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Concept

Vortex generator

Related publications (14)

Numerical study on the scale effect of tip vortex cavitation induced by incoming velocities and scale ratios

Mohamed Farhat

Large eddy simulations of tip vortex cavitation (TVC) around an elliptical hydrofoil is performed to study its scale effect. A satisfying agreement is obtained between the numerical and experimental data. It indicates that the scale effect of TVC is remark ...

PERGAMON-ELSEVIER SCIENCE LTD2023

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

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

Lagrangian analysis of bio-inspired vortex ring formation

Karen Ann J Mulleners, Mrudhula Baskaran

Pulsatile jet propulsion is a highly energy-efficient swimming mode used by various species of aquatic animals that continues to inspire engineers of underwater vehicles. Here, we present a bio-inspired jet propulsor that combines the flexible hull of a je ...

2022

Scaling of the translational velocity of vortex rings behind conical objects

Karen Ann J Mulleners, Guillaume de Guyon-Crozier

Ring vortices are efficient at transporting fluid across long distances. They can be found in nature in various ways: they propel squids, inject blood in the heart, and entertain dolphins. These vortices are generally produced by ejecting a volume of fluid ...

2021

Evolution of the vorticity distribution in vortex rings

Guillaume de Guyon-Crozier

Vortex rings are very efficient at transporting fluid on long distances and can generate large forces, either thrust or drag. These abilities are influenced by the vorticity distribution within the vortex. Previous work on vortices produced by piston-cylin ...

EPFL2021

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

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

Roll-up region of tip vortex: numerical investigation

Mohamed Farhat, Azin Amini, Matthieu Dreyer, Ali Amini, Martino Reclari

The appearance of gas-filled vortices at the tip of hydraulic machines blades is usually associated with increase of losses, vibrations, noise and erosion risk. The understanding of the roll-up region, where the boundary layer on the pressure side crosses ...

IOP Publishing2019

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

Distinct transition in flow statistics and vortex dynamics between low- and high-extent turbulent drag reduction in polymer fluids

Tobias Schneider

Flexible polymer additives are known to reduce the energy dissipation and friction drag in turbulent flows. As the fluid elasticity increases, the flow undergoes several stages of transitions. Much attention in the area has been focused on the onset of dra ...

2018

Bioinspired morphing wings for extended flight envelope and roll control of small drones

Dario Floreano, Stefano Mintchev, Grégoire Hilaire Marie Heitz, Flavio Noca

Small-winged drones can face highly varied aerodynamic requirements, such as high manoeuvrability for flight among obstacles and high wind resistance for constant ground speed against strong headwinds that cannot all be optimally addressed by a single aero ...

Royal Society, The2017

How oblique trailing edge of a hydrofoil reduces the vortex-induced vibration

François Avellan, Mohamed Farhat, Amirreza Zobeiri

The effect of hydrofoil trailing edge shape on the wake dynamic and flow induced vibration is investigated at high Reynolds number, Re = 0.5 x 10(6)-2.9 x 10(6). Two NACA 0009 hydrofoils with blunt and oblique trailing edges are tested. The velocity field ...

Elsevier2012

Effect of Hydrofoil Trailing Edge Geometry on the Wake Dynamics

Amirreza Zobeiri

In the present study, the effect of a hydrofoil trailing edge shape on the wake dynamic and its interaction with the mechanical structure is investigated. This would help better describe the physical reasons for vibration reduction when using oblique and D ...

EPFL2012