A Comparison of Volume of Fluid and Euler-Euler Approaches in Computational Fluid Dynamics Modeling of Two-Phase Flows With a Sharp Interface
A Comparison of Volume of Fluid and Euler-Euler Approaches in Computational Fluid Dynamics Modeling of Two-Phase Flows With a Sharp Interface
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锐界面两相流计算流体动力学建模中流体体积法和欧拉-欧拉法的比较
DOI：
10.1115/1.4051554
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Bertolotti L
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文献类型：
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作者：
Bertolotti L
在航空发动机中，重要的是预测不同部件（如轴承室或齿轮箱）中的剪切流行为。在轴承腔中，波纹膜的厚度分布得到了很好的研究，因为两相流仍然很难根据情况进行预测。实验研究仍然非常昂贵，并且计算流体动力学（CFD）仍然难以预测两相流，特别是当两相之间的尖锐界面必须建模时。采用CFD方法对发动机不同工况下的油膜厚度分布和界面速度进行了预测。目前，雷诺平均纳维尔-斯托克斯（RANS）计算流体动力学使用湍流阻尼的半经验方法，这是不准确的波浪膜，从而影响轴承室和齿轮箱的建模。为了改进大涡模拟（LES）方法的RANS模型，本文研究了两相流模型的VOF和Euler-Euler方法。流体体积（VOF）方法假设两相的动量方程为一组，体积分数除界面区域外均为1或0。VOF的另一种方法是剪切流的欧拉-欧拉方法。这种方法假设每个相都有一组动量方程，但有一个共享的压力场。在这项研究中，VOF和欧拉-欧拉方法进行了比较，使用LES与CFD代码OpenFOAM v6。该案例研究是基于实验工作调查分层流在水平通道，将进一步详细的文件。在这项研究中，一个简化的三维周期性通道填充有两个不同的阶段：空气和水。研究了一种流动状态，其中流动充分发展，水相具有比空气相小得多的速度，以获得剪切流。数值结果与文献中的实验测量进行了比较。在OpenFOAM中，用于研究的VOF求解器是interFoam，使用的欧拉-欧拉求解器是reacting-MultiphaseEulerFoam。速度剖面，剪切应力剖面和动能剖面进行了比较与实验测量的两个流动求解器的评估。还提供了涡量图，以支持欧拉-欧拉和VOF方法之间的比较，以及适当的涡识别方法。
In aero-engines, it is important to predict the behavior of shear flows in the different parts such as bearing chambers or gearboxes. In bearing chambers, the thickness distribution of wavy films is well studied as two-phase flows are still very hard to predict depending on the case. Experimental studies remain very expensive to carry out and Computational Fluid Dynamics (CFD) still struggles with two-phase flow prediction especially when a sharp interface between the two phases must be modelled. CFD is used to predict the oil film thickness distribution and interface velocity at different engine operating conditions. Currently Reynold-Averaged Navier-Stokes (RANS) CFD uses a semi-empirical method of turbulence damping, which is inaccurate for wavy films and so impacts the modelling of bearing chambers and gearboxes. With the objective of improving RANS models from Large Eddy Simulation (LES) methods, the Volume of Fluid (VOF) and Euler-Euler methods for two-phase flow modelling are investigated in this study. The Volume of Fluid (VOF) approach assumes a single set of momentum equations for the two phases and volume fractions are 1 or 0 everywhere except in the interface region. An alternative to VOF, is the Euler-Euler method with interface sharpening for shear flows. This approach assumes one set of momentum equations per phase but a shared field of pressure. The VOF and Euler-Euler approaches are compared in this study using LES with the CFD code OpenFOAM v6. The case study is based on experimental work investigating stratified flow in a horizontal channel that will be further detailed in the paper. In this study, a simplified 3D periodic channel filled with two distinct phases: air and water is used. A flow regime is studied in which flows are fully developed and the water phase has a much smaller velocity than the air phase in order to obtain a shear flow. Numerical results are compared with experimental measurements from the literature. With OpenFOAM, the VOF solver used for the study is interFoam and the Euler-Euler solver used is reacting-MultiphaseEulerFoam. Velocity profiles, shear-stress profiles and kinetic energy profiles are compared with experimental measurements for the assessment of the two flow solvers. Maps of vorticity magnitude are also provided to support the comparisons between the Euler-Euler and the VOF approaches as well as an appropriate vortex identification method.