Study On The Measurement And Mechanism Validation Of PAHs In Laminar Premixed Small Molecule Hydrocarbon Fuels Flames

Polycyclic aromatic hydrocarbons（PAHs）formed in the combustion process are kind of toxic and chemical carcinogenic substances,at the same time,are considered as the precursors of soot.Laser induced fluorescence（LIF）was used to investigate the formation of PAHs in laminar premixed C₂H₄,C₂H₆ and C₃H₆ small molecule hydrocarbon fuels flames.And at the same time,the calculated data of PAHs by ABF,USC2 and KAUST2 models were compared with the experimental data to validate these mechanisms.The results are as follows:（1）With the increase of height above burner（HAB）in laminar premixed C₂H₄,C₂H₆ and C₃H₆ flames,the PAHs fluorescence intensity increases too,the fluorescencespectra are centered on 500 nm and ranging from 300nm to 700nm.（2）With the increase of equivalence ratios,the PAHs fluorescence intensity increases in laminar premixed C₂H₄,C₂H₆ and C₃H₆ flames.For C₂H₄ and C₂H₆ flames,when the equivalence ratios increase from 1.9 to2.1,the PAHs fluorescence intensity increase slightly,but when the equivalence ratios are larger than 2.1,the fluorescence intensity increase sharply.For the PAHs in C₃H₆ flames,the PAHs fluorescence intensity increase sharply when the equivalence ratios increase from 2.5 to 2.7.（3）The formation of PAHs in laminar premixed C₂H₄,C₂H₆ and C₃H₆ flames are compared and found that the saturability and length of carbon chain have an important influence on PAHs formation.For A1,A2-A3 and A4,the difference in the PAHs reaction pathways lead to the fluorescence intensity in C₂H₄ flames larger than that in C₂H₆ flames,in C₂H₄ and C₃H₆ flames,the pathways of A1-A4 are almost the same,but the temperature in C₃H₆ flames are higher,which lead to the fluorescence intensity in C₃H₆ flames larger than that in C₂H₄ flames.（4）The mole fraction of A1-A4 was calculated in Chemkin Pro software combined with ABF Mech,USC Mech2 and KAUST Mech2.Three mechanisms could predict A1 formation well and KAUST Mech2 could predict A2-A4 formation better than ABF Mech in C₂H₄flames.For C₂H₆ flames,three mechanisms predict A1 formation well,KAUST Mech2 predicts A2 and A4 formation better than ABF Mech and the results of A3 in KAUST Mech2 and ABF Mech are similar but lower than experimental data.In C₃H₆ flames,USC Mech2 and KAUST Mech2could predict A1 formation well and A2-A4 could be predicted well by KAUST Mech2.