Unsteady Flamelet Modeling of Soot Formation in Turbulent Diffusion Flames

Abstract

The unsteady flamelet model is applied in a numerical simulation of soot formation in a turbulent C₂H₄ jet diffusion flame. A kinetically based soot model is used, which relies on a detailed kinetic mechanism to describe the formation of small polycyclic aromatic hydrocarbons. To describe the formation, growth, and oxidation of soot particles, flamelet equations for the statistical moments of the panicle size distribution are derived. Since the effective Lewis number of large panicles tends to infinity, a formulation is given, which allows the investigation of the effect of different diffusion coefficients of the particles on the soot formation process. The results of the calculation are compared to experimental data, showing very good agreement for the temperature, which is shown to depend strongly on soot and gas radiation. The predicted soot volume fraction compares reasonably well with the measured data, if differential diffusion of the panicles is considered, Calculations with unity particle Lewis numbers show similar results, but overpredicts the soot volume fraction in the rich part of the flame.

Keywords:

• turbulent diffusion flame
• soot formation
• Flamelet model

Additional information

Notes on contributors

H. PITSCH

[email protected] Center for Integrated Turbulence Simulations, Flow Physics and Computation Division, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305-3030 Tel: [phone] FAX: [phone] E-mail: [email protected]

E. RIESMEIER

[email protected], [email protected]