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采用亚网格动能(k方程)应力模型、二阶矩(SOM)燃烧模型和欧拉拉氏两相流模型,对乙醇-空气液雾燃烧进行了大涡模拟(LES)。瞬态结果显示:在火焰的高温区域,旋涡强度较大;在高温区边缘附近存在的拟序结构有脱落的趋势。在燃烧装置的燃料进口附近,近喷嘴中心区域,大量液滴聚集在条状湍流拟序结构的周围。LES模拟的统计结果给出的温度分布与实验结果吻合较好。说明SOM燃烧模型适用于液雾两相湍流燃烧研究,计算结果经过和实验数据对比发现,LES-SOM燃烧模型优于RANS-PDF及LES-FA计算结果。数值计算结果与实验结果的误差主要是由于采用统观一步反应机理引起的,表明燃烧模型还有待进一步改进。
Large-eddy simulation (LES) was performed on ethanol-air liquid mist combustion using sub-grid kinetic energy (k equation) stress model, second order moment (SOM) combustion model and Euler’s two-phase flow model. The transient results show that the vortex intensity is high in the high temperature region of the flame, and there is a tendency for the ordered structure existing near the edge of the high temperature region to fall off. In the vicinity of the fuel inlet of the combustion device, near the center of the nozzle, a large number of droplets gather around the stripe-like turbulence simulation structure. The temperature distribution given by the LES simulation results is in good agreement with the experimental results. The results show that the SOM combustion model is suitable for the two-phase turbulent combustion of liquid mist. Comparing the results with the experimental data, it is found that the LES-SOM combustion model is superior to the results of RANS-PDF and LES-FA. The error between the numerical calculation and experimental results is mainly due to the one-step reaction mechanism, which indicates that the combustion model needs to be further improved.