鼓泡床床层高度的细网格DEM模拟

气固流化床DEM的细网格模拟中，采用传统方法计算网格空隙率和局部空隙率会对模拟结果造成较大偏差，给出一个精确面积分数模型和一个完全依赖颗粒环境的局部空隙率模型，从而更加合理地计算网格空隙率和局部空隙率。采用二倍颗粒直径的细网格模拟了小规模鼓泡流化床，模拟的气泡形状和尺寸与实验结果接近。模拟结果表明：采用给出的面积分数模型和局部空隙率模型能较好地模拟鼓泡流化床床层高度随时间变化的波形。

Fine grid DEM simulation of bed layer height in bubbling fluidized-bed

For fine-grid DEM simulation of gas-solids fluidized-bed, the traditional methods of calculating grid porosity and local porosity lead to large deviations in simulation results. This paper gives a precise area fraction model and a completely circumstance-dependent local porosity model to more properly calculate grid porosity and local porosity, respectively. These models were validated by the DEM simulation test on a small-scale bubbling fluidized system, using fine-grid size of two particle diameters. The simulated bubble shape and size were close to the measurement. Simulations showed that DEM could perform well in modeling time-varying waveforms for the bed layer height, when using the precise area fraction model and the local porosity model.