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Concept

Flap (aeronautics)

Publications associées (23)

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

Wing and tail morphing in birds and drones

Enrico Ajanic

To aid humans in civilian tasks, future drones will have to operate in large cities that abound with difficult flight conditions such as confined spaces, obstacles, and turbulent air. Such drones must cruise efficiently to cover vast distances fast and als ...

EPFL2023

Vortex shedding from a composite hydrofoil: Experimental evidence of a novel "partial lock-in"

Mohamed Farhat, Thomas Antoine Nicolas Berger

Lock-in is of great importance in many engineering applications due to its practical implications for structural safety. The influence of composite bend-twist coupling on the wake dynamics and vortex-induced vibration around a carbon fiber composite hydrof ...

Aip Publishing2023

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

How ornithopters can perch autonomously on a branch

Raphael Zufferey

Flapping wings produce lift and thrust in bio-inspired aerial robots, leading to quiet, safe and efficient flight. However, to extend their application scope, these robots must perch and land, a feat widely demonstrated by birds. Despite recent progress, f ...

Nature Portfolio2022

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

Comparative dynamic flight stability of insect-inspired flapping-wing micro air vehicles in hover: Longitudinal and lateral motions

Hoang Vu Phan

In this paper, we compare the characteristics of hovering stability for two insect-inspired flapping-wing micro air vehicles (FW-MAVs) with different strategies to generate control moments for the longitudinal and lateral attitude controls. The two robots ...

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

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

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

Hydrodynamic mechanisms of aggressive collapse events in leading edge cavitation

Mohamed Farhat, Ali Amini

Transient cavities generated from unsteady leading-edge cavitation may undergo aggressive collapses which are responsible for cavitation erosion. In this paper, we studied the hydrodynamic mechanisms of these events in the leading edge cavitation formed ov ...

SPRINGER2020

Power Maximization and Fatigue-Load Mitigation in a Wind-turbine Array by Active Yaw Control: an LES Study

Fernando Porté Agel, Mou Lin

In this study, we perform a multi-objective parametric study for an array of three miniature wind turbines subjected to active yaw control (AYC), with the objectives of maximizing the power and minimizing the fatigue loads. Using the time series extracted ...

2020

Performance enhancement of downwind sails due to leading edge flapping: A wind tunnel investigation

Julien Dominique Claude Deparday

This work presents a wind tunnel experimental study on the effect of the leading edge flapping on the aerodynamic performance of a spinnaker. Four J80-class spinnaker models, combining two different assembling structures (panel layout) and two different sa ...

PERGAMON-ELSEVIER SCIENCE LTD2018

Locomotion Dynamics for Bio-inspired Robots with Soft Appendages: Application to Flapping Flight and Passive Swimming

Yannick Morel

In animal locomotion, either in fish or flying insects, the use of flexible terminal organs or appendages greatly improves the performance of locomotion (thrust and lift). In this article, we propose a general unified framework for modeling and simulating ...

Springer2017

Effects of chordwise flexibility on 2D flapping foils used as an energy extraction device

Guillaume Jeanmonod

The effects of chordwise pressure- and inertia-driven deformations on the power extraction potential of a kinematically constrained oscillating thin plate that undergoes a heaving and pitching motion are investigated. 2D fully coupled fluid-structure inter ...

Academic Press Ltd- Elsevier Science Ltd2017

On the Efficiency Alteration Mechanisms Due to Cavitation in Kaplan Turbines

François Avellan, Sebastián Camilo Leguizamón Sarmiento

A transport-equation-based homogeneous cavitation model previously assessed and validated against experimental data is used to investigate and explain the efficiency alteration mechanisms in Kaplan turbines. On the one hand, it is shown that the efficiency ...

2017

The effect of the phase angle between the forewing and hindwing on the aerodynamic performance of a dragonfly-type ornithopter

Jamie Paik, Alice Ghislaine Concordel

Dragonflies achieve agile maneuverability by flapping four wings independently. Different phase angles between the flapping forewing and hindwing have been observed during various flight modes. The aerodynamic performance depends on phase angle control, as ...

2016

RANS and LES computations of the tip-leakage vortex for different gap widths

Mohamed Farhat, Matthieu Dreyer

In hydraulic turbines, the tip-leakage vortex is responsible for flow instabilities and for promoting erosion due to cavitation. To better understand the tip vortex flow, Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) computations a ...

Taylor & Francis2015

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