A Statistical Description of Knock Intensity and Its Prediction
Cycle-to-cycle variation in combustion phasing and combustion rate cause knock to occur differently in every cycle. This is found to be true even if the end gas thermo-chemical time history is the same. Three cycles are shown that have matched combustion phasing, combustion rate, and time of knock onset, but have knock intensity that differs by a factor of six. Thus, the prediction of knock intensity must include a stochastic component. It is shown that there is a relationship between the maximum possible knock intensity and the unburned fuel energy at the time of knock onset. Further, for a small window of unburned energy at knock onset, the probability density function of knock intensity is self similar when scaled by the 95th percentile of the cumulative distribution, and log-normal in shape. A methodology to predict the maximum possible knock intensity based on the volumetric expansion rate of the end gas was developed, and the expansion rate was modeled based on blast wave theory, which is proportional to the energy of the initial explosion. The results showed a comparable level of scatter as the measurements.
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/issn/01487191
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Supplemental Notes:
- Abstract reprinted with permission of SAE International.
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Authors:
- Ghandhi, Jaal
- Kim, Kenneth Seonguk
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Conference:
- WCX™ 17: SAE World Congress Experience
- Location: Detroit Michigan, United States
- Date: 2017-4-4 to 2017-4-6
- Publication Date: 2017-3-28
Language
- English
Media Info
- Media Type: Web
- Features: Figures; References;
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Serial:
- SAE Technical Paper
- Publisher: Society of Automotive Engineers (SAE)
- ISSN: 0148-7191
- EISSN: 2688-3627
- Serial URL: http://papers.sae.org/
Subject/Index Terms
- TRT Terms: Combustion; Engine knock; Mathematical prediction; Spark ignition engines; Statistical analysis
- Subject Areas: Highways; Vehicles and Equipment;
Filing Info
- Accession Number: 01657204
- Record Type: Publication
- Source Agency: SAE International
- Report/Paper Numbers: 2017-01-0659
- Files: TRIS, SAE
- Created Date: Jan 24 2018 9:11AM