【作者】 丁琴；

【导师】 吴志超；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2006， 硕士

【摘要】 干砂负压消失模铸造技术中模样是消失模铸造成败的关键,而泡沫珠粒的充填是获得优质泡沫模样的关键工序之一。泡沫珠粒在模具中充填不均或不密实会使模样出现残缺不全或融合不充分等缺陷,影响产品的表面质量。因此利用计算机对泡沫珠粒射料充填过程的流动场进行数值模拟,定量地了解射料过程的影响因素,有利于优化射料工艺、提高效率和减少废品。本文建立了基于欧拉-拉格朗日模型的考虑可压缩性影响的密相气固两相流的模型,比较全面系统地推导出含有10个未知变量的密相可压气固两相流的封闭的偏微分方程组,其中考虑了变密度的影响,为流场的数值分析奠定了坚实的理论基础。本文建立了基于欧拉-拉格朗日模型的适用于密相可压气固两相流的数值解法。在建立压力修正方程时考虑了气相的可压缩性,使得这种修正方法可适用于变密度的各种情况。基于欧拉-拉格朗日模型,采用计算流体分析软件Fluent对发泡模具射料充填过程进行数值模拟。与物理模拟对比表明,数值模拟结果中的泡沫珠粒的流动趋势与实际情况基本上是一致的。更多还原

【Abstract】 In lost foam casting ,the foam pattern is the key qualification, and the filling process is one of the crucial processes to ensure the high quality of the foam pattern. Filling without uniformity and denseness will cause various defects and affect the quality of the surface. The influential factors of filling process are realized .And optimizing filling process, enhancing efficiency, decreasing waster and so on are obtained by the numerical simulation of filling process .The partial differential equations which is based on Euler-Lagrange model containing 10 variables are established systematically to control dense gas-solid two-phase turbulent flow in which variable density in two-phase turbulent flow have been taken into account, and the foundation is thus laid for numerical analysis.A new algorithm is proposed to solve dense compressible gas-solid two-phase flow. The pressure correction equations of gas pressure is established in which correction of gas concentration is considered so that it can be applied to variable density case.Based on Euler-Lagrange method, the filling process is simulated by Fluent, an analysis software of the computation fluid dynamics. By comparing the result of numerical simulation with the examinations, it is found that the fluid trend of foam beads in the numerical simulation is accordant to the actual process.更多还原