Large-eddy simulation of shear flows and high-speed vaporizing liquid fuel sprays
Large-eddy simulation of shear flows and high-speed vaporizing liquid fuel sprays
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DOI：
10.1016/j.compfluid.2014.09.014
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发表时间：
2014-12
影响因子：
2.8
通讯作者：
Chi-Wei Tsang;M. Trujillo;C. Rutland
中科院分区：
文献类型：
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作者：
Chi-Wei Tsang;M. Trujillo;C. Rutland
用大涡模拟模型对高速蒸发液体喷雾进行了试验。对三种模型进行了检验：标准Smagorinsky模型、一方程粘性模型和动态结构模型。对模型进行了槽道流动、平面气体喷射和柴油喷雾试验。这项工作的目的是评估可用于直接喷油内燃机建模的大涡模拟模型的准确性和适用性，其中中等网格分辨率是标准的。通道流动和气体喷射的结果为影响液体喷雾模拟性能的模型能力提供了更多的洞察力。采用等高线图像对模拟结果进行了分析，以比较流动的总体结构，并用实验数据比较了总体平均速度分布、均方根速度分布、液、汽穿透以及质量分数分布。结果表明，这三种模型在渠道流中的表现相似，与平均流速结果吻合较好，有些模型的均方根值低于预测值。动态结构模型的RMS值在壁面附近略陡峭，更接近实验数据。在射流中，一方程模型的结果在速度量级的图像中显示了意想不到的流动结构。平均速度分布与所有三个模型的数据都匹配得很好。但中心线速度衰减率和均方根速度径向分布与动态结构模型的结果吻合得更好。在液体喷雾中，一方程模型与实验数据相比表现较差。在这些比较中，Smagorinsky模型给出了合理的结果，而动力结构模型给出了非常好的结果。总体来说，动态结构模型是直喷式发动机模拟的三种模型中最好的。
Large eddy simulation models are tested for use on high speed evaporating liquid sprays. Three models are tested: standard Smagorinsky, a one-equation viscosity based model, and the dynamic structure model. The models are tested using channel flow, planar gas jet, and a diesel spray. The motivation of the work is to evaluate the accuracy and suitability of LES models that can be used for internal combustion engine modeling with direct injection of fuel in which moderate mesh resolution is the norm. Results from the channel flow and the gas jet provide additional insight into model capabilities that impact performance in liquid spray simulations. Simulation results were analyzed using contour images to compare the general structure of the flows, and experimental data for comparison of ensemble averaged mean and rms velocity profiles, liquid and vapor penetration, and mass fraction profiles. Results show that all three models perform similarly in the channel flow with good matches on the mean velocity results and some under prediction of rms values. The dynamic structure model showed slightly steeper near wall rms values closer to the experimental data. In the jet flow, the one-equation model results showed unexpected flow structures in images of the velocity magnitude. Mean velocity profiles matched data well for all three models. But centerline velocity decay rates and rms velocity radial profiles matched data much better for the dynamic structure model results. In the liquid spray the one-equation model performed poorly when compared to experimental data. The Smagorinsky model gave reasonable results and the dynamic structure model gave very good results in these comparisons. The overall conclusion is that the dynamic structure model is the best of the three models for direct injection engine simulations.