A comparison of large eddy simulation and Reynolds-averaged Navier–Stokes combustion models was performed using simulations of a diesel–methanol dual-fuel engine. The two models share the assumption that the reaction rate for each species is determined by the chemical kinetic processes as well as the relative magnitude of mixing and reaction effects, which are characterized by a kinetic timescale and a turbulence timescale. The main difference in the two models lies in their formulations of the turbulence timescale. The turbulence timescale in the Reynolds-averaged Navier–Stokes model is proportional to the eddy turnover time, while the turbulence timescale in the large eddy simulation model is the time needed for the mixture to reach perfectly mixed conditions based on the scalar dissipation rate. The models were tested using data from experiments on a modified heavy-duty diesel engine. Test cases using low methanol ratios, high methanol ratios and different initial temperatures were examined. In general, the ignition delay increases as the methanol ratio increases. In the models, this was found to occur due to the chemical interaction of the methanol and the diesel fuel. In addition, methanol auto-ignition occurs when the initial temperature is over 425 K. The large eddy simulation model and Reynolds-averaged Navier–Stokes model give similar predictions for the low methanol ratio cases. The large eddy simulation model shows improved capability to predict the high methanol ratio cases and methanol auto-ignition cases, represented by good agreement with experimental results.
DempseyABWalkerNRReitzRD. Effect of cetane improvers on gasoline, ethanol, and methanol reactivity and the implications for RCCI combustion. SAE Int J Fuels Lubr2013; 6(1): 170–187.
2.
HuangZHLuHBJiangDMZengKLiuBZhangJQWangXB. Engine performance and emissions of a compression ignition engine operating on the diesel-methanol blends. Proc IMechE, Part D: J Automobile Engineering2004; 218(4): 435–447.
3.
BayraktarH. An experimental study on the performance parameters of an experimental CI engine fueled with diesel-methanol-dodecanol blends. Fuel2008; 87(2): 158–164.
4.
ChengCHCheungCSChanTLLeeSCYaoCDTsangKS. Comparison of emissions of a direct injection diesel engine operating on biodiesel with emulsified and fumigated methanol. Fuel2008; 87(10): 1870–1879.
5.
CheungCSChengCHChanTLLeeSCYaoCDTsangKS. Emissions characteristics of a diesel engine fueled with biodiesel and fumigation methanol. Energ Fuel2008; 22(2): 906–914.
6.
YaoCDCheungCSChengCHWangYS. Reduction of smoke and NOx from diesel engines using a diesel/methanol compound combustion system. Energ Fuel2007; 21(2): 686–691.
7.
UdayakumarRSundaramSSivakumarK. Engine performance and exhaust characteristics of dual fuel operation in DI diesel engine with methanol. SAE paper 2004-01-0096, 2004.
8.
SayinC. Engine performance and exhaust gas emissions of methanol and ethanol-diesel blends. Fuel2010; 89(11): 3410–3415.
9.
DecJE. Advanced compression-ignition engines-understanding the in-cylinder processes. P Combust Inst2009; 32(2): 2727–2742.
10.
DecJEHwangWSjöbergM. An investigation of thermal stratification in HCCI engines using chemiluminescence imaging. SAE paper 2006-01-1518, 2006.
11.
ChenGYuWFuJMoJHuangZHYangJZ. Experimental and modeling study of the effects of adding oxygenated fuels to premixed n-heptane flames. Combust Flame2012; 159(7): 2324–2335.
12.
ChenGYuWJiangXHuangZWangZChengZ. Experimental and modeling study on the influences of methanol on premixed fuel-rich n-heptane flames. Fuel2013; 103: 467–472.
13.
XuHJYaoCDXuGL. Chemical kinetic mechanism and a skeletal model for oxidation of n-heptane/methanol fuel blends. Fuel2012; 93: 625–631.
14.
XuHJYaoCDXuGLWangZDJinHF. Experimental and modelling studies of the effects of methanol and ethanol addition on the laminar premixed low-pressure n-heptane/toluene flames. Combust Flame2013; 160(8): 1333–1344.
15.
HaworthDCJansenK. Large-eddy simulation on unstructured deforming meshes: towards reciprocating IC engines. Comput Fluids2000; 29(5): 493–524.
16.
JanickaJSadikiA. Large eddy simulation of turbulent combustion systems. P Combust Inst2005; 30(1): 537–547.
17.
PitschH. Large-eddy simulation of turbulent combustion. Annu Rev Fluid Mech2006; 38: 453–482.
18.
RutlandCJ. Large-eddy simulations for internal combustion engines—a review. Int J Engine Res2011; 12(5): 421–451.
19.
ZhangYXRutlandCJ. A further evaluation of the mixing controlled direct chemistry (MCDC) combustion model for diesel engine combustion using large eddy simulation. Fuel2013; 105: 272–282.
20.
ZhangYXRutlandCJ. A mixing controlled direct chemistry (MCDC) model for diesel engine combustion modelling using large eddy simulation. Combust Theor Model2012; 16(3): 571–588.
21.
KongSCMarriottCDReitzRDChristensenM. Modeling and experiments of HCCI combustion using detailed chemical kinetics with multidimensional CFD. SAE paper 2001-01-1026, 2001.
22.
KongSCReitzRD. Application of detailed chemistry and CFD for predicting direct injection HCCI engine combustion and emissions. P Combust Inst2002; 29(1): 663–669.
23.
ReynoldsWC, STANJAN, Interactive Computer Programs for Chemical Equilibrium Analysis, Stanford University, 1986.
24.
PopeSB. CEQ: a Fortran library to compute equilibrium compositions using Gibbs function continuation. Available at: http://eccentric.mae.cornell.edu/;pope/CEQ/ (accessed 2003).
25.
ChumakovSGRutlandCJ. Dynamic structure subgrid-scale models for large eddy simulation. Int J Numer Meth Fl2005; 47(8–9): 911–923.
26.
LeonardA, Energy Cascade in Large-Eddy Simulations of Turbulent Fluid Flows, Turbulent Diffusion in Environmental Pollution, Proceedings of a Symposium held at Charlottesville. Series: Advances in Geophysics, Elsevier, 1975, vol. 18, pp. 237–248.
27.
ChumakovSG. Scaling properties of subgrid-scale energy dissipation. Phys Fluids2007; 19(5): 058104.
28.
ZhangYXPetersenBGhandhiJRutlandCJ. Large eddy simulation of scalar dissipation rate in an internal combustion engine. SAE paper 2010-01-0625, 2010.
29.
AmsdenAA. KIVA-3V: a block-structured KIVA program for engines with vertical or canted valves. Press Release. LA-13313-MS, July1997. Los Alamos, NM: Los Alamos National Laboratory.
LiYHKongSC. Diesel combustion modelling using LES turbulence model with detailed chemistry. Combust Theor Model2008; 12(2): 205–219.
32.
MenonSYeungPKKimWW. Effect of subgrid models on the computed interscale energy transfer in isotropic turbulence. Comput Fluids1996; 25(2): 165–180.
33.
ZhangYXPetersenBGhandhiJRutlandCJ. Large eddy simulation of scalar dissipation rate in an internal combustion engine. SAE paper 2010-01-0625, 2010.
34.
IhmeM. Pollutant formation and noise emission in turbulent non-premixed flames. PhD Thesis, Stanford University, Stanford, CA, 2007.
35.
WernerHWengleH. Large-eddy simulation of turbulent flow over and around a cube in a plate channel. In: DurstFFriedrichRLaunderBESchmidtFWSchumannUWhitelawJH (eds) 8th turbulent shear flows. Berlin and Heidelberg: Springer, 1993, pp.155–168.
36.
ReitzRDRutlandCJ. Development and testing of diesel engine CFD models. Prog Energy Combust1995; 21(2): 173–196.
37.
HuBRutlandCJShethajiTA. A mixed-mode combustion model for large-eddy simulation of diesel engines. Combust Sci Technol2010; 182(9): 1279–1320.
38.
MunnannurAReitzRD. Comprehensive collision model for multidimensional engine spray computations. Atomization Spray2009; 19(7): 597–619.
39.
LefebvreA. Atomization and sprays, combustion: an international series. New York: Taylor & Francis, 1989.
40.
Von KuensbergSCCharngKSReitzRD. Modeling the effects of injector nozzle geometry on diesel sprays. SAE paper 1999-01-0912, 1999.
41.
BharadwajNRutlandCJChangSM. Large eddy simulation modelling of spray-induced turbulence effects. Int J Engine Res2009; 10(2): 97–119.
42.
LiJZhaoZWKazakovAMarcosCDryerFLJamesJS. A comprehensive kinetic mechanism for CO, CH2O, and CH3OH combustion. Int J Chem Kinet2007; 39: 109–136.
43.
DempseyAB. Dual-fuel reactivity controlled compression ignition (RCCI) with alternative fuels. Ph.D. Dissertation, University of Wisconsin–Madison, Madison, WI, 2013.
MillerJAMitchellRESmookeMDKeeRJ: Toward a comprehensive chemical kinetic mechanism for the oxidation of acetylene: comparison of model predictions with results from flame and shock tube experiments. In: Proceedings of the Nineteenth Symposium (International) on Combustion, pp. 181–196. The Combustion Institute, Pittsburgh (1982).
