A series of experiments was performed to investigate the spreading behavior of firefighting foam solutions on liquid fuel surfaces. The spreading coefficients of six kinds of aqueous film-forming foam solutions and one fluorine-free foam solution on the surface of four liquid fuels, namely, cyclohexane, diesel, n-heptane, and ethanol, were calculated on the basis of surface and interfacial tension. Spreading behavior was studied systematically using a high-speed camera, and then the relationship between spreading behavior and spreading coefficient was analyzed. Furthermore, the spreading area and spreading rate of different foam solution droplets on liquid fuel surfaces were studied in depth. The spreading amount of the foam solution droplets on the liquid fuel surfaces was measured. Four typical spreading phenomena, namely, spreading, suspension, dissolution, and sinking, of AFFF solutions on liquid fuel surfaces were identified. Moreover, a positive spreading coefficient did not necessarily lead to the formation of an aqueous film. The spreading area, spreading rate, and spreading amount were not proportional to the spreading coefficient. During the evaluation of the spreading property of firefighting foam, the spreading coefficient, spreading rate, and spreading amount must be focused on instead of only the spreading coefficient.

中文翻译：

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消防泡沫溶液在典型液体燃料表面的扩散行为

进行了一系列实验来研究灭火泡沫溶液在液体燃料表面的扩散行为。基于表面和界面计算了六种水性成膜泡沫溶液和一种无氟泡沫溶液在环己烷、柴油、正庚烷和乙醇四种液体燃料表面的铺展系数紧张。利用高速摄像机系统地研究了铺展行为，然后分析了铺展行为与铺展系数之间的关系。此外，还深入研究了不同泡沫溶液液滴在液体燃料表面的扩散面积和扩散速率。测量液体燃料表面上泡沫溶液液滴的铺展量。四种典型的传播现象，即传播、悬浮、确定了 AFFF 溶液在液体燃料表面的溶解和下沉。此外，正铺展系数不一定导致水膜的形成。铺展面积、铺展速度、铺展量与铺展系数不成正比。在评价消防泡沫的铺展性能时，必须关注铺展系数、铺展速率和铺展量，而不仅仅是铺展系数。