On Hydrodynamic Regimes of Pulse Ignition in Methane-Air Flow

Nanosecond Pulsed High-Frequency Discharge (NPHFD) plasmas have shown promising results as an ignition method in high-velocity applications. This study tests different electrode gap distances (d) across a wide range of inter-pulse times. The partially coupled regime (a set of conditions with low ignition probability) is reduced as d increased, but never disappeared. The small d cases influenced by heat loss to the electrodes create small flame kernels. The large d cases suffer from inconsistent discharge resulting in low ignition probabilities. The minimum ignition power (MIP) also drops with increasing d, but the change of ignition regime near d = 3.5 mm shows a significant effect on ignition probabilities, MIP, and kernel growth. In conclusion, there exists an optimal electrode gap distance for a high ignition probability and large kernel growth.