Systematic investigation of power enhancement of Vertical Axis Wind Turbines using bio-inspired leading edge tubercles

Abstract

Wind energy is employed as an effective source for catering to the increasing energy demands and depleting fossil fuels, while also counteracting their adverse environmental effects. VAWTs have numerous advantages over HAWTs. But, the relatively low power coefficient of VAWTs in comparison to HAWTs restricts their utilization. Bio-inspired leading-edge tubercles appear to be one of the potential design changes for enhancing the power performance of VAWTs. This study systematically investigated the relative influence of tubercle design variables and their geometrical trend subjected to power performance by employing a hybrid Design of Experiments (DoE) approach and Response Surface Methodology (RSM) rather than choosing random values of tubercle variables. Furthermore, the conflict existing in the literature about the improved or degraded power performance of VAWTS with tubercles is resolved by evaluating the power performance of VAWT at on-design and off-design conditions. For the computation of aerodynamic forces, unsteady Computational Fluid Dynamics (CFD) was utilized with a 4-equation transition SST turbulence model. Tubercle amplitude influences the aerodynamic efficiency of VAWTs relatively more than its wavelength. It is evident from the results that energy is harnessed efficiently at on-design conditions considering lower tubercle amplitude and higher wavelength. However, the reverse trend of variables is observed under off-design conditions. At on-design conditions, tubercles degraded the VAWTs performance in comparison to baseline VAWT configuration by a minimum of 13.55% among the 14 hybrid DoE generated cases, while the performance was enhanced by a maximum of 55% at off-design conditions of VAWT.