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## 摘要

At 38th Symposium, Shy and co-workers investigated a turbulence-facilitated-ignition (TFI) phenomenon via both conventional-single-spark-discharge (CSSD) and nanosecond-repetitively-pulsed-discharge (NRPD) at various pulsed-repetitive-frequency (PRF=5–70 kHz) using a fixed inter-electrode gap (d_{gap}=0.8 mm) in a randomly-stirred lean n-butane/air mixture with Lewis number Le≈2.2 ≫ 1 over a range of r.m.s. turbulent fluctuating velocity (u′=0–2.1 m/s). It was found that the ignition probability (P_{ig}) decreases significantly with increasing u′ for most PRFs, except at PRF=60 kHz having turbulent P_{ig,}_{T} = 37% at u′=0.5 m/s > laminar P_{ig,}_{L} = 34%, showing possible TFI. Using the same methodology, this paper presents two new P_{ig} datasets at d_{gap}=0.6 mm and 2.0 mm over wider ranges of PRF=1–90 kHz and u′=0–2.8 m/s. All NRPD experiments apply the same total ignition energy E_{tot}≈23 mJ via a train of 11 pulses, each pulse having about 2.2 mJ except for the first pulse having about 1 mJ when using sufficiently high open-circuit-voltage of 28 kV. Note that E_{tot}≈MIE_{L}≈23 mJ at d_{gap}=0.8 mm as a baseline for comparison; MIE_{L} is the laminar minimum ignition energy measured by CSSD at 50% ignitability and MIE_{L}=26.3 mJ/3.4 mJ at d_{gap}=0.6 mm/2.0 mm. While TFI is noticeably observed at d_{gap}=0.6 mm when PRF=60 kHz with P_{ig,}_{T} = 92% at u′=0.5 m/s > P_{ig,}_{L} = 78%, turbulence reclaims its dominating role when u′ > 1.4 m/s with P_{ig,}_{T} << P_{ig,L}. At d_{gap}=2.0 mm, there is no TFI; a P_{ig,T} transition is found where the decrease of P_{ig,T} with u′ changes from gradually to rapidly when u′ > u′_{c} (critical u′ depending on PRF). We also discover that the curves of P_{ig,T} versus PRF are highly non-monotonic with peaks around PRF=40 kHz for u′ > 1.4 m/s; too high PRFs are detrimental for spherical flame ignition. These results are explained by coupling effects of d_{gap}, PRF, u′, and differential diffusion.

原文 | ???core.languages.en_GB??? |
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文章編號 | 111506 |

期刊 | Combustion and Flame |

卷 | 231 |

DOIs | |

出版狀態 | 已出版 - 9月 2021 |

## 指紋

深入研究「Ignition enhancement and deterioration by nanosecond repetitively pulsed discharges in a randomly-stirred lean n-butane/air mixture at various inter-electrode gaps」主題。共同形成了獨特的指紋。## 專案

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