中文摘要：

在一台单缸火花点火发动机上开展了燃用不同组分配比的低热值气体燃料燃烧特性的试验研究，分析了发动机燃用天然气掺加氮气0％～35％组成的低热值气体燃料在不同负荷下的缸压、压力升高率、放热率、火焰发展期、快速燃烧期及其循环变动性能。研究结果表明：不同负荷下，随着低热值气体中氮气体积分数的增加，最大缸内压力和压力升高率降低，燃烧放热率下降，火焰发展期变长，同时低热值气体中氮气体积分数增加导致发动机放热率曲线型心明显偏离上止点；低热值气中氮气体积分数小于20％时，燃烧稳定性较好，平均指示压力和最大缸压具有强线性相关性，但当氮气体积分数达到30％，小负荷工况下燃烧循环变动明显加强。

英文摘要：

In this paper, an experimental study on combustion and emission characteristics of a single cylinder spark ignition engine fueled with different composition lower-heat-value gases is investigated under different loads. The maximum cylinder pressure, the rate of pressure rise, the heat release rate, the flame development duration and the rapid combustion duration of the engine are analyzed for nitrogen volume fractions in CNG/nitrogen blends ranging from 0% to 35%. Based on experimental results, the maximum cylinder pressure, the maximum rate of pressure rise and the rate of heat release are decreased, while the flame development duration is increased, and the crank angle of the center of heat release curve moves apart from the TDC with the increase of nitrogen volume fraction. When nitrogen volume fraction in lowerheat-value gases is less than 20%, the process of combustion maintains stably and the Pmi has good linear correlation with Pmax However, when nitrogen volume fraction is larger than 30%, large increase in cycle to cycle variation is presented under low load conditions.