Effect of ambient wind on horizontal flame spread over discrete multi-column fuel arrays

The flame spread behaviors of discrete charring fuels are significantly influenced by ambient wind. This paper studied the horizontal flame spread characteristics of discrete birch rod arrays under ambient wind experimentally and theoretically. Here, seven kinds of array spacings (denoted by S, 7-19 mm) and four kinds of wind speeds (denoted by U, 0.5-2.0 m/s) were designed to develop 28 experiments. The experimental results show that the flame inclination angle decreases as wind speed increases. The non-dimensional flame length and the non-dimensional heat release rate are also found to be correlated, and two ignition modes under the action of ambient wind were differentiated. The flame spread rate and wind speed have a linear relationship based on experimental data. The ratio of wind speed to fuel loading is introduced to further examine the variation of flame spread rate. In this article, a heat transfer model is established by simplifying discrete flame spread process and incorporating both radiative and convective heat transfer. A prediction model for flame spread rate is presented, which aligns well with the experimental results. Finally, the mass loss rate under the ambient wind is discussed.