### Abstract

Spherically propagating laminar and turbulent flames were studied using iso-octane / air mixtures with and without dilution. The main purpose of this study is to clarify the influence of thermo-diffusive effects on the turbulent flames. In order to examine the thermo-diffusive effects solely by separating them from the effects of flame stretch, turbulent burning velocities were compared at constant flame stretch factors. The mean flame stretch factor acting on turbulent flame front may be represented by the turbulence Karlovitz number. Thus, turbulent explosions were carried out at fixed turbulence Karlovitz numbers. The ratio of turbulent burning velocity to unstretched laminar burning velocity increased with the equivalence ratio for non-diluted mixtures at fixed turbulence Karlovitz numbers. And this ratio for CO _{2} diluted mixtures was larger than N _{2} diluted mixtures. The Markstein number that denotes the sensitivity of the flame to thermo-diffusive effects depends on the equivalence ratio and diluents of the mixture. The ratio of turbulent burning velocity to unstretched laminar one increased with decreasing Markstein number. Especially, it changed stepwise around Markstein number of zero. However, the burning velocity ratios did not increase with increasing mixture pressure although the Markstein number decreased with pressure.

Original language | English |
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Title of host publication | ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 |

Publication status | Published - Dec 1 2011 |

Event | ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 - Honolulu, HI, United States Duration: Mar 13 2011 → Mar 17 2011 |

### Publication series

Name | ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 |
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### Other

Other | ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 |
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Country | United States |

City | Honolulu, HI |

Period | 3/13/11 → 3/17/11 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Energy Engineering and Power Technology

### Cite this

*ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011*(ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011).

**Study of thermo-diffusive effects on iso-octane/air flames at fixed turbulence Karlovitz number.** / Hayakawa, Akihiro; Takeo, Tomohiro; Miki, Yukito; Nagano, Yukihide; Kitagawa, Toshiaki.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011.*ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, Honolulu, HI, United States, 3/13/11.

}

TY - GEN

T1 - Study of thermo-diffusive effects on iso-octane/air flames at fixed turbulence Karlovitz number

AU - Hayakawa, Akihiro

AU - Takeo, Tomohiro

AU - Miki, Yukito

AU - Nagano, Yukihide

AU - Kitagawa, Toshiaki

PY - 2011/12/1

Y1 - 2011/12/1

N2 - Spherically propagating laminar and turbulent flames were studied using iso-octane / air mixtures with and without dilution. The main purpose of this study is to clarify the influence of thermo-diffusive effects on the turbulent flames. In order to examine the thermo-diffusive effects solely by separating them from the effects of flame stretch, turbulent burning velocities were compared at constant flame stretch factors. The mean flame stretch factor acting on turbulent flame front may be represented by the turbulence Karlovitz number. Thus, turbulent explosions were carried out at fixed turbulence Karlovitz numbers. The ratio of turbulent burning velocity to unstretched laminar burning velocity increased with the equivalence ratio for non-diluted mixtures at fixed turbulence Karlovitz numbers. And this ratio for CO 2 diluted mixtures was larger than N 2 diluted mixtures. The Markstein number that denotes the sensitivity of the flame to thermo-diffusive effects depends on the equivalence ratio and diluents of the mixture. The ratio of turbulent burning velocity to unstretched laminar one increased with decreasing Markstein number. Especially, it changed stepwise around Markstein number of zero. However, the burning velocity ratios did not increase with increasing mixture pressure although the Markstein number decreased with pressure.

AB - Spherically propagating laminar and turbulent flames were studied using iso-octane / air mixtures with and without dilution. The main purpose of this study is to clarify the influence of thermo-diffusive effects on the turbulent flames. In order to examine the thermo-diffusive effects solely by separating them from the effects of flame stretch, turbulent burning velocities were compared at constant flame stretch factors. The mean flame stretch factor acting on turbulent flame front may be represented by the turbulence Karlovitz number. Thus, turbulent explosions were carried out at fixed turbulence Karlovitz numbers. The ratio of turbulent burning velocity to unstretched laminar burning velocity increased with the equivalence ratio for non-diluted mixtures at fixed turbulence Karlovitz numbers. And this ratio for CO 2 diluted mixtures was larger than N 2 diluted mixtures. The Markstein number that denotes the sensitivity of the flame to thermo-diffusive effects depends on the equivalence ratio and diluents of the mixture. The ratio of turbulent burning velocity to unstretched laminar one increased with decreasing Markstein number. Especially, it changed stepwise around Markstein number of zero. However, the burning velocity ratios did not increase with increasing mixture pressure although the Markstein number decreased with pressure.

UR - http://www.scopus.com/inward/record.url?scp=84860904255&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84860904255&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:84860904255

SN - 9780791838921

T3 - ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011

BT - ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011

ER -