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曳力模型对流态化模拟的准确性起着决定性作用。现有的非均匀曳力模型能否普遍适用于各种流态化操作条件还缺乏深入研究。本文基于多尺度最小能量理论和对流态化过程中介尺度结构特性的深入认识,提出了新的非均匀曳力模型(QC-EMMS模型),并开展了模型的流动自适应性研究。通过引入非均匀因子Ψ,表征颗粒团特性参数(固含率)随操作条件的变化,引入基于整体气固滑移速度的状态雷诺数,表征随操作条件的变化而呈现不同非均匀度的流化状态,建立了宏观操作参数与局部曳力和颗粒团特性之间的关系,实现了模型的流动自适应性。经实际工况验证,该曳力模型具有较高的计算精度和良好的网格无关性。
The drag model plays a decisive role in the accuracy of the fluidization simulation. Whether the existing non-uniform drag model can be universally applicable to various fluidized operating conditions is still lack of further study. Based on the multi-scale minimum energy theory and in-depth understanding of the mesoscale structural properties of the fluidized process, a new non-uniform drag model (QC-EMMS model) is proposed and its flow adaptability is studied. By introducing the non-uniform factor Ψ, characterizing the variation of the characteristic parameters (solid content) of the pellet with the operating conditions, a state Reynolds number based on the overall gas-solid slip velocity is introduced to characterize the flow with different nonuniformities as the operating conditions change The relationship between the macro-operation parameters and the local drag and particle properties is established, and the flow adaptability of the model is achieved. The actual working conditions verify that the drag model has high computational accuracy and good grid independence.