Characterization of the ECN spray A in different facilities. Part 2: Spray vaporization and combustion

Engine Combustion Network (ECN) has the objective to provide experimental data with high accuracy in order to reach new steps in scientific understanding of spray combustion at conditions specific to diesel and gasoline engines to improve and validate computational fluid-dynamic models. To extend this network, two new facilities based on rapid compression machines were designed and improved to reach the spray A thermodynamic conditions, which are recommended by the ECN to represent current common-rail light duty diesel engines. In this paper, the results of liquid and vapor spray penetration as well as ignition delay (ID) and lift-off length (LOL) obtained with these rapid compression machines were compared to the results obtained in the constant volume preburn vessel of IFPEN. The specificities of each experimental apparatus allowed to bring complementary elements of understanding like confinement effects. In non-reactive condition, the liquid and vapor sprays were characterized by diffused-back illumination and Schlieren technique, and in reactive conditions, the LOL and the ID by OH* chemiluminescence. The analysis of the results with regard to the boundary conditions (temperature, velocity, confinement) enabled validation of these two new facilities and contributed to enhance the database of ECN, highlighting the confinement effect typical of piston engine operation.