By taking a natural gas lean premixed combustor as the research object

this paper carries out numerical study on flow field

component field and temperature field in combustor as well as the pollutants emission characteristics under conditions with different pilot load ratios

using Flamelet Generated Manifold(FGM) model with GRI-3.0 mechanism. The effect of steam diluting pilot fuel on NO_x emissions was simulated. The temperature filed and OH concentration distribution were analyzed to predict the emissions of NO_x and CO under condition that only the pilot burner with steam-diluted fuel works. The FR-ED combustion model coupled with simplified chemical reaction mechanism was used to predict the effect of steam diluting pilot fuel on emissions of NO_x and CO under design condition. The results show that

the NO_x emission at the combustion chamber outlet increases sharply with the pilot load ratio. When using steam to dilute the pilot fuel

the pilot flame peak temperature decreases by about 10%

and the NO_x mass concentration at the combustor outlet decreases by 88.5%

while that of CO changes little. The research can provide basic data support for subsequent actual combustor applications.