LES-CMC of oxy-combustion of hydrogen jet

Large Eddy Simulation / Conditional Moment Closure (LES-CMC) simulations of non-premixed turbulent hydrogen jet in oxy-combustion regimes are performed. The fuel is pure hydrogen and the oxidiser is a mixture O-2/H2O with mass fraction of water vapour in the range Y-H2O = 0.1 - 0.9. The fuel issues into a hot oxidiser stream (1030K-1045K), auto-ignites and the flame propagates through the domain. The problem analysed offers new challenges to combustion modelling as depending on O-2 content in the oxidiser stream the combustion process may be strongly unsteady and on the border of stability and flammability limits. It is shown that LES-CMC is well suited for such studies. We analyse the auto-ignition and forced ignition processes followed by flame propagation and stabilisation phases. The results obtained show that the content of Y-H2O directly affects the flame size and its lift-off height. It was observed that for low content of water vapour the auto-ignition time is a linear function of Y-H2O, whereas the axial locations of auto-ignition spots increase with Y-H2O content.