The Enhancement of Hydrogen Addition on Ignition and Flame Propagation Stability of Direct Injection Natural Gas Lean Combustion

摘要

Effect of hydrogen addition on ignition and flame propagation stability of direct injection natural gas lean combustion was investigated experimentally and numerically. The flame propagating photos and pressure derived initial combustion duration of premixed combustion and direct injection combustion was obtained by using a constant volume vessel. The laminar premixed methane-hydrogen-air flames were calculated with PREMIX code of CHEMKIN II program with GRI 3.0 mechanism. The results showed that the ignition characteristics of lean burn natural gas-air mixtures was enhanced as hydrogen is added to natural gas in the case of both premixed combustion and direct injection combustion. The mole fraction of OH and O are increased with the increase of hydrogen fraction and the position of maximum OH and O mole fraction move closing to the unburned mixture side. A monotonic correlation between initial combustion duration with the reciprocal maximum OH mole fraction in the flames is observed. The enhancement of the spark ignition of natural gas with hydrogen addition can be ascribed to the increase of OH and O mole fraction in the flames.