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Experimental analysis of super-knock occurrence based on a spark ignition engine with high compression ratio.
- Source :
-
Energy . Dec2018:Part B, Vol. 165, p68-75. 8p. - Publication Year :
- 2018
-
Abstract
- Abstract The super-knock phenomenon is a major obstacle for further improving the power density in SI engines. The objective of this paper is to experimentally investigating the mechanism involved in the occurrence of super-knock. In this work, a high compression ratio (CR = 13) coupled with advanced spark timings were employed to achieving intense or critical thermal-dynamic conditions to easily inducing the super-knock. The results show that super-knock can originate from spark ignition, which is different from previous results regarding pre-ignition. Changing the spark timing super-knock can be induced with very high pressure oscillation at the present high compression ratio. The high compression ratio could generate sufficiently high thermal-dynamic conditions to inducing the abnormal combustion. In this research, four combustion phenomena were observed. The present work indicates that there is a nonlinear relationship between knock intensity and knocking onset in terms of pressure profiles at different cycles. The super-knock or knock phenomena were dominantly induced by spark ignition, which were controlled by the pre-ignition after several cycles. Finally, the analysis of the mechanism of super-knock with severe pressure oscillation was employed based on the thermal explosion theory and cavity resonances. There are two possible auto-ignition combustion modes that can induce the intense pressure oscillation. Highlights • The cause of super-knock occurrence is comprehensively studied. • Pre-ignition is not a unique condition leading to super-knock. • There is no direct relationship between super-knock intensity and super-knock onset. • The fundamental theories were employed to explaining the mechanism. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 03605442
- Volume :
- 165
- Database :
- Academic Search Index
- Journal :
- Energy
- Publication Type :
- Academic Journal
- Accession number :
- 133150389
- Full Text :
- https://doi.org/10.1016/j.energy.2018.09.166