Displacement speed, flame surface density and burning rate in highly turbulent premixed flames characterized by low Lewis numbers

Lee, H. C.1,2; Dai, P.1; Wan, M.1,2,3; Lipatnikov, A. N.4

2023-04-19

10.1017/jfm.2023.257

JOURNAL OF FLUID MECHANICS   影响因子和分区

0022-1120

1469-7645

Direct numerical simulation data obtained from four pairs of turbulent, lean hydrogen-air, complex-chemistry flames are analysed to explore the influence of molecular diffusion on flame surface density, displacement speed Sd and the flame surface density transport equation terms. Each pair involves (i) a flame where mixture-averaged molecular diffusivities are adopted and Lewis number Le is significantly less than unity and (ii) an equidiffusive flame where all molecular diffusivities are set equal to molecular heat diffusivity of the mixture and Le = 1, with other things being equal. Reported results show that significantly higher turbulent burning rates simulated in the former flames result mainly from an increase in the local fuel consumption rate, whereas an increase in flame surface area plays a secondary role, especially in more intense turbulence. The rate increase stems from (i) an increase in the peak local fuel consumption rate and (ii) an increase in a width of a zone where the rate is significant. The latter phenomenon is of more importance in richer flames and both phenomena are most pronounced in the vicinity of the flame leading edges, thus indicating a crucial role played by the leading edge of a premixed turbulent flame in its propagation. Moreover, mean displacement speed differs significantly from the laminar flame speed even in the equidiffusive flames, varies substantially across flame brush and may be negative at the leading edges of highly turbulent flames.

combustion flames turbulent reacting flows

SCI ; EI

英语

第一 ; 通讯

NSFC["12225204","51976088","92041001"] ; Shenzhen Science and Technology Program["KQTD20180411143441009","JCYJ20210324104802005"] ; Department of Science and Technology of Guangdong Province["2019B21203001","2020B1212030001"]

Mechanics ; Physics

Mechanics ; Physics, Fluids & Plasmas

WOS:000974800000001

CAMBRIDGE UNIV PRESS

20231714013398

Combustion ; Diffusion in liquids

Chemical Products Generally:804

ENGINEERING

Web of Science

1.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Guangdong Prov Key Lab Turbulence Res & Applicat, Shenzhen 518055, Peoples R China
2.Southern Univ Sci & Technol, Guangdong Hong Kong Macao Joint Lab Data Driven Fl, Hong Kong 518055, Guangdong, Peoples R China
3.Southern Univ Sci & Technol, Jiaxing Res Inst, Jiaxing 314031, Zhejiang, Peoples R China
4.Chalmers Univ Technol, Dept Mech & Maritime Sci, S-41296 Gothenburg, Sweden

Lee, H. C.,Dai, P.,Wan, M.,et al. Displacement speed, flame surface density and burning rate in highly turbulent premixed flames characterized by low Lewis numbers[J]. JOURNAL OF FLUID MECHANICS,2023,961.

Lee, H. C.,Dai, P.,Wan, M.,&Lipatnikov, A. N..(2023).Displacement speed, flame surface density and burning rate in highly turbulent premixed flames characterized by low Lewis numbers.JOURNAL OF FLUID MECHANICS,961.

Lee, H. C.,et al."Displacement speed, flame surface density and burning rate in highly turbulent premixed flames characterized by low Lewis numbers".JOURNAL OF FLUID MECHANICS 961(2023).