TY  - JOUR
UR  - https://doi.org/10.1016/j.ijhydene.2018.12.027
SP  - 3195
KW  - Science & Technology
KW  -  Physical Sciences
KW  -  Technology
KW  -  Chemistry
KW  -  Physical
KW  -  Electrochemistry
KW  -  Energy & Fuels
KW  -  Chemistry
KW  -  Direct numerical simulation
KW  -  Lean premixed flame
KW  -  Heat release rate
KW  -  Equivalence ratio
KW  -  DIRECT NUMERICAL-SIMULATION
KW  -  THERMAL UNIMOLECULAR REACTIONS
KW  -  HYDROGEN JET FLAME
KW  -  FALL-OFF RANGE
KW  -  LEWIS NUMBER
KW  -  PRESSURE
KW  -  COMBUSTION
KW  -  LAMINAR
KW  -  SPEED
KW  -  MIXTURES
TI  - Response of heat release to equivalence ratio variations in high Karlovitz premixed H2/air flames at 20 atm
N1  - This version is the author accepted manuscript. For information on re-use, please refer to the publisher?s terms and conditions.
SN  - 1879-3487
ID  - discovery10068827
AV  - public
EP  - 3207
JF  - International Journal of Hydrogen Energy
N2  - This paper presents three-dimensional direct numerical simulations of lean premixed H2/air flames with equivalence ratios 0.4, 0.5 and 0.6, respectively. The initial Karlovitz number is around 2335 and the pressure is 20 atm, which is relevant to gas turbine conditions. The heat release in reaction zones under different equivalence ratios is examined statistically with the aim to extend our understanding of lean combustion under high-pressure conditions. With increasing equivalence ratio, the relative thickness of reaction zone (?f/?L) is increasing for both laminar and turbulent flames, but the extent of increase is reduced under high equivalence ratio. By examining the local structures of flame fronts, it is found that trenches and plateaus of local equivalence ratio are located on separate sides of the reaction zone edge. Due to the decreased Lewis number under high equivalence ratio, the trench ?depth? and plateau ?height? are reduced. For the flame under ultra-lean conditions, there are some spots with temperatures above adiabatic temperature. This is attributed to the high-fraction of radicals in these regions, which will promote heat release. Furthermore, the heat release rates of elementary reactions are investigated with the analysis of radical fractions and rate constants. When the mixture equivalence ratio varies, the local heat release is changed in different temperature windows due to the combined effects of radical fractions and reaction rate constants.
VL  - 44
IS  - 5
A1  - Wang, X
A1  - Jin, T
A1  - Luo, KH
PB  - PERGAMON-ELSEVIER SCIENCE LTD
Y1  - 2019/01/28/
ER  -