In this paper, the dynamic instabilities of a Trapped Vortex Combustor (TVC) were studied experimentally. In particular, the recurrences in the pseudo-phase space of pressure and radiant energy uctuations were analyzed with a view to quantifying the recurrence plots and study the nonlinear behavior of the thermoacoustic instabilities. The present results reveal clearly three different regimes: combustion noise regime characterized by chaotic low-amplitude aperiodic oscillations, a transition regime towards instabilities comprised of intermittent high-amplitude periodic bursts that emerge among low-amplitude aperiodic oscillations, and the combustion instability regime formed by high-amplitude periodic oscillations. A quantification of the recurrence plots was performed by computing the recurrence rate index. The results show that the recurrence rate index fluctuated during the transition and dropped to a minimum in the proximity of instabilities. Therefore, the quantification of recurrence plots proved to be an useful method in order to define precursors that predict in advance combustion instabilities. © 2018 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Chaotic analysis of the thermoacoustic instabilities of a trapped vortex combustor
Troiani, G.
2018-01-01
Abstract
In this paper, the dynamic instabilities of a Trapped Vortex Combustor (TVC) were studied experimentally. In particular, the recurrences in the pseudo-phase space of pressure and radiant energy uctuations were analyzed with a view to quantifying the recurrence plots and study the nonlinear behavior of the thermoacoustic instabilities. The present results reveal clearly three different regimes: combustion noise regime characterized by chaotic low-amplitude aperiodic oscillations, a transition regime towards instabilities comprised of intermittent high-amplitude periodic bursts that emerge among low-amplitude aperiodic oscillations, and the combustion instability regime formed by high-amplitude periodic oscillations. A quantification of the recurrence plots was performed by computing the recurrence rate index. The results show that the recurrence rate index fluctuated during the transition and dropped to a minimum in the proximity of instabilities. Therefore, the quantification of recurrence plots proved to be an useful method in order to define precursors that predict in advance combustion instabilities. © 2018 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
