Fernando Porté Agel

FERNANDO PORTÉ AGEL Professor Director, Wind Engineering and Renewable Energy Laboratory (WIRE) School of Architecture, Civil and Environmental Engineering (ENAC) École Polytechnique Fédérale de Lausanne (EPFL) e-mail: fernando.porte-agel@epfl.ch RESEARCH INTERESTS Environmental fluid mechanics. Computational fluid dynamics. Atmospheric boundary layers. Turbulence. Large-eddy simulation. Wind energy. Wind engineering. Renewable energy. EDUCATION Ph.D. 1999 Johns Hopkins University, Environmental Engineering M.Sc. 1995 Hydrologic Engineering, IHE - Delft, The Netherlands B.S. 1992 Universidad Politécnica de Cataluña, Spain ACADEMIC POSITIONS 2010-present: Full Professor, School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), Switzerland 2005-2009: Associate Professor, St. Anthony Falls Laboratory and Department of Civil Engineering, University of Minnesota, Minneapolis, MN, USA 2000-2005: Assistant Professor, St. Anthony Falls Laboratory, Department of Civil Engineering, University of Minnesota, Minneapolis, MN, USA AWARDS AND FELLOWSHIPS McKnight Presidential Fellow (2006-2009), University of Minnesota, USA McKnight Land-Grant Professorship (2003-2005), University of Minnesota, USA NASA Young Investigator Award (2001-2004), USA NSF CAREER Award (2001-2006), (Division of Earth Sciences Hydrological Sciences), USA Outstanding Student Paper Award: Hydrology Section, Fall Meeting of the American Geophysical Union; San Francisco, 1998. Research Award (1995-1997): La Caixa fellowship program; Barcelona, Spain. Research Award (1993-1995): Dutch Ministry of Foreign Affairs fellowship. Research Award (1990-1993): Spanish Civil Engineering Association.

An experimental and analytical study of wind turbine wakes under pressure gradient

Arslan Salim Dar, Abraham Starbuck Gertler, Fernando Porté Agel

This work is dedicated to the systematic investigation of wind turbine wakes under the effect of pressure gradients. Wind tunnel experiments are carried out with a wind turbine positioned on straight ramps of increasing angle such that it experiences an approximately linear flow speed-up/slow-down from the induction region into the far wake. Fifteen ramp angles are studied: 7 favorable (FPG), 7 adverse (APG), and 1 zero pressure gradient. The wake center is shown to follow the base flow streamline originating from a virtual turbine hub height. A quasi-linear relationship between the pressure gradient and near wake length is demonstrated. Far wake characteristics, such as the recovery of the wake center velocity deficit and wake growth rate, are observed to systematically vary with the pressure gradient. The wake recovery rate increases (decreases) with the increase in the FPG (APG), and the wake growth rate shows a linear increase from most favorable to most adverse pressure gradient. The turbine power coefficient decreases significantly with increasing APG to a greater degree than the increase in power coefficient under FPG. The engineering approach of superposing the wake deficit predicted by the standard Gaussian model on the modified base flow is shown to work for very moderate pressure gradients. In light of this, a threshold in terms of flow speed-up/slow-down along the wake trajectory is established, below which the engineering approach can be reasonably employed. Finally, a physics-based model for wakes under the pressure gradient is tested. A new theoretical relation for near wake length under the pressure gradient is proposed. Using the theoretical near wake length, the pressure gradient model predicts the turbine wakes for all cases with good accuracy and shows a significant improvement from the engineering approach.

2023

Power Production and Blade Fatigue of a Wind Turbine Array Subjected to Active Yaw Control

Mou Lin, Fernando Porté Agel

This study investigated the power production and blade fatigue of a three-turbine array subjected to active yaw control (AYC) in full-wake and partial-wake configurations. A framework of a two-way coupled large eddy simulation (LES) and an aeroelastic blade simulation was applied to simulate the atmospheric boundary layer (ABL) flow through the turbines and the structural responses of the blades. The mean power outputs and blade fatigue loads were extracted from the simulation results. By exploring the feasible AYC decision space, we found that in the full-wake configuration, the local power-optimal AYC strategy with positive yaw angles endures less flapwise blade fatigue and more edgewise blade fatigue than the global power-optimal strategy. In the partial-wake configuration, applying positive AYC in certain inflow wind directions achieves higher optimal power gains than that in the full-wake scenario and reduces blade fatigue from the non-yawed benchmark. Using the blade element momentum (BEM) theory, we reveal that the aforementioned differences in flapwise blade fatigue are due to the differences in the azimuthal distributions of the local relative velocity on blade sections, resulting from the vertical wind shear and blade rotation. Furthermore, the difference in the blade force between the positively and negatively yawed front-row turbine induces different wake velocities and turbulence distributions, causing different fatigue loads on the downwind turbine exposed to the wake.

MDPI2023

An experimental and analytical study of wind turbine wakes under pressure gradient

Arslan Salim Dar, Abraham Starbuck Gertler, Fernando Porté Agel

2023

An experimental and analytical study of wind turbine wakes under pressure gradient

Power Production and Blade Fatigue of a Wind Turbine Array Subjected to Active Yaw Control

"A physics-based model for wind turbine wake expansion in the atmospheric boundary layer"

An experimental and analytical study of wind turbine wakes under pressure gradient

"A physics-based model for wind turbine wake expansion in the atmospheric boundary layer"

Power Production and Blade Fatigue of a Wind Turbine Array Subjected to Active Yaw Control