This study investigates the kinetic modeling of CH4/H2/Air mixture with nanosecond pulse discharge (NSPD) by varying H2/CH4 ratios from 0 to 20% at ambient pressure and temperature. A validated version of the plasma and chemical kinetic mechanisms was used. Two numerical tools, ZDPlasKin and CHEMKIN, were combined to analyze the thermal and kinetic effects of NSPD on flame speed enhancement. The addition of H2 and plasma excitation increased flame speed. The highest improvement (35%) was seen with 20% H2 and 1.2 mJ plasma energy input at ϕ = 1. Without plasma discharge, a 20% H2 blend only improved flame speed by 14% compared to 100% CH4. The study found that lean conditions at low flame temperature resulted in significant improvement in flame speed. With 20% H2 and NSPD, flame speed reached 37 cm/s at flame temperature of 2040 K at ϕ = 0.8. Similar results were observed with 0% and 5% H2 and a flame temperature of 2200 K at ϕ = 1. Lowering the flame temperature reduced NOx emissions. Combining 20% H2 and NSPD also increased the flammability limit to ϕ = 0.35 at a flame temperature of 1350 K, allowing for self-sustained combustion even at low temperatures.

This work focuses on the development of a multiscale computational fluid dynamics (CFD) simulation framework for the investigation of the effects of plasma kinetics on the performance of a microscale dielectric barrier discharge plasma actuator (DBD-PA). To this purpose, DBD-PA multi-scale dual-step modelling approach has been implemented, by considering plasma chemistry and flow dynamic. At first, a microscopic plasma model based on the air plasma kinetics has been defined and plasma reactions have been simulated in zero-dimensional computations in order to evaluate the charge density. At this aim computations have been performed using the toolbox ZDPlasKin, which solves plasma reactions by means of Bolsig+ solver. An alternate current (AC) electrical feeding has been assumed: in particular, the sinusoidal voltage amplitude and the frequency have been fixed at 5 kV and 1 kHz at atmospheric pressure and 300 K temperature in quiescent environment. The predictal charge density has been in a macroscopic plasma-fluid model based on Suzen Dual Potential Model (DPM), which has implemented in the computation fluid dynamic CFD code OpenFoam. Hence, as second step, 2D-CFD simulations of the electro-hydrodynamic body forces induced by the microscale DBDPA have been performed, based on the previously predicted charge densities at the operating conditions. Quiescent flow over a dielectric barrier discharge actuator has been simulated using the plasma-fluid model. The novel modelling framework has been validated with experimental data.

This work performs an analysis of plasma-assisted non-premixed H2-air flames in Y-shaped micro combustors in the presence of field emission dielectric barrier discharge (FE-DBD) plasma actuators. The combustion, flow, and heat transfer characteristics are numerically investigated, and the effect of sinusoidal plasma discharges on combustion performance is examined at various equivalence ratios (φ). A coupled plasma and chemical kinetic model is implemented, using a zero-dimensional model based on the solution of the Boltzmann equation and the ZDPlasKin toolbox to compute net charges and radical generation rates. The estimated body forces, radical production rates, and power densities in the plasma regions are then coupled with hydrogen combustion in the microchannel. Plasma-assisted combustion reveals improvements in flame length and maximum gas temperature. The results demonstrate that FE-DBDs can enhance mixing and complete the combustion of unreacted fuel, preventing flame extinction. It is shown that even in cases of radical and thermal quenching, these plasma actuators are essential for stabilizing the flame.

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.