Shaklein Artem, Karpov Alexander, Trubachev Stanislav, Morar Gabriela, Balobanov Nikita, Mitriukova Ekaterina
Udmurt Federal Research Center, Russian Academy of Science, Ural Branch, T. Baramzinoi, 34, 426067 Izhevsk, Russia.
Institute of Chemical Kinetics and Combustion, Russian Academy of Science, Siberian Branch, Institutskaya 3, 630090 Novosibirsk, Russia.
Polymers (Basel). 2024 Nov 27;16(23):3313. doi: 10.3390/polym16233313.
A mixture fraction approach was applied to predict the combustion behavior of polymeric materials. In comparison to the combustion of gaseous mixtures, the presence of solid fuels complicates the description of the combustion. Accurate predictions of burning characteristics can only be achieved through the proper resolution of heat and mass transfer between the gas-phase flame and the solid fuel. We focused on a model case of flame spread over a solid fuel surface. Polymethyl methacrylate (PMMA) was selected as a polymeric material. An approach was proposed to account for heat loss from the gas phase to the solid material through calculations of counterflow diffusion flames with the flame positioned closely to the fuel supply. A combination of these solutions was applied to restore temperature and species mass fractions from tabulated chemistry. An analysis of the numerical results from previous studies on flame spread over PMMA, based on one-step combustion reaction and calculating the chemical source term at each time step, demonstrated a monotonic distribution of the mixture fraction in the flame region between the fuel and oxidizer streams. The shape of the flame tip was satisfactorily resolved using the proposed approach that employs a skeletal chemical mechanism for gas-phase combustion consisting of 29 species and 33 reactions. However, the heat flux from the flame to the solid fuel was overpredicted, resulting in higher flame spread rates compared to experimental data and previous calculations. Preliminary results show a promising opportunity for the mixture fraction approach to describe the combustion behavior of polymers. An analysis showed that oversimplifying the heat transfer process in the flame tip area is a main source of prediction inaccuracies. Multidimensional heat transfer has to be properly incorporated into a tabulated chemistry approach. Several potential directions for future work have been outlined.
采用混合分数方法来预测聚合物材料的燃烧行为。与气体混合物的燃烧相比，固体燃料的存在使燃烧过程的描述变得复杂。只有通过正确解析气相火焰与固体燃料之间的传热和传质，才能准确预测燃烧特性。我们聚焦于火焰在固体燃料表面蔓延的模型案例。选用聚甲基丙烯酸甲酯（PMMA）作为聚合物材料。通过计算逆流扩散火焰（火焰紧邻燃料供应处），提出了一种考虑从气相到固体材料热损失的方法。将这些解决方案相结合，从表格化学数据中恢复温度和物种质量分数。基于一步燃烧反应并在每个时间步计算化学源项，对先前关于PMMA表面火焰蔓延的数值结果分析表明，在燃料流和氧化剂流之间的火焰区域中，混合分数呈单调分布。使用所提出的方法（该方法采用由29种物质和33个反应组成的气相燃烧骨架化学机理），火焰尖端的形状得到了令人满意的解析。然而，从火焰到固体燃料的热通量被高估，导致与实验数据和先前计算相比，火焰蔓延速率更高。初步结果表明，混合分数方法在描述聚合物燃烧行为方面具有广阔前景。分析表明，过度简化火焰尖端区域的传热过程是预测不准确的主要原因。必须将多维传热正确纳入表格化学方法中。已概述了未来工作的几个潜在方向。
