The Anatomy of Knock
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...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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SAE International
2017
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| Online Access: | http://hdl.handle.net/1721.1/109431 https://orcid.org/0000-0002-7044-8156 |
| _version_ | 1826198678564503552 |
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| author | McKenzie, Jacob Elijah Cheng, Wai K |
| author2 | Massachusetts Institute of Technology. Department of Mechanical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Mechanical Engineering McKenzie, Jacob Elijah Cheng, Wai K |
| author_sort | McKenzie, Jacob Elijah |
| collection | MIT |
| description | 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. |
| first_indexed | 2024-09-23T11:08:26Z |
| format | Article |
| id | mit-1721.1/109431 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:08:26Z |
| publishDate | 2017 |
| publisher | SAE International |
| record_format | dspace |
| spelling | mit-1721.1/1094312022-10-01T01:32:30Z The Anatomy of Knock McKenzie, Jacob Elijah Cheng, Wai K Massachusetts Institute of Technology. Department of Mechanical Engineering Cheng, Wai K. McKenzie, Jacob Elijah Cheng, Wai K 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. Industrial Consortium on Engine and Fuels Research 2017-05-30T18:22:49Z 2017-05-30T18:22:49Z 2016-04 Article http://purl.org/eprint/type/ConferencePaper 0148-7191 http://hdl.handle.net/1721.1/109431 McKenzie, Jacob, and Wai K. Cheng. “The Anatomy of Knock.” SAE Technical Paper, SAE International, 2016. https://orcid.org/0000-0002-7044-8156 en_US http://dx.doi.org/10.4271/2016-01-0704 SAE Technical Papers Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf SAE International Prof. Cheng via Angie Locknar |
| spellingShingle | McKenzie, Jacob Elijah Cheng, Wai K The Anatomy of Knock |
| title | The Anatomy of Knock |
| title_full | The Anatomy of Knock |
| title_fullStr | The Anatomy of Knock |
| title_full_unstemmed | The Anatomy of Knock |
| title_short | The Anatomy of Knock |
| title_sort | anatomy of knock |
| url | http://hdl.handle.net/1721.1/109431 https://orcid.org/0000-0002-7044-8156 |
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