A DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixture
We examine the effects of temperature non-uniformity and turbulence on homogeneous charge compression ignition (HCCI) of a homogeneous n-heptane/air mixture, using three-dimensional direct numerical simulations of the mixture flows. We use a reduced chemical reaction model for the HCCI combustion. T...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | Japanese |
| Published: |
The Japan Society of Mechanical Engineers
2014-12-01
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| Series: | Nihon Kikai Gakkai ronbunshu |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/transjsme/80/820/80_2014tep0361/_pdf/-char/en |
| _version_ | 1798019071178964992 |
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| author | Takashi ISHIHARA Takamasa ITO Takashi MIKI Katsunori YOSHIMATSU Atsushi TERAJI |
| author_facet | Takashi ISHIHARA Takamasa ITO Takashi MIKI Katsunori YOSHIMATSU Atsushi TERAJI |
| author_sort | Takashi ISHIHARA |
| collection | DOAJ |
| description | We examine the effects of temperature non-uniformity and turbulence on homogeneous charge compression ignition (HCCI) of a homogeneous n-heptane/air mixture, using three-dimensional direct numerical simulations of the mixture flows. We use a reduced chemical reaction model for the HCCI combustion. Time evolutions of the flows are obtained under the initial conditions having three different initial velocity fluctuations at 4.0 MPa and with temperature fluctuation around 781 K. Heat-release by the low-temperature oxidation, a key reaction in the ignition process, is analyzed along the trajectories of the temperature gradients, using dissipation-elements decomposition of the temperature fields. It is shown that the high heat-release rate occurs in the membrane-like regions where the temperature is about 870 K. The membrane-like regions move along the trajectories from high to low temperature. The analysis on the trajectories shows that the conditionally averaged moving speed and thickness of the regions are decreasing functions of the magnitude of temperature gradient. When the velocity fluctuation is strong, the turbulent flow is found to play a key role in retarding the ignition: The turbulent flow reduces the maximum temperature and slows down the averaged moving speed of the membrane-like regions. |
| first_indexed | 2024-04-11T16:34:35Z |
| format | Article |
| id | doaj.art-3b62f3ac0a754033929104f87978754d |
| institution | Directory Open Access Journal |
| issn | 2187-9761 |
| language | Japanese |
| last_indexed | 2024-04-11T16:34:35Z |
| publishDate | 2014-12-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Nihon Kikai Gakkai ronbunshu |
| spelling | doaj.art-3b62f3ac0a754033929104f87978754d2022-12-22T04:13:52ZjpnThe Japan Society of Mechanical EngineersNihon Kikai Gakkai ronbunshu2187-97612014-12-0180820TEP0361TEP036110.1299/transjsme.2014tep0361transjsmeA DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixtureTakashi ISHIHARA0Takamasa ITO1Takashi MIKI2Katsunori YOSHIMATSU3Atsushi TERAJI4Graduate School of Engineering, Nagoya UniversityGraduate School of Engineering, Nagoya UniversityGraduate School of Engineering, Nagoya UniversityGraduate School of Engineering, Nagoya UniversityNissan Motor CO., Ltd.We examine the effects of temperature non-uniformity and turbulence on homogeneous charge compression ignition (HCCI) of a homogeneous n-heptane/air mixture, using three-dimensional direct numerical simulations of the mixture flows. We use a reduced chemical reaction model for the HCCI combustion. Time evolutions of the flows are obtained under the initial conditions having three different initial velocity fluctuations at 4.0 MPa and with temperature fluctuation around 781 K. Heat-release by the low-temperature oxidation, a key reaction in the ignition process, is analyzed along the trajectories of the temperature gradients, using dissipation-elements decomposition of the temperature fields. It is shown that the high heat-release rate occurs in the membrane-like regions where the temperature is about 870 K. The membrane-like regions move along the trajectories from high to low temperature. The analysis on the trajectories shows that the conditionally averaged moving speed and thickness of the regions are decreasing functions of the magnitude of temperature gradient. When the velocity fluctuation is strong, the turbulent flow is found to play a key role in retarding the ignition: The turbulent flow reduces the maximum temperature and slows down the averaged moving speed of the membrane-like regions.https://www.jstage.jst.go.jp/article/transjsme/80/820/80_2014tep0361/_pdf/-char/enhomogeneous charged compression ignition (hcci)low temperature oxidationn-heptaneturbulencedirect numerical simulationdissipation element |
| spellingShingle | Takashi ISHIHARA Takamasa ITO Takashi MIKI Katsunori YOSHIMATSU Atsushi TERAJI A DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixture Nihon Kikai Gakkai ronbunshu homogeneous charged compression ignition (hcci) low temperature oxidation n-heptane turbulence direct numerical simulation dissipation element |
| title | A DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixture |
| title_full | A DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixture |
| title_fullStr | A DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixture |
| title_full_unstemmed | A DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixture |
| title_short | A DNS study of the effects of temperature non-uniformity and turbulence on an auto-ignition process in a homogeneous n-heptane/air mixture |
| title_sort | dns study of the effects of temperature non uniformity and turbulence on an auto ignition process in a homogeneous n heptane air mixture |
| topic | homogeneous charged compression ignition (hcci) low temperature oxidation n-heptane turbulence direct numerical simulation dissipation element |
| url | https://www.jstage.jst.go.jp/article/transjsme/80/820/80_2014tep0361/_pdf/-char/en |
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