The Anatomy of Knock

2016-01-0704

04/05/2016

Event
SAE 2016 World Congress and Exhibition
Authors Abstract
Content
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
Meta TagsDetails
DOI
https://doi.org/10.4271/2016-01-0704
Pages
8
Citation
McKenzie, J., and Cheng, W., "The Anatomy of Knock," SAE Technical Paper 2016-01-0704, 2016, https://doi.org/10.4271/2016-01-0704.
Additional Details
Publisher
Published
Apr 5, 2016
Product Code
2016-01-0704
Content Type
Technical Paper
Language
English