铸造用大颗粒型砂气力输送行为的数值模拟研究

Numerical simulation of pneumatic conveying behavior based on large granule molding sand in casting

对铸造用型砂颗粒在垂直提升管中的气力输送过程往往需要靠经验公式来设计计算。通过采用数值模拟的方法,基于FLUENT模拟过程中对气相采用k-ε标准方程模型,将型砂固体颗粒看作拟流体,建立了气力输送的数学物理模型和计算方法,对粒径大、真密度高铸造用型砂颗粒在垂直提升管中的流动特性进行了模拟分析。模拟结果表明,当空气输送速度保持不变时,气固两相在垂直提升管中存在加速段及恒速段;在不同的空气输送速度下,气固两相在垂直提升管中都存在加速段及恒速段,而且随着空气输送速度的增加,固相颗粒在提升管内的停留时间越短,即固相颗粒的输送速度越高。

Pneumatic conveying process of molding sand particles in vertical riser pipe often need to rely on experience design and calculation formula to this issue. Simulation analysis of flow characteristics in vertical riser pipe was carried aiming at the large particle size, high density of molding sand granule through numerical simulation method. Based on FLUENT simulation for gas phase in the process of the k-epsilon standard equation model, molding sand was taken as continuum or Quasi-fluid, and mathematical model and calculation method for pneumatic conveying was built up. The simulation results reveal that, gas-solid two phase exist accelerating and constant speed in the vertical riser pipe when the air speed stays constant; Gas-solid two phase exist accelerating and constant speed in the vertical riser pipe even when the air convey in different speeds. And with the increase of the air conveyor speed, the residence time of solid particles in vertical riser pipe reduce, the solids conveyor speed increase.