Study on Flame Behavior Control by the Electric Field

The purpose of this study is to elucidate flame propagation behavior of homogeneous propane-air mixture under application of non-uniform electric field. A needle-shaped electrode was attached to the ceiling and a plate electrode was set at bottom of combustion chamber, so that the electric field was applied in the direction of the chamber's vertical axis. A homogeneous propane-air mixture was supplied at equivalence ratio of 1.0 and was ignited by leaser induced breakdown under atmospheric pressure and room temperature. It was found that the flame front and plate electrode were repelled each other and a thin air layer was formed between the flame and plate electrode when a relatively low positive DC non-uniform electric field was applied to the needle-shaped electrode. It might be thought that the induced current was generated in the flame front, so that the flame front and plate electrode repelled each other. However, when a high DC voltage which generated corona wind was applied, the flame front was deformed and the thin air layer was not formed. In case of a negative DC non-uniform electric field, the electrical breakdown was occurred through the flame. When the flame front approached the plate electrode and a positive single pulse high voltage was applied to the needle-shaped electrode (input voltage was 8 kV and pulse width was 2 ms), a thin air layer was effectively formed and the maximum combustion pressure was higher than that of conventional combustion due to reduction of heat loss by the thin air layer.