Highly Turbocharged Gasoline Engine and Rapid Compression Machine Studies of Super-Knock

CATEGORY: SUPER-KNOCK
Highly Turbocharged Gasoline Engine and Rapid Compression Machine Studies of Super-Knock

Type	Journal Article
URL	http://papers.sae.org/2016-01-0686/
Volume	9
Issue	3
Publication	SAE Int. J. Engines
Date	2016
Abstract	Super-knock, because of the catastrophic damage it can cause to an engine, poses a significant challenge for the development of highly turbocharged gasoline engines with spark ignition,. Authors’ previous research shows that one combustion process leading to super-knock may be described as hot-spot induced pre-ignition followed by deflagration, inducing detonation from another hot spot followed by high pressure oscillation. The sources of the hot spots which lead to pre-ignition may occur sporadically, resulting in random occurrence of super-knock at practical engine operating conditions. Researchers employed a spark plasma to induce preignition. They examined the correlation between super-knock combustion and the thermodynamic state of the reactant mixture in a four-cylinder production gasoline engine. Results show early spark ignition could be used to trigger pre-ignition and to induce super-knock when the mixture thermodynamic state was above a critical condition. At a constant air temperature and high intake pressure, advancing the spark timing caused transitions from normal combustion to knocking conditions, to super-knocking conditions and then back to knocking conditions and to normal combustion. Results indicate RCM studies can be used to investigate the physical and chemical mechanisms of super-knock and E-P-T diagrams can be used to predict and distinguish super-knock from other combustion modes.