Title :

Effect of time-varying freestream on performance and vortex dynamics of forward and reversed pitching airfoils

Author(s) :

Shi, Lei [Auteur]
JiangSu University
Laboratoire de Mécanique des Fluides de Lille - Kampé de Fériet [LMFL]
Wang, Yefang [Auteur]
JiangSu University
Bayeul-Laine, Annie-Claude [Auteur]
Laboratoire de Mécanique des Fluides de Lille - Kampé de Fériet [LMFL]
Coutier-Delgosha, Olivier [Auteur]
Department of Aerospace and Ocean Engineering [Blackburg]
Laboratoire de Mécanique des Fluides de Lille - Kampé de Fériet [LMFL]

Journal title :

Journal of Fluids and Structures

Pages :

103508

Publisher :

Elsevier

Publication date :

2022-04

ISSN :

0889-9746

English keyword(s) :

Flapping foil
Energy extraction
Renewable energy
Non-sinusoidal trajectory
CFD

HAL domain(s) :

Sciences de l'ingénieur [physics]

English abstract : [en]

The goal of the present work deals with the influence of the oscillating freestream on the global performance, transition and vortex dynamics of forward and reversed airfoils. Three important parameters, involving the ...
Show more >The goal of the present work deals with the influence of the oscillating freestream on the global performance, transition and vortex dynamics of forward and reversed airfoils. Three important parameters, involving the phase lag, oscillating amplitude and mean reduced frequency, are analyzed systematically. The primary results show that both the phase lag and oscillating amplitude have great impact on the transition and flow structures, depending on the instantaneous freestream Reynolds number. The reversed airfoil is more prone to being affected by these parameters, characterized by the earlier flow separation near the sharp leading edge and the more complex vortex shedding, compared with that over the forward airfoil. It shows that increasing the oscillating amplitude can improve the mean performance, but it decreases with the increase of the mean reduced frequency. Additionally, it is observed that there is a second transition on both two sides near the trailing edge of the reversed airfoil, which becomes weak when the instantaneous freestream Reynolds number is relatively low. Afterwards, the time-averaged performance of the reversed airfoil is better than forward airfoil at low reduced frequency, but it deteriorates dramatically with the increase of the reduced frequency. Furthermore, the transition and vortex evolution are delayed as the reduced frequency increases, and the delayed flow structures can be inferred from the velocity profiles in the wake region. Moreover, it can be seen that the velocity profile has a transition from the drag-indicative to thrust-indicative type when the reduced frequency increases, and the velocity variation in the vertical direction is more evident for the reversed airfoil due to the massive flow separation.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

Collections :

• Laboratoire de Mécanique des Fluides de Lille Kampé de Fériet (LMFL) - UMR 9014

Source :

Harvested from HAL