Visualization of the Effect of Dimethyl Ether on Lean Methane-Air Mixture Combustion
DOI:10.13949/j.cnki.nrjgc.2019.01.004
Key Words:optical engine  dimethyl ether  methane  combustion  flame
Author NameAffiliation
JIN Chao, HE Bangquan, ZHAO Guoxing State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China 
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Abstract:The effect of DME injection timing on the compression ignition and flame development of lean methane-air mixture was studied on a single cylinder optical engine equipped with port methane injection and in-cylinder DME direct injection. Results show that in the case of DME direct injection,the combustion process in the cylinder is mainly controlled by DME injection timing. When the DME injection timing is in the range of 40° to 60° BTDC, the heat release rate curve shows a unimodal distribution and a bimodal distribution in the range of 15° to 30° BTDC. At this time, the in-cylinder combustion of DME/methane/air mixture shows the characteristics of self ignition and flame propagation. Moreover, the DME injection timing also influences the location of ignition point. With the delay of DME injection timing, the distribution of ignition zone is more concentrated. Compared with port methane injection with spark ignition, under compression ignition conditions, the DME direct injection can significantly increase the flame propagation speed of methane air mixture in the early stage of combustion, thus accelerating the combustion process.
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