SC-CO2及工艺条件对高固含量发射药CA/CaCO3体系挤出停留时间的影响

为了研究挤出过程中超临界二氧化碳（SC-CO₂）对高固含量发射药停留时间分布的影响，采用示踪粒子轨迹跟踪技术研究了醋酸纤维素（CA）/碳酸钙（CaCO₃）/SC-CO₂代料停留时间的影响因素，结合反应器流动模型确定了CA/CaCO₃/SC-CO₂在机筒中的流动情况。数值模拟结果显示,注入体积流量为0.1 mL/min的SC-CO₂后，平均停留时间缩短了35%，Pe减小了196.4；螺杆转速由6 r/min增加到14 r/min时，平均停留时间缩短了54.5%，Pe减小了210.8；当机筒温度从40 ℃升高至60 ℃，平均停留时间减少了19%，Pe减小了75.0。反应器流动模型拟合结果显示,螺杆转速由6 r/min增加到14 r/min时，CA/CaCO₃/SC-CO₂的体积分数从0.65降低到0.62。由此可知，SC-CO₂的加入、螺杆转速的增加以及机筒温度的升高都显著缩短了物料的停留时间，并促进了轴向混合，CA/CaCO₃/SC-CO₂在螺杆内的主要流型为活塞流。

Effect of SC-CO2 and Process Conditions on Residence Time of High Solid Content Propellant Substitute in Extrusion

In order to study the effect of supercritical carbon dioxide (SC-CO₂) on the residence time distribution of high solid propellant in extrusion process, numerical simulation of CA/CaCO₃/SC-CO₂ substitutes was performed to analyze the influencing factors of residence time by particle tracing method. Combined with reactor flow pattern, the main flow patterns of CA/CaCO₃/SC-CO₂ in the barrel were determined. The results show that after injection of SC-CO₂ with a volume flow of 0.1 mL/min, the mean residence time reduces by 35%, and the Pe?number reduces by 196.4. When the screw speed increases from 6 r/min to 14 r/min, the mean residence time reduces by 54.5%, and the Pe?number decreases 210.8. The mean residence time reduces by 19% and the Pe?number reduces by 75.0 when the cylinder temperature increases from 40℃ to 60℃. The fitting results show that the volume fraction of CA/CaCO₃/SC-CO₂ decreases from 0.65 to 0.62 as the screw speed increases from 6 r/min to 14 r/min. The residence time of the material is significantly shortened, the axial mixing is enhanced by the addition of SC-CO₂, and the acceleration of screw speed and the increase in barrel temperature. Plug flow is the dominant flow pattern of CA/CaCO₃/SC-CO₂ in the screw.