The advent of annular combustors introduced a new facet of flame-acoustic interaction: flame coupling with standing and spinning azimuthal acoustic waves. Such coupling involves an acoustic field that is essentially transverse to the flame. Recent experiments on single burner test rigs have provided significant insight into flame interaction with transverse standing waves. However, experiments that focus on the spinning/rotating nature of azimuthal instabilities are still lacking. In this report, we demonstrate a methodology for studying spinning azimuthal instabilities on a single burner test rig. This methodology is based on analyzing flame response to a traveling acoustic wave generated in the combustor. We generate traveling acoustic waves in our transverse acoustic forcing test-rig by converting one end of the transverse extensions to a non-reflecting end. This is achieved through the implementation of the technique of impedance tuning. In the paper, we have discussed this implementation, followed by discussions on the effects of a traveling acoustic wave on a swirl-stabilized flame. The discussion is in the form of a comparison of flame oscillations for traveling wave and standing wave transverse forcing cases. Results show that the effect of transverse pressure oscillations dominates the flame response to traveling acoustic waves.

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