Phase Averaging Analysis of the Unsteady Velocity Profiles in a Separated Flow

By using phase averaging technique, turbulent structure in a flow was studied. For the phase angle of the time dependent signal modulated in frequency, data acquisition is difficult. This study proposed a new method of phase averaging by wavelet transformation. The purpose of the present study is to compare the results of the phase averaging by wavelet transformation with those by the traditional phase averaging technique. These two phase averaging techniques were applied to the experimental data of the velocities in a separated flow with periodical fluctuation. Between the results by these techniques, noticeable differences were shown. If the velocity signals include the frequency modulation, the profiles of phase-averaged velocity by the traditional technique will have nearly the same shapes and be similar to those of time-averaged velocity. On the other hand, the profiles by wavelet transformation showed the clear differences at each phase angle even for the velocity signals with modulated frequencies.