This paper investigates the effects of ullage height (distance between the fuel surface and the pool upper rim) on heat feedback and combustion emission mechanisms of heptane pool fires. Results showed that ullage height significantly influences the flame structure and fuel mass loss rate. The incident radiative heat flux to the fuel surface and its heat feedback fraction first increase and then decrease with ullage height. Correspondingly, the convective heat feedback fraction presents a reverse trend. This attributes to flame base suspension effect and the evolution of soot volume fraction of the flame due to incomplete combustion. While for the conductive heat feedback fraction, it increases with ullage height and becomes the dominant heat feedback mode when the ullage height increases to a certain value. The profiles of the generation rate of the smoke particulates well explain the evolutions of the incident radiative heat flux. The combustion completeness is characterized by the ratio of CO/CO₂. Furthermore, it is calculated that the maximum combustion completeness decreases by 18.4% and 14.3% for pool diameters of 10 cm and 15 cm, respectively. These findings will help to develop and establish more general heat transfer and heat release rate models for pool fires.

本文研究了空量高度（燃料表面与池上缘之间的距离）对庚烷池火灾的热反馈和燃烧排放机制的影响。结果表明，空量高度显着影响火焰结构和燃料质量损失率。到燃料表面的入射辐射热通量及其热反馈分数随着缺损高度先增加后减小。相应地，对流热反馈分数呈现相反的趋势。这归因于火焰基础悬浮效应和由于不完全燃烧导致的火焰烟灰体积分数的演变。而对于传导热反馈分数，它随着空缺高度的增加而增加，当空缺高度增加到一定值时成为主要的热反馈方式。烟雾颗粒的生成速率曲线很好地解释了入射辐射热通量的演变。燃烧完全度用 CO/CO 的比值表征₂ . 此外，据计算，当池直径为 10 cm 和 15 cm 时，最大燃烧完全度分别降低了 18.4% 和 14.3%。这些发现将有助于为池火开发和建立更通用的传热和热释放率模型。