Nanosecond pulsed discharge regime transitions in response to dynamic combustion environments

Nanosecond pulsed discharges are a promising technology to improve the static and dynamic stability of flames. Whereas most works have centered on the impact of the plasma on the flame, fewer studies have focused on the implications of having a strongly inhomogeneous and unsteady environment on the discharge characteristics. In this contribution we present experimental efforts to quantify the response of the discharge mode and energy deposition to dynamic combustion environments. The first experimental setup considers a premixed methane/air mesoscale combustor, that allows for 1D laminar flame propagation and provides a simple-to-characterize gaseous background, coupled to nanosecond repetitively pulsed discharges in a dielectric barrier discharge configuration. The study reveals the strong coupling of the discharge mode and energy deposition with the relative positioning of the flame. The second experiment considers a burner of more practical interest: a swirl-stabilized combustor of 14kW power under lean conditions and experiencing a 120Hz acoustic instability. The discharge is now generated in a pin-to-ring configuration with the objective of suppressing this instability. In a similar way to the 1D laminar experiment, the discharge evolves over the oscillation cycle of the flame. The results from this work have implications when designing plasma-assisted actuation strategies.