Imperial College London


Faculty of Natural SciencesDepartment of Mathematics

Chair in Applied Mathematics







753Huxley BuildingSouth Kensington Campus






BibTex format

author = {Dunne, R and Schmid, PJ and McKeon, BJ},
doi = {10.2514/1.J054784},
journal = {AIAA Journal},
pages = {3421--3433},
title = {Analysis of flow timescales on a periodically pitching/surging airfoil},
url = {},
volume = {54},
year = {2016}

RIS format (EndNote, RefMan)

AB - Time-resolved velocity fields around a pitching and surging NACA 0018 airfoil were analyzed to investigate the influence of three independent timescales associated with the unsteady flowfield. The first of these timescales, the period of the pitch/surge motion, is directly linked to the development of dynamic stall. A simplified model of the flow using only a time constant mode and the first two harmonics of the pitch surge frequency has been shown to accurately model the flow. Full stall and leading-edge flow separation, however, were found to take place before the maximum angle of attack, indicating that a different timescale was associated with leading-edge vortex formation. This second, leading-edge vortex, timescale was found to depend on the airfoil convection time and compare well with the universal vortex formation time. Finally, instantaneous non-phase-averaged measurements were investigated to identify behavior not directly coupled to the airfoil motion. From this analysis, a third timescale associated with quasi-periodic Strouhal vortex shedding was found before flow separation. The interplay between these three timescales is discussed in detail, particularly as they relate to the periodic velocity and angle-of-attack change apparent to the blades of a vertical axis wind turbine.
AU - Dunne,R
AU - Schmid,PJ
AU - McKeon,BJ
DO - 10.2514/1.J054784
EP - 3433
PY - 2016///
SN - 0001-1452
SP - 3421
TI - Analysis of flow timescales on a periodically pitching/surging airfoil
T2 - AIAA Journal
UR -
UR -
VL - 54
ER -