Numerical Modeling of Turbulent Jet Diffusion Flames Challenges and Implications for Flare Flame Simulations

Flare systems play an important role in the petrochemical, chemical processing, mining and waste handling industries. These systems need to perform satisfactorily under a wide range of operating conditions. Computational Fluid Dynamics (CFD) can be a powerful tool in conjunction with experimental testing in evaluating flare system performance to ensure reliability and safety. Utilizing CFD fully in the design of flare systems requires an understanding of the relevant physics as well as the current modeling tools available. To gain further insight into the numerical modeling of flare flames, CFD results using the standard k-e, realizable k-e and Reynolds stress turbulence models in FLUENT V5 were compared with experimental measurements in a buoyant, turbulent jet diffusion flame. Over the range of data available, all models perform comparably. Good agreement is seen for mean profiles of velocity, mixture fraction and temperature. Experimental data and simulation results compare well with established scaling laws for jet spreading rate and centerline momentum flux density. Based on these results, the realizable k-e model provides the most accurate, cost-effective solution for turbulence modeling in flare flames. Further investigation of these models in the buoyancy dominated, plume regime is suggested.