Experimental and numerical characterization of a lean premixed flame stabilized by nanosecond discharges

Abstract

This article presents a joint experimental and numerical analysis of a lean turbulent premixed methane-air flame stabilized by nanosecond repetitively pulsed discharges. In the experiments, the transient effects of the discharge on combustion are quantified by optical diagnostics to characterize their impact on flame stabilization. The flame shape is studied with OH* chemiluminescence imaging and the temperature is measured by optical emission spectroscopy. In parallel, Large Eddy Simulation (LES) of the turbulent premixed flame is conducted. Combustion chemistry is modeled by an analytically reduced mechanism whereas the plasma discharge is described by a semi-empirical model. The comparison between experiments and simulations validates the numerical methodology.

Stabilization of lean flames with nanosecond discharges in a gas turbine model combustor

“…Moreover, an optimization could also be carried out to minimize the plasma-to-flame power ratio while improving the combustion efficiency and minimizing the pollutant emissions. Finally, numerical simulations of plasma-assisted combustion in this burner, as done in [23,24], would help improve the understanding of the mechanisms at stake and thus optimize the combustor. This work will be useful to provide guidelines for the integration of NRP discharges in plasmaassisted combustors.…”

Numerical analysis of turbulent flame enhancement by nanosecond repetitively pulsed plasma discharges

“…The discharges properties have been experimentally characterized [21]. They have a quasi-cylindrical shape of 5 mm length corresponding to the interelectrode distance, and a radius equal to 1.0 mm, a pulse energy of 2 mJ deposited in 50 ns and repeated at a frequency of 20 kHz.…”

“…Quantitative comparisons between experiments and simulations have been performed to validate the modeling approach consistency. The comparisons of the gas temperature evolution at the center of the discharge in [21] and OH profile along the line passing through the center of the discharge (4.5 mm above the bluff body) [26] during the pulsing sequence show a very good agreement between the experiment and the numerical simulation with less than 10% difference when steady state is reached. The local effects of the NRP discharges applied on lean burnt gases are well capture by the model.…”

Effect of plasma-flow coupling on the ignition enhancement with non-equilibrium plasma in a sequential combustor

“…Often, the key advantage of using NRPDs is the ability to significantly push lean stability and blow-off limits at a relatively low energy consumption [24,25]. The vast majority of the results that can be found in the literature are carried out in fresh combustible fuel/air mixtures, with only a few recent papers presenting the effect of NRPDs on flames stabilization in a hot vitiated combustion products [4,[26][27][28][29]. The extensive experimental study of the dynamics of NRPD-produced active species and heat release was carried out by Minesi et al [27,28].…”