二甲醚均质压燃发动机燃烧特性的研究

二甲醚均质压燃发动机由一台单缸柴油机改造而成，其压缩比为10．7。二甲醚气体随进气进入气缸，形成均质混合气。通过试验采集分析缸内压力，结果表明二甲醚均质压燃燃烧是一个两阶段放热过程，分别发生在610K和900K左右。第一阶段放热量较少，约占10％，正常情况下第二阶段集中在上止点附近，释放出70％以上的燃料热量。发动机负荷对最大缸压力及其出现位置、压力升高率和放热率曲线形状等都有重要影响，而发动机转速对它们的影响比较小。

Combustion Characteristics of a DME HCCI Engine

A test engine was modified from a single cylinder diesel engine by lowering its compression ratio to 10.7. The gaseous dimethyl ether (DME) is introduced to the inlet pipe with a constant temperature and the combustion characteristics of the HCCI engine were investigated. The experimental results showed that the HCCI engine combustion demonstrates a two-stage heat release process which occurs at 610 K and 900 K. About 10% of total heat is released in the first stage, while over 70% of total heat release is given by the second stage concentrated near TDC. Engine load or mixture A/F ratio has significant influence on the maximum cylinder pressure and its occurring position, the pattern of the pressure rise rate and the heat release rate while little influence on these combustion parameters by engine speed.