CVI processes of different diameter of preforms were studied in this research to analyze the influence of the scale of perform to the densification in CVI.Preforms of the equivalent height of 90mm and each diame-ter was 60,120 and 180mm was used to simulate the porosity and density field in 4 periods.Results showed that it was easy to get uniform and high score of density in small diameter preform,when crust occurred on the surface of larger diameter preform,additionally,in larger size preform density in surface area was higher and negative density gradient formed from the center to the boundary of the final product.%对不同直径圆柱预制体的 CVI 增密过程进行数值模拟研究,分析预制体尺度对增密过程及密度分布的影响。针对高90mm,直径分别为60、120、180mm的预制体,分别模拟 CVI 过程中预制体的孔隙率、密度以及孔隙平均尺寸分布和变化特征。结果显示,小直径预制体经过一段时间的沉积后密度分布较为均匀,且平均密度值很高；预制体直径较大时,沉积易发生在表面区域,导致表面区域密度较高,中心区域密度值较低,影响进一步的增密过程。
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