Optimization of a Flanged DAWT Using a CFD Actuator Disc Method

Abstract

For improving the efficiency of horizontal axis wind turbines, shrouded or ducted wind turbines have become state of the art research topics. Getting energy from a wind turbine more than the Betz limit is a great motivation for researchers. Recent Computational Fluid Dynamics (CFD) simulations and experimental techniques show the effects of dominant factors such as the length of the duct, the angle of the diffuser, the height of the flange. In the current study, a ducted wind turbine is simulated numerically combined with an Actuator Disc (AD) method. The first step is to find the maximum velocity in the duct by improving the angles of the flange to finalize the geometry of the duct. Then, the power of the bare wind turbine and the Diffuser Augmented Wind Turbine (DAWT) are compared numerically while an AD method is used for modeling the rotor of the horizontal axis wind turbine. For the numerical simulation, the \(K-\omega \) turbulent model is applied. For the 2D axisymmetric geometry, more than 0.5 million cells are used. The results show that the axial velocity can be enhanced more than 60%. The CFD analysis proves that the angle of the flange dominates the efficiency of the DAWTs and DAWT plays a key role in the enhancement of the power extraction of horizontal axis wind turbines. With a DAWT more power from a low wind speed can be extracted.