Effects of nonthermal plasma and hydrogen blending on lean blowout limit and CO/NOX emissions for turbulent CH4/air premixed flames in a swirled combustor

Abstract

This study examines the combined influence of non-thermal plasma (NTP) activation and hydrogen blending (Omega H2 = 0-0.2) on lean blowout (LBO) limits and pollutant emissions in turbulent CH4/air premixed flames stabilized in a swirl combustor. Hydrogen blending enhances chemical reactivity and extends the LBO limit, whereas applying NTP under optimized discharge conditions (7 kV, 4 kHz) further extended the LBO limit through direct streamer-flame interaction and indirect stabilization mediated by ozone formation and ionic-wind effects. Applying NTP markedly reduced CO emissions by improving combustion performance, while NOX exhibited only a slight increase and remained within acceptable low-emission limits. These results demonstrate that hydrogen blending combined with applying NTP provides an effective route toward lean, low-emission combustion.