2 2.1 1.3 L DISI DISI DISI PIV DISI DISI 3-8 -
2.2 DISI 1954 300SL (3) 6 SOHC 3L DISI 1950 1960 1970 MAN-FM (4) HC Soot PFI DISC 1970 TCCS Texaco Controlled Combustion System Ford-PROCO programmed combustion control system (4) BSFC Break Specific Fuel Consumption HC MAN-FM PFI 1.3 DISC 1996 GDI (5) PFI (6), D-4 (7) NEO Di (8) FSI (9) DISC DISC (10),(11),(12) (13) - 9 -
Direct Injection: DI 1.0~1.5 L PFI PFI THC TGV Tumble Generation Valve (14),(15) - 10 -
2.3 DISI 2 2.1 Spark Plug Injector Premixed flame T/C A. Homogeneous combustion DISI engine Air + Fuel Mixture Spark Plug Premixed flame Air Injector Air + Fuel Mixture B. Stratified combustion DISI DISC engine Fig. 2.1 Schematic of typical DISI engines A DISI PFI A PFI B A B A A 1.3L - 11 -
DISC Fig.2.2 Schematic of G-DI combustion systems (16) DISC 2.2 3 PFI DISI 2-12 -
DISI PFI 2.3 2.1 1.3 L 4 10.5 Swirl Control Valve SCV Straight Helical SCV SCV (Swirl control valve) Spark plug Injector Fig. 2.3 Schematics of mixture preparation concept Table 2.1 DISI engine specification Displacement L 1.3 Cylinder layout In-line 4 cylinders Number of valve Intake 2, Exhaust 2 Intake port Helical port Straight port with SCV Piston Cavity type Cam phaser Intake VVT Bore mm 78.0 Stroke mm 69.5 Compression ratio 10.5 Fuel supply system Direct injection 2.4 DISI - 13 -
2.5 8 mm Cd SCV opened 0.36 SCV closed2.5 Cd m& m& = A ρ U = CdA ρ U (2.1) eff is is r is is A eff ρ is U is A r ρ is U is ρ is 1 ( P ) κ = ρ (2.2) 0 r 1 2 1 2κ κ U = 0 1 κ is RT P r 1 (2.3) κ ρ 0 P r R T 0 κ A r 2 A 4 d r 2 = π (2.4) A r = π d L (2.5) d L (2.5) Cd Fig.2.4 Schematic of swirl injector (17) - 14 -
Straight Helical Fig. 2.5 Schematic of intake port - 15 -
2.4 DISI General Motors R&D 3 GMTEC (18) 2.2 Table 2.2 Calculation scheme and model for GMTEC Calculation code GMTEC Gaseous phase solving Finite volume method Convective term scheme Quasi second order upwind Pressure solution PISO algorithm Turbulence model Standard k-ε model Spray dynamics solving Discrete droplet model Breakup model Modified TAB model Collision model Modified O Rourke model Evaporation model Modified Faeth model Wall film model O Rourke model Multi component fuel model Continuous distribution model Navier-Stokes k-ε 3 PISO (19) 1 2 (20) TAB O Rourke (22) O Rourke Wall film (23) Stanton & Rutland (24) (21) Drake - 16 -
(25) Lippert Continuous distribution (26),(27) 2 2 DISI - 17 -
2.5 2.5.1 GMTEC PIV 2.3 2.6 2 65000 55000 90000 1 Table 2.3 Calculation conditions for in-cylinder flow calculation validation Engine speed rpm 1200 Throttle position WOT SCV position open, close Piston Flat Intake pressure kpa 101 Intake temperature K 293 Initial temperature in cylinder K 330 Initial intake port temperature K 300 Cylinder wall temperature K 330 Piston surface temperature K 330 (a) Intake stroke mesh (b) Compression stroke mesh Fig.2.6 Calculation meshes for flat piston - 18 -
2.5.2 2.7 Fig. 2.7 Schematics of elongated piston and optical access Fig. 2.8 Bottom view optical engine experimental set-up - 19 -
PIV 4 2 φ78.0 mm φ60 mm 40 mm 72 mm 74 mm O 2.8 2.5.3 PIV PIV 2 (28) Particle Tracking Velocimetry: PTV PIV PIV 2 2 2 2 2 2 2 2 2 2 2 CCD CCD FIT-CCD 2 1-20 -
2 2.9 PIV PIV 2.4 PIV Nd-YAG 2 2 Nd-YAG 2 FIT CCD 532 nm 10 0.5~2 µm 1200 rpm WOT(Wide Open Throttle) SCV opened closed 2 50 200 cycle Fig. 2.9 PIV experimental set-up - 21 -
Table 2.4 PIV experimental conditions Engine speed rpm 1200 Throttle position WOT SCV position open, close Piston Flat Intake pressure kpa 101 Intake temperature K 293 Camera Frame interline CCD Image resolution pixels 1280 1024 Dynamic range bit 12 Camera Lens NIKON Nikkor 50 mm F/1.4 Optical filter nm (Half band width) Band pass 532 (10) Light source Double pulse Nd-YAG Wave length nm 532 Maximum power mj 125 Maximum flashlamp frequency Hz 15 Pulse separation 10, 20, 30 LASER light sheet thickness mm 1 Capture number 50~200 Tracer material SiO 2 DOS Tracer particle size µm 0.5~ 2 (29) Recursive cross-correlation 2 Hierarchical cross-correlation 2.5.4 PIV 2.10 2.11 2.10 x=0 mm, y=-18,0,18, z= -1,-10,-20,-30-22 -
X Y1 Y2 Y3 Z1 Z2 Z3 Z4 IVC Intake Valve Close timing 3 +U Distance from head gasket +V Ex In Z=-1mm Z=-10mm Z=-20mm Z=-30mm Y= 18mm Y= 0mm Y=-18mm Z Y X -W X X=0mm Fig.2.10 Cross section for PIV measurement Fig.2.11 Valve lift profile and PIV measurement timing Fig. 2.12 PIV image location - 23 -
U ( x y) = U ( i= 1 <U(x,y)> N 1, i x, y) (2.6) N N U i (x,y) i (x,y) 1/4 2.12 Z PIV 2.13~ 2.20 PIV SCV opened 240 deg. BTDC Helical Y1 Helical Y2 Straight Y3 Helical Straight Y1, Y3 170 deg. BTDC BDC Y2 240 deg. BTDC Y2 IVC 120 deg. BTDC Z Y2 (28) Helical X Y Z - 24 -
X, Y SCV opened SCV closed Straight Helical opened 2 240 deg. BTDC X opened SCV opened Y1 170 deg. BTDC Y1, Y3 Z Z Y2 Y1, Y3 120 deg. BTDC Z SCV opened 120 deg. BTDC - 25 -
Fig.2.13 Averaged velocity distribution comparison between experiment and calculation on SCV opened condition with flat piston at 240 deg. BTDC (Cross section: X, Y1, Y2 and Y3) - 26 -
Fig.2.14 Averaged velocity distribution comparison between experiment and calculation on SCV opened condition with flat piston at 170 deg. BTDC (Cross section: X, Y1, Y2 and Y3) - 27 -
Fig.2.15 Averaged velocity distribution comparison between experiment and calculation on SCV opened condition with flat piston at 120 deg. BTDC (Cross section: X, Y1, Y2 and Y3) - 28 -
Fig.2.16 Averaged velocity distribution comparison between experiment and calculation on SCV opened condition with flat piston at 120 deg. BTDC (Cross section: Z1, Z2, Z3 and Z4) - 29 -
Fig.2.17 Averaged velocity distribution comparison between experiment and calculation on SCV closed condition with flat piston at 240 deg. BTDC (Cross section: X, Y1, Y2 and Y3) - 30 -
Fig.2.18 Averaged velocity distribution comparison between experiment and calculation on SCV closed condition with flat piston at 170 deg. BTDC (Cross section: X, Y1, Y2 and Y3) - 31 -
Fig.2.19 Averaged velocity distribution comparison between experiment and calculation on SCV closed condition with flat piston at 120 deg. BTDC (Cross section: X, Y1, Y2 and Y3) - 32 -
Fig.2.20 Averaged velocity distribution comparison between experiment and calculation on SCV closed condition with flat piston at 120 deg. BTDC (Cross section: Z1, Z2, Z3 and Z4) - 33 -
SR,TR 2.21 SR Z1 TR Y2 SR,TR SR TR ζ, = 2 ( x, y) Ne ζ Ne SR TR SR,TR (2.7) Swirl Tumble Swirl ratio 3 2.5 2 1.5 1 0.5 0-0.5 140 Experiment opened Calculation opened 120 100 80 60 Crank angle deg. BTDC Experiment closed Calculation closed 40 Tumble ratio 1.5 1 0.5 0-0.5-1 -1.5-2 280 Experiment opened Calculation opened 240 200 160 120 Crank angle deg. BTDC Experiment closed Calculation closed Fig. 2.21 Comparison of swirl and tumble ratio between experiment and calculation results with flat piston (Swirl: Z1, tumble: Y2) 80 40 SR TR SCV IVC IVC 2 (30) k-ε k ε k ε (31) (32) - 34 -
6.5 5 RNG k-ε - 35 -
2.6 2.6.1 2.22 φ80 120 mm 70000 1 1.1 mm 2.5 0.01 ms 20000 0.08 ms 40 deg. 150 µm 63 deg. 150 µm Rosin-Rammler 1.74 ms 2.23 Gaussian TAB 0.0 2.5 Φ80 mm 70 mm 120 mm 30 mm 30 mm Fig.2.22 Calculation mesh for spray modeling - 36 -
Table 2.5 Calculation conditions for spray modeling Ambient pressure MPa 0.05, 0.1, 0.3, 0.5 Ambient temperature K 300 Fuel Gasoline Initial spray angle deg. 40 Main spray angle deg 63 Injection duration msec. 1.74 Injection quantity mg 13.1 Initial droplet temperature K 300 Initial droplet diameter µm 150 Slug injection duration msec. 0.08 Number of parcel 20000 140 120 Injection velocity m/s Injected mass of fuel % 100 80 60 40 20 0 Injection velocity Injected mass of fuel 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Time after start of injection msec. Fig.2.23 Table of injection velocity and fuel mass 2.3 Lippert Continuous distribution (26),(27) Γ f ( I ) = α 1 ( I γ ) α β Γ( α ) I γ exp β I f(i) α=7.4 β=12.0 γ=0.0 2 2 N n+1 N n+1 N n+1 = N n + N θ L 2 Ψ L L V (2.8) (2.9) - 37 -
n+1 n n ( Nθ ) = ( Nθ ) + Nθ L L V (2.10) n n n ( N ) = ( NΨ ) + NΨ Ψ +1 (2.11) L L V m Nθ=m (2.10) m n+1 = m n + m (2.12) m = Nθ n V (2.13) m (33) m = 2 πrρ D B Sh (2.14) d d r ρ d D S h B d B y y FR FL d = (2.15) 1 yfr y FR y FL (2.9) m θ L n+ 1 n m + m m = n θ = L θ + 1 L n m + θ n V (2.16) θ n+1 L ( m + m) θ θ = mθ + m n V n n V L n θ L (2.11) n L n V n L n L (2.17) n n n mθv Ψ + mθ ΨV Ψ +1 L = (2.18) mθ + mθ 2 α, β θ = αβ (2.19) Ψ = α + 2 ( α 1) β 2 θ L θv = A BΨL 1+ θ L (2.20) (2.21) Ψ V θ V = ΨL θ L (2.22) - 38 -
A,B 2 α, β 2.6.2 2.24 Fig. 2.24 Constant volume chamber experimental set-up 80 mm 115 mm 115 mm 1.42 10-3 m 3 φ115 mm 10 mm 115 mm - 39 -
40 mm 5 MPa N 2 O 2 423 K 2.6.3 2.25 2.6 Nd-YAG 4 ICCD Image intensified CCD 265 nm 298 K 0.05, 0.1, 0.3, 0.5 MPa 4 Fig. 2.25 Optical set-up for spray cross section visualization - 40 -
Table 2.6 Experimental conditions for spray cross section visualization Ambient pressure MPa 0.05, 0.1, 0.3, 0.5 Ambient temperature K 298 Fuel Iso-octane Fuel temperature K 298 Injector type Swirl injector Spray angle (design spec.) deg. 50 Static flow rate cc/min 700 (fuel pressure: 5 MPa) Fuel pressure MPa 5.0 Injection duration ms 1.5 Injection quantity g 0.012 Camera ICCD Image resolution pixels 384 576 Camera lens UV Nikkor 105mm F/4.5 Optical filter nm (Half band width) Band pass 265 (10) Light source ND-YAG Wave length nm 266 LASER power mj 50 LASER pulse frequency Hz 10 LASER light sheet thickness mm 1 2.6.4 2.26 1 0.1 MPa 0.9 ms 2 0.05 MPa - 41 -
Fig.2.26 Comparison of spray cross section shapes between experiment and calculation at various ambient pressures Liquid fuel axial/radial penetration mm Liquid fuel axial/radial penetration mm Ambient pressure: 0.05 MPa 70 Slug spray axial penetration 60 Calculation Experiment 50 Main spray axial penetration 40 30 20 10 0 40 30 20 10 0 Main spray radial penetration 0 0.5 1 1.5 2 2.5 Time msec. ASOI Liquid fuel axial/radial penetration mm Liquid fuel axial/radial penetration mm Fig.2.27 Spray characteristics comparison - 42-70 60 50 40 30 20 10 0 40 30 20 10 0 Slug spray axial penetration Main spray radial penetration 0 0.5 1 1.5 2 2.5 Time msec. ASOI 70 0.1 MPa 0.5 MPa 70 Slug spray axial penetration 60 60 Main spray axial penetration 50 50 Slug spray axial penetration Main spray radial penetration 0 0.5 1 1.5 2 2.5 Time msec. ASOI 0.3 MPa Main spray radial penetration 0 0.5 1 1.5 2 2.5 Time msec. ASOI
60 Sauter Mean Diameter m 50 40 30 20 10 0 Calculation Experiment 0 0.5 1 1.5 2 Time msec. ASOI Fig.2.28 Sauter mean diameter comparison at 0.1 MPa 2.27 2.28 0.1 MPa Sauter Sauter mean diameter: SMD DISI SCV opened EOI 286 deg. BTDC 2.29 DISI - 43 -
Fig.2.29 Spray motion verification in cylinder condition - 44 -
2.7 2.7.1 SCV 2.7 1200 rpm End of Injection timing: EOI 65 75 85 deg. BTDC 3 SCV opened closed 2.30 A B A,B A, B A B Continuous distribution model Table 2.7 Calculation conditions for in-cylinder mixture distribution Engine speed rpm 1200 Fuel Gasoline Initial spray angle deg. 40 Main spray angle deg 63 Injection duration msec. 0.73 End of injection deg. BTDC 65, 75, 85 without delay Injection quantity mg 6.4 Initial droplet temperature K 298 Initial droplet diameter µm 150 Slug injection duration msec. 0.08 Number of parcel 20000 Piston A, B SCV opened, closed Type A Type B Fig.2.30 Schematics of piston shape - 45 -
4 1 THC 2.31 smoke smoke Fig.2.31 Relation between wallfilm mass and smoke (34) 2.7.2 SCV 2.32 2.33 65 deg. BTDC Y2 X0,Z0 X0 2.5 mm Z0 4 mm A SCV opened X0 Y2-46 -
Z0 Helical Straight SCV closed X0 opened Straight Y2 opened Z0 SCV closed B A SCV SCV closed X0 A Y2 X0 4 SCV - 47 -
Fig. 2.32 Predicted velocity distributions with piston A at 65 deg. BTDC - 48 -
Fig. 2.33 Predicted velocity distributions with piston B at 65 deg. BTDC - 49 -
2.7.3 SCV SCV A 2.34 B 2.35 EOI 65 deg. BTDC SCV opened SCV opened 40 deg. BTDC SCV closed SCV closed A B A A SCV EOI - 50 -
SCV: Opened Closed Fig. 2.34 Predicted spray droplet behavior with piston A - 51 -
SCV: Opened Closed Fig. 2.35 Predicted spray droplet behavior with piston B - 52 -
2.7.4 EOI 65 75 85 deg. BTDC 3 2.36 20 deg. BTDC Y2 1 EOI 85 deg. BTDC 1 EOI 85 deg. BTDC 1200 rpm EOI 75 deg. BTDC 65 deg. BTDC 1 A SCV opened 65 deg. BTDC B SCV opened 75 deg. BTDC 1 SCV closed EOI 75 deg. 1 65 deg. BTDC 1 A EOI 75 deg. BTDC 65 deg. BTDC 1 B EOI 65 deg. BTDC A B A 1 mm 0.25 2.37 2.36 EOI 85 deg. BTDC A SCV closed A SCV opened B B SCV EOI 65 deg. BTD EOI 65 deg. BTDC 2.36 2.37 SCV opened - 53 -
SCV closed EOI 65 deg. BTDC SCV Fig.2.36 Mixture preparation comparison (Crank angle: 20 deg BTDC, Cross section: Y2) - 54 -
Fig.2.37 Comparison of isovolume of equivalence ratio above 0.25 (Crank angle: 20 deg. BTDC) - 55 -
2.7.5 SCV SCV SCV 25 deg. SCV closed 0 deg opened 90 deg. SCV 25 deg. SR 1.5 2.38 20 deg. BTDC Y2 1.0 2.36 EOI SCV closed 1.0 2.39 0.25 A B 2.40 4 mm A 30~20 deg. BTDC SCV SCV closed A 20 deg. BTDC 1 B HC 2.41 A B A B A SCV A B SCV A A - 56 -
Fig.2.38 Mixture preparation comparison (Crank angle: 20 deg BTDC, Cross section: Y2, SCV: 25 deg.) Fig.2.39 Comparison of isovolume of equivalence ratio above 0.25 (Crank angle: 20 deg. BTDC, SCV: 25 deg.) Equivalence ratio @ spark plug 3 2.5 2 1.5 1 0.5 0 55 50 45 40 35 30 A SR 1.5 (-std. dev.) A SR 1.5 (+std. dev.) B SR 1.5 (-std. dev.) B SR 1.5 (+std. dev.) 25 20 15 10 Crank angle deg. BTDC Fig.2.40 Spark gap equivalence ratio (4 mm spheres average) - 57 -
Wallfilm liquid mass % 20 18 16 14 12 10 8 6 4 A SR 1.5 B SR 1.5 2 0 65 60 55 50 45 40 35 30 25 20 15 10 Crank angle deg. BTDC Fig.2.41 Wall film liquid mass 2.7.6 B PFI BSFC 2.42 2.8 2.9 2500 rpm BMEP 450 kpa PFI 10 DISI Table 2.8 Emission target EINO x g/kg fuel 10 EITHC g/kg fuel 50 EICO g/kg fuel 50 Table 2.9 Evaluation operation points Number Engine speed rpm BMEP kpa 1 650 Idle 2 1500 189 3 2000 200 4 2000 284 5 2500 331 6 2500 450-58 -
BSFC improvement rate for PFI % 30 25 20 15 10 5 0 650/Idle 1550/189 2000/200 2000/284 2500/331 2500/450 Evaluation operation points Fig.2.42 Fuel consumption improvement compared with PFI engine - 59 -
2.8 2.8.1 2.10 0.1 Pa 0.3 MPa 298 K 423 K 2.10 Table 2.10 Experimental conditions for hot fuel spray cross section visualization Ambient pressure MPa 0.1, 0.3 Ambient temperature K 298~323 Fuel Iso-octane Fuel temperature K 298~423 Injector type Swirl injector Spray angle (design spec.) deg. 50 Static flow rate cc/min 700 (fuel pressure: 5 MPa) Fuel pressure MPa 5.0 Injection duration ms 1.5 Injection quantity g 0.012 Camera ICCD Image resolution pixels 384 576 Camera lens UV Nikkor 105mm F/4.5 Optical filter nm (Half band width) Band pass 265 (10) Light source ND-YAG Wave length nm 266 LASER power mj 50 LASER pulse frequency Hz 10 LASER light sheet thickness mm 1 2.43 0.1 MPa 1.5 ms 348 K 373 K 373 K 423 K - 60 -
0.3 MPa 2.44 0.1 MPa 0.1 MPa 2.45 370 K 400 K 0.1 MPa (35)~(39) 0.1 MPa 372 K 0.3 MPa 420 K Van Der Wege (38) 3 A. B. C. A B 373 K B C 398 K 398 K - 61 -
Fig. 2.43 LASER lightsheet images of hot fuel spray (Ambient pressure: 0.1 MPa, Timing: 1.5 msec. ASOI) - 62 -
Fig. 2.44 LASER lightsheet images of hot fuel spray (Ambient pressure: 0.3 MPa, Timing: 1.5 msec. ASOI) - 63 -
Main spray penetration mm Corn angle deg. Spray width mm 120 100 80 60 40 20 Corn angle Main spray penetration Spray width 0 300 320 340 360 380 400 420 440 Fuel Temperature K Fig.2.45 Comparison of spray characteristics for various fuel temperatures (Ambient pressure 0.1 MPa) PDPA 2.46 400 K 407 K 14 Sauter mean radius µm 12 10 8 6 4 2 0 280 300 320 340 360 380 400 420 440 Fuel Temperature K Fig.2.46 Sauter mean radius comparison for various fuel temperatures (Ambient pressure: 0.1 MPa - 64 -
2.8.2 DISI 1 PFI HC DISI 2.11 2.11 3 % 2.47 373 K 423 K Table 2.11 Calculation conditions for hot fuel spray modeling Ambient pressure MPa 0.1 Ambient temperature K 300, 330, 335 Fuel Gasoline Initial spray angle deg. 40 Main spray angle deg 63 Injection duration msec. 1.74 Injection quantity mg 13.1 Initial droplet temperature K 300, 373, 423 Initial droplet diameter µm 150, 130, 110 Slug injection duration msec. 0.08 Number of parcel 20000-65 -
Fuel temperature: 300 K 373 K 423 K Calculation Experiment Timing: 0.4 msec. ASOI 0.9 msec. ASOI 1.3 msec. ASOI Fig.2.47 Comparison of spray cross section shapes between experiment and calculation at various fuel temperatures - 66 -
2.48 2.49 SMD SMD Liquid fuel axial/radial penetration mm 120 100 80 60 40 20 0 Cal. Fuel temperature: 373 K Cal. Fuel temperature: 423 K Exp. Fuel tempereture: 373 K Exp. Fuel temperature: 423 K Main spray axial penetration Main spray radial penetration 0 0.5 1 1.5 2 2.5 Time ms Fig.2.48 Spray characteristics comparison at various fuel temperatures Sauter Mean Diameter m 60 50 40 30 20 10 0 Cal. Fuel temperature: 300 K Cal. Fuel tempereture: 373 K Cal. Fuel temperature: 423 K Exp. Fuel temperature: 300 K Exp. Fuel temperature: 373 K Exp. Fuel temperature: 423 K 0 0.5 1 1.5 2 Time ms Fig.2.49 Sauter mean diameter comparison at various fuel temperatures - 67 -
2.8.3 (34) 3 DISI 2.12 300 rpm 0.5 mm 339.5 deg. BTDC 316.1 deg. BTDC Table 2.12 Calculation conditions for cold start condition Engine speed 300 Fuel Gasoline Start of injection deg. BTDC 339.5 End of injection deg. BTDC 316.1 Injection quantity mg 112.15 Intake pressure kpa 101.325 Intake temperature K 298 Initial temperature in cylinder K 298 Cylinder wall temperature K 298 Number of parcel 40000 Piston B SCV opened 2.50 30 deg. 20 deg. 2.51 2.52 9 ms - 68 -
Fig.2.50 Spray motion at various fuel temperatures Fuel temperature: 300K 373K 423K Fig. 2.51 Velocity distribution on Y2 at various fuel temperatures (Crank angle: 400 deg. ATDC) - 69 -
Fuel concentration Fuel temperature: 300K 373K 423K Fig.2.52 Fuel distributions at various fuel temperatures 2.53 Wallfilm height m Fuel temperature: 300 K 373 K 423 K Cylinder head Piston Fig.2.53 Wall film height on cylinder head and piston surface - 70 -
2.54 2.55 6.2 % 423 K 2.5 % IVC 560 deg. ATDC 75 % 423 K 34 % 7 Particle Mass % 6 5 4 3 2 300 K 373 K 423 K 1 0 380 430 480 530 Crank Angle deg. ATDC Fig.2.54 Particle mass at various fuel temperatures 100 80 Wallfilm Mass % 60 40 20 0 300 K 373 K 423 K 380 430 480 530 580 Crank Angle deg. ATDC Fig.2.55 Wall film mass at various fuel temperatures - 71 -
2.56 710 deg. ATDC 423 K 3 100 Total Vaporized Mass % 80 60 40 20 300 K 373 K 423 K 0 380 480 580 680 Crank Angle deg. ATDC Fig.2.56 Vaporized mass at various fuel temperatures 100 Wallfilm Particles Vapor 80 Mass Fraction % 60 40 20 0 300 373 423 Fuel temperature K Fig.2.57 Fuel status at 720 deg. ATDC - 72 -
2.57 100 % 300 K 423 K 66 % 300 K 18 % 423 K 58 % 1/3 THC DISI - 73 -
2.9 (1) (2) PIV (3) (4) PFI (5) DISI (6) - 74 -