Recurrence analysis of forced synchronization in a self-excited thermoacoustic system

Murugesan, Meenatchidevi and B, Saravanan and Hochgreb, Simone and Li, Larry K B (2017) Recurrence analysis of forced synchronization in a self-excited thermoacoustic system. In: International Congress on Sound and Vibration, 23-27, July 2017, London.

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Abstract

We use recurrence analysis to investigate the forced synchronization of a self - excited thermoacoustic system . The system consists of a swirl - stabilized turbulent premixed flame in a n open - ended duct. We apply periodic acoustic forcing to this system at different amplitudes and frequencies around its natural self - excited frequency, and examine its response via unsteady pressure measurements. On increasing the forcing amplitude, we observe two bifurcations: from a periodic limit cycle (unforced) to qua- sipe riodic ity (weak forcing) and then to lock - in (strong f orcing). To analyse the se bifurcations , we use cross - recurrence plots (CRPs) of the unsteady pressure and acoustic forcing. We find that the different time scales characterizing the quasiperiodic ity and the transition to lock - in appear as d istinct structures in the CRPs . We then examine those structures using cross recurrence quantification analysis ( C RQA) and find that the ir recurrence quantities change even before the system transitions to lock - in . This shows that CRPs and CRQA can be used as alternative nonlinear tool s to study forced synchronization in thermoacoustic systems, complementing classical linear tools such as spectral analysis.

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