Publications associées à Angle de flèche

Fluid-structure interactions of bristled wings: the trade-off between weight and drag

Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla, Yuexia Luna Lin

The smallest flying insects often have bristled wings resembling feathers or combs. We combined experiments and three-dimensional numerical simulations to investigate the trade-off between wing weight and drag generation. In experiments of bristled strips, ...

Royal Soc2023

The effects of kinematics, flexibility, and planform on the vortex formation and aerodynamic performance of flapping wing flight

Alexander Gehrke

In this thesis, the aerodynamic challenges in flapping wing flight are addressed. In particular, the effects of different wing kinematics, flexibilities, and planforms on the the leading edge vortex development and aerodynamic performance are investigated. ...

EPFL2023

Aeroelastic characterisation of a bio-inspired flapping membrane wing

Karen Ann J Mulleners, Alexander Gehrke, Esra Uksul, Jules Ange Philippe Richeux

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

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

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

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

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

Stefano Mintchev, Matteo Di Luca

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

Second-order sensitivity in the cylinder wake: Optimal spanwise-periodic wall actuation and wall deformation

François Gallaire, Edouard Boujo, Andrea Fani

Two-dimensional (2D) flows can be controlled efficiently using spanwise "waviness," i.e., a control (e.g., wall blowing and suction or wall deformation) that is periodic in the spanwise direction. This study tackles the global linear stability of 2D flows ...

AMER PHYSICAL SOC2019

A New Miniature Wind Turbine for Wind Tunnel Experiments. Part II: Wake Structure and Flow Dynamics

Fernando Porté Agel, Majid Bastankhah

An optimized three-bladed horizontal-axis miniature wind turbine, called WiRE-01, with the rotor diameter of 15 cm is designed and fully characterized in Part I of this study. In the current part of the study, we investigate the interaction of the turbine ...

2017

Stability analysis of boundary layers controlled by miniature vortex generators

Lorenzo Siconolfi

It is currently known that Tollmien–Schlichting (TS) waves can be attenuated by the introduction of spanwise mean velocity gradients in an otherwise two-dimensional boundary layer (BL). The stabilizing effect, associated with an extra turbulence production ...

Cambridge University Press2015

Adjustment of Turbulent Boundary-Layer Flow to Idealized Urban Surfaces: A Large-Eddy Simulation Study

Fernando Porté Agel, Wai Chi Cheng

Large-eddy simulations (LES) are performed to simulate the atmospheric boundary-layer (ABL) flow through idealized urban canopies represented by uniform arrays of cubes in order to better understand atmospheric flow over rural-to-urban surface transitions. ...

Springer2015

Large-Eddy Simulation of Very-Large-Scale Motions in the Neutrally Stratified Atmospheric Boundary Layer

Fernando Porté Agel, Jiannong Fang

Large-eddy simulation is used to investigate very-large-scale motions (VLSMs) in the neutrally stratified atmospheric boundary layer at a very high friction Reynolds number, . The vertical height of the computational domain is m, which corresponds to the t ...

Springer Verlag2015

Aeroeleasic Investigation of an Annular Transonic Compressor Cascade: Experimental Results

Peter Ott, Virginie Anne Chenaux, Achim Zanker

A reliable determination of the unsteady aerodynamic loads acting on the blades is essential to predict the aeroelastic stability of vibrating compressor cascades with accuracy. At transonic flow conditions, the vibration of the shock may change the blade ...

2015

Sediment Evacuation from Reservoirs through Intakes by Jet-Induced Flow

Anton Schleiss, Giovanni De Cesare, Jolanda Maria Isabella Jenzer Althaus

Reservoir sedimentation is considered as a sustainability problem. A concept getting down to the root of the cause was developed and tested in laboratory experiments. The idea is to maintain sediment in suspension, i.e., avoiding its settling near the dam ...

American Society of Civil Engineers2015

Evolution of the Aerodynamic Stability of an Oscillating Annular Compressor Cascade with Inlet Reverse Flow Condition Variations

Peter Ott, Virginie Anne Chenaux

While the advancement of computing hardware now enables accurate predictions of flutter and forced response at normal flow conditions during the compressor design phase, aeroelastic computations at off-design or reverse flow conditions remain a challenging ...

Lappeenranta University of Technology2013

High Voltage Pulsed DBD Effects on the Aerodynamic Performances and on the Shock Buffet

Christoph Hollenstein, Peter Ott, Pénélope Leyland, Philip Peschke

The applications of surface dielectric barrier discharge plasma actuators, (DBD), have known a considerable interest recently in the field of flow control. In general, such actuators consist of two electrodes separated by an insulation covering the lower e ...

2013

The EPFL jumpglider: A hybrid jumping and gliding robot with rigid or folding wings

Dario Floreano, Mirko Kovac, Jean-Christophe Zufferey, Wassim Hraiz, Oriol Fauria Torrent

Recent work suggests that wings can be used to prolong the jumps of miniature jumping robots. However, no functional miniature jumping robot has been presented so far that can successfully apply this hybrid locomotion principle. In this publication, we pre ...

2011

Experimental investigation of the vortex shedding dynamic in the wake of oblique and blunt trailing edge hydrofoils using PIV-POD method

François Avellan, Mohamed Farhat, Philippe Ausoni, Amirreza Zobeiri

This paper presents an experimental investigation of the vortex shedding in the wake of blunt and oblique trailing edge hydrofoils at high Reynolds number, Re=5 10 5 - 2.9 10 6. The velocity field in the wake is surveyed with the help of Particle-Image-Vel ...

American Soc Mechanical Engineers2010

Effects of high-speed airflows on a surface dielectric barrier discharge

Christoph Hollenstein, Peter Ott, Pénélope Leyland, Samantha Pavon

A detailed study of the interaction between high-speed gas flows and surface dielectric barrier discharges (DBD) is presented. In the present paper, it is demonstrated that a DBD can be sustained in transonic airflows, up to isentropic Mach numbers of 1.1. ...

2007