Progress-variable approach for large-eddy simulation of turbulent combustion
Progress-variable approach for large-eddy simulation of turbulent combustion
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发表时间：
2001
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通讯作者：
C. Pierce
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作者：
C. Pierce
发展了一种新的化学模拟方法，用于湍流反应流的大涡模拟。本研究采用间接映射方法，将所有详细的化学过程映射到一个简化的跟踪标量系统中，而不是求解典型化学机制中所有众多物种的输运方程，并对未闭合的化学源项进行建模。目前，只有两个这样的标量被认为是：一个混合物分数变量，跟踪燃料和氧化剂的混合，和一个进度变量，跟踪全球范围内的反应的本地混合物。映射函数，它描述了所有的详细的化学过程相对于跟踪变量，确定通过求解准稳态扩散反应方程与复杂的化学动力学和多组分质量扩散。新模型的性能进行了比较，快速化学和稳定的火焰面模型预测的速度，物种浓度和温度场的甲烷燃料同轴射流燃烧室的实验数据是可用的。的进展变量的方法是能够捕捉到的不稳定的，在实验中观察到的火焰动力学，并获得良好的协议与实验数据和显着优于快速化学和稳定的小火焰模型，这两个预测附着火焰。
A new approach to chemistry modeling for large eddy simulation of turbulent reacting flows is developed. Instead of solving transport equations for all of the numerous species in a typical chemical mechanism and modeling the unclosed chemical source terms, the present study adopts an indirect mapping approach, whereby all of the detailed chemical processes are mapped to a reduced system of tracking scalars. Presently, only two such scalars are considered: a mixture fraction variable, which tracks the mixing of fuel and oxidizer, and a progress variable, which tracks the global extent-of-reaction of the local mixture. The mapping functions, which describe all of the detailed chemical processes with respect to the tracking variables, are determined by solving quasi-steady diffusion-reaction equations with complex chemical kinetics and multicomponent mass diffusion. The performance of the new model is compared to fast chemistry and steady flamelet models for predicting velocity, species concentration, and temperature fields in a methane-fueled coaxial jet combustor for which experimental data are available. The progress-variable approach is able to capture the unsteady, lifted flame dynamics observed in the experiment, and to obtain good agreement with the experimental data and significantly outperform the fast chemistry and steady flamelet models, which both predict an attached flame.