Experiments on plasma assisted combustion using a dielectric barrier surface discharge

Summary form only given. Plasmas in thermal equilibrium have been in use in different kinds of combustion systems since the invention of the internal combustion engine and the spark ignition systems. Recently the possibility of using plasmas in non-thermal equilibrium for energy-efficient production of radicals and excited species that increase the combustion speed has attracted attention. This interest stems not only from the need for more efficient combustion but also from a wish to increase fuel flexibility with a minimum of modification in existing combustor designs. This paper report experiments performed using a dielectric barrier surface discharge to increase the combustion rate in a Bunsen type burner. The burner has a coaxial geometry where premixed fuel-air flows in the outer annular tube while a jet of air can be injected through the central tube, thus increasing turbulent mixing and flame speed. When the central jet is used the power density but not the total power of the flame increases and gives the possibility of studying the influence of the discharge as a function of power density in the flame. Measurements of the electrical parameters together with two-dimensional distributions of OH, CH₂O and CH using Planar Laser-Induced Fluorescence have been used to analyze the influence of the electrical energy on the combustion process. It is found that, although the total power in the flame is held constant, when the power density in the flame increases the influence of the electrical power on the flame characteristics decreases.