Large-eddy simulation on the influence of injection pressure in reacting Spray A

The Engine Combustion Network (ECN) Spray A target case corresponds to high-pressure liquid fuel injection in conditions relevant to diesel engines. Following the procedure by Wehrfritz et al. (2016), we utilize large-eddy simulation (LES) and flamelet generated manifold (FGM) methods to carry out an injection pressure sensitivity study for Spray A at 50, 100 and 150 MPa. Comparison with experiments is shown for both non-reacting and reacting conditions. Validation results in non-reacting conditions indicate relatively good agreement between the present LES and experimental data, with some deviation in mixture fraction radial profiles. In reacting conditions, the simulated flame lift-off length (FLOL) increases with injection pressure, deviating from the experiments by 4-14%. Respectively, the ignition delay time (IDT) decreases with increasing injection pressure and it is underpredicted in the simulations by 10-20%. Analysis of the underlying chemistry manifold implies that the observed discrepancies can be explained by the differences between experimental and computational mixing processes.