Ammonia (NH3) has received considerable attention as a near future carbon-free synthetic fuel due to its economic storage/transportation/distribution, and its potential to be thermally decomposed to hydrogen (H2). To promote the low burning velocity and heat of combustion of ammonia, one viable option is to enrich pure ammonia with hydrogen. In this study, two quasi direct numerical simulations (quasi-DNS) with detailed chemistry and the mixture-averaged transport model are examined to study stoichiometric planar ammonia/hydrogen/air flames under decaying turbulence. The reactants temperature and pressure are set to 298 K and 1 atm, respectively. The initial turbulent Karlovitz number is changed from 4.3 to 16.9, implying that all the test conditions are located within the thin reaction zones combustion regime. The results indicate that the density-weighted flame displacement speed (), on average, is higher than the unstrained premixed laminar burning velocity () value for both test cases. This suggests that the flame elements propagate faster than their laminar flame counterpart. With increasing the Karlovitz number, the turbulent burning velocity and the wrinkled flame surface area increase by about 35%. Furthermore, the mean flame stretch factor defined as the ratio of the turbulent to the laminar burning velocity divided by the ratio of the wrinkled to the unwrinkled flame surface area is equal to 1.08. This indicates that the local flamelet velocity value, on average, is higher than the unstrained premixed laminar burning velocity. In addition, the results show that the mean value of the local equivalence ratio for the turbulent conditions is higher than its laminar counterpart due to the preferential diffusion of hydrogen and turbulent mixing. Furthermore, the net production rate of hydrogen is shown to be negatively correlated with the flame front curvature suggesting that the local burning rate is intensified in positively curved regions.
Valera-MedinaAXiaoHOwen-JonesMDavidWIFBowenPJ. Ammonia for power. Prog Energy Combust Sci2018; 69: 63–102.
2.
KobayashiHHayakawaASomarathneKDOkaforE. Science and technology of ammonia combustion. Proc Combust Inst2019; 37(1): 109–133.
3.
HawkesERChenJH. Comparison of direct numerical simulation of lean premixed methane–air flames with strained laminar flame calculations. Combust Flame2006; 144(1-2): 112–125.
4.
PetersNTerhoevenPChenJHEchekkiT. Statistics of flame displacement speeds from computations of 2-D unsteady methane-air flames. Proc Combust Inst1998; 27(1): 833–839.
5.
EchekkiTChenJH. Analysis of the contribution of curvature to premixed flame propagation. Combust Flame1999; 118(1-2): 308–311.
6.
SongWHernández PérezFETingasEAImHG. Statistics of local and global flame speed and structure for highly turbulent H2/air premixed flames. Combust Flame2021; 232: 111523.
7.
ChakrabortyNCantS. Unsteady effects of strain rate and curvature on turbulent premixed flames in an inflow–outflow configuration. Combust Flame2004; 137(1-2): 129–147.
8.
ChakrabortyNCantRS. Influence of Lewis number on curvature effects in turbulent premixed flame propagation in the thin reaction zones regime. Phys Fluids2005; 17(10): 105105.
9.
ChakrabortyNHerbertAAhmedUImHGKleinM. Assessment of extrapolation relations of displacement speed for detailed chemistry direct numerical simulation database of statistically planar turbulent premixed flames. Flow Turbul Combust2022; 108: 489–507.
10.
GülderÖL. Turbulent premixed flame propagation models for different combustion regimes. Proc Combust Inst1991; 23(1): 743–750.
11.
LipatnikovANChomiakJ. Turbulent flame speed and thickness: phenomenology, evaluation, and application in multi-dimensional simulations. Prog Energy Combust Sci2002; 28(1): 1–74.
DamköhlerG. Zeitschrift für elektrochemie und angewandte physikalische chemie. Z Electrochem1940; 46: 601–652.
14.
HanIHuhKY. Roles of displacement speed on evolution of flame surface density for different turbulent intensities and Lewis numbers in turbulent premixed combustion. Combust Flame2008; 152(1-2): 194–205.
15.
NivartiGCantS. Direct numerical simulation of the bending effect in turbulent premixed flames. Proc Combust Inst2017; 36(2): 1903–1910.
16.
KleinMHerbertAKosakaH, et al. Evaluation of flame area based on detailed chemistry DNS of premixed turbulent hydrogen-air flames in different regimes of combustion. Flow Turbul Combust2020; 104: 403–419.
17.
BrearleyPAhmedUChakrabortyN. The relation between flame surface area and turbulent burning velocity in statistically planar turbulent stratified flames. Phys Fluids2020; 32(12): 125111.
18.
ChakrabortyNWangLKleinM. Streamline segment statistics of premixed flames with nonunity Lewis numbers. Phys Rev E2014; 89: 033015.
19.
GülderÖL. Contribution of small scale turbulence to burning velocity of flamelets in the thin reaction zone regime. Proc Combust Inst2007; 31(1): 1369–1375.
20.
TamadonfarPGülderÖL. Effects of mixture composition and turbulence intensity on flame front structure and burning velocities of premixed turbulent hydrocarbon/air Bunsen flames. Combust Flame2015; 162(12): 4417–4441.
21.
ChakrabortyNAlwazzanDKleinMCantRS. On the validity of Damköhler’s first hypothesis in turbulent Bunsen burner flames: A computational analysis. Proc Combust Inst2019; 37(2): 2231–2239.
22.
LipatnikovANChomiakJ. Molecular transport effects on turbulent flame propagation and structure. Prog Energy Combust Sci2005; 31(1): 1–73.
23.
RutlandCJTrouvèA. Direct simulations of premixed turbulent flames with nonunity Lewis numbers. Combust Flame1993; 94(1-2): 41–57.
24.
HaworthDCPoinsotTJ. Numerical simulations of Lewis number effects in turbulent premixed flames. J Fluid Mech1992; 244: 405–436.
25.
BellJBChengRKDayMSShepherdIG. Numerical simulation of Lewis number effects on lean premixed turbulent flames. Proc Combust Inst2007; 31: 1309–1317.
26.
DayMBellJBremerP-TPascucciVBecknerVLijewskiM. Turbulence effects on cellular burning structures in lean premixed hydrogen flames. Combust Flame2009; 156(5): 1035–1045.
27.
AspdenAJ. A numerical study of diffusive effects in turbulent lean premixed hydrogen flames. Proc Combust Inst2017; 36(2): 1997–2004.
28.
LeeHCDaiPWanMLipatnikovAN. Influence of molecular transport on burning rate and conditioned species concentrations in highly turbulent premixed flames. J Fluid Mech2021; 928: A5.
29.
RiethMGruberAWilliamsFAChenJH. Enhanced burning rates in hydrogen-enriched turbulent premixed flames by diffusion of molecular and atomic hydrogen. Combust Flame2022; 239: 111740.
30.
ZirwesTZhangFHabisreutherP, et al. Quasi-DNS dataset of a piloted flame with inhomogeneous inlet conditions. Flow Turbul Combust2020; 104: 997–1027.
31.
PassotTPouquetA. Numerical simulation of compressible homogeneous flows in the turbulent regime. J Fluid Mech1987; 181: 441–466.
32.
SaadTClineDStollRSutherlandJC. Scalable tools for generating synthetic isotropic turbulence with arbitrary spectra. AIAA J2017; 55(1): 327–331.
33.
IchikawaAHayakawaAKitagawaYKunkuma Amila SomarathneKDKudoTKobayashiH. Laminar burning velocity and Markstein length of ammonia/hydrogen/air premixed flames at elevated pressures. Int J Hydrogen Energy2015; 40(30): 9570–9578.
34.
BorghiR. Recent advances in the aerospace sciences, ch. On the structure and morphology of turbulent premixed flames. Boston, MA: Springer, 1985. pp.117–138.
35.
PetersN. The turbulent burning velocity for large-scale and small-scale turbulence. J Fluid Mech1999; 384: 107–132.
36.
WellerHGTaborGJasakHFurebyC. A tensorial approach to computational continuum mechanics using object-oriented techniques. Comput Phys1998; 12(6): 620–631.
37.
StagniACavallottiCArunthanayothinS, et al. An experimental, theoretical and kinetic-modeling study of the gas-phase oxidation of ammonia. React Chem Eng2020; 5: 696–711.
38.
ZhongSZhangFPengZBaiFDuQ. Roles of CO2 and H2O in premixed turbulent oxy-fuel combustion. Fuel2018; 234: 1044–1054.
39.
ZhongSZhangFJangiMBaiXSYaoMPengZ. Structure and propagation of n-heptane/air premixed flame in low temperature ignition regime. Appl Energy2020; 275: 115320.
40.
ZhongSZhangFDuQPengZ. Characteristics of reactivity controlled combustion with n-heptane low temperature reforming products. Fuel2020; 275: 117980.
41.
ZhangNZhangFZhongS, et al. Numerical and theoretical investigation of ethanol/air flame instability. Combust Theory Model2020; 24(6): 1108–1129.
42.
RochaRCZhongSXuL, et al. Structure and laminar flame speed of an ammonia/methane/air premixed flame under varying pressure and equivalence ratio. Energy Fuels2021; 35(9): 7179–7192.
43.
AspdenAJDayMSBellJB. Lewis number effects in distributed flames. Proc Combust Inst2011; 33(1): 1473–1480.
44.
NiemeyerKECurtisNJSungCJ. PyJac: Analytical Jacobian generator for chemical kinetics. Comput Phys Commun2017; 215: 188–203.
45.
TekgülBPeltonenPKahilaHKaarioOVuorinenV. DLBFoam: an open-source dynamic load balancing model for fast reacting flow simulations in OpenFOAM. Comput Phys Commun2021; 267: 108073.
46.
KannanJGadallaMTekgülBKarimkashiSKaarioOVuorinenV. Large eddy simulation of diesel spray–assisted dual-fuel ignition: A comparative study on two n-dodecane mechanisms at different ambient temperatures. Int J Engine Res2021; 22(8): 2521–2532.
47.
KarimkashiSGadallaMKannanJTekgülBKaarioOVuorinenV. Large-eddy simulation of diesel pilot spray ignition in lean methane-air and methanol-air mixtures at different ambient temperatures. Int J Engine Res2023; 24: 965–981.
48.
GadallaMKannanJTekgülBKarimkashiSKaarioOVuorinenV. Large-eddy simulation of tri-fuel combustion: Diesel spray assisted ignition of methanol-hydrogen blends. Int J Hydrogen Energy2021; 46(41): 21687–21703.
49.
TamadonfarPKarimkashiSKaarioOVuorinenV. Inner flame front structures and burning velocities of premixed turbulent planar ammonia/air and methane/air flames. Flow Turbul Combust2022; 109: 477–513.
DriscollJFChenJHSkibaAWCarterCDHawkesERWangH. Premixed flames subjected to extreme turbulence: some questions and recent answers. Prog Energy Combust Sci2020; 76: 100802.
52.
AspdenAJDayMSBellJB. Turbulence–flame interactions in lean premixed hydrogen: transition to the distributed burning regime. J Fluid Mech2011; 680: 287–320.
53.
VeynanteDVervischL. Turbulent combustion modeling. Prog Energy Combust Sci2002; 28(3): 193–266.
54.
GranIREchekkiTChenJH. Negative flame speed in an unsteady 2-D premixed flame: a computational study. Proc Combust Inst1996; 26: 323–329.
55.
GiannakopoulosGKGatzoulisAFrouzakisCEMatalonMTomboulidesAG. Consistent definitions of “Flame Displacement Speed” and “Markstein Length” for premixed flame propagation. Combust Flame2015; 162: 1249–1264.
56.
DopazoCCifuentesLAlwazzanDChakrabortyN. Influence of the Lewis number on effective strain rates in weakly turbulent premixed combustion. Combust Sci Technol2018; 190(4): 591–614.
57.
NivartiGVCantRS. Stretch rate and displacement speed correlations for increasingly-turbulent premixed flames. Flow Turbul Combust2019; 102: 957–971.
58.
DriscollJ. Turbulent premixed combustion: Flamelet structure and its effect on turbulent burning velocities. Prog Energy Combust Sci2008; 34(1): 91–134.
59.
NetzerCAhmedAGruberALøvåsT. Curvature effects on NO formation in wrinkled laminar ammonia/hydrogen/nitrogen-air premixed flames. Combust Flame2021; 232: 111520.
