Dynamic response of diffusion flames under the high voltage direct current electric field

An experimental investigation of the dynamic response of diffusion flames under the high voltage direct current electric field was conducted. The flame height, volume, and surface area are extracted from the three-dimensional reconstructions. The results indicate that the dynamic responses for the liquid fuel flame and the gas fuel flame show entirely different behaviors. For the liquid fuel flame, the height was shortened, which is due to the ionic wind effect. However, for gas fuel flames, the height was lengthened, representing the first observation of the elongation effect for the co-flow jet flame which can be attributed to the forced air and gas flow. Based on the oscillation of the flame height, three and five modes are reported for the liquid and gas fuel flames, respectively. Besides, this is also the first time to estimate the flame volume and surface under the electric field. It was found that the volume and surface area are in phase with height for liquid fuel flame but not for gas fuel flame. These observations may give a comprehensive insight into electric-field assisted combustion.