Modeling of Trace Knock in a Modern SI Engine Fuelled by Ethanol/Gasoline Blends

2015-01-1242

04/14/2015

Event
SAE 2015 World Congress & Exhibition
Authors Abstract
Content
This paper presents a numerical study of trace knocking combustion of ethanol/gasoline blends in a modern, single cylinder SI engine. Results are compared to experimental data from a prior, published work [1]. The engine is modeled using GT-Power and a two-zone combustion model containing detailed kinetic models. The two zone model uses a gasoline surrogate model [2] combined with a sub-model for nitric oxide (NO) [3] to simulate end-gas autoignition.
Upstream, pre-vaporized fuel injection (UFI) and direct injection (DI) are modeled and compared to characterize ethanol's low autoignition reactivity and high charge cooling effects. Three ethanol/gasoline blends are studied: E0, E20, and E50. The modeled and experimental results demonstrate some systematic differences in the spark timing for trace knock across all three fuels, but the relative trends with engine load and ethanol content are consistent. Possible reasons causing the differences are discussed. Finally, the influence of NO on autoignition is investigated, yielding results that are consistent with prior works. Overall, the same, two-zone kinetic model appears to capture both the UFI and DI autoignition similarly well. These results also provide further evidence suggesting that inclusion of a NO sub-model is necessary for mechanistically accurate modeling of autoignition and knock in general.
Meta TagsDetails
DOI
https://doi.org/10.4271/2015-01-1242
Pages
13
Citation
Yuan, H., Foong, T., Chen, Z., Yang, Y. et al., "Modeling of Trace Knock in a Modern SI Engine Fuelled by Ethanol/Gasoline Blends," SAE Technical Paper 2015-01-1242, 2015, https://doi.org/10.4271/2015-01-1242.
Additional Details
Publisher
Published
Apr 14, 2015
Product Code
2015-01-1242
Content Type
Technical Paper
Language
English