Leonardi, Stefano
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/4788
Stefano Leonardi is currently an Associate Professor of Mechanical Engineering. His research interests include turbulence, computational fluid mechanics, wind energy, drag reduction, super hydrophobic surfaces, and heat transfer.
Browse
Browsing Leonardi, Stefano by Subject "Eddies--Simulation methods"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Effect of the Turbine Scale on Yaw Control(John Wiley & Sons Ltd) Ciri, Umberto; Rotea, Mario A.; Leonardi, Stefano; 0000-0002-9809-7191 (Leonardi, S); Ciri, Umberto; Rotea, Mario A.; Leonardi, StefanoYaw misalignment between the incoming wind and the rotor of a turbine causes a lateral displacement of the wake. This effect can be exploited to avoid or mitigate wake interactions in wind farms, so that power losses are minimized. We performed large-eddy simulations to evaluate yaw control for a three-turbine wind farm. We used two different turbine models to assess how the size of the turbine rotor affects the farm efficiency and the effectiveness of the control strategy. A utility-scale wind turbine with rotor diameter of 126 m is compared with a scaled research wind turbine with rotor diameter of 27 m. In both cases, a model-free algorithm is used to determine the turbine yaw set point, which maximizes total power production. The algorithm is the nested extremum-seeking control (NESC), which allows for the coordinated optimization of the wind turbine operating points. The results achieved with NESC are validated by computing a static performance map for different yaw angles. NESC converges to optimal operating conditions, which are in good agreement with the static map benchmark. Numerical results show that a larger rotor diameter induces larger wake deflection, thus achieving higher power improvements. From the analysis of the turbine structural loads, an increase in damage equivalent load is observed for both the yawed turbine and the waked one. Present results suggest that there is a cost-effective trade-off between performance and loads for large turbines. © 2018 John Wiley & Sons, Ltd.Item Large-Eddy Simulations of Two In-Line Turbines in a Wind Tunnel with Different Inflow Conditions(MDPI AG) Ciri, Umberto; Petrolo, Giovandomenico; Salvetti, Maria Vittoria; Leonardi, Stefano; Ciri, Umberto; Leonardi, StefanoNumerical simulations reproducing a wind tunnel experiment on two in-line wind turbines have been performed. The flow features and the array performances have been evaluated in different inflow conditions. Following the experimental setup, different inlet conditions are obtained by simulating two grids upstream of the array. The increased turbulence intensity due to the grids improves the wake recovery and the efficiency of the second turbine. However, the inlet grid induces off-design operation on the first turbine, decreasing the efficiency and increasing fatigue loads. Typical grid flow patterns are observed past the rotor of the first turbine, up to the near wake. Further downstream, the signature of the grid on the flow is quite limited. An assessment of numerical modeling aspects (subgrid scale tensor and rotor parameterization) has been performed by comparison with the experimental measurements.