Abstract: The combustion of fossil fuels is the main form of energy supply in today's society, but with the depletion of fossil fuels, it is urgent to develop new alternative fuels. n-Dodecane is one of the important components of aviation kerosene, and also an important component of various alternative fuels for aviation kerosene. Laminar combustion characteristics of n-dodecane/air flames were investigated using CHEMKIN/PREMIX, providing a theoretical reference for the development of alternative fuel aviation kerosene. The initial temperatures were set as 400, 403, 423, and 470 K, the initial pressures were set as 0.1, 0.2, 0.3, 0.5, and 1.0 MPa, and the equivalence ratio was set as 0.6~1.6. This study mainly focused on the combustion characteristics of flames, temperature sensitivity analysis, and the distribution of intermediate free radicals. The laminar burning velocity (LBV), adiabatic flame temperature (AFT), net heat release rate (NHRR), and rate of production (ROP) of free radicals were obtained with the increase of initial temperatures and pressures. The results showed that the simulation values of LBV can well-predict other experimental values, whose trend was consistent with other models. The peaks of AFT appeared near the stoichiometric ratio. Similar to other hydrocarbon fuels, the most sensitive reaction was R1 (H+O2?O+OH) in the oxidation process. It was verified that there was an obvious spatial difference between the flame front and fuel pyrolysis through ROP analysis and the distribution of mole fraction. The increase in initial pressures reduced the reaction zone and accelerated the formation rate of free radicals. Laminar premixed combustion characteristics of n-dodecane/air flames were studied using Jetsurf 2.0 mechanism, and the effect of elevated temperatures and pressures was comprehensively discussed. The numerical results can enrich the basis of data at high pressure, which provides a reference for looking for alternative fuels for aviation kerosene.

Key words: n-dodecane, laminar burning velocity, net heat release rate, sensitivity analysis

摘要： 化石燃料的燃烧是当今社会主要的能源供给形式，但随着化石能源的消耗殆尽，发展新型替代燃料已刻不容缓。正十二烷(n-C12H26)是航空煤油的重要组成成分之一，也是多种航空煤油替代燃料的重要组成。本工作采用CHEMKIN/PREMIX数值模拟研究了正十二烷/空气火焰的层流燃烧特性，为发展航空煤油替代燃料提供一定的理论参考。实验的初始温度设置为400, 403, 423和470 K，初始压力设置为0.1, 0.2, 0.3, 0.5, 1.0 MPa，当量比设置为0.6~1.6。本研究主要聚焦火焰的传播燃烧特性、温度敏感性分析和中间自由基的分布情况，探究了正十二烷/空气火焰的层流燃烧速度、绝热火焰温度、净热释放率和中间自由基生成速率随初始温度和压力的变化规律。结果表明，层流燃烧速度的模拟值对其他研究者的实验值预测良好，与其他模型的预测趋势保持一致。绝热火焰温度在化学计量比附近达到峰值。温度敏感性分析表明，与其他碳氢燃料相似，在正十二烷氧化过程中引起火焰温度升高促进放热的最敏感反应为R1 (H+O2?O+OH)。通过对中间自由基的生成速率及摩尔分数分布规律的研究，验证了正十二烷燃烧火焰前锋与燃料裂解存在明显的空间位置差距。初始压力的升高使反应区域缩小，进一步加快了自由基的生成速率。本工作的数值计算结果丰富了高压下的正十二烷层流燃烧特性数据库，为研发新型航空煤油替代燃料提供了参考。

关键词: 正十二烷, 层流火焰速度, 净热释放率, 敏感性分析