To better understand the formation and evolution processes of soot, the two-color laser induced incandescence diagnostic method was applied on a single cylinder optical direct injection spark ignition engine. Soot volume fraction was measured, and soot distribution was imaged as cyclic fuel quantity changes. The results show that 45.5 mg/cycle generates the most soot at the same measure plane. Pool fire dominates the formation of soot in the tested engine and generates more soot on the top surface of the piston near the injector. In-cylinder soot increases until 42°CA ATDC and then reduces due to oxidation. Pool fire continues through the expansion stroke till 52°CA ATDC, and then soot cloud gathers near the 10 mm plane. After 82°CA ATDC, in-cylinder soot basically in equilibrium, and residual soot moves follow the in-cylinder flow randomly and evenly distributes within the whole combustion chamber. With increasing cyclic fuel quantity, particles number concentration gradually increases and their distribution present dual-peak shape. In detail, 45.5 mg/cycle emits the most accumulation mode particles while 52 mg/cycle emits the most nucleation mode particles.

为了更好地了解烟灰的形成和演化过程，将双色激光诱导白炽灯诊断方法应用于单缸光学直喷火花点火发动机。测量煤烟的体积分数，并将煤烟的分布成像为循环燃料量的变化。结果表明，在同一测量平面上，每周期45.5 mg产生的烟灰最多。池火在测试发动机中的烟灰形成中起主要作用，并在靠近喷油嘴的活塞顶面上产生更多的烟灰。缸内烟灰增加直到ATDC达到42°C，然后由于氧化而减少。池火继续通过膨胀冲程，直至达到ATDC 52°CA，然后烟尘云在10毫米平面附近聚集。在82°CA ATDC之后，缸内烟灰基本处于平衡状态，残余的烟尘运动随缸内流动而随机地并均匀地分布在整个燃烧室内。随着循环燃料量的增加，颗粒数浓度逐渐增加，其分布呈双峰形。详细地，45.5 mg / cycle发射最多的累积模式粒子，而52 mg / cycle发射最多的成核模式粒子。