Exploring the Impact of Voltage and Frequency Modulation on Flame Kernel Development for Bursts of Nanosecond Discharges

The advent of new exciter technology has recently allowed for both the voltage per pulse and pulsation frequency within a burst of nanosecond discharge to be customized. The present work explores the effects of this through comparing a constant voltage, constant frequency burst (baseline condition) to a modulated voltage, modulated frequency burst (modulated condition) at matched average power conditions. Experiments were conducted in a linear flow tunnel across a range of lean equivalence ratios. Ignition probability and flame kernel morphology/area were designated as metrics of comparison. Initial results showed that the modulated burst configuration maintained a higher ignition probability and produced larger flame kernels (on average) at leaner conditions compared to the baseline configuration. Ultimately, these results suggest that utilizing multiple, lower voltage discharges applied at a higher PRF is beneficial to ignition compared to using fewer, higher voltage/higher energy discharges.