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Publications associées (27)

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Dynamic stall characterisation and control for vertical-axis wind turbines

Sébastien Le Fouest

According to the International Energy Agency, the global net-zero emissions objective requires the installed wind power capacity to increase 11-fold between 2020 and 2050. The scientific community has recently voiced concerns about the logistic feasibility ...

EPFL2023

Time scales of dynamic stall development on a vertical-axis wind turbine blade

Karen Ann J Mulleners, Sébastien Le Fouest, Daniel Marie Fernex

Vertical-axis wind turbines are excellent candidates to diversify wind energy technology, but their aerodynamic complexity limits industrial deployment. To improve the efficiency and lifespan of vertical-axis wind turbines, we desire data-driven models and ...

2023

Wind Turbine Wakes in Active Yaw Control: Numerical and Theoretical Studies

Mou Lin

In this thesis, we explore the best practice of simulating the wakes of the turbines under active yaw control (AYC) using large-eddy simulation (LES). In the first study, we validate the blade-element actuator disk model (ADM-BE) for a yawed wind turbine. ...

EPFL2023

The dynamic stall dilemma for vertical-axis wind turbines

Karen Ann J Mulleners, Sébastien Le Fouest

Vertical-axis wind turbines (VAWT) are excellent candidates to complement traditional wind turbines and increase the total wind energy capacity. Development of VAWT has been hampered by their low efficiency and structural unreliability, which are related t ...

Pergamon-Elsevier Science Ltd2022

All you need is time to generalise the Goman-Khrabrov dynamic stall model

Karen Ann J Mulleners, Fatma Ayancik Cinoglu

Dynamic stall on airfoils negatively impacts their aerodynamic performance and can lead to structural damage. Accurate prediction and modelling of the dynamic stall loads are crucial for a more robust design of wings and blades that operate under unsteady ...

Cambridge University Press2022

A Lightweight Device for Energy Harvesting from Power Lines with a Fixed-Wing UAV

Dario Floreano, William John Stewart

Modern UAVs (Unmanned Aerial Vehicles) suffer from restrictions in flight range and time due to battery capacity limitations. One way to overcome these limitations is to harvest energy from overhead power lines. A growing body of scientific literature has ...

IEEE2022

Sharp turning maneuvers with avian-inspired wing and tail morphing

Dario Floreano, Valentin Wüest, Enrico Ajanic

Flight in dense environments, such as forests and cities requires drones to perform sharp turns. Although fixed-wing drones are aerodynamically and energetically more efficient than multicopters, they require a comparatively larger area to turn and thus ar ...

2022

Aeroelastic characterisation of a bio-inspired flapping membrane wing

Karen Ann J Mulleners, Alexander Gehrke

Natural fliers like bats exploit the complex fluid-structure interaction between their flexible membrane wings and the air with great ease. Yet, replicating and scaling the balance between the structural and fluid-dynamical parameters of unsteady membrane ...

IOP Publishing Ltd2022

Experimental quantification of unsteady leading-edge flow separation

Karen Ann J Mulleners, Julien Dominique Claude Deparday

We propose here a method to experimentally quantify unsteady leading-edge flow separation on aerofoils with finite thickness. The methodology relies on the computation of a leading-edge suction parameter based on measured values of the partial circulation ...

Cambridge University Press2022

The dynamics and timescales of static stall

Karen Ann J Mulleners, Sébastien Le Fouest, Julien Dominique Claude Deparday

Airfoil stall plays a central role in the design of safe and efficient lifting surfaces. We typically distinguish between static and dynamic stall based on the unsteady rate of change of an airfoil’s angle of attack. Despite the somewhat misleading denotat ...

2021

Robotic Elytra: Insect-Inspired Protective Wings for Resilient and Multi-Modal Drones

Dario Floreano, William John Stewart, Charalampos Vourtsis

Winged drones that fly in close proximity to obstacles or that are capable of aerial and terrestrial locomotion can benefit from protective systems that prevent damage to delicate aerial structures. Existing protective solutions focus on multi-copter drone ...

2021

Experimental investigation and analytical modelling of active yaw control for wind farm power optimization

Fernando Porté Agel, Haohua Zong

In this study, the physics and effectiveness of active yaw control under various wind conditions are investigated systematically, based on wind tunnel experiments and a new analytical wind farm model. The power and wake velocity measurements of a three-row ...

Pergamon-Elsevier Science Ltd2021

Effects of leading-edge separation on the vortex-induced vibration of an elongated bluff body

Guiyue Duan

Wind-tunnel experiments were conducted to investigate the effects of leading-edge separation on the vortex-induced vibration (VIV) of an elastically-supported elongated bluff body. Solid wind barriers of various heights were fixed in the leading edge to ad ...

ELSEVIER2021

Stall Delay and Leading-Edge Suction for a Pitching Airfoil with Trailing-Edge Flap

Karen Ann J Mulleners, Julien Dominique Claude Deparday, Guosheng He

The flow around a pitching NACA0015 airfoil with an oscillating trailing-edge flap is experimentally investigated to characterize the influence of the flap kinematics on the development of dynamic stall. We specifically focus on the timing of the stall dev ...

2020

Dynamic stall on an airfoil undergoing VAWT blade angle of attack variations

Karen Ann J Mulleners, Sébastien Le Fouest, Sabrina Henne

Vertical axis wind turbines have several attractive features in the context of energy production in urban areas, but the inherent aerodynamic complexity of the flow around them has challenged their development on a larger scale. They generally operate at l ...

2020

A point vortex transportation model for yawed wind turbine wakes

Fernando Porté Agel, Haohua Zong

In this study, stereo particle imaging velocimetry measurements are performed at multiple streamwise locations behind a yawed wind turbine to reveal the formation mechanisms of the counter-rotating vortex pair (CVP), and a point vortex transportation (PVT) ...

Cambridge University Press2020

A bioinspired Separated Flow wing provides turbulence resilience and aerodynamic efficiency for miniature drones

Stefano Mintchev

Small-scale drones have enough sensing and computing power to find use across a growing number of applications. However, flying in the low-Reynolds number regime remains challenging. High sensitivity to atmospheric turbulence compromises vehicle stability ...

AMER ASSOC ADVANCEMENT SCIENCE2020

Suppressing tip-leakage vortex cavitation by overhanging grooves

Mohamed Farhat

In the present paper, a new control method for tip-leakage vortex (TLV) cavitation is proposed. This method, which combines the effects of grooves and winglets, is made of overhanging grooves (OHGs) fitted at the tip of a hydrofoil. Experimental and numeri ...

SPRINGER2020

Mechanisms of Control Authority by Nanosecond Pulsed Dielectric Barrier Discharge Actuators on Flow Separation

Peter Ott, Pénélope Leyland, Christoforos Skourides

The mechanisms that should be considered for separation flow control applications of nanosecond pulsed dielectric barrier discharge (DBD) actuators were investigated on a NACA 0015 profile for velocities of 10 m/s (Re = 100, 000) and 20 m/s (Re = 200, 000) ...

2019

Flow dynamics of a dandelion pappus: A linear stability approach

François Gallaire, Pier Giuseppe Ledda, Francesco Viola, Lorenzo Siconolfi

The study and control of flow instabilities is a key problem in aerodynamics. Aircrafts are designed not only to generate the lift force needed to balance their weight but, more importantly, to be stable and reasonably steady when in cruise conditions. Sim ...

2019