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In this paper we explore the effects of nanosecond repetitively pulsed discharges (NRPD) on combustion instabilities and NOx emissions of CH4/NH3 flames, in a swirl-stabilized, 6 kW combustor. The combustor has a large dump plane ratio resulting in a turbulent flame with a single compact macrostructure across all operating conditions. Discharges are setup with a central pin-to-cylindrical-wall type electrode configuration with a discharge gap of 4.55 mm at the dump plane. For pure methane, instabilities occur at various frequencies and amplitudes, up to 1000 Pa. NPRD actuation was successful in suppressing instabilities across all conditions, with best reduction being as much as 23 dB. The discharge voltages ranged from 6-9 kV at a pulse rate of 9 kHz, equivalent to 5-12 mJ/pulse energies and plasma powers less than 99W. For pure CH4 flames, the NRPD actuation increased NOx emissions, but for high NH3/CH4 blends, the NRPD actuation reduced NOx emissions.
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A modular flat-flame experimental platform for mechanistic studies of plasma-assisted ammonia-methane combustion
Recent efforts to reduce emissions of NOx, N2O, and NH3-slip in ammonia-methane (NH3/CH4) combustion using Nanosecond Repetitively Pulsed Discharges (NRPD) have relied largely on complex plasma-assisted combustion experiments in three-dimensional, turbulent, swirl-stabilized burners. In this work, we introduce a modular experimental platform based on a flat-flame McKenna burner to isolate and study the fundamental plasma-flame interactions that govern NRPD-assisted combustion of NH3/CH4/air mixtures. The burner-plasma assembly supports both nanosecond-spark and uniform-discharge operating modes when generating the plasma in the hot exhaust gases. Preliminary NO measurements, with NRPD applied either in the post-flame region or directly within the reaction zone, indicate a net NO penalty under the conditions tested. These results highlight the need for further mechanistic investigation of NRPD-driven chemistry in ammonia-methane flames and its implications for emissions reduction strategies.
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- Award ID(s):
- 2339518
- PAR ID:
- 10661573
- Publisher / Repository:
- AIAA SciTech 2026 Forum
- Date Published:
- Format(s):
- Medium: X
- Location:
- https://arc.aiaa.org/doi/abs/10.2514/6.2026-0164
- Sponsoring Org:
- National Science Foundation
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