利用快速压缩装置研究天然气直喷燃烧循环变动

摘要

利用快速压缩装置研究了天然气直喷燃烧循环变动.研究结果表明: 借助于分层燃烧和由燃料喷射的湍流引发的快速火焰传播,天然气直喷燃烧在小当量比条件下能实现良好的燃烧稳定性,低的压力峰值循环变动,低的压力升高率峰值循环变动和低的燃烧放热率峰值循环变动.研究发现燃烧期和燃烧产物的循环变动高于压力峰值和燃烧放热率峰值循环变动.CO和未燃碳氢的循环变动依赖于后续燃烧期的循环变动,NOx的循环变动依赖于快速燃烧期的循环变动.在燃料最佳喷射条件下,天然气直喷燃烧的循环变动随当量比的变化并不敏感.%Cycle-by-cycle variations of natural gas direct-injection (CNG DI) combustion were studied by using a rapid compression machine. Results show that CNG DI combustion can realize high combustion stability with less cycle-by-cycle variation in maximum pressure rise, maximum rate of pressure rise and maximum rate of heat release at the small equivalence ratio, which is due to stratified combustion and fast flame propagation with the aid of turbulence produced by high-speed fuel jet. Cycle-by-cycle variations in combustion durations and combustion products present high magnitude to these of maximum pressure rise and maximum rate of heat release. Cycle-by-cycle variations of CO and unburned CH4 depend on the variation of late combustion duration, and the variation of NOx depends on the variation of rapid combustion duration. Cycle-by-cycle variations are insensitive to the equivalence ratio in CNG DI combustion.