Cellularization characteristics of ethyl acetate spherical expanding flame

Abstract

The cellular instability of ethyl acetate (EA) premixed flame has been studied theoretically and experimentally under different initial temperature, pressure and equivalence ratio. The constant pressure method (CPM) was used to determine the laminar burning velocity of EA spherical expanding flame in this research. In addition, the cellular evolution image of EA spherical expansion flame surface was obtained using high-speed schlieren technology. The image processing technology combined with three-dimensional reconstruction algorithm was used to extract and reconstruct the flame surface crack length, the number of cells on the flame surface, cellular area and cellular length scale. From the quantitative analysis of surface crack and cellular structure of EA flame, it can be seen that the evolution of flame surface crack and surface cellular structure is largely affected by equivalence ratio and initial pressure. With the increase of initial pressure or equivalence ratio, the earlier the flame surface cracks and cell formation. Furthermore, according to the cellular length scale in different radius, the wavenumber was deduced, and compared with the theoretical curve, it is found that the experimental wave numbers have the same evolution trend. Although, when the equivalence ratio is 1.4 with high Peclet number, the experimental wave numbers are somewhat beyond the boundary of the peninsula curve due to the influence of the nonlinear effects, the trend is consistent with the theoretical results.