摘要
基于static bed模型为电加热的滚塑工艺在加热阶段建立了一个传热模型,通过FLUENT软件对3种情形下模具的表面温度和模内温度进行了仿真计算,并将仿真结果与实验结果进行了比较。首先假设加热功率在整个加热阶段是大小恒定的,然后在改进模型中通过在模具的外表面分别设置升温段和保温段的内热源强度来模拟加热功率的变化。同时认为在粉料开始熔融之前模内温度等于模内粉料和空气的质量平均温度,在此之后等于模内空气的温度。结果表明改进模型对模具表面温度的仿真精度高于对模内温度的仿真精度。对于厚度不超过10 mm的氢气瓶,在整个加热阶段模具表面和模内的仿真温度与实测温度的均方根相对误差都在10%以内。而对于12 mm厚的氢气瓶,这两个均方根相对误差分别为5.1%和14.1%。另外由仿真结果还得到了在3种情形下塑料层中的液相百分比随时间的变化规律。
A heat transfer model was established for rotational molding process heated electrically in heating phase based on static bed model to simulate temperatures at mold surface and inside mold in three cases by means of FLUENT software,and simulated results were compared with experimental results.At first,heating power was assumed to be constant in entire heating phase,and then in the improved model,the intensity of internal heat source at outer surface of mold was set as the one during temperature-increasing stage and the one during temperature-holding stage respectively to simulate variation of heating power.Meanwhile the temperature inside mold was equal to the mass-average temperature of powder and air inside mold before the start of powder melting,and the temperature of air inside mold after the moment.It was indicated that simulating accuracy for temperatures at mold surface by the improved model was higher than that for temperatures inside mold.For the thickness of hydrogen cylinder no more than 10 mm,root-mean-square relative errors of simulated temperatures with tested temperatures at mold surface and inside mold were both within 10 % in entire heating phase.These two root-mean-square relative errors were 5.1 % and 14.1 % respectively for hydrogen cylinder with thickness of 12 mm.In addition,the variation of liquid fraction of plastic layer with time was also obtained from simulated results in three cases.
作者
刘学军
LIU Xuejun(School of Artificial Intelligence,Beijing Technology and Business University,Beijing 100048,China)
出处
《中国塑料》
CAS
CSCD
北大核心
2023年第7期53-61,共9页
China Plastics
关键词
电加热
滚塑工艺
传热模型
模具表面和模内温度
FLUENT仿真
electrical heating
rotational molding process
heat transfer model
temperatures at mold surface and inside mold
FLUENT simulation
