Flame spread over liquid fuel is an evitable process during the development of spilling liquid fires. The scale of the combustion zone may be expanded by the spreading fire, making the fire uncontrollable. Thus, the flame spread is a major threat to the process safety of the usage of liquid fuels. An experimental apparatus is designed to study the flame spread over n-butanol under the effect of the gas step that is built by the low-heat conductivity marbles. The flame morphology, flame resident time, and movement of subsurface liquid convection are measured under various widths and heights of the marble steps. The resident time is affected by the coupling effects of the viscous resistance of step and the heat loss to unburned fuel. The flame height is decreased by the width of the step but enhanced by the height of the step. The convective heat transfer through subsurface flow and flame radiation to the unburned fuel behind the step is calculated. The convective heat transfer rate accounts for more than 90% of the total heat transfer rate. This current finding provides a theoretical basis for the safety application and emergency management of liquid fuels.

中文翻译：

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火焰在亚闪点温度下在正丁醇燃料上蔓延，并在气相中出现台阶

在溢出液体火灾的发展过程中，火焰在液体燃料上蔓延是一个不可避免的过程。燃烧区的规模可能会因火势蔓延而扩大，使火势无法控制。因此，火焰蔓延是液体燃料使用过程安全的主要威胁。设计了一个实验装置来研究火焰在n上的传播-丁醇在由低导热性大理石构建的气体步骤的作用下。测量了不同宽度和高度的大理石台阶下的火焰形态、火焰停留时间和地下液体对流的运动。滞留时间受台阶粘滞阻力和未燃烧燃料热损失的耦合作用影响。火焰高度随着台阶的宽度而降低，但随着台阶的高度而提高。计算通过地下流动和火焰辐射到台阶后面的未燃烧燃料的对流传热。对流传热率占总传热率的90%以上。这一发现为液体燃料的安全应用和应急管理提供了理论依据。