Combustion characteristics of well-dispersed boron submicroparticles and plasma effect

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Combustion characteristics of well-dispersed boron submicroparticles and plasma effect. / Yu, Dan; Kong, Chengdong; Zhuo, Jiankun; Yao, Qiang; Li, Shuiqing; Wang, Mengze; Tian, Zhen Yu.

In: Combustion and Flame, Vol. 188, 2018, p. 94-103.

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Yu, Dan ; Kong, Chengdong ; Zhuo, Jiankun ; Yao, Qiang ; Li, Shuiqing ; Wang, Mengze ; Tian, Zhen Yu. / Combustion characteristics of well-dispersed boron submicroparticles and plasma effect. In: Combustion and Flame. 2018 ; Vol. 188. pp. 94-103.

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TY - JOUR

T1 - Combustion characteristics of well-dispersed boron submicroparticles and plasma effect

AU - Yu, Dan

AU - Kong, Chengdong

AU - Zhuo, Jiankun

AU - Yao, Qiang

AU - Li, Shuiqing

AU - Wang, Mengze

AU - Tian, Zhen Yu

PY - 2018

Y1 - 2018

N2 - Boron is an attractive high-energy fuel additive. But it could not burn efficiently in practical systems due to its high ignition temperature and slow burning velocity. Finding methods to enhance the combustion of boron is desired. This work focused on the combustion characteristics of boron submicroparticles with and without plasma discharges in a hot environment supported by CH4/N2/O2 flat flame based on the optical diagnostics. The boron submicroparticles were dispersed by the nebulization method to control the agglomeration. The well-dispersed boron flame exhibited two different burning modes, depending on the ambient temperature. As the ambient temperature was above 1520 K, the boron flame showed definitely two-stage characteristics where the upstream of particle flow was yellow, corresponding to the first-stage flame, while the downstream was green and diffusive, corresponding to the second-stage flame. The first-stage and second-stage burn times were respectively in the range of 0.46–1.08 ms and 0.92–1.87 ms, as the ambient temperature decreased from 1752 K to 1520 K. The chemical kinetics-controlled mechanism was confirmed by the nearly linear size dependence of the burn time (d1 law). Nevertheless, as the ambient temperature was below 1520 K, the boron submicroparticles were partially burned or oxidized, exhibiting a mildly orange stream. This mild boron flame could be enhanced using a plasma discharge. The ignition delay time was shortened from 3.06 ms to 0.77 ms when the discharge was introduced at the ignition delay stage. The two-stage combustion characteristics occurred when the discharge was introduced at the combustion stage.

AB - Boron is an attractive high-energy fuel additive. But it could not burn efficiently in practical systems due to its high ignition temperature and slow burning velocity. Finding methods to enhance the combustion of boron is desired. This work focused on the combustion characteristics of boron submicroparticles with and without plasma discharges in a hot environment supported by CH4/N2/O2 flat flame based on the optical diagnostics. The boron submicroparticles were dispersed by the nebulization method to control the agglomeration. The well-dispersed boron flame exhibited two different burning modes, depending on the ambient temperature. As the ambient temperature was above 1520 K, the boron flame showed definitely two-stage characteristics where the upstream of particle flow was yellow, corresponding to the first-stage flame, while the downstream was green and diffusive, corresponding to the second-stage flame. The first-stage and second-stage burn times were respectively in the range of 0.46–1.08 ms and 0.92–1.87 ms, as the ambient temperature decreased from 1752 K to 1520 K. The chemical kinetics-controlled mechanism was confirmed by the nearly linear size dependence of the burn time (d1 law). Nevertheless, as the ambient temperature was below 1520 K, the boron submicroparticles were partially burned or oxidized, exhibiting a mildly orange stream. This mild boron flame could be enhanced using a plasma discharge. The ignition delay time was shortened from 3.06 ms to 0.77 ms when the discharge was introduced at the ignition delay stage. The two-stage combustion characteristics occurred when the discharge was introduced at the combustion stage.

KW - Boron particle

KW - Kinetics-controlled

KW - Plasma assistance

KW - Two-stage combustion

U2 - 10.1016/j.combustflame.2017.09.022

DO - 10.1016/j.combustflame.2017.09.022

M3 - Article

VL - 188

SP - 94

EP - 103

JO - Combustion and Flame

T2 - Combustion and Flame

JF - Combustion and Flame

SN - 0010-2180

ER -