中文摘要：

通过一台改装的直列双缸柴油机,将进气由空气改为比热比更高的氩气和氧气的混合气,研究了氩-氧氛围下天然气的缸内燃烧特性.结果表明：氩-氧氛围下发动机获得了较高的热效率,且热效率随氩气比例的升高而提高,在化学当量比下的试验工况中,当进气中氩比例为82%,时,指示热效率最高达到了47.8%,,相比空气氛围相对提高近33%,.相比于空气氛围,氩-氧氛围下天然气的着火延迟期缩短,燃烧更为迅速,缸内压力峰值更高.需要选择合适的进气氩比例和点火时刻以降低燃烧的粗暴性.氩-氧氛围下氩气比例为75%,时缸内易出现爆震,当提高进气氩气比例至82%,时,能有效避免爆震发生.

英文摘要：

Experimental study on the effects of mr-O2 atmosphere on combustion characteristics of natural gas was conducted on a modified in-line two-cylinder diesel engine. Air is replaced byO2 and Ar （with higher specific heat ratio） mixture as the engine intake gas. Results show that when Ar percentage is 82%, the peak indicated thermal effi- ciency reaches 47.8% in stoichiometric operation condition, which increases by 33% relatively compared with that under air atmosphere in this study. The ignition delay and combustion period become shorter under Ar-O2 atmos- phere. An appropriate Ar percentage and spark timing are needed to reduce combustion roughness. Knock occurs fre- quently when the Ar percentage is 75%, while it can be avoided when Ar percentage is 82%.