【作者】 姜俊侠；

【导师】 吴志超；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2005， 硕士

【摘要】 干砂负压消失模铸造技术(简称LFC)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。本文系统全面地推导出密相可压气固两相流的封闭的控制方程,并讨论了方程组中各相的物理意义,建立了适用于射料充填过程的欧拉-欧拉双流体数学模型,为数值模拟奠定了坚实的理论基础。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,在Fluent 中使用SIMPLE 算法和隐式分离数值求解方法计算已推导的控制方程组的解,计算出不同时刻的各个控制体单元内的泡沫珠粒的体积百分数,得到了射料充填过程中泡沫珠粒的流动状态。通过对多种情况下的射料充填过程进行物理模拟,考察不同射料方式和挡块位置的影响,用数码摄像机记录射料过程,总结了射料充填过程的一些特点和规律。试验结果与数值模拟结果对比表明,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,使用该数学模型对射料充填过程进行数值模拟是一种行之有效的方法。更多还原

【Abstract】 In lost foam casting(LFC),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 using computer . In this paper the governing equations of the dense compressible gas-solid two-phase flow are established, and the physical signification of each one in the equations is discussed. The filling process is solved by Euler-Euler two fluid model .It is crucial for the simulation. The filling process is simulated by Fluent, an analysis software of the computation fluid dynamics. In the simulation, SIMPLE and implicit segregated methods are used. The volume of foam bead in every governing unit at different time is calculated, and the trend of foam bead flow is obtained. The filling process of various different conditions are simulated, considering different shooting methods and the position of baffles, and recorded by digital vidicon. The characteristics and the rules of the process are summarized. By contrasting the result of numerical simulation with the one of examination, it is found that the fluid trend of foam bead in the numerical simulation is accordant to the actual process. So the numerical simulation of filling process by applying this model is an effective method.更多还原