Blow-out of nonpremixed turbulent jet flames at sub-atmospheric pressures

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• 作者：Qiang Wangup>aup>up> ; up>up>bup> ; Longhua Huup>aup>up> ; up>up>hlh@ustc.edu.cnup> ; Suk Ho Chungup>cup>
• 关键词：Nonpremixed turbulent jet flame ; Blow-out limit ; Sub-atmospheric pressure ; Laminar burning velocity ; Damkö ; hler number
• 刊名：Combustion and Flame
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：176
• 期：Complete
• 页码：358-360
• 全文大小：840 K
• 卷排序：176

文摘

Blow-out limits of nonpremixed turbulent jet flames in quiescent air at sub-atmospheric pressures (50–100 kPa) were studied experimentally using propane fuel with nozzle diameters ranging 0.8–4 mm. Results showed that the fuel jet velocity at blow-out limit increased with increasing ambient pressure and nozzle diameter. A Damköhler (Da) number based model was adopted, defined as the ratio of characteristic mixing time and characteristic reaction time, to include the effect of pressure considering the variations in laminar burning velocity and thermal diffusivity with pressure. The critical lift-off height at blow-out, representing a characteristic length scale for mixing, had a linear relationship with the theoretically predicted stoichiometric location along the jet axis, which had a weak dependence on ambient pressure. The characteristic mixing time (critical lift-off height divided by jet velocity) adjusted to the characteristic reaction time such that the critical Damköhler at blow-out conditions maintained a constant value when varying the ambient pressure.