ナノ構造同心度解析を用いた火炎内及び筒内すす粒子酸化過程の調査

抄録

The oxidation processes of soot particles in the cylinder of direct-injection gasoline engine and at the oxidation-dominant periphery of diesel spray flame were investigated using newly developed nano-structure concentricity analysis on HRTEM images of the soot particles. The results for direct-injection gasoline in-cylinder soot at different fuel injection pressures showed that the soot for 15MPa injection pressure case exhibits more disordered outer-shell structure and more indistinguishable concentricity distributions between the outer-shell/inner-core structures compared to the 5MPa injection pressure case. These results support the conjecture of preceding study that higher injection pressure helps to form more oxidation-reactive soot particles. The results for diesel flame core/periphery soot demonstrated that the concentricity analysis can reveal the inner-core/outer-shell structural distribution changes of soot particles during rapid oxidation at the diesel flame periphery to which the conventional morphological analysis is not readily applicable due to indistinguishable primary particle boundaries. Compared to wider and more distinctive distribution of concentricity for flame core soot, flame periphery soot showed narrower concentricity distribution, significantly reduced areas of lower (<0.35) and higher (>0.55) concentricity, and more indistinguishable concentricity distributions between the outer-shell/inner-core structures, indicating rapid oxidation of soot by in-flame OH radicals.