Phase drift characteristics of self-excited, combustion-driven oscillations

This paper describes an experimental characterization of the phase drift ch aracteristics of the oscillating pressure in an unstable combustor. It is s hown that the phase continuously drifts in a predominantly irregular manner and, given enough cycles, substantially drifts from its "initial" value. I t is also shown that the mean-squared value of the phase drift monotonicall y 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 insta bility. (C) 2001 Academic Press.