1. Modeling of Pollutant Formation in a Spark Ignition Engine Using Forte Final Project ME 769: Combustion Processes Stephen Sakai, Alison Ferris, Mitchell Hageman

2. Motivation Particulate research is currently being performed on a spark- ignition direct-injected (SIDI) engine at the ERC Sources and conditions of particulate formation are not well known Effects of injector spray, intake charge motion, end gas, and ring pack on soot and soot precursor formation are of interest May 2, 2013 2

3. Scope Develop model of SIDI engine in FORTE Compare thermodynamic data from model to experimental data Compare emissions data from model to experimental data Explore analytical capabilities of computational model to perform further studies May 2, 2013 3

4. MODEL May 2, 2013 4

5. Model Inspiration: SIDI Research Engine May 2, 2013 5 35° 45° Fuel Injector Stroke: 94.6 mm Bore: 84.96 mm Compression Ratio: 11.97 Displacement: 549 cm 3 DimensionUnitValue Connecting Rod Length[mm]152.4 Clearance Volume[cm 3 ]50.0 Intake Valve Lift[mm]9.9 Exhaust Valve Lift[mm]9.9 Intake Valve Open[  BTDC]10 Intake Valve Close[  ATDC]220 Exhaust Valve Open[  ATDC]150 Exhaust Valve Close[  ATDC]5 Stroke: 94.6 mm Bore: 84.96 mm Compression Ratio: 11.97 Displacement: 549 cm 3 F/A Swirl Ratio = 0.75 Intake Exhaust EVO 150 EVC 350 IVO 365 IVC 580 Actual Engine has SIDI geometry Experiments have been completed using Premixed A/F mixtures Swirl ratio is approximated and matches default setting in FORTE

6. Running Conditions May 2, 2013 6 Stoich Baseline LeanRich Φ0.980.801.2 Speed (RPM)2100 Spark Timing (bTDC)253223 T BDC (K)450383487 P BDC (atm)0.4 Fuel: Iso-octane Oxidizer: 21% O 2 / 79% N 2

7. Imported SIDI geometry Solid model of experimental engine created in SolidWorks and imported into FORTE Imported geometry led to mesh generation error May 2, 2013 7

8. Sector Mesh Custom piston bowl profile was created and used to generate a 45 ° sector mesh Pros: decreased computational time (1/8 computational zone) Cons: inaccurate cylinder head geometry, does not account for valve motion, etc. May 2, 2013 8

9. SI Tutorial Geometry Code consistently failed at injection event: Switched to a simulation of premixed air-fuel mixture May 2, 2013 9

10. A Summary: Model vs. Actual Engine May 2, 2013 10 SimilaritiesDifferences Compression RatioPiston bowl profile Equivalence RatioCylinder geometry (stroke, connecting rod) SpeedFuel (EEE vs C 8 H 18 ) BDC Temperature BDC Pressure Spark timing Spark duration Valve Timing Valve motion profile Φ = 0.98, T BDC = 450 K, P BDC = 0.4 atm, 2100 RPM

11. May 2, 2013 End: 900Start: 540IVC: ~600 SI Tutorial Geometry and Model Settings Mesh sizes set finer at wall boundaries and squish regions Tutorial geometry includes wall- guided cylinder geometry Non-combustion portion of cycle ignored to save computational time (exhaust and first part of intake) 11 SettingUnitValue Global Mesh size[cm]0.32 Wall Mesh size[cm]0.16 Squish Region Mesh Size[cm]0.08 Spark Flame Mesh Size[cm]0.16 Valve Mesh Size[cm]0.16 Intake Valve Close-- Exhaust Valve Open-- Exhaust Valve Close--

12. RESULTS May 2, 2013 12

13. Baseline Thermodynamic Comparisons May 2, 2013 13

14. Crank-Angle Resolved Emissions Plot resembles species mole fractions plot for a laboratory flame Fast chemistry region coincides with TDC/ PP / PHRR/ PT, as expected Overestimates NO X, but underestimates UHC and O 2, these are likely to be related (if NO X increases, O 2 must decrease, it has been seen in experiments that when HC is low, NO X is high) Measurement points for engine-out emissions are NOT the same. Simulation emissions are for the end-of-combustion emissions, at the beginning of EVO, whereas the experimental emissions are measured well downstream of the exhaust manifold May 2, 2013 14 EmissionUnitsExpSim EINOxPPM32675311 UBHCPPM6700 COVol%0.001190.00114 CO 2 Vol%0.1450.122 H2OH2OVol%-0.137 O2O2 Vol%0.00890.00187 Engine-Out Emissions

15. May 2, 2013 15 EmissionUnits Exp 0.98 Sim 0.98 Exp 0.80 Sim 0.80 EINOxPPM32675311 16604503 UBHCPPM6700 5330 COVol%0.001190.00114 9.96E-49.32E-6 CO 2 Vol%0.1450.122 0.1160.101 H2OH2OVol%-0.137 -0.114 O2O2 Vol%0.00890.00187 0.04770.0373 Trends are as expected

16. Conclusions A FORTE model was developed for a spark-ignited gasoline engine Several modeling parameters and settings were studied in order to determine the most efficient way to closely represent the engine conditions Parametric studies were performed including compression ratio and equivalence ratio At a baseline case, the model was shown to predict the engine thermodynamic data well, and differences in the emissions data can be accounted for The model adds useful data analysis capabilities that would be very difficult to achieve with a physical experimental setup May 2, 2013 16

17. Future Model Modifications Add soot model Add crevice model Utilize actual cylinder geometry SIDI Combustion Investigate effect of PRF vs. EEE fuel May 2, 2013 17

18. Thank You. Questions? “Results! Why, man, I have gotten a lot of results. I know several thousand things that won’t work.” -Thomas A. Edison May 2, 2013 18

19. SI Tutorial Geometry and Model Settings May 2, 2013 19 Parameter / ModelSettingSource Chemistry Flame Speed ModelPower LawDefault Reference SpeedGulderDefault T&P, Diluent effect, S T Various – See CodeDefault Transport Turbulence ModelRNG k-epsilonDefault Boundary Conditions Wall ModelLaw of The WallDefault Heat TransferOnCommon Knowledge TemperatureConstant, Component-DependentExperimental Data/ Assumptions Initial Conditions (Initialization, Intake Port, Exhaust Port) Mixture CompositionConstantExperimental Data FuelIso-OctaneCommon PRF Oxidizer21% O 2 / 79% N 2 Common Knowledge TemperatureConstant, Condition-DependentExperimental Data PressureConstant 0.4 [atm]Experimental Data Turbulence, Gas Velocity, SwirlConstantDefaults Simulation Controls Time Step, Chemistry Solver, Transport Terms Defaults Output Controls Spatially Resolved Spatially Averaged User Preference