Modeling Phase Transition during Primary Breakup of Turbulent Liquid Jets and Sheets

模拟湍流液体射流和片材初级破碎过程中的相变

• 批准号: 21459908
• 负责人: Professor Dr.-Ing. Norbert Peters (†)
• 金额: --
• 依托单位: Laboratoire de Modélisation en Mécanique
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/21459908?language=en
• 关键词: Modeling; Phase; Transition; during; Primary

We consider a Large Surface Structure (LSS) model for the numerical simulation of phase transition during primary breakup of turbulent liquid jets or sheets in three dimensions. To develop and verify the LSS model, Direct Numerical Simulations (DNS) studies of the phase transition effects during primary breakup will be performed. To this end the Level Set/Vortex Sheet (LSVS) method will be extended to include the effects of phase change. Two scenarios representative of engineering applications and consistent with the Large Eddy Simulation (LES) approach of the LSS model will be analyzed: a) the phase change velocity is a constant on the subgrid scale and b) the phase change velocity on the subgrid scale is a function of local subgrid turbulent transport and shear.The first scenario represents a typical LES modeling approach, in that the subgrid phase change velocity is a function of resolved scale quantities only. Its local subgrid PDF is thus a delta function. In the second scenario, local subgrid variations of the phase change velocity due to fluctuations in the subgrid turbulent transport and shear are taken into account. Should these prove to yield significant different DNS results than the first scenario, the use of a non-delta function subgrid PDF of the phase change velocity, dependent on the PDFs, or moments, of transport and shear are required for the LSS model closure.In order to achieve sufficient accuracy for the DNS studies, the partial differential equations will be solved numerically using either a Discontinuous Galerkin method or a Refined Level Set Grid approach employing high-order WENO schemes. Two complimentary strategies will be employed to resolve the wide range of length scales present in the problem. Mesh refinement in the region close to the phase interface ensures the handling of structures of size about one order of magnitude smaller than the Kolmogorov scale. Structures of this or smaller size are then transferred into a Lagrangian spray model. While a localized narrow band approach will ensure that the computational cost remains feasible, parallelization of the whole algorithm will allow access to the high computational power of modern parallel computer systems in order to perform extensive DNS calculations.Practical usefulness of the final LSS method will imply a statistical approach. Turbulence modeling requires the development of appropriate interface based filters and modeling of the unclosed subgrid terms. In the two phase transition cases described above, the modeling strategies developed for premixed turbulent combustion can be applied directly to derive these closure models. The generated LSVS DNS data will be subjected to the same filters in order to validate the closure assumptions. Furthermore, the LSVS method and the final LSS model will be validated using both numerical data obtained by different numerical approaches, specifically the VOF calculations of the French partner, as well as experimental data obtained in the research group and as reported in the literature.

本文采用大表面结构（LSS）模型对三维湍流液体射流或片层的初始破碎过程进行了数值模拟。为了开发和验证LSS模型，将对初级破碎过程中的相变效应进行直接数值模拟（DNS）研究。为此，水平集/涡面（LSVS）方法将被扩展到包括相变的影响。将分析代表工程应用并与LSS模型的大涡模拟（LES）方法一致的两种方案：a）相变速度在亚网格尺度上是常数，B）相变速度在亚网格尺度上是局部亚网格湍流输送和剪切的函数。第一种情况代表典型的LES模拟方法，因为亚网格相变速度仅仅是分辨尺度量的函数。因此，其局部子网格PDF是δ函数。在第二种情况下，当地的亚网格变化的相变速度，由于在亚网格湍流传输和剪切的波动被考虑在内。如果这些被证明产生与第一种情况明显不同的DNS结果，则需要使用相变速度的非δ函数次网格PDF，其取决于PDF或力矩，运输和剪切，用于LSS模型闭合。为了实现DNS研究的足够精度，偏微分方程将使用不连续Galerkin方法或采用高阶韦诺格式的精化水平集网格方法数值求解。两个互补的战略将被用来解决目前的问题中的长度尺度范围广泛。网格细化的区域接近相界面，确保处理的结构的大小约一个数量级小于柯尔莫哥洛夫尺度。然后将这种或更小尺寸的结构转移到拉格朗日喷雾模型中。虽然一个本地化的窄带方法将确保计算成本仍然可行，整个算法的并行化将允许访问现代并行计算机系统的高计算能力，以执行广泛的DNS calculation.Practical有用的最终LSS方法将意味着一个统计方法。湍流建模需要开发适当的基于界面的过滤器和未闭合子网格项的建模。在上述两种相变情况下，为预混湍流燃烧开发的建模策略可以直接应用于导出这些封闭模型。生成的LSVS DNS数据将经过相同的过滤器，以验证闭包假设。此外，LSVS方法和最终LSS模型将使用通过不同数值方法获得的数值数据进行验证，特别是法国合作伙伴的VOF计算，以及研究小组获得的实验数据和文献中报道的数据。