Simulation of a MILD combustion burner using ILDM chemistry

Abstract

A numerical study was performed to accommodate mathematical simplification of kinetics and non-premixed reactants in three-dimensional computations. Specifically, the ILDM technique was combined with the presumed probability density function approach to simulate turbulent combustion in a burner operating at MILD combustion, which was characterised by relatively uniform temperatures with no visible flame and sound. An Eulerian solution strategy was implemented in a CFD code on a structured mesh. Predictions of the mean flow field, turbulence kinetic energy, mixture fraction and its variance, temperature, and mass fraction of CO2 and H2O were presented. It is found that the flow near the burner exhibited strong anisotropy and, thus, k – ε turbulence model has over predicted the spread of the jets. Nevertheless, the calculated mean velocities and temperatures reproduce experimental data reasonably well. The mixing mechanism in the near field of the burner was fully described with remarks on the entrainment of flue gas. Low levels of turbulence in the lifted reaction zone were particularly emphasised with relevance to the homogeneity of the temperature field.