甲醇缸内直喷复合导流分层燃烧系统的优化研究

Optimization of Complex-Guided Stratified Charge Combustion System for Direct Injection Methanol Engine

综合缸内直喷发动机壁面引导、喷雾引导和气流引导分层燃烧系统的特点,在一台柴油机改造的火花点火发动机上,开展了甲醇缸内直喷复合导流分层燃烧的研究.对影响燃烧系统性能的导流面位置、火花塞伸出缸盖的距离、涡流比、供油提前角、点火提前角、喷油器启喷压力、喷油嘴形式等主要参数进行了优化.优化后的甲醇发动机可以实现过量空气系数为2.23的分层燃烧,在1 500r/min时扭矩为135 N.m(是同工况下原柴油机的65.5%),热效率达到29.7%,较好地实现了分层燃烧系统的优化匹配.

On the basis of the wall-guided, spray-guided and air-guided technologies related with gasoline direct injection, the scheme of complex-guided stratified charge combustion system for direct-injection spark-ignited （DISI） methanol engine was developed. The test engine was retro- fitted from a 4-cylinder diesel engine. The major parameters were optimized, such as the location of the wall guider, the protruding distance of the spark plug, swirl ratio, injection and ignition timing, nozzle type, and needle valve open pressure. The DISI methanol engine can work with the excessive air/fuel ratio as high as 2.23 at a speed of 1 500 r/min. The engine torque is 135 N · m（65.5% of diesel engine torque） and the thermal efficiency reaches 29.7%. The test results indicate that the developed DISI methanol engine can realize a good match for the stratified charge combustion.