Laminar jet diffusion flame under AC electric fields

The effects of AC electric fields on a laminar jet diffusion flame in a coflow burner have been experimentally investigated. A fuel nozzle made by stainless steel has been used as an electrode to generate AC electric fields in a flame zone. As results, reduction in soot luminosity together with two distinctive instabilities, i. e., a tip flickering behavior and the rotational motion of a flame, has been found. When we increased either an applied voltage or an applied AC frequency, we could observe sudden reduction in the area of a sooting zone as well as drop in the soot luminosity which implies less soot formation. For further increasing frequency, the flame flickering behavior, through FFT analysis, could be identified to has the frequency around 12Hz, which is similar to a buoyancy driven Kelvin-Helmholtz (K-H) instability. In addition, a new flame behavior, the rotational motion of a flame, has been found in a high frequency (3 kHz) and high voltage (4 kV) condition. The characteristic frequency of this rotational motion is around 15 Hz. Detailed characteristics for aforementioned electrically triggered flame modifications are discussed.