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Experimental analysis of super-knock occurrence based on a spark ignition engine with high compression ratio
journal contributionposted on 2018-10-08, 08:16 authored by Lei Zhou, Rui Kang, Haiqiao Wei, Dengquan Feng, Jianxiong Hua, Jiaying Pan, Rui Chen
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.
This study is supported by the National Natural Science Foundation of China (Grant No. 91641203, 91741119, 51476114).
- Aeronautical, Automotive, Chemical and Materials Engineering
- Aeronautical and Automotive Engineering
CitationZHOU, L. ... et al, 2018. Experimental analysis of super-knock occurrence based on a spark ignition engine with high compression ratio. Energy, 165, Part B, pp.68-75.
- AM (Accepted Manuscript)
Publisher statementThis paper was accepted for publication in the journal Energy and the definitive published version is available at https://doi.org/10.1016/j.energy.2018.09.166.