Large eddy simulation of turbulent spray combustion
Large eddy simulation of turbulent spray combustion
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DOI：
10.1016/j.combustflame.2014.07.029
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发表时间：
2015-02
影响因子：
4.4
通讯作者：
Abolfazl Irannejad;A. Banaeizadeh;F. Jaberi
中科院分区：
文献类型：
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作者：
Abolfazl Irannejad;A. Banaeizadeh;F. Jaberi
采用两相过滤质量密度函数（FMDF）方法，采用简单（全局）和复杂（骨架）化学动力学机理对高速蒸发和燃烧的正庚烷喷雾进行了大涡模拟。用高阶欧拉有限差分法求解过滤后的可压缩Navier-Stokes方程，得到了已分解的流体速度场和压力场。液体喷雾场和气体标量场（温度和物质质量分数）均由拉格朗日随机模型求得。采用平行原位自适应制表法（ISAT）加快了化学计算速度。欧拉场和拉格朗日场之间存在双向相互作用。在不同的气体温度和氧气浓度下，对有燃烧和无燃烧的蒸发喷雾的模拟结果表明，两相LES/FMDF的结果与已有的实验数据一致。随着氧浓度的降低和/或环境气体温度的升高，由于喷雾引起的湍流和混合的变化，喷雾控制的火焰倾向于从扩散火焰结构向预混火焰结构移动。在较低的气体温度下，由于反应速度较慢，湍流-化学相互作用较强，LES/FMDF的点火延迟结果对化学动力学模型更敏感。起飞长度对动力学不太敏感。
The two-phase filtered mass density function (FMDF) method is employed for large eddy simulation (LES) of high speed evaporating and combusting n-heptane sprays using simple (global) and complex (skeletal) chemical kinetic mechanisms. The resolved fluid velocity and pressure fields are obtained by solving the filtered compressible Navier–Stokes equations with high-order Eulerian finite difference methods. The liquid spray and gas scalar (temperature and species mass fractions) fields are both obtained by Lagrangian stochastic models. The chemistry calculation is accelerated by incorporating the parallel in situ adaptive tabulation (ISAT) method. There are two-way interactions among Eulerian and Lagrangian fields. Simulations of evaporating sprays with and without combustion indicate that the two-phase LES/FMDF results are consistent and compare well with the available experimental data at different gas temperatures and oxygen concentrations. The spray controlled flame tends to move away from a diffusion flame structure toward a premixed one as the oxygen concentration decreases and/or the ambient gas temperature increases because of changes in spray-induced turbulence and mixing. The LES/FMDF results for ignition delay show more sensitivity to the chemical kinetic model at lower gas temperatures due to slower reaction and stronger turbulence–chemistry interactions. The liftoff length is less sensitive to the kinetics.