基于Cup-burner的超细水雾与火焰相互作用规律研究
毕业论文关键词 超细水雾 灭火 最低灭火浓度 杯式燃烧器 全混流反应器 CFD 建模
Title An study on the interaction of ultra fine water mist and flame in a cup burner
Abstract An experimental and numerical study was carried out on the interaction of ultra fine water mist with cup burner flame. The predicted minimum extinguishment concentrations (MECs) of ultra fine water mist(UFM) extinguishing methane, ethanol and n-heptane flame were 6.236 g/ min, 11.427 g/ min and 8.239 g/ min. The measured MECs of the UFM extinguishing ethanol and n-heptane flame were 7.590 g/ min and 6.817 g/ min respectively. A further study on the model reveals the main factors causing the gaps between the experimental results and predicted values. An analysis was conducted on the flame image，flame oscillation frequency and temperature of the flame and plume when the flame interacted with the UFM. The subsequent Fluent simulations of the n-heptane cup burner flame were agree with the experimental phenomenon. The interaction process is postulated as follows: 1) when the mist is introduced to the flame, it evaporates before entering into the flame boundary, displaces the oxygen, intensifies the flame and elongates its axial length; 2) with more mist interacts with the flame, a portion of water droplets penetrates the flame, disturbing the fluid field and destabilizing the flame base; 3) when water mist concentration closes to MEC, its cooling effect decreases the flame temperature to its critical value, where the flame oscillates and drifts downstream.
Keywords Ultra-fine water mist; Flame extinction; Minimum extinguishing concentration; Cup burner; Perfectly stirred reactor; CFD modeling
目 次
1 绪论 . 1
1.1 背景和意义 . 1
1.3 主要工作和研究内容 4
2 实验准备 .. 4
2.1 氮气灭火系统 4
2.2 超细水雾灭火系统 . 5
2.3 超声波雾化装置的标定 .. 6
2.4 实验系统的校正 .. 7
2.5 灭火实验步骤 8
3 超细水雾最低灭火浓度的预测和测定 .. 9
3.1 PSR 模型预测超细水雾最低灭火浓度 .. 9
3.2 超细水雾最低灭火浓度的实验测定 . 12