Thermoacoustic stabilization of a sequential combustor with ultra-low-power nanosecond repetitively pulsed discharges

This study demonstrates the stabilization of a sequential combustor with Nanosecond Repetitively Pulsed Discharges (NRPD). Sequential combustors offer advantages such as enhanced fuel flexibility and broader operational range compared to the conventional combustors. However, thermoacoustic instabilities limit their potential. While passive control strategies like Helmholtz dampers have been utilized, active control methods have been hindered by the lack of robust actuators for harsh conditions with sufficient control authority. This study demonstrates successful suppression of instabilities using NRPD in a labscale atmospheric sequential combustor, even at low plasma power (1.1 W, about 1 . 5 x 10 -3 percent of thermal power of 73.4 kW). We also examine the effect of pulse repetition frequency and plasma generator voltage on NO emissions and the sequential flame topology. Notably, higher plasma power can further enhance suppression, albeit with a slight increase in NO emissions. However, the highest plasma power in our study (81 W, 1 . 1 x 10 -1 percent of flame thermal power) shows a slight improvement in acoustic suppression while significantly elevating NO emissions. Intriguingly, specific plasma parameter combinations can excite another acoustic mode, necessitating further exploration for optimized control. This pioneering study highlights the potential of ultra-low-power plasma-based thermoacoustic control in sequential combustors, paving the way for enhanced stability and performance. (c) 2023 The Author(s). Published by Elsevier Inc. on behalf of The Combustion Institute. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )