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探讨了降低涡流室燃烧室柴油机颗粒排放物(PM)的方法,利用一台可用光学仪器观察的发动机,研究了降低PM的机理。本研究阐明了以下一些要点:(1)在低负荷时,抑制初始喷油率使PM降低,因为改变着火点降低了可溶性有机成分(SOF)和延迟浓碳粒流出涡流室降低了烟度。(2)在中和高负荷工况下,排气烟度的主要成因是喷束严重撞击燃烧室壁,从而导致燃油粘附在壁上和浓燃油-空气混合气的滞止。(3)加大涡流室的容积比抑制了在涡流室内浓碳粒的形成。然而在主燃室内由于燃烧室深度有相当大的减小,使混合效果下降,碳粒的氧化作用变得不够充分。(4)为使碳粒-空气在主燃室内得到充分混合的效果,最有效的方法是保持活塞顶部的沟槽区有足够的深度,以阻止从燃烧室通道喷出的火焰流扩宽而因此保证形成双涡流。
The method of reducing particulate matter (PM) in the vortex chamber combustor was discussed. The mechanism of reducing PM was studied by using an engine which can be observed by optical instruments. The following points were clarified in this study: (1) At low loads, the suppression of the initial fuel injection rate reduced the PM, as changing the ignition point to lower the soluble organic fraction (SOF) and delaying the flow of concentrated carbon out of the vortex chamber reduced the smoke level. (2) Under medium and high load conditions, the main cause of smoke evacuation is the severe impact of the jet on the wall of the combustion chamber, resulting in the sticking of fuel to the walls and the stagnation of the rich fuel-air mixture. (3) Increase the volume ratio of the vortex chamber inhibits the formation of concentrated carbon in the vortex chamber. However, due to the considerable reduction of the depth of the combustion chamber in the main combustion chamber, the mixing effect is reduced and the oxidation of the carbon particles becomes insufficient. (4) The most effective way to achieve sufficient mixing of the carbon-air in the main combustion chamber is to keep the groove area at the top of the piston at a sufficient depth to prevent the flow of flame emanating from the combustion chamber passage from widening Thus ensuring the formation of double vortex.