Abstract: A lifted turbulent H₂/N₂ jet flame in a hot and vitiated coflow is investigated numerically to explore the issues of autoignition as well as the flame lift-off. The composition probability density function (PDF) method is employed to facilitate the implementation of detailed chemical kinetics. A multiple-time-scale k-ε turbulence model is combined for the calculation of flow and turbulence fields. Detailed chemical reaction mechanisms of hydrogen oxidation are incorporated in the calculation. The predictions are compared with experimental data. The flame lift-off height and auto-ignition process are reproduced accurately by the model.

Key words: flame lift-off, auto-ignition, PDF, MTS k-ε model, detailed chemical kinetics, numerical method