Iungo, Giacomo V.
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/4790
Giacomo Iungo is currently an Associate Professor of Mechanical Engineering and head of the WindFluX (Wind, Fluids, and eXperiments) Lab. His research interests include wind energy, flow instability, bluff body aerodynamics; atmospheric boundary layer, reduced order models; signal processing; wind tunnel design; experimental fluid mechanics; and wind LiDAR technology.
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Browsing Iungo, Giacomo V. by Author "Gallaire, F."
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Item Effects of Incoming Wind Condition and Wind Turbine Aerodynamics on the Hub Vortex Instability(Institute of Physics Publishing) Ashton, Ryan; Viola, F.; Gallaire, F.; Iungo, Giacomo V.; 0000-0002-0990-8133 (Iungo, GV); Sorensen J.N.; Ivanell S.; Barney A.; Ashton, Ryan; Iungo, Giacomo V.Dynamics and instabilities occurring in the near-wake of wind turbines have a crucial role for the wake downstream evolution, and for the onset of far-wake instabilities. Furthermore, wake dynamics significantly affect the intra-wind farm wake flow, wake interactions and potential power losses. Therefore, the physical understanding and predictability of wind turbine wake instabilities become a nodal point for prediction of wind power harvesting and optimization of wind farm layout. This study is focused on the prediction of the hub vortex instability encountered within wind turbine wakes under different operational conditions of the wind turbine. Linear stability analysis of the wake flow is performed by means of a novel approach that enables to take effects of turbulence on wake instabilities into account. Stability analysis is performed by using as base flow the time-averaged wake velocity field at a specific downstream location. The latter is modeled through Carton-McWilliams velocity profiles by mimicking the presence of the hub vortex and helicoidal tip vortices, and matching the wind turbine thrust coefficient predicted through the actuator disc model. The results show that hub vortex instability is promoted by increasing the turbine thrust coefficient. Indeed, a larger aerodynamic load produces an enhanced wake velocity deficit and axial shear, which are considered the main sources for the wake instability. Nonetheless, wake swirl also promotes hub vortex instability, and it can also affect the azimuthal wavenumber of the most unstable mode.Item Instability of Wind Turbine Wakes Immersed in the Atmospheric Boundary Layer(Institute of Physics Publishing) Viola, F.; Iungo, Giacomo V.; Camarri, S.; Porté-Agel, F.; Gallaire, F.; Sorensen J.N.; Ivanell S.; Barney A.; Iungo, Giacomo V.In this work a technique capable to investigate the near-wake stability properties of a wind turbine immersed in the atmospheric boundary layer is presented. Specifically, a 2D local spatial stability analysis is developed in order to take into account typical flow features of real operating wind turbines, such as the presence of the atmospheric boundary layer and the turbulence heterogeneity of the oncoming wind. This stability analysis can be generally applied on either experimental measurements or numerical data. In this paper it was carried out on wind tunnel experiments, for which a downscaled wind turbine is immersed in a turbulent boundary layer. Through spatial stability analysis, the dominant mode in the near wake, i.e. the most amplified one, is characterized and its frequency matches the hub-vortex instability frequency measured in the wind tunnel. As in the case of 10], where an axisymmetric wake condition was investigated, the hub-vortex instability results in a single-helical mode.