A DNS study of extreme and leading points in lean hydrogen-air turbulent flames-part II: Local velocity field and flame topology

Lee, HsuChew1,2; Dai, Peng1; Wan, Minping1,2; Lipatnikov, Andrei N.3

2022

10.1016/j.combustflame.2021.111712

COMBUSTION AND FLAME   影响因子和分区

0010-2180

1556-2921

Data obtained in recent direct numerical simulations (Lee et al.) of statistically one-dimensional and planar, lean complex-chemistry hydrogen-air flames characterized by three different Karlovitz numbers Ka ranging from 3 to 33 are further analyzed in order to explore local characteristics and structure of (i) extreme points characterized by the peak (over the computational domain) Fuel Consumption Rate (FCR) or Heat Release Rate (HRR) and (ii) leading points that are also characterized by a high FCR or HRR, but advance furthest into unburned reactants. Results show that, on the one hand, common characteristics of flame perturbations (curvature, strain and stretch rates, displacement speed) fluctuate significantly in the extreme or leading, FCR or HRR points and are different in different flames. Moreover, other two-point local quantities such as the local gradients of combustion progress variables or species (e.g., the radical H) mass fractions are different in different flames. Therefore, a common simple configuration of a perturbed laminar flame cannot be used as a catchall model of the entire local structure of zones surrounding the discussed points at various Ka . On the other hand, single-point local characteristics (temperature, species mass fractions, rates of their production) of the FCR extreme points are comparable in all three turbulent flames and in the critically strained planar laminar flame. In particular, the FCRs in the extreme points fluctuate weakly and are approximately equal to each other and to the peak FCR in the critically strained laminar flame. The latter finding implies that (i) the maximum FCR evaluated in the critically strained laminar flame could be used to characterize, in a first approximation, the local FCR in the extreme or leading points in turbulent flames, thus, supporting the leading point concept, and (ii) almost the same extreme FCR can be reached in substantially different local burning structures. (c) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Hydrogen DNS Turbulent combustion Lewis number Turbulent consumption speed Diffusive-thermal effects Leading point concept

SCI ; EI

英语

第一 ; 通讯

NSFC[91752201,51976088] ; Shenzhen Science and Technology Program[KQTD20180411143441009] ; Department of Science and Technology of Guangdong Province["2019B21203001","2020B1212030001"] ; Joint Program of Shenzhen Clean Energy Research Institute[LCH-2019011] ; SUSTech[CERI-KY-2019-003]

Thermodynamics ; Energy & Fuels ; Engineering

Thermodynamics ; Energy & Fuels ; Engineering, Multidisciplinary ; Engineering, Chemical ; Engineering, Mechanical

WOS:000735767500009

ELSEVIER SCIENCE INC

20213710890713

Air ; Chemical analysis ; Combustion ; Computational chemistry ; Strain rate ; Velocity

Chemistry:801 ; Chemical Products Generally:804 ; Numerical Methods:921.6

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 F, Shenzhen 518055, Peoples R China
3.Chalmers Univ Technol, Dept Mech & Maritime Sci, SE-41296 Gothenburg, Sweden

Lee, HsuChew,Dai, Peng,Wan, Minping,et al. A DNS study of extreme and leading points in lean hydrogen-air turbulent flames-part II: Local velocity field and flame topology[J]. COMBUSTION AND FLAME,2022,235.

Lee, HsuChew,Dai, Peng,Wan, Minping,&Lipatnikov, Andrei N..(2022).A DNS study of extreme and leading points in lean hydrogen-air turbulent flames-part II: Local velocity field and flame topology.COMBUSTION AND FLAME,235.

Lee, HsuChew,et al."A DNS study of extreme and leading points in lean hydrogen-air turbulent flames-part II: Local velocity field and flame topology".COMBUSTION AND FLAME 235(2022).