多室连续混合设备流场仿真与实验验证

Flow field simulation and experimental verification of multi-chamber continuous mixing equipment

为了揭示多室连续混合设备混合过程中流场特性参数的动态变化规律,采用数值仿真方法建立了典型工况下单室容积2.5 L的多室连续混合工艺模型,得到了混合压力、剪切应力和分布均匀性的变化规律,并通过实验验证了混合压力和分布均匀性的仿真结果。结果显示:多室连续混合设备的各混合室之间混合压力差别不显著,泵压室底部最大混合压力的仿真值为62 954 Pa,远低于1 L两桨行星式混合设备的最大混合压力;预混室中剪切应力较大,最大剪切应力为21 798 Pa,远低于1 L两桨行星式混合设备的最大剪切应力,表明多室连续混合设备的混合安全性高于传统的两桨行星式混合设备;各混合室中铝粉体积分数(仿真值)的标准差随混合室数量的增加呈下降趋势,泵压室中铝粉体积分数的标准差仅为0.260 3%;实验结果与仿真结果一致,物料状态稳定后混合压力的仿真值与实验值的偏差在5%以内,仿真模型中铝粉的分布均匀性变化趋势与实际混合过程相同;当投料速度为20 kg/h,桨叶转速为45 r/min时,混合物料的分布均匀性随混合室数量的增加而提升,混合物料中铝粉含量的标准差从混合加强室3开始不再显著下降,6室结构为该量级设备的最佳结构。

In order to reveal the dynamic change rule of flow field characteristic parameters in the mixing process of multi-chamber continuous mixing equipment,a multi-chamber continuous mixing process model with a single chamber volume of 2.5 L under typical working conditions was established by numerical simulation methods.The rules governing changes in the mixing pressure,shear stress and distribution uniformity were obtained,and the simulation results of mixing pressure and distribution uniformity were verified by experiment.The results show that the mixing pressure difference between the mixing chambers of the multi-chamber continuous mixing equipment is not significant.The simulation value of the maximum mixing pressure at the bottom of the pump chamber is 62954 Pa,which is much lower than the maximum mixing pressure of the 1 L two-propeller planetary mixing equipment.The shear stress in the premixing chamber is large,and the maximum shear stress is 21798 Pa,which is much lower than the maximum shear stress of the 1 L two-propeller planetary mixing equipment,indicating that the safety of the multi-chamber continuous mixing equipment is higher than that of the traditional two-propeller planetary mixing equipment.The standard deviation of aluminum powder volume fraction(simulation value)in each mixing chamber decreases with the increase of the number of mixing chambers,and the standard deviation of the aluminum powder volume fraction in the pump chamber is only 0.2603%.The experimental results are consistent with the simulation results.After the material state is stable,the deviation between the simulation value and the experimental value of the mixing pressure is within 5%.The variation trend of the distribution uniformity of aluminum powder in the simulation model is the same as that in the actual mixing process.When the feeding speed is 20 kg/h and the blade speed is 45 r/min,the distribution uniformity of the mixture material increases with the increase of the number of mixing chambers.The standard deviation of the aluminum powder content in the mixture material does not decrease significantly from the beginning of reinforced mixing chamber 3,and the six-chamber structure is the best structure for equipment of this magnitude.