Flame-Front Instabilities of Outwardly Expanding Isooctane/n-Butanol Blend鈥揂ir Flames at Elevated Pressures

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• 作者：Xinyi Zhang ; Chenglong Tang ; Huibin Yu ; Zuohua Huang
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：March 20, 2014
• 年：2014
• 卷：28
• 期：3
• 页码：2258-2266
• 全文大小：461K
• 年卷期：v.28,no.3(March 20, 2014)
• ISSN：1520-5029

文摘

Experiments were conducted in a constant volume bomb filled with isooctane/n-butanol blend鈥揳ir mixtures over a wide range of n-butanol blending ratios, equivalence ratios, and initial pressures. High-speed schlieren photography was used to measure the critical radius for the onset of flame-front instability. Results show that, for a given n-butanol blending ratio, cellular instabilities appear earlier and the critical Peclet number, which represents the onset of instability, is decreased with the increase of the initial pressure and equivalence ratio. Under fuel-rich conditions, the critical Peclet number increases with the increase of the n-butanol blending ratio. Theoretical calculation of the critical Peclet number was also conducted to interpret the effects of n-butanol on the flame-front instabilities of the blends. Results show that, for rich mixture conditions, with the increase of the n-butanol blending ratio, the overall activation energy of the mixtures is decreased and, thus, the thermal鈥揹iffusional instabilities are suppressed. While under fuel-lean conditions, the thermal鈥揹iffusional instabilities are favored. As a consequence, with an increasing n-butanol blending ratio, the critical Peclet number is expected to be decreased under fuel-lean conditions and increased under fuel-rich conditions.