A numerical calculation on the flame structure and soot particle distribution in a coannular laminar diffusion flame was performed. Flame analysis model utilized basically flame sheet concepts, Shvab-Zel'dovich assumption and one step overall irreversible reaction. It was also considered the variation of thermodynamic and transport properties, and solved the temperature field by using stagnation enthalpy. The energy equation was included to account for radiation, which earlier studies have found to be important in determing the flame temperature in sooty flames and soot particle distribution. This flame analysis model was verified by comparisions with other methods. For soot particle analysis, we adopted coagulation, surface condensation, and oxidation model in addition to Tesner's two-step formation model. Equations for primary soot particle except for agglomeration process were solved. From the analysis results, it were obtained that the profile of temperature, velocity, species, and volume fraction of soot particle in the flame and investigated radiation and thermophoretic effects. Based on the results, the regions of soot generation, growth, and oxidation in the flame have been observed and radiation strongly affected the flame temperature and soot distribution.
