Investigation of 2D Soot Distribution and Characteristic Soot Volume Fraction of Flames in the Confined Compartment with a Horizontal Opening

To comprehensively understand the effect of horizontal opening size on the soot evolution and transportation of flames in the confined compartment, 2D soot distribution and characteristic soot volume fraction of non-premixed propane flames were theoretically and experimentally investigated in the confined compartment (0.2 m x 0.2 m x 0.2 m) with different horizontal openings (0.03 m to 0.10 m) in this work. The oxygen concentration supplied by the horizontal opening was determined by the ratio of dimensionless opening size and dimensionless flame volume within a range of 14.5% to 20.7%. Results showed that the soot distribution of non-premixed propane flames in the confined compartment with a horizontal opening complied with the classical three-zone assumption. The maximum soot volume fraction, the characteristic length of the soot formation zone and the characteristic length of the soot oxidation zone were all positively related to the dimensionless flame volume and negatively correlated with the dimensionless opening size. There was a positive correlation between the ratio of two characteristic lengths and dimensionless flame volume, and the correlation was independent of the dimensionless opening size. Moreover, a linear correlation of characteristic soot volume fraction was proposed to predict the maximum soot volume fraction of non-premixed flames in the confined compartment with a horizontal opening.