低温起动热力学条件下柴油机喷雾着火特性

Ignition Characteristics of Diesel Engine UnderLow-Temperature Start Condition

针对一款V型八缸增压柴油机,首先分析了其低温起动过程中缸内压缩压力和压缩温度的变化规律,然后在定容喷雾燃烧装置中研究了低温起动热力学条件下柴油的喷雾着火特性,分析了背景温度和背景密度的变化过程中喷雾射流滞燃期和着火位置的变化规律.研究发现:随着背景温度降低,柴油自由喷雾着火滞燃期逐渐增加,着火稳定性逐渐降低;背景密度越高,最低着火温度越低;背景温度低于430℃时,柴油射流的着火成功率非常低,很难着火.该研究对提高起动稳定性,降低燃油消耗率和改善排放有重要的指导意义.

The compression pressure and temperature during low-temperature start was analyzed on a V-type 8-cylinder turbocharged diesel engine,and then the ignition characteristics of diesel spray was studied in a constantvolume spray combustion test device with background temperature and density based on the low-temperature start condition of the engine.The relationship between ignition delay period and ignition position under different background temperature and density conditions was studied.It is found that the ignition delay of diesel free spray increases and the ignition stability decreases with the decrease of background temperature.When the background temperature is below 430℃,the success rate of diesel jet ignition is very low,leading to misfire.The research result is of great significance for improving the stability of low-temperature start and improving fuel consumption and emissions for the diesel engine.