The interaction between the premixed counterflow flame and the electric field driven by DC/AC/NS waveforms

The interaction between the premixed counterflow flame and electric fields driven by various waveforms was studied experimentally. The sub-breakdown electric field driven by DC supply or AC supply operating at a low frequency, was able to manipulate the flame geometries considerably, in which the cone-shaped flame, enveloped flame with various amplitudes and the wrinkled flame, were observed. The current density was plotted to elucidate the electric body force resulting in flame kinematics, and particularly verify the hysteresis phenomenon during the increase and decrease of the voltage in both positive and negative polarities. Next, nanosecond pulses were loaded, and discharges occurred, of which the transient emission was recorded. Plasma and flame images illustrate that the flame acts as the boundary between the diffuse and filamentary discharges. The time-resolved and spatial-resolved electric fields, sustained in the plasma and the flame, were measured using picosecond electric field induced second harmonic generation diagnostic. The characterization of plasma morphologies and the electric field distributions of nanosecond pulsed discharge enables a better understanding of the interaction among plasmas, electric fields, and flames.