Kinetics in Gas Mixtures for Problem of Plasma Assisted Combustion
Final rept. 1 Apr 2007-1 Apr 2010
ECOLE POLYTECHNIQUE PALAISEAU (FRANCE)
Pagination or Media Count:
Throughout the whole period of the research we performed the following tasks The current state of the art in approaches to the study of kinetics of plasma assisted combustion and ignition has been reviewed. It was demonstrated that, in spite of a large body of research in this field, up to now there had been no kinetic model describing adequately plasma assisted ignition and combustion. Kinetics of ignition in CnH2n2O2Ar mixtures for n 1 to 5 has been studied experimentally and numerically under the action of a high-voltage nanosecond discharge. The experiments were carried out in a shock tube behind a reflected shock wave. Ignition delay time, shock wave velocity and discharge characteristics were measured in each experiment. The delay time for plasma-assisted ignition was compared with auto-ignition delay time, which was also measured. It was shown that the initiation of the gas discharge leads to an order of magnitude decrease in ignition delay time. A kinetic scheme was developed to simulate the production of active particles during the discharge and in its afterglow. Using this scheme, production of atoms, radicals and excited and charged particles was numerically simulated based on measured time-resolved discharge current and electric field in the discharge phase. The calculated densities of active particles were used as input data to simulate plasma-assisted ignition of hydrocarbons. Calculated ignition delay time agrees well with experimental data. The analysis of the simulation results showed that the composition of active particles generated by the discharge is dominated by O and H atoms and the following non-equilibrium plasma ignition mechanism occurs under the conditions considered i O atom production by the non-equilibrium plasma, ii chemical reactions of hydrocarbon oxidation with participation of O atoms and gas heating due to net exothermal chemical hydrocarbon oxidation process, and iii subsequent thermal ignition.
- Physical Chemistry
- Plasma Physics and Magnetohydrodynamics