Application of Three-Dimensional Diagnostics on the Direct-Current Electric-Field Assisted Combustion

Recent research has shown that the electric field could impact the flame in multiple aspects, especially in flame propagation and diffusion. However, the available literature all focused on one- or two-dimensional flow characteristics and the flame under study was simple, such as a Bunsen flame or a flat flame. In this work, a method aiming to measure the three-dimensional deformation speed was developed, which combines endoscopic tomography with three-dimensional optical flow algorithm. This method was first validated on an oil lamp flame under the effects of a 10 kV direct-current electric field. The result was compared with that calculated from the spatial derivative of the flame height or edge. After the validation, the proposed method was adopted to study the impact of the external direct-current electric field on swirl-stabilized flames. The results showed that the electric field was able to significantly increase the swirl-stabilized flame height and restrain the horizontal flame deformation speed. This method represents the first attempt to measure the three-dimensional distribution of the flame deformation speed in the field of combustion diagnostics. Besides, different dynamic responses of the two kinds of flames were observed.