Assessment of icing effects on the wake shed behind a vertical axis wind turbine

Abstract

To shed light on the effect of the icing phenomenon on the vertical-axis wind turbine (VAWT) wake characteristics, we present a high-fidelity computational fluid dynamics simulation of the flow field of H-Darrieus turbine under the icing conditions. To address continuous geometry alteration due to the icing and predefined motion of the VAWT, a pseudo-steady approach proposed by Baizhuma et al. [“Numerical method to predict ice accretion shapes and performance penalties for rotating vertical axis wind turbines under icing conditions,” J. Wind Eng. Ind. Aerodyn. 216, 104708 (2021)] was implemented, which enables the utilization of appropriate approaches for handling turbine rotation and turbulence prediction for each solver. Proper orthogonal decomposition (POD) was utilized to perform a deep analysis of the wake and aerodynamics of the wind turbine for the clean and iced turbines with large eddy simulation turbulence method. Icing causes the leading edge vortex and trailing edge vortex to separate faster than the clean case resulting in a steeper drop in the power coefficient. As for POD modes, those of the streamwise component of velocity illustrated more difference in the amount of modal energy especially at the first modes proving that the icing phenomenon mainly affects the vortex shedding of the flow structures with larger energy and size. The modes of the transversal component of velocity of the clean and iced cases demonstrated more similarity in essence, which could also be understood from the accumulated energy curve.