PHASE DRIFT CHARACTERISTICS OF SELF-EXCITED, COMBUSTION-DRIVEN OSCILLATIONS

This paper describes an experimental characterization of the phase drift characteristics of the oscillating pressure in an unstable combustor. It is shown that the phase continuously drifts in a predominantly irregular manner and, given enough cycles, substantially drifts from its “initial” value. It is also shown that the mean-squared value of the phase drift monotonically increases with the number of cycles, a result that is consistent with the predictions of a random walk model. It is concluded that these phase drift characteristics are primarily caused by random processes (i.e., noise) and, thus, do not reflect the underlying low-dimensional dynamics of the instability.