小型航空二冲程煤油发动机小负荷试验研究

Study on Spark-ignited Two-stroke Direct Injection Heavy-oil Engines at Low Loads

将1台点燃式二冲程气道喷射汽油机改造为缸内直喷煤油发动机,在3000r/min小负荷工况下进行了点火提前角、喷气结束角、过量空气系数对性能影响的试验研究。结果表明,喷气结束角为50°和80°(上止点前)时,适当增大点火提前角,能使功率增加、油耗降低,但点火提前角不宜过大,否则会造成HC和CO排放量的增加;点火提前角为15°和30°(上止点前)时,适度提前喷气结束时刻,可以使功率增加、油耗和排放降低;另外,偏浓混合气有利于提高功率输出,偏稀混合气有利于降低排放。

An experimental study on the performances was carried out on a two-stroke engine with low pressure air assisted injection technology by aviation kerosene.The influences of ignition angle advance,end angle of air injection and excess air coefficient on the performance of the engine was studied under the conditions of 3000r/min low loads.Test results show that：when end time of air injection is set to 50° and 80° before top dead center（BTDC）,the increases of ignition advance angles may make the engine power increase and the fuel economy reduce.But,the increases may not be too much,or it will cause the increases of CO and HC.When the ignition advance angles are set to 15° and 30° BTDC,the engine powers,fuel consumptions and emission performances may be improved by the advances of the end time of the air injection.And,the rich mixture is beneficial to improve the power outputs,and the lean mixture is beneficial to reduce the emission.