The Anatomy of Knock
Name
2016-01-0704 Anatomy of Knock.pdf
Size
598.59 KB
Format
Adobe PDF
Checksum (MD5)
a92efab6e9621dea061476bf40567f09
Author(s)
McKenzie, Jacob Elijah
Cheng, Wai K
Date Issued
April 2016
Journal
SAE Technical Papers
Publisher
SAE International
Citation
McKenzie, Jacob, and Wai K. Cheng. “The Anatomy of Knock.” SAE Technical Paper, SAE International, 2016.
Version
Author's final manuscript
Abstract
The combustion process after auto-ignition is investigated. Depending on the non-uniformity of the end gas, auto-ignition could initiate a flame, produce pressure waves that excite the engine structure (acoustic knock), or result in detonation (normal or developing). For the “acoustic knock” mode, a knock intensity (KI) is defined as the pressure oscillation amplitude. The KI values over different cycles under a fixed operating condition are observed to have a log-normal distribution. When the operating condition is changed (over different values of λ, EGR, and spark timing), the mean (μ) of log (KI/GIMEP) decreases linearly with the correlation-based ignition delay calculated using the knock-point end gas condition of the mean cycle. The standard deviation σ of log(KI/GIMEP) is approximately a constant, at 0.63. The values of μ and σ thus allow a statistical description of knock from the deterministic calculation of the ignition delay using the mean cycle properties.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.4271/2016-01-0704
