Search Results

Wall-deposition of soot particles occurs due to the interaction between spray flame and cylinder liner wall/piston surface, which can potentially affect soot morphology after the in-flame formation/oxidation processes and before the exit from engine cylinder. In order to investigate these effects, flame wall impingement was simulated in a constant volume combustion vessel and thermophoretic soot sampling was conducted for Transmission Electron Microscopic analysis. A TEM grid for the sampling was exposed to a single-shot diesel spray flame multiple times and the variation of soot morphology (concentration, primary particle diameter and aggregate gyration radius) among the multiple exposures was compared. Furthermore, a newly designed impingement-type sampler vertically exposed the grid to the spray flame and sampled soot particles under different boundary condition from that of conventionally used skim-type sampler.

For better understanding, model development and its validation of in-cylinder soot formation processes of Gasoline Direct Injection (GDI) engines, crank-angle-resolved mass and size distribution of in-cylinder soot during a GDI combustion cycle were investigated via optical measurements and total cylinder sampling technique in an optically accessible Rapid Compression and Expansion Machine (RCEM). A direct-injection, spark-ignited and single-shot combustion event was achieved in the RCEM operated with engine speed 600 rpm, compression ratio 9.0, equivalence ratio 0.9 and natural aspiration. A three-component (iso-octane 65%, n-heptane 10%, toluene 25%) gasoline surrogate fuel and a multi-hole injector shared within the Japanese SIP Innovative Combustion Technology research program were used.