不同喷射时刻缸内直喷天然气燃烧特性

利用快速压缩装置研究不同喷射沓刻缸内直喷天然气燃烧特性。结果表明，天然气直喷燃烧可实现快速燃烧，缩短喷射时刻与点火时刻的时间差可明显缩短燃烧期。与均匀混合气燃烧相比，碳氢的排放增加，缩短喷射时刻与点火时刻的时间差可达到均匀混合气燃烧时相同的排放量。在很宽的当量比范围内，NOx增加，而CO仍维持很低数值，且不受喷射时刻的影响，直喷天然气燃烧可实现较高的压力升高值，且其数值不受喷射时刻的影响，所达到的高燃烧效率也不受喷射时刻的影响。

Characteristics of Natural Gas Direct Injection Combustion Under Various Fuel Injection Timing

Characteristics of natural gas direct-injection combustion(CNG DI) under various fuel injection timing were studied by using a rapid compression machine. Results show that CNG DI can realize much faster combustion than that of homogeneous combustion while shortening the time interval between injection timing and ignition timing can remarkably decrease the combustion duration. Unburned hydrocarbon would increase over a wide range of equivalent ratio, shortening the time interval between injection timing and ignition timing can decrease the value to that of homogeneous mixture combustion.While CO keeps low level over a wide range of equivalent ratio,NO x is high and CO is little affected by fuel injection timing. High value of pressure rise due to combustion can be realized and it is insensitive to the variation of fuel injection timing. High combustion efficiency can be achieved and it is also independent on injection timing.