The suppression effectiveness of an intrinsically clean hybrid fire suppressant consisting of nitrogen and water mist was experimentally studied by a cup burner method with methane/air coflowing flame. A series of hybrid agents with different weight ratios of nitrogen and water mist (Sauter mean diameter: 12.6 Î¼m) were tested and compared with nitrogen and water mist used alone. The minimum mass-based extinction concentration (MEC) of neat nitrogen and water mist was measured as 32.1% and 15.2%, respectively. When combined, MEC of the hybrid agents fell between the limiting values of nitrogen and water mist used alone. An approximately linear relationship was shown for the suppression behavior of nitrogen and water mist in combination. The flow field of suppressants during the flame suppression process was studied by particle imaging velocimetry (PIV) technique. A small portion of water droplets near the flame front evaporated, which contributed to flame extinction by heat absorption and oxygen dilution. The remaining bulk mist was entrained vertically with the air flow, showing little effect on the flame base.

中文翻译：

---

用杯式燃烧器共流火焰评估混合氮和水雾的抑制效果

采用杯式燃烧器法，采用甲烷/空气共流火焰，实验研究了由氮气和水雾组成的本质清洁混合型灭火剂的抑制效果。对一系列具有不同重量比的氮和水雾（Sauter 平均直径：12.6 μm）的混合剂进行了测试，并与单独使用的氮和水雾进行了比较。纯氮和水雾的基于质量的最小消光浓度 (MEC) 分别测量为 32.1% 和 15.2%。当结合使用时，混合剂的 MEC 落在单独使用的氮和水雾的极限值之间。氮和水雾的组合抑制行为显示出近似线性关系。采用粒子成像测速（PIV）技术研究了火焰抑制过程中抑制剂的流场。火焰前沿附近的一小部分水滴蒸发，这有助于通过吸热和氧气稀释来熄灭火焰。剩余的散装雾随气流垂直夹带，对火焰底部的影响很小。