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Drop Drag/Wall Impinge/Vaporization/Sprays

Drop Drag/Wall Impinge/Vaporization/Sprays 18
Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Reciprocating Internal Combustion Engines Prof. Rolf D. Reitz Engine Research Center University of WisconsinMadison 2014 PrincetonCEFRC Summer School on Combustion Course Length: 15 hrs (Mon. Fri., June 23 – 27, 2014) Copyright ©2014 by Rolf D. Reitz. This material is not to be sold, reproduced or distributed without prior written permission of the owner, Rolf D. Reitz. 1 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Short course outine: Engine fundamentals and performance metrics, computer modeling supported by indepth understanding of fundamental engine processes and detailed experiments in engine design optimization. Day 1 (Engine fundamentals) Part 1: IC Engine Review, 0, 1 and 3D modeling Part 2: Turbochargers, Engine Performance Metrics Day 2 (Combustion Modeling) Part 3: Chemical Kinetics, HCCI SI Combustion Part 4: Heat transfer, NOx and Soot Emissions Day 3 (Spray Modeling) Part 5: Atomization, Drop Breakup/Coalescence Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Day 4 (Engine Optimization) Part 7: Diesel combustion and SI knock modeling Part 8: Optimization and Low Temperature Combustion Day 5 (Applications and the Future) Part 9: Fuels, Aftertreatment and Controls Part 10: Vehicle Applications, Future of IC Engines 2 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Beale, 1999 RT Model ERC Spray modeling  1 LCa / f(T) Breakup length  2 Blob injection model KelvinHelmoltz Rayleigh Taylor R/D Linearized instability analysis L/D r=B 0 t = e 0  KH Model Spray Models Nozzle flow/cavitation Jet atomization KHRT Drop breakup Drop collision/coalescence Discrete drop Drop drag model Multicomponent fuel evaporation Spraywall impingement 3 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Liu, 1993 Droplet drag modeling Steadystate Stokes viscous drag, addedmass and Basset history integral dv t ' dv 1 4 3 2 ' dt dv/dt = F 6r v (r ) 6r dt g g g 2 3 ' 0 dt tt General form 2  U g  V dv/dtC A U / U L d D f 2 1 2/3  24Re (1 Re / 6), Re 1000  d d d C  d 0.424, Re1000   d • Drop distortion (TAB model) 2 yy82  U l rel y5 2 3 2  r r 3 r l d l d l d C C (1 2.632y) d d ,sphere 4 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Gosman, 1981 Turbulence drop dispersion Vortex structure • Monte Carlo method St 1  u u  u  St 1 3/2 2 St 1 G(u )4 / 3k exp(3u  / 4k) Stokes St=t /t Dropeddy interaction time e p Eddy life time Residence time t l / u v t l / 2k / 3 p e 3/ 4 3/ 2  = l l = C k /  t min(t ,t ) int e p 5 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wachters, 1966 Spray wall impingement At low approach velocities (We) drops rebound elastically With hot walls cushion of vapor fuel forms under the drop As approach velocity is increased, normal velocity component decreases and drop may break up 2  d/2 U n  We  Beyond We = 40 liquid spreads into surface layer At high temperatures film boiling takes place We= 0.678We exp( 0.088We ) o i i   We 40 We 40 6 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Naber, 1988 Dry wall impingement models Stick drops stick to the wall Reflect drops rebound Slide/Jet incident drop leaves tangent to the surface From mass and momentum conservation: p yb = ln1 p(1 exp( ) b where 0 p 1 random number exp(b )+1 2 sina=+ ( ) /1 (p /b ) exp(b ) 1 7 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Senecal, 1997 Lippert, 2000 ERC wall impingement models • Rebound or slide based on We • Enhanced breakup due to drop destabilization B = 1.73 1 3 2.5 2 1.5 1 measured (Naber et al.) predicted (present) 0.5 measured (Booth) predicted (present) 0  B 3 1 B 40 1 0 0.5 1 1.5 2 2.5  time (ms) B 3 1 B 40 1   We 40 We 40 8 CEFRC36, 2014 radial penetration (cm)Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Deng, 2014 Wet wall impingement – grid independent model Saffman lift force on splashed drops 2  U g  V dv / dt C A U / U F L d D f Saff 2 Fd1.61 Uv Re Saff g g  du g 2 H w Re d g  dy g Wall Jet Model R w (b) Glauert analytical solution Drop splash criterion u real 1 22 E We E 3,330 L,i crit h 1 1 o u min( ,1) m 2 d Re Li , Splash mass ratio v y 1/ 4 drop 1 2  C  u  We m h Li ,  o m 0.1 0.4min( ,1) y  m d  2 Ud L inj noz u CFD C We L,inj  9 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Deng, 2014 H w R w 40 40 R R w Without Wall Jet Model 0.25 mm With Wall Jet Model w 0.25 mm 0.5 mm 0.5 mm 1.0 mm 1.0 mm 30 30 2.0 mm 2.0 mm exp exp 20 20 10 10 0 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Time / ms Time / ms 10 CEFRC36, 2014 Wall Spray Radius / mm Wall Spray Radius / mmPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Deng, 2014 Effect of ambient pressure 8 8 H w H w Pa = 7.5 bar Pa = 5 bar 0.25 mm 0.25 mm 0.5 mm 0.5 mm L = 24 mm L = 24 mm 1.0 mm 1.0 mm 6 6 2.0 mm 2.0 mm exp exp 4 4 2 2 0 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Time / ms Time / ms 8 8 H H w w Pa = 10 bar Pa = 15 bar 0.25 mm 0.25 mm 0.5 mm L = 24 mm 0.5 mm L = 24 mm 1.0 mm 1.0 mm 6 6 2.0 mm 2.0 mm exp exp 4 4 2 2 0 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Time / ms Time / ms 11 CEFRC36, 2014 Wall Spray Height / mm Wall Spray Height / mm Wall Spray Height / mm Wall Spray Height / mmPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Sirignano, 1999 Law, 197677 Aggarwal, 2000 Drop Vaporization – well understood for single component, low ambient pressure 2 – D Law LiquidVapor Interface: Tinf Equilibrium or YR Nonequilibrium T Drop Y Yinf R TR Mass transfer with Internal circulation and surroundings: vaporization, r profiles: temperature, condensation, gas solubility concentration, velocity Heat transfer to drop: convection (conduction), radiation Relative Drop Motion 12 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Amsden, 1989 Lefebvre, 1989 KIVA vaporization models Frossling correlation Rdr /dtDBSh/ (2r) Y 1 1 Mass transfer number Y 1 r B (YY ) /(1Y ) 1 1 1 Sherwood number ln(1B) 1/ 2 1/ 3 Sh (2.0 0.6 Re Sc ) d B Fuel mass fraction at drop surface p Y W / WW (1) 1 1 1 0 p (T ) v d Vapor pressure P from thermodynamic tables v 13 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Amsden, 1989 Lefebvre, 1989 Drop heatup modeling Change in drop temperature from energy balance 4 3 2 2 r c T 4r RL(T ) 4r Q d d d d d 3 Rate of heat conduction to drop from T ∞ RanzMarshall correlation Q (T T )Nu / 2 r T d r dd where ln(1 B) 1/ 2 1/3 Nu (2.0 0.6Re Pr ) d B 14 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Ra, 2003 Vaporization regimes q q o o m m Boiling Flash boiling q q i i heating cooling T T d d q o q T T o T s s ∞ m m T T T T b b Tq q T amb i i s T T d d T d T T T T d s T s s ∞ r r T T Normal Normal T ∞ T evaporation evaporation d T =T s b heating cooling T =T s b T d r r 15 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Ra, 2003 Vaporization regimes Normal evaporation energy balance  C m P  mL(T ) h (TT ) (TT ) s i,eff d s s  2r C m C (y y ) Sh o P A F Fs exp1  Nu Nu  mass balance y y Fs F  m g ln(1 B ) g ln(1 ) m M m 1 y Fs Boiling evaporation (T from Clausius Clapeyron equation) b  C m P  mL(T ) (h )(TT ) (TT ) b i,eff sh d b b  2r C m C (y1) Sh o P A F exp1  Nu Nu T TT  d b  m 0.26 Superheated   0.76T (0T 5) sh h ,  t droplet  i,eff e eff e 2.33  correlation  0.027T (5T 25) e T T (Adachi et al., s 0.39 d 1997) 13.8T (25T )  q 16 CEFRC36, 2014 distribution or mole fraction Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Ra, 2003 Lippert, 1997 Multicomponent fuel modeling Diesel Gasoline d dies iese el l A A d dies iese el B l B A Ar rom omati atic c 34 34 16 16 S Su ulfu lfur r ppm ppm 10.5 10.5 7.3 7.3 P Para arafin fins s 33 33 42 42 N Nap apth then enes es 33 33 42 42 O Olef lefin in 0.2 0.2 0.3 0.3 C Cetan etane e 43 43 47 47 C C/H /H r rati atio o 7.014 7.014 6.393 6.393 1.6 50 gasoline composition Discrete g (mw ) 1.4 p i isooctane approximation Common automotive fuels are 40 1.2 Single comp approx multicomponent 1 30 Components: Various molecular 0.8 weights and chemical structures 20 Continuous f (I) 0.6 Three approaches; p i) single component approximation 0.4 10 ii) continuous multicomponent 0.2 iii) discrete multicomponent 0 0 0 50 100 150 200 250 300 molecular weight 17 CEFRC36, 2014 distribution or mole fraction Yi, 2001 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Ra, 2003, 2009 Multicomponent model formulation Continuous MultiComponent Discrete MultiComponent  Continuous system of a liquid phase +  Discrete system of a liquid phase + Semicontinuous mixture system of Discrete mixture system of vapor vapor phase fuel and ambient gas: phase fuel and ambient gas: N N N F s p p p p G (I) x f (I) x (I I ) G (I) x (I I ) x (I I ) p F p s s  p F F s s s1 F1 s1 continuous phase discrete phase discrete phase of fuel discrete phase of air/fuel mixture  Vapor phase transport equation,   Vapor phase transport equation, n n  I f (I)dI (n 0, 1, 2,) p p  0  y y v(Dy ) s i i i i g,i   n n n t   v  I J dI S f v f v I g  0 t    func  Assumed distribution function :  1 y y v(Dy ) S (I ) (I ) F F F g f (I) exp t  () 2 2   ,  18 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Ra, 2009 DMC model tests 0.030 Diesel A Modeled species contents 0.025 species MW Mass fraction 0.020 Diesel A (US narrowcut Diesel) 0.015 c14h30 198 0.6253 0.010 c12h26 170 0.0559 0.005 c16h34 226 0.3025 c18h38 254 0.0163 0.000 0 50 100 150 200 250 300 350 Diesel B (Euro Diesel) molecular weight g/mol c14h30 198 0.2376 0.012 Diesel B ic8h18 114 0.0153 0.010 c10h22 142 0.0807 0.008 c12h26 170 0.1863 0.006 c16h34 226 0.1984 0.004 c18h38 254 0.2817 0.002 0.000 0 50 100 150 200 250 300 350 molecular weight g/mol 19 CEFRC36, 2014 probabilty density probabilty densityPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Ra, 2009 Fuel component distributions MW=199.61 MW=196.06 0.0025 0.0120 0.0100 0.0020 0.0080 0.0015 0.0060 0.0010 0.0040 0.0005 0.0020 0.0000 0.0000 ic8h18 c10h22 c12h26 c14h30 c16h34 c18h38 ic8h18 c10h22 c12h26 c14h30 c16h34 c18h38 Diesel B MW =200 ini CA=14 ( first ignition timing) 20 CEFRC36, 2014 mass fraction mass fractionPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Ra, 2009 Multicomponent spray vaporization Gasoline Do=300 m Vinj=100 m/s 2.0 ms after SOI 1 1 0 0..5 5 0 0..8 8 0 0..4 4 M MW W=7 =77 7..1 1 M MW W=1 =119 19..7 7 0 0..6 6 0 0..3 3 0 0..4 4 0 0..2 2 0 0..2 2 0 0..1 1 0 0 0 0 iiC C5 5H H1 12 2 iiC C6 6H H1 14 4 iiC C7 7H H1 16 6 iiC C8 8H H1 18 8 C C9 9H H2 20 0 C C1 10 0H H2 22 2 C C1 12 2H H2 26 6 iiC C5 5H H1 12 2 iiC C6 6H H1 14 4 iiC C7 7H H1 16 6 iiC C8 8H H1 18 8 C C9 9H H2 20 0 C C1 10 0H H2 22 2 C C1 12 2H H2 26 6 c co om mp po on ne en nt t c co om mp po on ne en nt t 21 CEFRC36, 2014 m mo olle e f fr ra ac ct tiio on n m mo olle e f fr ra ac ct tiio on nPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Jiao, 2011 Fredenslund, 1975 Nonideal mixing using UNIFAC method For mixtures composed of polar components, both initial and final boiling points in the distillation curve are not well predicted assuming Ideal Mixing (Raoult’s Law) misses the azeotrope behavior of the mixture. P vap,i xx i i L,i P m H H H C C OH H H Differences in size Energy interactions and shapes of the between functional 3 molecules groups P P vap,i Vapor pressure of pure comp. i ; Total mixture pressure m x Mole fraction of comp. i in liquid phase; x Mole fraction of comp. i in gas phase Li , i 22 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Pfahl,1996 Jiao, 2011 Ethanol/gasoline surrogate mixture 23 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Jiao, 2011 Drop evaporation simulation Droplet lifetime 0.010 E10 noUNIFAC E10 UNIFAC 0.008 Temp. vs. mole fraction 0.006 80 noUNIFAC 0.004 75 UNIFAC 70 0.002 65 0.000 0.0 0.1 0.2 0.3 0.4 60 0 15 C Time s 55 50 45 0.0 0.2 0.4 0.6 0.8 1.0 x ethanol 24 CEFRC36, 2014 Droplet radius cm 0 Temperature C Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Jiao, 2011 Andersen, 2010 Distillation curve 140 noUNIFAC Simulation E00 Experiment 120 E10 E20 E50 100 E85 E100 80 60 140 UNIFAC 40 E00 Simulation 0 20 40 60 80 100 120 E10 Volume E20 E50 100 E20 has the lowest E85 E100 initial boiling 80 temperature 60 40 0 20 40 60 80 100 Volume 25 CEFRC36, 2014 0 Temperature C 0 Temperature C Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Anand, 2011 Surrogate fuels 18 component model alkanes aromatics cycloalkanes PAH corrected 26 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Anand, 2011 Diesel hydrocarbon class distributions and surrogates Paraffins Naphthenes Alkylbenzenes Benzene(MAH) Polynuclear aromatics 100 80 60 20 species physical property surrogate database 40 20 0 FUELS for Advanced Combustion Engines (FACE) Measured hydrocarbon class distributions 27 CEFRC36, 2014 FACE1 FACE2 FACE3 FACE4 FACE5 FACE6 FACE7 FACE8 FACE9 Hydrocarbon concentration ( mass)Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Anand, 2011 Chemical structure and activity coefficients of Face 9 surrogates activity coefficient component chemical structure  at 373 K nTetradecane (C H ) 1.01 14 30 Cyclohexane (C H ) 0.88 6 12 Decalin (C H ) 1.03 10 18 Departure nDecane (C H ) 1.06 10 22 from Raoult’s nHexadecane (C H ) 0.95 16 34 law nEicosane (C H ) 0.81 20 42 Nonideal Phenanthrene (C H ) 2.22 14 10 vaporization influences mXylene (C H ) 1.06 heavyend 8 10 of distillation curve mCymene (C H ) 1.07 10 14 p x P i,v i,v Pentylbenzene (C H ) 1.08 11 16  x P i,l i sat,i Tetralin (C H ) 1.17 10 12 Heptylbenzene (C H ) 1.10 13 20 28 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Anand, 2011 Example face fuel 1 surrogate composition m q o 700 Measured q i Distillation profile T d Model Batch distillation 640 T s T modeled as T d 580 flash boiling droplet T =T s b T amb 520 r Physical property surrogates 460 0.3 0.25 400 0.2 0.0 0.2 0.4 0.6 0.8 1.0 0.15 Evaporated fraction 0.1 0.05 Chemical classes 0 PC – normal paraffins IP – isoparaffins MCP – mono cyclo paraffins DCP – dicycloparaffins AB – Alkyl benzenes PA – poly aromatics 29 CEFRC36, 2014 ndodecane(PC) noctadecane(PC) tmh(IP) hmn(IP) cyclohexane(MCP) decalin(DCP) mcymene(AB) npentylbenzene(AB) nheptylbenzene(AB) tetralin(AB) naphthalene(PA) Distillation temperature (K) Surrogate mass fractionPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Abani, 2008 Putting them all together Grid independent spray models Coarse mesh: Drop drag overpredicted Fine mesh: Drop coalescence under predicted 4 mm 3mm 2 mm 1 mm 0.5 mm 0.25mm Gasjet subgrid momentum exchange near nozzle Nozzle Hole + = Z Liquid Spray Droplets (Solved) Entrained Air (Modeled) Better axial relative velocity for droplets 30 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2010 Spray model validation (Wang SAE 2010010626) INJ P=120bar 6hole injector; Isooctane; constant volume 90 chamber, cold ambient; Injection pressure: 80 120, 200bar; chamber pressure: 12bar; 70 60 50 40 30 mesh=3mm, dtmax=1e6s 20 mesh=2mm, dtmax=1e6s 10 mesh=1mm, dtmax=1e6s experiment 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Expts: Mitroglou, 2006 Time (ms) 60 80 mesh=3mm, dtmax=1e6s mesh=2mm, dtmax=1e6s 70 mesh=1mm, dtmax=1e6s 50 experiment 60 40 50 40 30 30 20 20 mesh=3mm, dtmax=1e6s mesh=2mm, dtmax=1e6s 10 10 mesh=1mm, dtmax=1e6s experiment 0 0 0.0 0.5 1.0 1.5 time (ms) 0.0 0.5 1.0 1.5 time (ms) 31 CEFRC36, 2014 Local SMD (um) Spray Tip Penetration (mm) Droplet Axial Velocity (m/s) Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Naber, 1996 Siebers, 1998 Validation – evaporating sprays Diesel and other fuels; Constant volume chamber; various temperatures; Varying chamber densities: 13.9, 28.6, 58.6kg/m3. Schlieren imaging Pickett, Sandia National Laboratory, "Engine Combustion Network", https://share.sandia.gov/ecn/ 32 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2010 Evaporating diesel spray – grid size and time step independency mesh=3mm, dtmax=1e6s 100 100 mesh=2mm, dtmax=1e6s 90 mesh=1mm, dtmax=1e6s 90 Exp.Liquid Penetration 80 80 Exp.Vapor Penetration 70 70 60 60 mesh=2mm, dtmax=10e6s 50 50 mesh=2mm, dtmax=5e6s mesh=2mm, dtmax=5e7s 40 40 mesh=2mm, dtmax=2e7s 30 30 Exp.Liquid Penetration Exp.Vapor Penetration 20 20 10 10 0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Time (ms) Time (ms) Predicted vapor and liquid penetrations. Experimental data of Naber and Siebers (1996) and Pickett (2007). Diesel fuel injection, nozzle diameter 257 mm, injection 3 pressure 1370bar, gas temperature 1,000K, gas density 58.6 kg/m . 33 CEFRC36, 2014 Spray Tip Penetration (mm) Spray Tip Penetration (mm)Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Juneja, 2004 Evaporating diesel spray liquid length 100 Experiment Computation 90 Experiment Computation Experiment Computation 80 70 3 Liquid Penetration Length 60 7.3 kg/m Siebers, 1998 50 3 40 Injection Pressure : 135 MPa 14.8 kg/m 30 Fuel : DF2 3 59.0 kg/m 20 Orifice Diameter : 246 µm 10 0 700 800 900 1000 1100 1200 1300 Temperature (K) Comparison of model results with experimental liquid penetration length data 34 CEFRC36, 2014 Liquid Penetration Length (mm)Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 ECN Spray A modeling Temp K 800 850 900 1000 1100 1200 O vol 15 13/15/17/21 13/15/17/21 13/15/17/21 13/15/17/21 13/15/17/21 2 Density 7.6/15.2/ 7.6/15.2/ 7.6/15.2/ 7.6/15.2/ 7.6/15.2/ 22.8 3 kg/m 22.8/30.4 22.8/30.4 22.8/30.4 22.8/30.4 22.8/30.4 P MPa 150 50/100/150 50/100/150 50/100/150 50/100/150 50/100/150 inj Computational grid Related submodels Phenomenon Model Liftoff length Spray breakup KHRT instability Onset of the Evaporation Discrete multicomponent (DMC) averaged OH Turbulence Generalized RNG k−ε model concentration Combustion SpeedChem Ignition delay Droplet collision ROI model Maxmium dT/dt Near nozzle flow Gasjet model Maxmium dOH/dt Soot formation Multistep phenomenological 35 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 ECN Spray A modeling 1 Liquid and vapor penetrations Nonreacting mixing process 100 ECN SprayA nC12 nonreacting Ambient conditions 80 T =900K amb O2 0.0 3 Density=22.8kg/m 60 Inj Dur=6.0 ms N2 0.8971 Expt. CO2 0.0652 40 Simulation H2O 0.0377 20 Pressure 60.45 bar Temperature 900 K 0 0 1 2 3 4 3 Density 22.8 kg/m Time ASI ms 30 ECN SprayA Injector specifications nC12 nonreacting Expt. 25 T =900K Type Commonrail Simulation amb 3 Density=22.8kg/m 20 Nozzle Singlehole, 0.89 Inj Dur=6.0 ms Nozzle diameter 0.084 mm (0.090mm) 15 Injection pressure 150 MPa 10 Injection duration 6.0 ms 5 Injection fuel mass 13.77 mg 0 0 1 2 3 4 5 1. Engine Combustion Network, http://www.sandia.gov/ecn/ Time ASI ms 36 CEFRC36, 2014 Vapor Penetration mm Liquid Penetration mmPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 Vishwanathan, 2010 ECN Spray A modeling Physical process Expression Inception:Asoot 4 C H surface growth 2 2 Coagulation O oxidation 2 OH oxidation PAH condensation Transport equations 37 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2013 Reaction mechanism formulation nC12 nC H PAH mechanism 12 26 reaction 104 species and 444 reactions pathway • Reduced ndodecane mechanism 80 species and 299 reactions • Reduced PAH mechanism 1 42 species and 228 reactions PAH mechanism PAH  A1 formation mechanism C H +C H =C H 3 3 3 3 6 6 validation C H +C H =C H +H 3 3 3 3 6 5 C H +C H =C H +H 4 5 2 2 6 6 C H +C H =C H 4 3 2 2 6 5  Larger PAH formation 1. HACA sequence 2. Small radical and molecule 3. Addition reactions between aromatic radicals and molecules 38 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2013 Reaction mechanism validation 2 1 Shock Tube Ignition delay 0.015 1500 nC125 nDodecane/O /N in JSR nDodecane/O /Ar nC 5 2 2 SymbolExpt. 2 12 O2/2 P = 10.0 atm Solid255 species Shock tube O2 ERCPAH 1250 CO ERCPAH Phi = 1.0 DashERCPAH Phi = 2.05 CO CO 1 2 0.010 P=49.55 atm C H 2 1000 2 2 C H 150 2 2 C H 2 4 C H 5 2 4 750 A 1000 1 0.1 0.005 500 50 bar, phi=1.0, Pfahl et al. 50 bar, phi=2.0, Pfahl et al. 250 50 bar, phi=0.67, Pfahl et al. 0.000 0 0.01 500 600 700 800 900 1000 1050 1200 1350 1500 1650 0.8 0.9 1.0 1.1 1.2 1.3 1.4 Temperature K Temperature K 1000/T 1/K 3 JSR 10 1000 SymbolExpt. 0.015 nDodecane/O /Ar nC 5 2 nC125 12 nDodecane/O /N in JSR Solid255 species 2 2 Shock tube O2 O2/2 P = 10.0 atm DashERCPAH ERCPAH ERCPAH Phi = 1.06 CO CO 750 Phi = 2.0 1 P=49.88atm CO C H 10 2 2 2 0.010 C H 150 C H 2 2 2 4 C H 5 500 2 4 A 1000 1 0.1 0.005 20 bar, phi=1.0, Vasu et al. 250 80 bar, phi=1.0, Zhukuv et al. 0.01 0 0.000 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1050 1200 1350 1500 1650 500 600 700 800 900 1000 1000/T 1/K Temperature K Temperature K 1. Narayanaswamy, 2014 2. MzéAhmed, 2012 3. Malewicki, 2013 39 CEFRC36, 2014 Ignition delay ms Ignition delay ms Mole frac. Mole frac. ppm Mole frac. Mole frac. ppmPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 ECN Spray A modeling Nonreacting mixing process Fuel mixture fraction 0.20 0.15 ECN SprayA ECN SprayA Expt. Axial Z=20mm nC12 nonreacting nC12 nonreacting Simulation 0.16 0.12 T =900K T =900K 0.25 amb amb ECN SprayA Expt. 3 3 Density=22.8kg/m Density=22.8kg/m nC12 nonreacting Simulation Inj Dur=6.0 ms 0.12 Inj Dur=6.0 ms 0.09 T =900K 0.20 amb 3 Density=22.8kg/m Z=30mm Expt. 0.08 0.06 Inj Dur=6.0 ms Axial Simulation 0.15 0.04 0.03 0.10 0.00 0.00 0.0 1.5 3.0 4.5 6.0 0 2 4 6 8 0.05 Radial distance mm Radial distance mm 0.15 0.10 ECN SprayA ECN SprayA 20 25 30 35 40 45 50 55 Expt. Z=40mm nC12 nonreacting nC12 nonreacting Axial distance mm Simulation 0.12 0.08 T =900K T =900K amb amb 3 3 Density=22.8kg/m Density=22.8kg/m  Predicted mixture fraction Inj Dur=6.0 ms 0.09 0.06 Inj Dur=6.0 ms distributions agree Expt. Z=50mm 0.06 0.04 Simulation reasonable well with experimental data in both 0.03 0.02 radial and axial directions 0.00 0.00 by calibrating the spray 0.0 2.5 5.0 7.5 10.0 0.0 2.5 5.0 7.5 10.0 12.5 Radial distance mm Radial distance mm model constants 1. Engine Combustion Network, http://www.sandia.gov/ecn/ 40 CEFRC36, 2014 Mixture Fraction Mixture Fraction Mixture Fraction Mixture Fraction Mixture Fraction Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 Skeen, 2013 Reacting conditions Soot formation vs. Ambient temperature 60 ECNSprayA nC12 15 O 2 3 Ambient density 22.8 kg/m 850K 900K 1000K 1100K 1200K 45 Expt. 255 species Present 30 15 SolidExpt. OpenSimulation 0 800 900 1000 1100 1200 Ambient Temperature K 3.0 ECNSprayA nC12 15 O 2 3 Ambient density 22.8 kg/m 2.5 Expt. Soot 2.0 Simultion ppm 1.5 1.0 0.5 0 0 0 0 0 1.4 7 14 16 0.0 10 10 10 10 10 800 900 1000 1100 1200 20 14 Ambient Temperature K 1.2 6 12 75 20 20 20 20 20 ECN SprayA 12 800 K 3 1 5 10 density22.8 kg/m 850 K 60 15 oxygen15 10 900 K 30 30 30 30 30 0.8 4 8 1000 K 45 1200 K 8 10 40 40 40 40 0.6 3 6 40 6 30 0.4 2 4 50 50 50 50 50 4 5 15 0.2 1 2 2 60 60 60 60 60 0 0 1 2 3 4 5 6 0 0 0 10 0 10 10 0 10 10 0 10 10 0 10 10 0 10 Time ms R(mm) R(mm) R(mm) R(mm) R(mm) 41 CEFRC36, 2014 Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Ignition delay ms Liftoff length mm Soot ugPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 ECN Spray A modeling 0 0 0 0 0 1.4 7 14 16 10 10 10 10 10 20 14 1.2 6 12 20 20 20 20 20 12 1 5 10 Soot 15 10 30 30 30 30 30 0.8 4 8 ppm 8 10 40 0.6 40 3 40 6 40 40 6 0.4 2 4 50 50 50 50 50 4 5 0.2 1 2 2 60 60 60 60 60 0 0 0 10 0 10 10 0 10 10 0 10 10 0 10 10 0 10 R(mm) R(mm) R(mm) R(mm) R(mm) 0 0 0 0 0 7 6 5 4 4 x 10 x 10 x 10 x 10 x 10 8 16 2.5 10 10 10 10 10 10 5 7 14 2 20 20 20 20 20 6 12 8 4 5 10  The soot formation 30 30 30 30 30 A 1.5 4 6 3 4 8 40 40 40 40 40 regions agree with the 1 3 6 4 2 50 50 50 50 50 2 4 high A concentration 0.5 4 2 1 1 2 60 60 60 60 60 regions; 0 0 0 10 0 10 10 0 10 10 0 10 10 0 10 10 0 10 R(mm) R(mm) R(mm) R(mm) R(mm) 0 0 0 0 0 7 6 7 7 7 x 10 x 10 x 10 x 10 x 10  Predicted soot particle 14 2 14 16 16 D 10 10 10 10 10 soot 14 14 12 12 size is in the reasonable 20 20 20 20 20 1.5 12 12 Peak 10 10 range compared to 10 10 30 30 30 30 30 16 nm 8 8 1 8 8 experimental data; 40 6 40 40 6 40 40 6 6 4 4 50 50 50 50 50 0.5 4 4 2 2 2 2 60 60 60 60 60 0 0 0 10 0 10 10 0 10 10 0 10 10 0 10 10 0 10 R(mm) R(mm) R(mm) R(mm) R(mm) 42 CEFRC36, 2014 Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm)Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 Reacting conditions Soot formation Overview Total soot mass 4.5ms 60 60 3 75 ECN SprayA ECN SprayA ECN SprayA Pressure MPa Density kg/m 3 O 15 O 15 50 Density 22.8 kg/m 50 2 50 2 7.6 60 100 15.2 Soot 40 40 150 O 22.8 2 45 13 30.4 30 30 15 17 30 20 20 21 15 10 10 0 0 0 1000 1100 1200 1000 1100 1200 1000 1100 1200 850 900 850 900 850 900 Ambient Temperature K Ambient Temperature K Ambient Temperature K Liftoff length 60 60 ECN SprayA ECN SprayA 3 45 3 ECN SprayA Pressure MPa Density kg/m O 50 Density 22.8 kg/m 2 50 O 15 2 O 15 2 7.6 50 13 40 15.2 100 15 40 Liftoff 22.8 150 17 30 30 30.4 21 30 20 20 15 10 10 0 0 0 1000 1100 1200 850 900 1000 1100 1200 1000 1100 1200 850 900 850 900 Ambient Temperature K Ambient Temperature K Ambient Temperature K 43 CEFRC36, 2014 Liftoff length mm Total Soot mass ug Total Soot mass ug Liftoff length mm Total Soot mass ug Liftoff length mmPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2014 Reacting conditions Soot formation model sensitivity baseline C H surface growth 2 2 0 0 0 5 5 10 10 10 Soot particle coagulation 5 20 4 4 20 20 20 4 baseline ECN SprayA 30 30 30 3 3 3 surface1.5 3 900K, 22.8 kg/m 15 coagulation/3 40 40 40 2 2 2 50 50 50 10 1 1 1 60 60 60 0 0 10 0 10 10 0 10 10 0 10 5 R(mm) R(mm) R(mm) 0 0 0 6 6 6 x 10 x 10 x 10 1.8 1.8 1.8 10 10 10 0 1.6 1.6 1.6 0 1 2 3 4 5 6 1.4 1.4 1.4 20 20 20 Time ms 1.2 1.2 1.2  C H assisted surface growth process is the 30 30 30 2 2 1 1 1 most important process that affects the soot 0.8 0.8 0.8 40 40 40 emission, followed by OH oxidation process; 0.6 0.6 0.6 50 50 50 0.4 0.4 0.4  The surface growth process and the 0.2 0.2 0.2 60 60 60 coagulation process affect the soot particle 0 0 0 10 0 10 10 0 10 10 0 10 size; R(mm) R(mm) R(mm) 44 CEFRC36, 2014 Soot g/kgfuel Z(mm) Z(mm) Z(mm) Z(mm) Z(mm) Z(mm)Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2010 Validation – CumminsSandia optical engine Case A Case B Case C (Early Injection, Low (Late Injection, Low (Long Ignition Delay, Temperature) Temperature) High Temperature) IMEP bar 3.9 4.1 4.5 Injection Pressure bar 1600 1600 1200 SOI deg ATDC 22 0 5 Injection Quantity mg 56 56 61 DOI deg 7 7 10 Peak Temperature 2200 K 2200 K 2700 K O2 Concentration Vol 12.7 12.7 21 (with EGR) (with EGR) (without EGR) 45 CEFRC36, 2014 Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Wang, 2010 Singh, 2007 (A) Low Temperature, Early Injection (B) Low Temperature, Late Injection Liquid and vapor fuel penetration 60 Exp Exp Ave 50 1mm5e6 1mm2e6 1mm1e6 40 1mm5e7 2mm2e6 30 3mm2e6 20 10 0 22 21 20 19 18 17 16 15 14 CAD ATDC (C) High Temperature, Long Injection delay 46 CEFRC36, 2014 Liquid Penetration mmPart 6: Drop Drag/Wall Impinge/Vaporization/Sprays Singh, 2007 Summary Extensively validated spray models accurately capture the physics of vaporizing sprays under engine conditions Realistic fuels with nonideal vaporization effects can be represented Improved spray models provide consistent fuel distribution predictions, which is a prerequisite for combustion modeling and engine optimization. Spray predictions can be independent of mesh size and time step; Recent experimental and modeling work can be accessed through the Sandia Engine Combustion Network (ECN) http://www.sandia.gov/ecn/ Blue: Liquid Scatter Green: UV Fluorescence 47 CEFRC36, 2014
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