基于快速压缩机的二甲醚燃烧特性研究

Study of Combustion Characteristics of Dimethyl Ether Based on a Rapid Compression Machine

为了研究二甲醚（DME）的燃烧特性,在初始温度293 K、驱动压力0.6 MPa、初始压力0.04~0.08 MPa、氮气稀释率47.29%~60.81%、压缩比8.82~12.02的实验条件下,利用快速压缩机（RCM）研究了初始压力、氮气稀释率、压缩比对DME-O2-N2混合气着火延迟期和最高燃烧压力的影响。结果表明：DME-O2-N2混合气出现两阶段放热现象与两阶段着火延迟期;随着压缩比的增加,混合气的着火延迟期出现负温度系数（NTC）现象,随初始压力的升高,出现NTC现象的温度向高温方向发展;随氮气稀释率的增加,出现NTC现象的温度向低温方向发展;初始压力一定,不同压缩比下,随氮气稀释率的增加,混合气的最高燃烧压力和第2阶段着火延迟期呈相反的变化趋势;氮气稀释率一定,不同初始压力下,随压缩比的增加,混合气的最高燃烧压力和总着火延迟期呈相反的变化趋势。

In order to investigate the combustion characteristics of dimethyl ether（ DME）,the experiments are conducted under the initial temperature of 293 K,the driving gas pressure of 0. 6 MPa,the initial pressure of 0. 04 ~ 0. 08 MPa,the nitrogen dilution ratio of 47. 29 ~ 60. 81% and the compression ratio of 8. 82 ~ 12. 02. The effects of the initial pressures,nitrogen dilution ratio and compression ratio on the ignition delay time and peak combustion pressure of the DME-O2-N2 mixtures are investigated using a rapid compression machine（ RCM）. The two-stage heat release and two-stage ignition delay time are observed. The negative temperature coefficient（ NTC） behavior of the mixtures is observed with the increase in compression ratio. The temperature in the presence of NTC increases with the increase in initial pressure. The temperature in the presence of NTC decreases with the increase in nitrogen dilution ratio.Under a certain initial pressure,with the increase in nitrogen dilution ratio,the peak combustion pressure and the second ignition delay time show the opposite trend under different compression ratios. Under a certain nitrogen dilution ratio,with the increase in compression ratio,the peak combustion pressure andoverall ignition delay time show the opposite trend under different initial pressures.