论文部分内容阅读
行星式搅拌装置内搅拌桨的运动轨迹复杂,对固体颗粒与高黏度聚合物熔体的混合效果较好。混合时间是表征搅拌釜内流体混合状况、评定搅拌釜效率的重要参数之一。利用FLUENT软件数值模拟一种行星式搅拌釜内高黏固液两相混合过程,采用传统混合时间定义方法和体积分数法2种方法计算搅拌桨不同自转转速的混合时间,并将2种方法的计算结果进行比较;采用体积分数法计算搅拌桨不同安装高度时的混合时间。计算中采用欧拉模型,使用动网格技术,利用FLUENT的用户自定义函数确定搅拌桨的速度。数值计算结果表明,采用选取监测点计算混合时间的方法,不同监测点的混合时间有较大差异,为保证全釜内混合均匀,应选取混合时间最长的监测点;选取监测点和体积分数2种混合时间计算方法得到的混合时间基本相同;随着搅拌桨自转转速的提高,混合时间明显缩短;采用釜底加料方式,搅拌桨安装高度从20mm提高到60mm时混合时间缩短。
Planetary mixing device within the mixing paddle movement trajectory complex, solid particles and high viscosity polymer melt mixing effect is better. The mixing time is one of the important parameters to evaluate the mixing status of the fluid in the stirred tank and evaluate the efficiency of the stirred tank. Using FLUENT software to simulate a high viscosity solid-liquid two-phase mixing process in a planetary stirred tank, the mixing time of different rotating speed of the stirring paddle was calculated by two methods of the traditional mixing time definition and the volume fraction method. Calculation results were compared. The volume fraction method was used to calculate the mixing time of different propeller height. The Euler model is used in the calculation, using the moving grid technique, the user-defined function of FLUENT is used to determine the speed of the paddle. The results of numerical calculation show that the mixing time of different monitoring points is quite different by adopting the method of selecting the mixing time. To ensure the uniform mixing in the whole reactor, the monitoring points with the longest mixing time should be selected. The monitoring points and the volume fraction The mixing time obtained by the two kinds of mixing time is basically the same. With the increase of rotation speed of the mixing paddle, the mixing time is obviously shortened. The mixing time is shortened when the installation height of the paddle is increased from 20mm to 60mm with the feeding method of the bottom.