Temporally and Spatially Resolved Investigation of Soot Morphology in a Transient Diesel Spray Flame via Transmission Electron Microscopy

抄録

For better understanding of soot formation processes in a diesel spray flame, soot particles in a single-shot diesel spray flame were sampled using a newly developed spring-actuated high-speed shuttered soot sampler at different in-flame locations and sampling timings and their morphology was investigated via Transmission Electron Microscopy (TEM). The sampling experiments were conducted using a constant volume combustion vessel under a diesel-like condition at 1100K and 2.7MPa. The soot samplers used in previous studies by the authors constantly exposed a TEM grid directly to the flame for thermophoretic soot deposition onto the grid surface during the whole single-shot combustion experiment. It was therefore likely that the sampled soot was a mixture of soot from different phases of in-flame soot processes from formation, growth to oxidation. The newly developed shuttered sampler enables time-resolved exposure of a TEM grid to the flame with 1ms exposure durations. The in-flame soot particles sampled at different in-flame locations and timings exhibited notable differences in size and morphology. The general trend of temporal and special variations of in-flame soot size, which were acquired for the first time via quantitative TEM analysis, was consistent with the ones previously measured via laser-based imaging technique under similar conditions.