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Karen Ann J Mulleners

Cette personne a quitté l’EPFL

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Publications associées (45)

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Phenomenology and scaling of optimal flapping wing kinematics

Karen Ann J Mulleners, Alexander Gehrke

Biological flapping wing fliers operate efficiently and robustly in a wide range of flight conditions and are a great source of inspiration to engineers. The unsteady aerodynamics of flapping wing flight are dominated by large-scale vortical structures tha ...

IOP PUBLISHING LTD2021

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

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

Fatma Ayancik Cinoglu, Karen Ann J Mulleners

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

Highly agile flat swimming robot

Mehdi Benbedda, Herbert Shea, Karen Ann J Mulleners, Mrudhula Baskaran, Gaétan Irénée Auguste Anatole Armand Raynaud

Navigating and exploring the surfaces of bodies of water allow swimming robots to perform a range of measurements while efficiently communicating and harvesting energy from the Sun. Such environments are often highly unstructured and cluttered with plant m ...

AMER ASSOC ADVANCEMENT SCIENCE2025

Strength and timing of primary and secondary vortices generated by a rotating plate

Karen Ann J Mulleners, Diego Francescangeli

Accurate predictions of how vortices grow, evolve, and separate from aerodynamic objects are desirable for various applications ranging from autonomous aerial vehicles to wind turbines. Here, we present an experimental characterisation of the formation pro ...

2023

Strategy for diagnosing the degree of dynamic stall on a vertical-axis wind turbine blade

Karen Ann J Mulleners, Sébastien Le Fouest, David Yefim Bensason

Vertical axis wind turbines boast several advantages over their horizontal counterparts. Their development and large-scale installation has been limited due to their inherent aerodynamic complexity and in particular due to the occurrence of dynamic stall. ...

Amer Inst Aeronautics & Astronautics2022

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

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

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

Critical evolution of leading edge suction during dynamic stall

Karen Ann J Mulleners, Julien Dominique Claude Deparday

Dynamic stall dominates the aerodynamic performance, the robustness, and the wake dynamics of vertical axis wind turbines. To better assess the dynamic stall onset and its associated unsteady effects, this paper analyzes experimentally the evolution of the ...

IOP PUBLISHING LTD2018

On the parametrisation of motion kinematics for experimental aerodynamic optimisation

Karen Ann J Mulleners, Alexander Gehrke

The levels of agility and flight or swimming performance demonstrated by insects, birds, fish, and even some aquatic invertebrates, are often vastly superior to what even the most advanced human-engineered vehicles operating in the same regimes are capable ...

2022

Self-exploring automated experiments for discovery, optimization, and control of unsteady vortex-dominated flow phenomena

Karen Ann J Mulleners

Typical unsteady vortex-dominated flows like those involved in bio-inspired propulsion, airfoil separation, bluff body wakes, and vortex-induced vibrations can be prohibitively expensive to simulate and impossible to measure comprehensively. These examples ...

American Physical Society (APS)2024

Coherent Structure Interaction During Unsteady Separation

Karen Ann J Mulleners

Unsteady flow separation in rotationally augmented flow fields plays a significant role in the aerodynamic performance of industrial rotors, including wind turbines. Current computational models underestimate the aerodynamic loads due to the inaccurate pre ...

2019

Discrete shedding of secondary vortices along a modified Kaden spiral

Karen Ann J Mulleners, Diego Francescangeli

When an object is accelerated in a fluid, a primary vortex is formed through the roll-up of a shear layer. This primary vortex does not grow indefinitely and will reach a limiting size and strength. Additional vorticity beyond the critical limit will end u ...

Cambridge University Press2021

Data from: Optimal blade pitch control for enhanced vertical-axis wind turbine performance

Karen Ann J Mulleners, Sébastien Le Fouest

This directory contains open-source data obtained using a single-bladed H-type vertical-axis wind turbine prototype with individual blade pitching. This data results from the optimisation of the blade's pitching kinematics using a genetic algorithm at two ...

Zenodo2024

To tread or not to tread: comparison between water treading and conventional flapping wing kinematics

Karen Ann J Mulleners, Alexander Gehrke, Swathi Badala Krishna

Hovering insects are limited by their physiology and need to rotate their wings at the end of each back-and-forth motion to keep the wing's leading edge ahead of its trailing edge. The wing rotation at the end of each half-stroke pushes the leading edge vo ...

IOP Publishing Ltd2022

Optimal blade pitch control for enhanced vertical-axis wind turbine performance

Karen Ann J Mulleners, Sébastien Le Fouest

Vertical-axis wind turbines are great candidates to enable wind power extraction in urban and off-shore applications. Currently, concerns around turbine efficiency and structural integrity limit their industrial deployment. Flow control can mitigate these ...

Nature Research2024

Modulation of the Leading-Edge Vortex Shedding Rate in Discrete-Vortex Methods

Karen Ann J Mulleners, Guosheng He

A new method to determine the rate of circulation fed into a leading-edge vortex (LEV) is presented for discrete-vortex methods (DVM). The strength of vortex particles shed from the leading edge is calculated based on the velocity at the shear layer, which ...

2022

Asymmetry of timescales, loads, and flow structures for a vertical-axis wind turbine blade undergoing dynamic stall

Karen Ann J Mulleners, Sébastien Le Fouest, David Yefim Bensason

Vertical-axis wind turbines have the potential to increase the share of primary energy from wind. The development of vertical-axis wind turbines for large-scale application has been limited by their self-starting capabilities and the occurrence of dynamic ...

Amer Inst Aeronautics & Astronautics2022

Estimating the non-dimensional energy of vortex rings by modelling their roll-up

Karen Ann J Mulleners, Guillaume de Guyon-Crozier

The non-dimensional energy of starting vortex rings typically converges to values around 0.33 when they are created by a piston-cylinder or a bluff body translating at a constant speed. To explore the limits of the universality of this value and to analyse ...

Cambridge University Press2022