合成气非预混燃烧的数值模拟

Numerical simulation on syngas non-premixed combustion

针对合成气非预混火焰结构开展数值模拟和试验验证,分析天然气改烧合成气后燃烧特性的变化规律.结果表明,大涡模拟(Large Eddy Simulation,LES)在速度分布和温度分布的预测中与试验结果比较吻合,而在对燃烧过程产物(如OH自由基)预测中则与试验结果有所差异.采用数值模拟与试验测量相结合的方法,探讨和分析合成气燃烧特性的变化规律:与天然气火焰相比,合成气燃烧时高温区域更大,火焰稳定性较好;随着当量比提高,燃烧室热负荷不断增大,同时最高回流速度增大,火焰根部受到压缩,逐渐呈现出推举火焰特征.

The numerical simulation and test validation are used to study syngas non-premixed flame structure, and the change rule of combustion characteristics of syngas which is instead of natural gas is analyzed. The results indicate that, the velocity and temperature distribution predicted by Large Eddy Simulation （LES） are in good consistency with the test results, but the prediction of substances generated during combustion process such as OH radical prediction is different from the test results. The method of numerical simulation combined with test measurement is used to discuss and analyze the change rule of syngas combustion. It shows that, comparing with natural gas flame, the high temperature zone is enlarged and the flame stability is better; with the increase of equivalence ratio, the heat load of combustion chamber increases, the top back flow velocity increases, and the flame shows push-up characteristic.