CFD-PBM simulation of gas–solid bubbling flow with structure-dependent drag coefficients
CFD-PBM simulation of gas–solid bubbling flow with structure-dependent drag coefficients
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DOI：
10.1016/j.cej.2020.127503
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发表时间：
2020-11
影响因子：
15.1
通讯作者：
Sha Hu;Xinhua Liu
中科院分区：
文献类型：
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作者：
Sha Hu;Xinhua Liu
气泡合并和破裂产生的气泡尺寸分布对气固鼓泡流化床中的有效相间阻力具有显着影响，但在之前的粗网格模拟中并未考虑到这一点。本研究采用群体平衡模型（PBM）来描述气固鼓泡流化过程中气泡的动态演化，其中考虑气泡速度差、尾流捕获和气泡不稳定性的影响，推导出聚结和破裂核。开发了一种改进的能量最小化多尺度（EMMS）冒泡模型来计算亚网格尺度的有效相间阻力。通过将 PBM 和 EMMS 阻力纳入欧拉连续体模型，进一步提出了 CFD-PBM-EMMS 耦合方案来预测鼓泡流化床的流体动力学。通过模拟结果与实验数据的比较验证了该方案的有效性。以可接受的计算成本合理地预测了床膨胀特性和固体速度的横向分布。测量的气泡尺寸分布和模拟的气泡尺寸分布之间也取得了令人满意的一致性。所提出的子网格阻力模型和耦合模拟方案可以帮助捕获气固鼓泡流化床流体动力学的显着特征。
Bubble size distribution resulted from bubble coalescence and breakup has significant effects on the effective interphase drag in gas–solid bubbling fluidized beds, which was however not taken into account in previous coarse-grid simulations. In this study, the population balance model (PBM) was used to describe the dynamic evolution of gas bubbles in gas–solid bubbling fluidization, wherein the coalescence and breakup kernels were derived by considering the effects of bubble velocity difference, wake capture and bubble instability. An improved energy-minimization multi-scale (EMMS) bubbling model was developed to calculate the effective interphase drag in sub-grid scale. By incorporating both the PBM and the EMMS drag into an Eulerian continuum model, a CFD-PBM-EMMS coupled scheme was further proposed to predict the hydrodynamics of bubbling fluidized beds. The scheme was validated through comparison of simulated results with experimental data. The bed expansion characteristics and the lateral profiles of solids velocities were reasonably predicted at acceptable computational cost. Satisfactory agreement was also achieved between the measured and simulated bubble size distributions. The proposed sub-grid drag model and coupled simulation scheme can facilitate capturing the salient features of the hydrodynamics of gas–solid bubbling fluidized beds.