Modeling turbulent flame enhancement by Nanosecond Repetitively Pulsed discharges using a low-order model

Plasma-Assisted Combustion (PAC), using Nanosecond Repetitively Pulsed (NRP) discharges, is a promising technique to stabilize lean premixed flames, which are prone to instabilities and extinction. PAC has been successfully demonstrated in various academic and semi-industrial configurations. It has been proven to be effective in preventing instabilities, improving combustion efficiency, and extending the lean blowout (LBO) limit. To transfer PAC technology toward higher Technology Readiness Levels (TRLs), numerical simulations are required by engineers for combustor design and optimization. Among the strategies available, several multi-D Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES) of plasma-assisted turbulent combustion have been conducted in the literature by combining phenomenological NRP discharge models with detailed or semi-detailed combustion mechanisms. While these simulations achieve good accuracy, their computational cost remains high because of the large variety of spatial and temporal scales involved in plasma, combustion, and turbulence interactions. The present work aims to develop a low-order model of flame stabilization by NRP discharges, as alternative to full 3-D CFD simulations, for the design and optimization of PAC systems at a low-CPU cost. PAC is modeled by a series of three connected canonical flame elements. First, the volume of gas affected by the plasma discharges is modeled by a Perfectly-Stirred Reactor (PSR), which employs Castela’s phenomenological NRP discharge model. Next, a Plug Flow Reactor (PFR) is employed to track the combustion reactions within the recirculation zone. Finally, a 1-D strain-imposed Premixed Counterflow Flame (PMX-CF) models the impact of these gas fluxes on the flame structure. The reduced-order model is validated against 3-D LES of the Mini-PAC configuration, and a parametric study is performed on some key modeling parameters, namely the dilution and the strain rate. Novelty and significance statement This work presents a novel reduced-order modeling framework for flame stabilization by Nanosecond Repetitively Pulsed plasma discharges, as an alternative to 3-D CFD simulations. The model combines classical canonical flame elements with a phenomenological representation of nanosecond plasma discharge physics, providing a unique way to capture key flame stabilization mechanisms without relying on fully resolved, computationally expensive simulations. The developed model supports both fundamental research and engineering applications, enabling broader use of plasma-assisted combustion in future clean and efficient energy and propulsion systems.