auto-ignited kernels during knocking combustion in a spark-ignition engine
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Auto-Ignited Kernels during Knocking Combustion
in a Spark-Ignition Engine
Okayama University Nobuyuki KAWAHARA Eiji TOMITA
End-gasEnd-gas320 340 360 380 400
0.0
1.0
2.0
3.0
4.0
Crank angle, deg.
Pre
ssu
re,
MP
a Knocking cycle
Standard cycle
Okayama University
Background
Requirements of spark-ignition (SI) engine - Lower fuel consumption - Reduced emission of pollutants.
Higher thermal efficiencies
Engine knocking due to higher compression ratio
Heater
Out
Mixturetank
Thermocouple
SolenoidValve-closure signal
Elongated piston
Electric motor
FlywheelTDC signalCrank angle pulse
Rotary encoder
Pressure transducer
ValveValve-stopper
WaterIn
Spark electrode
Bore: 78 mmStroke: 85 mmCompression ratio: 9.02Engine speed: 600 rpm
Okayama University
Compression-expansion engine
Bore: 78 mmStroke: 85 mmCompression ratio: 9.0Engine speed: 600 rpm
180
Crank angle, deg.
210 240 270 300 330 360(TDC)(BDC)
Side viewTop view
Timing chartValve closing Ignition
In
Water Out Burned gasUnburned gas
Okayama University
Compression-expansion engine
Knock intensity: KInt
H.P.F2.5kHz
360 380 4000
1
2
3
4
Pre
ssu
re,
MP
a
Inte
nsi
ty,
MP
aCrank angle, deg.
0 0.005 0.01 0.015-0.4-0.2
00.20.4
Time from ignition, s
KInt
0 5 10 15Time from ignition, ms
Experimental condition
Fuel (Octane number)Equivalence ratio, φ Initial pressure, P0
Spark ignition timing, θIT
n-C4H10 (94)1.0
40, 50, 60kPa335~ 355deg.
H2
1.040kPa
335~ 360deg.
Okayama University
Experimental condition
Use of Ar&O2 mixture instead of air
Mirror
Flywheel
Electric motor
PC
Cassegrain optics
Pressure Transducer
Valve
CylinderMeasurementpoint
Spark electrode
Experimental methods
Shimadzu Hyper vision, HPV-1Nac Image Technology, MEMRECAM GX1
High-speed video camera
320 340 360 380 400
Pre
ssu
re,
MP
a
Crank angle, deg.320 340 360 380 400
0.0
1.0
2.0
3.0
4.0
320 340 360 380 400
P0=50kPaΘIT=350deg. P0=60kPaΘIT=340deg. P0=60kPaΘIT=345deg.
Standard cycle KInt=0.434MPa
n-Butane(Φ=1.0) Rec.Speed:32kf.p.s Rec.Expose:1/8
KInt=0.180MPa
Okayama University
Knock image (n-Butane)
P0=50kPaIT=350deg.
P0=60kPaIT=345deg.
Normal cycle
Knocking cycle
A B C D E F G
a b c d e f g
Flame frontAuto-ignited kernel
350 360 370 3800
1
2
3
4
Pre
ssu
re, M
Pa
Crank angle, deg.350 360 370 3800
1
2
3
4
A B C D E F G H I
361 362 363 3642.5
3.0
3.5
4.0
Pre
ssu
re, M
Pa
Crank angle, deg.
350 355 360 365 3700
1.0
2.0
3.0
4.0
Rec.speed:63kfps
KInt=0.491MPa
360.0deg. ~366.4deg.
Φ=1.0 P0=60kPa,ΘIT=345deg.
A
B
C
E F G H ID
B Flame front
Auto-ignitedkernel
Okayama University
Knock image and pressure history (n-Butane)
A B C D E F G H I
361 362 363 3642.5
3.0
3.5
4.0
Pre
ssu
re, M
Pa
Crank angle, deg.
350 355 360 365 3700
1.0
2.0
3.0
4.0
Rec.speed:64kfps
360.0deg. ~366.4deg.
Φ=1.0 P0=60kPa,ΘIT=345deg.
A
B
C
D E F G H I
KInt=0.491MPa
Okayama University
Knock image and pressure history (n-Butane)
320 340 360 380 400 420 320 340 360 380 400 420
= 1.0 , P0=60kPa , T0=323K , Rec.speed : 20kfps.
Crank angle , deg. Crank angle , deg. Crank angle , deg.
Pre
ssur
e ,
MP
a
C4H10 , ΘIT=345deg.
Kint=0.07MPa
C4H10 , ΘIT=360deg.
Non-knock condition
CH4 , ΘIT=340deg.
Non-knock condition
320 340 360 380 400 420
4
3
2
1
0
Okayama University
Knock image and pressure history (n-Butane)
0
1
2
3
360 365 370 375 380
Pre
ssu
re, M
Pa
Normal cycle
Crank angle, deg.
H2-Air φ=1.0 P0=60kPa T0=323K θi=360deg.
Kint=0.03MPa
1
2
3
375 380
Knocking cycle
0360 365 370
Crank angle, deg.
H2-O2-Ar φ=1.0 P0=40kPa T0=323K θi=360deg.
Kint=1.53MPa
Compared normal cycle with knocking cycle
Rec. speed=60,000fps Rec. speed=60,000fps
Okayama University
Pressure wave
Auto-ignition
0
1
2
3
330 340 350 360 370
CA, deg.
Pre
ssu
re, M
Pa
H2-O2-Ar φ=1.0 θi=340deg. Rec. speed=250,000fps Exposure time=2s Kint=0.99MPa
Knocking cycle
Visualization of pressure wave and estimation of the frequency
1
1.5
2
345 345.5 346 346.5
CA, deg.
Pre
ssu
re, M
Pa
136s
A1
A2B1
B2
Frequency=7.35kHz
Okayama University
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