P. Wernert et D. Favier, Considerations about the phase averaging method with application to ELDV and PIV measurements over pitching airfoils, EXP FLUID, 27(6), 1999, pp. 473-483
Some considerations about the principles of the phase averaging method, oft
en used to decompose a measured signal into mean and fluctuating parts, are
presented for periodic flow configurations involving natural and forced un
steadiness, The order of procedure to theoretically determine the number N
of cycles required to perform a correct phase averaging decomposition is di
scussed and a practical criterion is proposed. The use of this criterion is
first illustrated in the case of ELDV measurements in and outside the boun
dary-layer on an airfoil oscillating in pitch at moderate conditions of uns
teadiness. The principles of the phase averaging method are then extended t
o the case of PIV measurements and both theoretical and practical criterion
s are given. Examples of potential applications of the phase averaging meth
od for quantitative PIV analyses on an airfoil oscillating through dynamic
stall and submitted to strong conditions of unsteadiness are also presented
.