This paper investigated the effect of separation distance on the flame appearance and radiation heat flux of medium-scale pool fires dominated by radiation. A series of experiments were conducted on two adjacent heptane pool fires with diameters of 20 cm, 40 cm and 60 cm at separation distances ranging from 0 to 60 cm. According to experimental results, flame height and flame inclination angle increase monotonously with the increase of pool diameter. As separation distance increases, flame height increases first and decreases gradually for 3 different sized pool fires. However, the variation law of flame inclination angle with separation distance varies with pool diameter. The normalized flame height ($H_f/\text{D}$) is found to increase exponentially with the dimensionless heat release rate (${\text{Q}}^{*}$) with an exponent of 0.71. The radiative heat flux at the center of the pool surface peaks at the critical separation distance of flame merging, which results from increased flame emissivity and view factor. Based on thermal analysis, a model to predict the radiative heat flux on the fuel surface is developed. The predicted radiative heat fluxes quantitatively match the experimental results but with 20% overvalued, due to the neglection of radiation blockage effect of cool fuel vapors zone and soot. The blockage effect is more pronounced for the merging pool fires with a diameter of 60 cm.

本文研究了间隔距离对以辐射为主的中等规模池火火焰形态和辐射热通量的影响。对两个相邻的直径分别为 20 厘米、40 厘米和 60 厘米的庚烷池火灾进行了一系列实验，间隔距离为 0 到 60 厘米。根据实验结果，火焰高度和火焰倾角随着熔池直径的增加而单调增加。随着间隔距离的增加，3种不同大小的池火火焰高度先增加后逐渐减小。然而，火焰倾角随分离距离的变化规律随熔池直径而变化。归一化火焰高度（$H_F/\text{D}$) 被发现随着无量纲放热率 (${\text{问}}^{*}$) 的指数为 0.71。熔池表面中心的辐射热通量在火焰合并的临界分离距离处达到峰值，这是由于火焰发射率和视角因子增加所致。在热分析的基础上，建立了燃料表面辐射热通量预测模型。由于忽略了冷燃料蒸汽区和烟尘的辐射阻塞效应，预测的辐射热通量与实验结果定量匹配，但高估了 20%。直径为60cm的合流池火堵塞效果更明显。