Plasmachemical processes in plasma-assisted combustion

We performed measurements of the gas flows (air and propane-air) temperatures in the barrier discharge. It was found that gas heating in a propane-air mixture is stronger than in the pure air. Basing on the results of numerical modelling we can conclude that additional heating in propane-air mixtures occurs due to radicals production in the discharge, and the direct thermal heating by the discharge is insufficient to promote a combustion. The main reasons for the temperature growth are additional energy release in chain reactions (this effect is important at high temperatures near the temperature of self-ignition) and the difference in mechanisms of O atoms recombination in air and propane-air: recombination in air proceeds via O-O and O-O₂ collisions, while in propane-containing mixtures the recombination goes with OH radical formation this process is much more faster. To prove the mechanism suggested above about the radical's role in the flame control by the barrier discharge we performed measurements of OH radical in the flame using LIF technique in time-resolved regime with an accuracy about 10μs. The results have showed that formation of OH radicals near the burner nozzle under the discharge action is similar to that one for OH(A). OH maximum corresponds to 1 μs, this result coincide with calculations for OH dynamics which were performed using GRI-Mech 2.1.