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Auto-Ignited Kernels during Knocking Combustion in a Spark-Ignition Engine

Auto-Ignited Kernels during Knocking Combustion in a Spark-Ignition Engine. Okayama University Nobuyuki KAWAHARA Eiji TOMITA. Knocking cycle. Standard cycle. End-gas. Okayama University. Requirements of spark-ignition (SI) engine

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Auto-Ignited Kernels during Knocking Combustion in a Spark-Ignition Engine

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  1. Auto-Ignited Kernels during Knocking Combustion in a Spark-Ignition Engine Okayama UniversityNobuyuki KAWAHARA Eiji TOMITA

  2. Knocking cycle Standard cycle End-gas Okayama University Requirements of spark-ignition (SI) engine - Lower fuel consumption - Reduced emission of pollutants. Higher thermal efficiencies Engine knocking due to higher compression ratio Background

  3. Okayama University Valve-stopper Solenoid Valve Valve-closure signal Thermocouple Pressure transducer Spark electrode Water Out In Elongated piston Bore: 78 mm Stroke: 85 mm Compression ratio: 9.02 Engine speed: 600 rpm Mixture tank Heater Crank angle pulse Flywheel TDC signal Rotary encoder Electric motor Compression-expansion engine

  4. Side view Unburned gas Burned gas Ignition Valve closing 180 210 240 270 300 330 360 (TDC) (BDC) Crank angle, deg. Okayama University Bore: 78 mm Stroke: 85 mm Compression ratio: 9.0 Engine speed: 600 rpm Top view Out Water In Timing chart Compression-expansion engine

  5. Experimental condition KInt 0 10 5 15 Time from ignition, ms Okayama University n-C4H10 (94) 1.0 40, 50, 60kPa 335～355deg. H2 1.0 40kPa 335～360deg. Fuel (Octane number) Equivalence ratio, φ Initial pressure, P0 Spark ignition timing, θIT Use of Ar&O2 mixture instead of air Knock intensity: KInt H.P.F 2.5kHz Experimental condition

  6. Mirror Measurement point Cylinder Experimental methods Valve High-speed video camera Cassegrain optics Shimadzu Hyper vision, HPV-1 Nac Image Technology, MEMRECAM GX1 Spark electrode Pressure Transducer PC Electric motor Flywheel

  7. P0=50kPaΘIT=350deg. P0=60kPaΘIT=340deg. P0=60kPaΘIT=345deg. KInt=0.180MPa KInt=0.434MPa Standard cycle Okayama University n-Butane(Φ=1.0) Rec.Speed:32kf.p.s Rec.Expose:1/8 Knock image (n-Butane)

  8. a b c d e f g Normal cycle 4 4 3 3 2 2 Pressure, MPa P0=50kPa qIT=350deg. P0=60kPa qIT=345deg. 1 1 0 0 350 360 370 380 350 360 370 380 Auto-ignited kernel Crank angle, deg. Flame front Knocking cycle A B C D E F G

  9. KInt=0.491MPa 360.0deg.～366.4deg. Rec.speed:63kfps Auto-ignited kernel Flame front B D Okayama University A B C D E F G H I B Φ=1.0 P0=60kPa, ΘIT=345deg. C A E G H F I Knock image and pressure history (n-Butane)

  10. KInt=0.491MPa 360.0deg.～366.4deg. Rec.speed:64kfps Okayama University A B C D E F G H I B Φ=1.0 P0=60kPa, ΘIT=345deg. C A D E G H F I Knock image and pressure history (n-Butane)

  11. Okayama University f = 1.0 , P0=60kPa , T0=323K , Rec.speed : 20kfps. C4H10 , ΘIT=345deg. C4H10 , ΘIT=360deg. CH4 , ΘIT=340deg. Kint=0.07MPa Non-knock condition Non-knock condition 4 3 Pressure , MPa 2 1 0 320 340 360 380 400 420 320 340 360 380 400 420 320 340 360 380 400 420 Crank angle , deg. Crank angle , deg. Crank angle , deg. Knock image and pressure history (n-Butane)

  12. Okayama University Normal cycle Knocking cycle H2-Air φ=1.0 P0=60kPa T0=323K θi=360deg. H2-O2-Ar φ=1.0 P0=40kPa T0=323K θi=360deg. Compared normal cycle with knocking cycle Rec. speed=60,000fps Rec. speed=60,000fps 3 3 Kint=0.03MPa Kint=1.53MPa 2 2 Pressure, MPa 1 1 0 0 360 365 370 375 380 360 365 370 375 380 Crank angle, deg. Crank angle, deg.

  13. A2 B1 A1 B2 Okayama University Pressure wave Knocking cycle Auto-ignition H2-O2-Ar φ=1.0 θi=340deg. Rec. speed=250,000fps Exposure time=2ms Kint=0.99MPa Frequency=7.35kHz 136ms Visualization of pressure wave and estimation of the frequency

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