单管火焰筒内燃烧过程的反应动力学数值模拟

Kinetic Simulation of Combustion Process in Individual Flame Tube

关键词:  单管火焰筒  简化机理  着火延迟时间  燃烧特性

Key words:  Individual flame tube  Reduced reaction mechanism  Ignition delay time  Combustion characteristics

摘要:

为了建立航空煤油替代燃料的反应机理,并对航空发动机燃烧过程进行详细反应动力学研究,选用正癸烷作为航空煤油的替代燃料,建立了该替代燃料的化学反应详细机理与简化机理。分别采用详细机理与简化机理对正癸烷在激波管中的着火过程、在预混燃烧炉内的燃烧过程进行了数值计算,并与实验结果进行了对比分析。同时,耦合该简化机理与CFD计算软件Fluent,对某单管火焰筒内燃烧过程、排放物及活性中间组分的生成规律进行了详细分析,并与采用C₁₂H₂₃为燃料的单步总包反应机理的计算结果进行了对比分析。结果表明,采用简化机理计算得到的着火延迟时间、反应物与各主要生成物摩尔分数的整体变化趋势与实验数据吻合较好；与采用C₁₂H₂₃为燃料的单步反应机理相比,采用正癸烷为替代燃料的简化反应机理能更好地对单管火焰筒的燃烧与排放特性进行详细的动力学分析。

Abstract:

In order to build the reaction mechanism of the surrogate fuel for kerosene in the aero-engine, the detailed and reduced reaction mechanisms of n-decane, which was chosen as a surrogate fuel for kerosene, were built. The ignition process in the shock tube and the premixed combustion process in the premixed burner of this surrogate fuel were simulated by adopting the detailed and reduced reaction mechanism, respectively, and the simulated results were compared with the experimental data. The combustion process and the formation of emissions and active species in the individual tube were analyzed by combining implementing the reduced reaction mechanism into the CFD computational software (Fluent), and the computational results were compared with that of the global reaction mechanism of C₁₂H₂₃ fuel. The results show that the ignition delay time, and the shape of the profiles of the mole fractions of the reactants, the major combustion products simulated using the reduced mechanism agreed well with the experimental data. Furthermore, compared with the global reaction mechanism of C₁₂H₂₃ fuel, the combustion and emissions characteristics of the individual flame tube can be analyzed well by adopting the reduced reaction mechanism of n-decane. 