Effects of applying non-thermal plasma on combustion stability and emissions of NOx and CO in a model gas turbine combustor

- Applying NTP to a model gas turbine combustor is an original work.
- Applying NTP extends the lean flammable limit appreciably and enhances flame stability.
- Some optimal flame conditions to simultaneously fulfill a stringent regulation for NOx and CO emissions under applying NTP exist.

The effect of applying non-thermal plasma (NTP) (by adopting a dielectric barrier discharge) to a lean premixed model gas turbine combustor on flame stability and emissions of NOx and CO has been investigated experimentally by varying mixture nozzle exit velocity (U0) and equivalence ratio (∅). The results showed that the existence of flame enhanced streamer intensity. The streamer intensity decreased as equivalence ratio deceased. Applying NTP to the combustor extended the lean flammable limit, and augmented the flame stability in a manner that the stable flame regime was extended to lower equivalence ratio and the regimes of lifted and oscillating flames are reduced. It was also found that it resulted in increase of NOx emission slightly (however, having a maximum of 10 ppm) and reduction of CO emission significantly due to exalting complete burning. Nonetheless, with applying the NTP extending the lean flammable limit for the baseline case without it, an optimal range in ∅ existed, i.e. <30 ppm for CO emission and ⩽10 ppm for NOx at 0.600 ⩽ ∅ ⩽ 0.650. These results suggest that applying NTP to a gas turbine combustor should be a useful tool to simultaneously reduce both emissions of NOx and CO.