文章使用超大涡模拟(very large eddy simulation,VLES)方法耦合离散相模型对液体射流在横向气流中雾化过程进行模拟,并对比多套网格尺度下不同湍流模型的预测结果。结果表明,VLES方法能够较为准确地预测横向射流的基本形态及参数。相...文章使用超大涡模拟(very large eddy simulation,VLES)方法耦合离散相模型对液体射流在横向气流中雾化过程进行模拟,并对比多套网格尺度下不同湍流模型的预测结果。结果表明,VLES方法能够较为准确地预测横向射流的基本形态及参数。相对其他湍流模型在不同网格尺度下模拟结果波动明显,VLES方法对网格尺寸敏感度较低,并在模拟流场流动细节方面能够捕捉到更多液柱破碎的表面结构,较雷诺平均(Reynolds-averaged Navier-Stokes,RANS)模拟方法有显著优势,且计算量比大涡模拟(large eddy simulation,LES)方法大大降低,在工程实际运用中是一种颇具潜力的数值研究方法。展开更多
This article studies numerically a familiar important phenomenon in spray combustion which is deformation and breakup of liquid drops in gas flow. The SIMPLER method is used to solve the two-dimensional （2D） unstead...This article studies numerically a familiar important phenomenon in spray combustion which is deformation and breakup of liquid drops in gas flow. The SIMPLER method is used to solve the two-dimensional （2D） unsteady axisymmetric Navier-Stokes equations for both the drop and the ambient gas flow. The level set method is applied to capturing the liquid/gas interface. Through calculation are obtained four typical breakup modes--oscillation, bag breakup, sheet stripping breakup and shear breakup governed by four non-dimensional numbers which are gas Weber number （Weg）, liquid Reynolds number （Rel）, gas Reynolds number （Reg） and density ratio （γ）. Their effects upon each mode are analyzed. The results indicate that among the four numbers, Weg is of the highest importance with Rel, Reg and γfollowing up. By widening the range of the density ratio up to 1 000, the breakup mode is discovered to be so complicated that a new one called multimode breakup mode turns up. This mode contains the shearing breakup and piercing breakup, which successively happen. The calculation results agree well with what is observed from the experiments.展开更多
文摘This article studies numerically a familiar important phenomenon in spray combustion which is deformation and breakup of liquid drops in gas flow. The SIMPLER method is used to solve the two-dimensional （2D） unsteady axisymmetric Navier-Stokes equations for both the drop and the ambient gas flow. The level set method is applied to capturing the liquid/gas interface. Through calculation are obtained four typical breakup modes--oscillation, bag breakup, sheet stripping breakup and shear breakup governed by four non-dimensional numbers which are gas Weber number （Weg）, liquid Reynolds number （Rel）, gas Reynolds number （Reg） and density ratio （γ）. Their effects upon each mode are analyzed. The results indicate that among the four numbers, Weg is of the highest importance with Rel, Reg and γfollowing up. By widening the range of the density ratio up to 1 000, the breakup mode is discovered to be so complicated that a new one called multimode breakup mode turns up. This mode contains the shearing breakup and piercing breakup, which successively happen. The calculation results agree well with what is observed from the experiments.
