房性会，郑尊清，刘海峰，崔雁清，丰雷，尧命发.两次喷射模式下部分预混燃烧火焰发展模式的光学诊断研究[J].内燃机工程,2019,40(2):1-7.
两次喷射模式下部分预混燃烧火焰发展模式的光学诊断研究
Optical Study on Flame Development Pattern of Partially Premixed Combustion with Split Injection Strategy
DOI：10.13949/j.cnki.nrjgc.2019.02.001
关键词:部分预混燃烧（PPC）  两次喷射  火焰发展模式  高速摄像
Key Words:partially premixed combustion  split injection  flame development pattern  high-speed imaging
基金项目:科技部重点研发计划资助项（2017YFC0806302）;国家自然科学基金项目（51576138）
作者单位
房性会，郑尊清，刘海峰，崔雁清，丰雷，尧命发 天津大学 动力工程系，天津 300072 
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摘要:基于一台光学发动机，在1200r/min的转速下以正庚烷为燃料，应用高速摄像的方法研究了两次喷射模式下部分预混燃烧（partially premixed combustion，PPC）中的火焰发展模式，分析了两次喷射控制燃烧反应速率的机理。研究发现，在上止点之前单次喷射时，燃烧为典型的PPC燃烧，火焰发展模式被多点自燃主导。上止点之前两次喷射，火焰同样被多点自燃主导。相比于单次喷射，两次喷射没有改变火焰发展模式，对放热规律的影响较小。推迟第二次喷射的喷射时刻，可以增加扩散燃烧比例，降低放热率峰值，但是燃烧图像中碳烟信号明显增强。两次喷射都位于上止点之后时，火焰发展模式以火焰传播为主，放热率峰值降低，燃烧图像没有明显的碳烟信号。两次喷射可以改变火焰发展模式，有效地控制燃烧反应速率的同时保持较低的碳烟排放。
Abstract:The flame development pattern of partially premixed combustion(PPC) with split injection strategy was studied on an optical engine fueled with n-heptane and operating at 1200r/min using the high-speed imaging of natural flame luminosity, and the mechanism of controlling combustion reaction rate was analyzed. The results show that when the fuel is injected into the combustion chamber with the single injection strategy before top dead center(TDC), the flame development is dominated by multipoint auto ignition. When the fuel is injected before TDC with the split injection strategy, the flame development is also dominated by multipoint auto-ignition. Compared to the single injection strategy, the split injection strategy has a little influence on combustion reaction rate because the flame development pattern does not change. When the second injection timing is delayed, the rate of diffusion combustion increases and the peak heat release rate(PHRR) decreases. However, the signal of soot in the combustion images increases dramatically. When the fuel is injected after TDC with the split injection strategy, flame develops in the way of flame propagation, PHRR decreases and no obvious signal of soot is found. The split injection strategy can change the flame development pattern and control the combustion reaction rate while keeping the soot emission low.
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