1. INTERNAL COMBUSTION ENGINES LECTURER PROF.Dr. DEMIR BAYKA

2. MECHANISM OF COMBUSTION COMBUSTION IS INITIATED BY A SPARK IN SI ENGINES COMBUSTION IS INITIATED BY AUTOIGNITION IN CI ENGINES

3. COMBUSTION IN SI ENGINES THERE ARE 3 MAIN PHASES 1. 2. 3. FLAME NUCLEUS FORMATION FLAME PROPAGATION FLAME TERMINATION

4. COMBUSTION IN SI ENGINES 1.FLAME NUCLEUS FORMATION SPARK IGNITION FLAME DEVELOPMENT a) b)

5. SPARK PLUG

6. L V=20 000 - 24 000 volts L = 0.5 - 1.0 mm

7. BREAKDOWN PHASE IONIZING STREAMERS IMPEDANCE OF THE GAP DECREASES DUE TO STREAMERS

8. ARC PHASE THIN CYLINDRICAL PLASMA EXPANDS THIS IS DUE TO HEAT CONDUCTION AND DIFFUSION

9. GLOW DISCHARGE PHASE IGNITION COIL DUMPS ITS ENERGY

11. BREAKDOWN PHASE IONIZING STREAMERS TEMPERATURE IN STREAMERS IS AROUND 60 000 K

13. ARC PHASE THIN CYLINDRICAL PLASMA EXPANDS TEMPERATURE OF GAS IN THE ARC IS AROUND 6000 K

15. GLOW DISCHARGE PHASE IGNITION COIL DUMPS ITS ENERGY TEMPERATURE OF THE GAS IS AROUND 3000 K

16. FLAME NUCLEUS HEAT CONDUCTION & DIFFUSION T>2500 K Q

17. FLAME NUCLEUS LAMINAR PROPAGATION T>2500 K Q UNTIL VOLUME > 1 % OF Vmin

18. TURBULENT FLAME FRONT SPARK PLUG

19. STAGES OF TURBULENT FLAME TRAVEL UNBURNED GAS MIXTURE (REACTANTS)

20. MAXIMUM PRESSURE AND TEMP ARE REACHED AFTER TDC (15 - 20 DEG)

21. FLAME TERMINATION AND AFTERBURNING

22. IGNITION TIMING