Multi-environment PDF modeling for n-dodecane spray combustion processes using tabulated chemistry

The multi-environment probability density function approach together with a tabulated chemistry model has been developed to numerically simulate spray combustion processes under Diesel-like combustion conditions. In this study, the joint composition PDF is approximated using the multi-environment PDF, consisting of a combination of weights and weighted scalars in both chemical composition space and physical space. To account for the auto-ignition process and subsequent flame propagation, a flamelet generated manifold is generated by utilizing steady and unsteady flamelet solutions. The spray dynamics are represented by the state-of-art physical models in context with the Eulerian-Lagrangian approach. The RANS-based computations are made for the n-dodecane non-reacting and reacting spray jets. In terms of spray and vapor penetration, the mean and rms mixture fraction, ignition delay, and lift-off height, the numerical results are in reasonably good agreement with the available experimental data of the Engine Combustion Network. Based on the numerical results, detailed discussions are made for the effects of the ambient conditions on the structures and characteristics of high-pressure Diesel-fueled spray jet flames.