MODELING OF CLUSTER AND ITS APPLICATION IN EMMS DRAG MODEL FOR HETEROGENEOUS GAS-SOLID FLOWS

摘要

Cluster sub-models are developed and combined with the Energy Minimization Multi-Scale (EMMS) method drag model to improve drag predictions for heterogeneous gas-solid flows.Theoretical cluster sub-models are developed to relate the cluster parameters with the solid volume fraction.The cluster sub-models are validated using experimental data in the literature.Drag coefficients predicted by the modified EMMS model with cluster sub-models are much lower than previous EMMS results and agree well with the experiment-based model.The drag coefficients are minimum between solid volume fractions of 0.1 and 0.15 and gradually increase to that for uniform flow from the minimum towards both sides.The modified EMMS drag model is further verified by CFD simulations of gas-solid flows in a CFB riser by coupling with the two-fluid model.The verification of the modified EMMS model once again demonstrates the applicability of the cluster sub-models.