Imperial College London
Alternate

ProfessorGeorgePapadakis

Faculty of Engineering, Department of Aeronautics

Professor of Aerodynamics
 
 
 
//

Contact

 

+44 (0)20 7594 5080g.papadakis

 
 
//

Location

 

331City and Guilds BuildingSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{Thomareis:2017:10.1063/1.4973811,
author = {Thomareis, N and Papadakis, G},
doi = {10.1063/1.4973811},
journal = {Physics of Fluids},
title = {Effect of trailing edge shape on the separated flow characteristics around an airfoil at low Reynolds number: A numerical study},
url = {http://dx.doi.org/10.1063/1.4973811},
volume = {29},
year = {2017}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Direct numerical simulations of the flow field around a NACA 0012 airfoil at Reynolds number 50 000 and angle of attack 5° with 3 different trailing edge shapes (straight, blunt, and serrated) have been performed. Both time-averaged flow characteristics and the most dominant flow structures and their frequencies are investigated using the dynamic mode decomposition method. It is shown that for the straight trailing edge airfoil, this method can capture the fundamental as well as the subharmonic of the Kelvin-Helmholtz instability that develops naturally in the separating shear layer. The fundamental frequency matches well with relevant data in the literature. The blunt trailing edge results in periodic vortex shedding, with frequency close to the subharmonic of the natural shear layer frequency. The shedding, resulting from a global instability, has an upstream effect and forces the separating shear layer. Due to forcing, the shear layer frequency locks onto the shedding frequency while the natural frequency (and its subharmonic) is suppressed. The presence of serrations in the trailing edge creates a spanwise pressure gradient, which is responsible for the development of a secondary flow pattern in the spanwise direction. This pattern affects the mean flow in the near wake. It can explain an unexpected observation, namely, that the velocity deficit downstream of a trough is smaller than the deficit after a protrusion. Furthermore, the insertion of serrations attenuates the energy of vortex shedding by de-correlating the spanwise coherence of the vortices. This results in weaker forcing of the separating shear layer, and both the subharmonics of the natural frequency and the shedding frequency appear in the spectra.
AU  - Thomareis,N
AU  - Papadakis,G
DO  - 10.1063/1.4973811
PY  - 2017///
SN  - 1089-7666
TI  - Effect of trailing edge shape on the separated flow characteristics around an airfoil at low Reynolds number: A numerical study
T2  - Physics of Fluids
UR  - http://dx.doi.org/10.1063/1.4973811
UR  - http://hdl.handle.net/10044/1/43747
VL  - 29
ER  -
Download