1 / 12

Combustion

Combustion. Detonation and Pre-ignition. Normal Combustion. Controlled burn of air/fuel mixture Lasts between .0005 and .004 seconds Flame front propagates at approx. 50 mph Combustion chamber temperature reaches between 2000 and 3000 degrees Fahrenheit. Detonation (post-ignition).

darrius
Download Presentation

Combustion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Combustion Detonation and Pre-ignition

  2. Normal Combustion • Controlled burn of air/fuel mixture • Lasts between .0005 and .004 seconds • Flame front propagates at approx. 50 mph • Combustion chamber temperature reaches between 2000 and 3000 degrees Fahrenheit

  3. Detonation (post-ignition) • The heat from compression along with the radiated heat from the initial flame front causes a secondary flame front to develop • This second flame front can propagate at supersonic speeds • This second flame front collides with the first creating extremely high cylinder temperatures (3500 F)and pressures (800 PSI)

  4. Detonation Causes • Excessive compression • Insufficient fuel octane • Carbon deposits

  5. Pre-ignition • Like detonation, pre-ignition causes two flame fronts to propagate and collide causing a dramatic increase in cylinder temperatures and pressure • When the second flame front occurs before the spark plug fires the abnormal combustion is called pre-ignition • Pre-ignition will cause excessive cylinder pressures (1200 PSI) and temperatures (4000 F)

  6. Pre-ignition Causes • Excessive compression – as the temperature of compression approaches 1700 Fahrenheit fuel will spontaneously combust (depending on octane) • Abnormal heat in the cylinder – caused by: • Detonation • Inoperative EGR valve • Faulty cooling system • Faulty intake air temperature control system • Low octane fuel

  7. Pre-ignition Causes • Hot spots • Sharp edge on combustion chamber or piston • Carbon deposits • Too high heat range plug • Overheated valve (insufficient valve margin) • Head gasket fire ring protruding into cylinder • Plug wire crossfiring

  8. Abnormal Combustion Effects

  9. Abnormal Combustion Effects • Piston damage • Cracks in piston head • Cracks in ring lands • Melted piston head (aluminum spattered spark plug) • Micro-melting of ring lands causing stuck rings • Broken rings • Blown head gasket • Spark plug damage • Connecting rod, bearing, and crankshaft damage

  10. Abnormal Combustion Effects

  11. Abnormal Combustion Effects

  12. Abnormal Combustion Effects

More Related