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对雾化过程的直接数值模拟需要巨大的计算资源和时间,而工程中的简化模型则经常会给出错误的结果。因此,可以折中地采用一种混合方法,即在不同尺度上采用不同的模型。提出了一种雾化过程的欧拉——拉格朗日耦合算法。较大的液团采用VOF法直接求解,与网格尺度相当或更小的液滴则采用双向耦合的拉格朗日粒子法进行追踪。而该方法要求粒子的体积小于网格体积的10%,为此又提出了一种虚网格粒子追踪法。由于湍流结构对雾化过程的影响很大,故湍流采用了大涡模拟模型。采用多个算例对开发的算法进行了验证,并对部分关键参数的影响进行了深入研究。采用新算法对两股撞击射流的雾化过程进行了研究,瞬态和统计结果均表明新算法能够给出良好的预测。
Direct numerical simulation of atomization requires tremendous computational resources and time, while simplified models in engineering often give erroneous results. Therefore, a hybrid approach can be used in a compromise, using different models at different scales. An Eulerian-Lagrangian coupling algorithm for atomization is proposed. Larger fluid groups were solved directly by the VOF method, and droplets of comparable or smaller size to the mesh were traced using a Lagrange particle method that is bidirectionally coupled. However, this method requires that the volume of the particles is less than 10% of the volume of the grid. For this reason, a method of tracking the particles by the virtual grid is proposed. Due to the large influence of turbulent structure on the atomization process, a large eddy simulation model is adopted for turbulence. Several examples are used to validate the developed algorithm, and the influence of some key parameters is deeply studied. A new algorithm is used to study the atomization process of two impinging jets. The transient and statistical results show that the new algorithm can give a good prediction.