stokes equations of motion. Our preliminary investigations suggest that introducing an asymmetry in the rotor can alter wake structures and their downstream development, causing a faster transition into the far wake leading to a higher power density.