甲醇蒸发喷雾的非线性大涡模拟

Non-linear Large Eddy Simulation of Methanol Vaporizing Spray

在使用拉格朗日-欧拉方法模拟柴油喷雾的框架下,Kelvin-Helmholtz&Rayleigh-Taylor(KH-RT)破碎模型是使用最广泛的预测喷雾液滴一次和二次破碎过程的模型。破碎产生的液滴喷雾特性由燃料性质(密度、粘性、表面张力等)及数个可以调整的KH-RT模型参数(B1、C子、CRT等)决定。本研究的目的是在使用梯度结构模型的甲醇蒸发喷雾大涡模拟中探究KH-RT模型参数对模拟结果的影响。研究表明,模型参数的调整对甲醇蒸发喷雾的贯穿距有一定影响,对喷雾的质量分数及索特平均直径影响较大。通过与实验的对照,本研究给出了能够准确地模拟甲醇蒸发喷雾的模型参数范围(其中B1可取80,CRT可取0.4-0.8,C子可取9)。但也揭示了KH-RT模型的准确性过于依赖模型参数数值的缺陷。

The Kelvin-Helmholtz Rayleigh-Taylor(KH-RT)breakup model is a commonly used model in predicting primary and secondary atomization and breakup processes in Lagrangian-Eulerian Diesel spray simulations.Spray characteristics predicted using this model are dependent on several parameters.The parameters include fuel physical properties,such as density,viscosity,and surface tension,and a number of adjustable model constants.The purpose of this study is to investigate the effects of these parameters on predicting methanol vaporizing spray using large-eddy simulation with the mixed gradient-type structural subgrid-scale stress model.We found that the penetration prediction is not very sensitive to the KH-RT constants,however,the predictions of the mass fraction of methanol vapor,and sauter mean diameter(SMD)of the spray are sensitive to the KH time constant,B1,the RT time constant,Cτ,and the RT size constant,CRT.The computational investigations in the study provide us with a range of the KH-RT model constants(which is B1:80,CRT:0.4-0.8,Cτ:9)for accurately simulating methanol spray,and also reveal the limitations of the KH-RT model.