Abstract:

In gas-solid fluidized beds, spatiotemporal mutiscale structures caused by the intrinsic instability of gas-solid flows have a large impact on the interphase interaction. Predicting and controlling the hydrodynamic characteristics in fluidization remain a difficult task. To overcome this challenge, a constitution of the interphase interaction considering the effect of the inhomogeneous structures should be built. As a dominating factor in determining hydrodynamic characteristics of fluidization, the constitution of the mesoscale drag force attract increased attention in recent years. This paper briefly describes the effect of the inhomogeneous structures on the drag force, starting with the mechanisms of the generation and evolution of these structures. The filtered drag models are summarized from the perspective of modeling process. The developments of these models including improving the accuracy and effectivity, enhancing the generality for different material properties and flow regimes, and considering more physical mechanisms in actual systems have been reviewed. According to these studies, further work should be done to improve the generality and consider more physical mechanisms. Combining rational modeling of structural evolution mechanism and giving full play to the advantages of machine learning data analysis and processing is the key to the further development of drag modeling.

Key words: two-phase flow, fluidization, mesoscale structure, drag, filtered model

摘要：

气固流化床中，介于颗粒与宏观尺度间的复杂的时空多尺度结构（介尺度结构）将完全改变气固相间作用规律，加大了流态化系统调控及预测的难度。为此，需要构建考虑结构影响的相间本构关系。其中，曳力作为影响流态化动力学特征的主导因素，对其研究尤为重要。从结构产生演化的机制出发，概述结构影响曳力的机理，以模型构建流程的角度对结构和过滤两类模型进行总结，并重点综述过滤模型构建在提升准确性、有效性、通用性和考虑更多物理机制方面的最新进展。研究表明：提升模型通用性和考虑真实系统中更丰富的物理机制仍是建模中亟待解决的问题，结合结构演化机制理性建模和充分发挥机器学习数据分析处理优势或是曳力建模进一步发展的关键。

关键词: 两相流, 流态化, 介尺度结构, 曳力, 过滤模型