Numerical Modeling of Phase Change Phenomena in Particulate Flows

颗粒流中相变现象的数值模拟

• 批准号: RGPIN-2014-06008
• 负责人: Nikrityuk, Petr
• 金额: $ 1.82万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567528
• 关键词: Numerical; Modeling; Phase; Change; Phenomena

The main objective of this research project consists in gaining a fundamental understanding of the behaviour of phase-change phenomena in particulate flows under the influence of gravity. This understanding will help to design novel technologies in metallurgical and applied materials engineering, e.g. such as casting high-temperature resistant alloys, which go on to help save energy and protect the environment. It is well known that the classical multiphase model (Euler-Euler) often fails to predict a gravity-driven solidification of multicomponent materials. In view of this, an alternative approach such as the Euler-Lagrange model can be used to adequately forecast solidification/melting processes occurring during casting of metal alloys. In this approach the motion of the solid particles is treated individually using Newton’s law of motion. So far, however, Euler-Lagrange-based models for phase-change-related problems have met with little attention in the literature, even though they might provide great potential for reliable numerical simulations of such complex flows including phase-change effects. The proposed research focuses on the following aims: 1. Development and validation of an Euler-Lagrange model for particulate flows with phase-change effects, where the particles undergoing the phase change are modelled using the three-dimensional (3D) discrete element model (DEM) formulated in Lagrangian space, while the liquid phase is simulated using a computational fluid dynamics (CFD)-based model formulated in Eulerian space. 2. Development of subgrid models for interfacial heat and mass transfer applied to moving particles undergoing phase change. These models serve as a coupling between DEM and CFD models. 3. Validation of numerical models against experiments carried out for a defined reference system under well-defined boundary conditions: this is the melting of ‘ice’ particles settling in water. Here the Direct Numerical Simulation (DNS) of existing ‘ice’ experiments are planned to validate subgrid models for interfacial heat and mass transfer between solid and liquid phases. 4. Investigation of the phase distribution and flow anomalies in the liquid phase, such as the interplay between buoyancy and Archimedes forces in dependence on the volume fraction of solid. The vision followed by the project in the long-term consists in the development of an Euler-Lagrange model for a numerical simulation of binary alloy (AlSi) columnar-equiaxed solidification. To reach this goal it is necessary to understand the ruling principles of the melting (solidification) of solid particles moving in the liquid phase. Recent experimental studies published in the literature show that special attention should be paid to explaining anomalies relating to interaction between the gravity-induced forces. The short-term goal of this project is to develop and validate a subgrid semiempirical model for the behaviour of solidifying/melting particles depending on specific nondimensional numbers such as the Archimedes number (Ar), the Grashof number (Gr) and the Stefan number (Ste). The project's success will help advance knowledge on the fundamentals of solidification and on the accurate forecast of multicomponent material properties. The practical significance of this research consists in the development and validation of simplified models describing the interfacial heat and mass transfer between solid and liquid phases undergoing phase changes. The models developed in this project will contribute to a significant improvement in the computational software used in the industry to improve processes, reducing the production costs of advanced materials in Canada.

该研究项目的主要目标是对重力影响下颗粒流中相变现象的行为有一个基本的了解。这种理解将有助于设计冶金和应用材料工程中的新技术，例如铸造耐高温合金，从而有助于节约能源和保护环境。众所周知，经典的多相模型（欧拉-欧拉）往往不能预测多组分材料的重力驱动凝固。鉴于此，可以使用诸如欧拉-拉格朗日模型的替代方法来充分预测在金属合金的铸造期间发生的凝固/熔化过程。在这种方法中，固体颗粒的运动是单独使用牛顿运动定律来处理的。然而，到目前为止，欧拉-拉格朗日为基础的模型相变相关的问题，在文献中很少得到关注，即使他们可能提供了可靠的数值模拟这种复杂的流动，包括相变效应的巨大潜力。本研究的主要目的是：1.发展和验证颗粒流的欧拉-拉格朗日模型与相变效应，其中的颗粒进行相变建模使用的三维（3D）离散元模型（DEM）制定拉格朗日空间，而液相模拟使用计算流体动力学（CFD）为基础的模型制定在欧拉空间。2.相变运动颗粒界面传热传质亚网格模型的发展。这些模型作为DEM和CFD模型之间的耦合。3.在明确定义的边界条件下，数值模型与定义的参考系统进行的实验验证：这是在水中沉降的“冰”颗粒的融化。在这里，现有的“冰”实验的直接数值模拟（DNS）计划，以验证亚网格模型的界面之间的固体和液体相的热量和质量传递。4.研究液相中的相分布和流动异常，例如浮力和阿基米德力之间的相互作用与固体体积分数的关系。该项目的长期愿景包括开发用于二元合金（AlSi）柱状等轴凝固数值模拟的Euler-Lagrange模型。为了达到这个目标，有必要了解在液相中移动的固体颗粒的熔化（固化）的主要原理。最近发表在文献中的实验研究表明，应特别注意解释与重力感应力之间的相互作用有关的异常。该项目的短期目标是开发和验证一个亚网格半经验模型，用于凝固/熔化颗粒的行为，该模型取决于特定的无量纲数，如阿基米德数（Ar），Grashof数（Gr）和Stefan数（Ste）。该项目的成功将有助于提高对凝固基本原理和多组分材料性能准确预测的认识。本研究的实际意义在于简化模型的开发和验证，描述了发生相变的固液两相之间的界面传热和传质。该项目中开发的模型将有助于显著改进工业中使用的计算软件，以改善工艺，降低加拿大先进材料的生产成本。