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为加深对气液两相湍流燃烧现象的认知,检测火焰面模型在液雾燃烧中的适用性,本文在欧拉-拉格朗日架构下使用火焰面/反应进度变量模型(FPV)数值模拟了乙醇-空气稀液雾值班火焰。欧拉坐标系下的气相湍流场使用大涡模拟方法模拟,离散液相则使用拉格朗日颗粒轨道模型进行描述,考虑了相间质量、动量、能量交换。燃烧模型中采用碳元素定义混合物分数,在混合物分数方程源项中体现液相对燃烧模型的影响。模拟得到的气相温度分布和液相统计值均和实验数据较好吻合,验证了该燃烧模型对稀液雾扩散类型火焰的适用性。分析瞬时图发现,该稀液雾火焰的最高燃烧温度往往位于当量混合物分数附近,在出口下游20倍直径处火焰完全点着,此处上游FPV模型能给出局部点火熄火现象。蒸发作用在剪切层和点火区域较强,而液滴和火焰作用较弱,单一液滴很少被火焰包围。
In order to deepen the cognition of turbulent combustion in gas-liquid two-phase and detect the applicability of flame surface model in liquid-vapor combustion, this paper uses the Flame / Reaction Progress Variable Model (FPV) under the Euler-Lagrange framework Simulated ethanol - air thin mist on duty flame. The gas-phase turbulence field in the Euler coordinate system was simulated using a large-eddy simulation method, while the discrete liquid phase was described using the Lagrangian particle orbital model, taking into account interphase mass, momentum and energy exchange. The carbon content in the combustion model is used to define the mixture fraction, which reflects the effect of liquid phase on the combustion model in the source term of the mixture fractional equation. The obtained gas phase temperature distribution and the statistics of the liquid phase are in good agreement with the experimental data, and the applicability of the combustion model to the flame of the diffusing type of thin mist is verified. Analysis of the instantaneous graph shows that the maximum combustion temperature of the mist of the dilute liquid is often located near the equivalent mixture fraction and the flame is completely lit at a diameter of 20 times downstream of the exit where the upstream FPV model gives a local ignition flameout. Evaporation in the shear layer and the ignition area is stronger, and the role of droplets and flame is weak, a single droplet is rarely surrounded by a flame.