Combustion PVM-MF. The PVM-MF model has been enhanced particularly for dualfuel

Contents Extensive new capabilities available in STAR-CD/es-ice v4.20 Combustion Models see Marc Zellat presentation Spray Models LES New Physics Developments in v4.22 Combustion Models PVM-MF Crank-angle resolved Conjugate Heat Transfer New Meshing Technologies Morphing/remeshing/mapping Overset Mesh

Combustion PVM-MF The PVM-MF model has been enhanced particularly for dualfuel combustion An example is shown here of diesel/gas combustion based on the Westport combustion system Picture source: http://www.westport.com/is/core-technologies/combustion

PVM-MF Dual-Fuel Combustion Engine Details Bore 130 Stroke 150 Conrod 260 Compression ratio 18 Operating Condition Engine speed 1500 rev/min AFR-NG 30.3, AFR-Diesel 273 EGR 2.5% Fuel injection SOI Diesel 707 o CA, Duration 3 o SOI Gas 711 o CA, duration 16 o

Pressure (Pa) Temperature (K) PVM-MF Dual-Fuel Combustion Cylinder pressure and temperature 2.0E+07 1.8E+07 1.6E+07 1.4E+07 1.2E+07 1.0E+07 8.0E+06 6.0E+06 4.0E+06 2.0E+06 Pressure Temperature 1,800 1,600 1,400 1,200 1,000 800 600 400 200 0.0E+00 600 630 660 690 720 750 780 Crankangle (deg) 0

Heat release rate (J/sec) PVM-MF Dual-Fuel Combustion Heat release rate Diesel Natural gas 2.0E+06 1.8E+06 1.6E+06 1.4E+06 1.2E+06 1.0E+06 8.0E+05 6.0E+05 4.0E+05 2.0E+05 0.0E+00 700 710 720 730 740 750 760 770 780 790 800 Crankangle (deg)

PVM-MF Dual-Fuel Combustion NG Diesel PV T 712o CA 710o CA 708o CA 711.5o CA

PVM-MF Dual-Fuel Combustion NG Diesel PV T 720o CA 715o CA 713o CA 717o CA

PVM-MF Dual-Fuel Combustion Fuel-1: Diesel Fuel-2: Natural gas

PVM-MF Dual-Fuel Combustion Combustion progress variable Temperature

Emissions models available in PVM-MF: Thermal Nitric Oxide Extended Zeldovich Mechanism (Daulch et al. 1973, Flower et al.1975, Monat et al. 1979) NO mass fraction (used in example) Flamelet Library (Lartsson et al. 1998) NO mass fraction Soot PVM-MF Dual-Fuel Combustion Das-Houtz-Reitz (1999) model implemented within ECFM-3Z Soot Mass (used in example) Moment Method (Lartsson et al. 1998) Soot Number Density Soot Volume Fraction Soot Surface Density Soot Mean Diameter Carbon Monoxide CO (Hautman et al. 1981) CO-CO2 Kinetics Chemistry implemented within ECFM-3Z CO mass fraction(used in example)

Temperature (K) Emissions mass fraction PVM-MF Dual-Fuel Combustion Emissions 1,700 1,600 1,500 1,400 1,300 Temperature Nox * 10 Soot CO 9.00E-03 8.00E-03 7.00E-03 6.00E-03 5.00E-03 1,200 4.00E-03 1,100 3.00E-03 1,000 2.00E-03 900 1.00E-03 800 0.00E+00 700 710 720 730 740 750 760 770 780 790 800 Crankangle (deg)

Crank-angle resolved Conjugate Heat Transfer Purpose of the Model: To have an easy-to-use capability for crank-angle resolved changes in surface temperature. Important for: Spray impingement reduced surface temperature and hence fuel evaporation rate which affects mixture distribution Surface coatings of high thermal resistance Easy-to-use by specifying a few simple parameters about the near-surface conducting layer 1D heat flow assumption does not need an additional mesh

Temperature Increase [K] Crank-angle resolved Conjugate Heat Transfer Temperature Increment vs Time 40 35 Time = 1 ms 30 Time = 5 ms 25 Time = 10 ms 20 15 10 5 0 0.0 1.0 2.0 3.0 Distance from surface [mm] Fluid Cell F Q F FSI Solid Layer 1 1 2 3 SSI 4 Solid Layer 2 5 6 contact resistance 7 8 B

Minimum Wall Temperature [K] Minimum Wall Temperature [K] Spray-induced heat transfer Predicted wall temperature at 15 ms after SOI BASELINE CHT 1DCHT 450 449 448 447 Wall temperature distribution at 15 ms after SOI: No major differences between the CHT & 1DCHT predictions 446 445 444 BASELINE CHT 1DCHT 0 5 10 15 Time [ms] Minimum temperature on bottom wall as a function of time: No major differences between the CHT & 1DCHT predictions, justifying the use of the 1D CHT model 450 448 446 444 442 440 438 436 434 432 2.50_80_1.0k 2.50_80_0.5k 2.50_80_0.1k 0 5 10 15 Time [ms] Thermal properties of the solid has a substantial effect on wall temperature, with low-conductivity material experiencing the largest temperature drop

Max. Wall Temperature [K] Max. Wall Temperature [K] Combustion induced heat transfer T wall = 500 K Predicted wall temperature 25 ms after SOI BASELINE CHT 1DCHT T air = 800 K P air = 5 bar Ω = 2000 rpm Y C8H18 = 0.0623 T wall = 500 K T wall = 500 K (BASELINE) Conduction (CHT) T bulk = 500 K (1DCHT) 514.0 512.0 510.0 508.0 506.0 504.0 502.0 500.0 514.0 512.0 510.0 508.0 506.0 504.0 502.0 500.0 Maximum Wall Temperature vs Time BASELINE CHT_1.25mm 1DCHT_1.25mm 0 5 10 15 20 25 30 35 40 45 50 Time [ms] 1DCHT_BaTiO3_1.25mm 1DCHT_Al_5.00mm 0 5 10 15 20 25 30 35 40 45 50 Time [ms] Wall temperature distribution 25 ms after SOI: No major differences between the CHT & 1DCHT predictions Maximum wall temperature increase as a function of time: No major differences between the CHT & 1DCHT predictions; verifying the validity of the 1D CHT model Thermal properties of the solid has a strong effect on wall temperature increase, must be properly accounted for in order to achieve accurate combustion and emissions predictions

LES LES Collaboration with University of Modena Focus on real-engine application: Cycle-by-cycle variations COV prediction Ignition process AKTIM and ISSIM models Knock sensitivity critical for highly rated and downsized engines Effect of non-uniform wall temperature CHT solution

GRUppoMOtori Internal Combustion Engine Research LES multicycle flame development 1 st 2 nd 3 rd 4 th 5 th 6 th 7 th 8 th 9 th 10 th 11 th 12 th 13 th 14 th 15 th 16 th 17 th 18 th 19 th 20 th

LES - 3D Results Insight: GRUppoMOtori Internal Combustion Engine Research Local flow field influence: 4 th fastest 16 th slowest A B A B A B A B

LES Correlation Coefficient 1 Correlation Coefficient (FSD_transition, Yj) ( X, Y i j ) abs( cov( X, Y ) var( X ) var( Y j j ) ) 0.8 0.6 0.4 FSD_transition VS Yj (20 cycles) 0.2 0 ER_local VMAG_local TE_local CCV itself relevantly depends on the FSD_transition CCV. This parameter (thus the transition between the ignition model and the FSD equation) is mostly influenced by equivalence ratio and velocity fields close to the spark plug at the spark time occurrence. GRUppoMOtori Internal Combustion Engine Research

Mapped Wall Temperature Conjugate Heat Transfer (CHT) analyses in Star-CCM+ to calculate the local heat transfer A realistic point-wise wall thermal field is applied to LES knocking combustion Mapped Wall Temperatures Combustion Dome Piston Crown GRUppoMOtori Internal Combustion Engine Research

[W] GRUppoMOtori Internal Combustion Engine Research Effect of Mapped Wall on Knock A more accurate prediction of knock is obtained Knock onset and intensity prediction benefit from the point-wise thermal field SAE Paper 2013-01-1088 1.E+07 Heat Release Rate - Autoignition 1.E+06 1.E+05 1.E+04 1.E+03 1.E+02 1.E+01 1.E+00 730 740 750 760 770 780 790 800 Crank Angle Uniform Wall - Fast Cycle Uniform Wall - Medium Cycle Uniform Wall - Slow Cycle Mapped Wall - Fast Cycle Mapped Wall - Medium Cycle Mapped Wall - Slow Cycle

Overset mesh STAR-CCM+ technology Meshing for IC Engines Meshing technology is critical to the ease-of-use and accuracy of in-cylinder calculations In addition to the existing es-ice meshing methodology new methods have been developed for use with IC Engine flows The options that will become available are: More automation of the existing es-ice meshing Technology based on morphing/remeshing/mapping available in 2014

Improved fully automatic 2D meshing Excellent quality 2D mesh

Improved fully automatic 2D meshing Aligned mesh between parallel features improves quality

Fully automatic 3D template generation 2D with Features

Fully automatic 3D template generation 3D Automatic

Fully automatic 3D template generation 3D Automatic

Morphing/Remeshing/Mapping - Setup Period: TDC > 30 o ABDC (210 o ) Period: TDC > 30 o ABDC (210 o ) Total of 6 meshes Scalar Flow & Mixing Max cells ~ 1.5M at BDC Solution mapped to next mesh Mesh morphed in - time Mesh morphed in + time Mesh generated at this time

Meshing Options Different types of meshes may be used at different stages of the calculation Constrained Polyhedra Prism Layers Core Cartesian Mesh Polyhedral Mesh Variable number of prism layers Local Coordinate Systems and Local Mesh Refinement

Example: 4-valve Gasoline Engine

Details around valve at low and high lifts

2-valve Gasoline with polyhedral mesh

2-valve Gasoline with polyhedral mesh

Inclusion of Spray-Adapted Mesh The same concept can be used to embed a local coordinate system for eg a spray-adapted mesh in a gasoline engine Selected morphing used to control mesh motion

Gasoline Spray-Adapted Mesh Period: TDC > 30 o ABDC (210 o ) Spray-adapted mesh between 80 o BBDC > 50 o BBDC Total of 7 meshes Max cells ~ 1.5M at BDC

Gasoline Spray-Adapted Mesh Period: TDC > 30 o ABDC (210 o ) Spray-adapted mesh between 80 o BBDC > 50 o BBDC Total of 7 meshes Max cells ~ 1.5M at BDC

STAR-CCM+ Meshing Developments for ICE Simulation Overset Mesh - the volumes are meshed and motions are applied to each moving region

STAR-CCM+ Meshing Developments for ICE Simulation Intake charge scalar animation

ICE in STAR-CCM+ CD-adapco is accelerating the development of full Internal Combustion Engine capabilities in STAR-CCM+ Development and Support of ICE in STAR-CD will continue indefinitely

Summary Significant Developments in all key areas: Combustion models multi-fuel, emissions developments Fuels open format for fuel chemistry libraries Sprays wall impingement models Crank-angle resolved conjugate heat transfer LES New automated and accurate meshing technologies Accelerated development of full ICE capability in STAR-CCM+