Investigation on the Effects of Field Emission Plasma on the Performance of a Micro-Combustor

This work provides a numerical investigation of the effects of micro field emission dielectric barrier discharge (FE-DBD) plasma actuation on the performance of a micro-combustion system composed of two straights perpendicular microchannels for propellant injection followed by a rectangular micro-combustion chamber in a T-shaped planar configuration. Concerning the modeling, a novel two-step approach has been developed. The first step consisted in solving the chemistry of a sinusoidal plasma discharge in a zero-dimensional modeling. To this purpose, the collisional processes involved in the plasma discharge have been solved using a Boltzmann-equation approach, which permits to predict the electron impact reactions based on a two-temperature model. Furthermore, the zero-dimensional hypothesis used for computations assumed uniform plasma during the overall discharge duration. Concerning the plasma chemistry, excitation and de-excitation processes, electron-ion recombination reactions, attachment and detachment for electrons and neutral species have been considered in order to improve the prediction accuracy. This step allowed to quantify the body force, the heat source and the propellant composition modification induced by sinusoidal plasma actuation operating at 10 MHz of repetition rate, atmospheric pressure and 300 K temperature. Therefore, the predicted cycle averaged plasma effects have been used in 2D steady-state simulations of the laminar, compressible, reactive micro flow, based on a continuum Navier-Stokes approach. SIMPLE pressure-velocity coupling scheme was chosen with a second order pressure spatial discretization. A second-order upwind scheme was applied. The hydrogen-oxygen combustion has been modeled using the Connaire mechanism. The comparison between the results of the reference case without plasma actuation, and those retrieved in presence of plasma actuation at different supplied voltages, highlighted the performance enhancement due to plasma discharge.