泡沫陶瓷离心过滤铝合金熔体的数值模拟与实验研究
发布时间：2018-09-18 13:43
【摘要】：铝合金作为汽车、电力和国防等领域普遍使用的有色金属结构材料,它具备一系列比其他有色金属更优良的特性。但由于铝合金熔体中夹杂物和气体等冶金缺陷的存在,会对产品的机械性能和使用性能产生极大的危害。因此为生产出高质量的铝合金铸件并提高其综合性能,对熔体进行除杂净化处理是必要的保证措施。过滤技术是公认的在铸造过程中能去除金属熔体内夹杂物的最简便、最便宜且有效的方法。泡沫陶瓷过滤器因其能显著降低铸件夹渣而被大量的应用于金属熔体的除杂净化系统内。为了提高过滤效果而采用大孔密度的泡沫陶瓷过滤器时,熔体在泡沫陶瓷内的流动会受到较大的阻力作用,使熔体不能通过过滤器。因此基于泡沫陶瓷在重力场下过滤的方法,引入离心力场的作用,增加熔体在进入泡沫陶瓷时所受的压力,使铝合金熔体能通过较小孔径的泡沫陶瓷过滤器,从而有效地增强泡沫陶瓷的除杂净化效果。本文通过对泡沫陶瓷进行离心过滤铝合金熔体的实验和数值模拟研究工作,深入了解了泡沫陶瓷过滤器内铝合金熔体的流动与换热过程,同时研究了泡沫陶瓷过滤器过滤夹杂物颗粒的机理及效率。数值模拟的关键步骤是建立表征泡沫陶瓷孔隙结构的单元体。通过扫描电镜获取泡沫陶瓷的孔隙结构特征参数,然后基于Weaire-Phelan泡沫模型构建了两个表征不同孔隙率范围的理想化的泡沫陶瓷孔隙结构单元体,最后利用ANSYS-FLUENT软件模拟泡沫陶瓷表征单元体内铝合金熔体的流动行为和夹杂物颗粒的运动轨迹。在孔隙尺度下研究了离心过滤工艺参数和泡沫陶瓷结构特性参数,如铝合金熔体温度、过滤装置的离心转速、泡沫陶瓷的孔隙率和孔密度等关键参数对过滤模型内流场和温度场的分布情况以及夹杂物颗粒的运动轨迹的影响规律。研究表明:(1)铝合金熔体在泡沫陶瓷内流动所受阻力的大小会随着泡沫陶瓷孔密度和过滤装置的离心转速的增大而增大,但铝合金熔体温度和泡沫陶瓷孔隙率的增大则会导致流动阻力的减小;(2)泡沫陶瓷的过滤效率会随着过滤装置的离心转速、泡沫陶瓷孔密度和铝合金熔体温度的增大而增大,但泡沫陶瓷孔隙率的增大会导致过滤效率的减小;(3)各关键参数对泡沫陶瓷的过滤效率和熔体在泡沫陶瓷内流动所受阻力的影响的强弱顺序为:泡沫陶瓷孔密度过滤装置的离心转速铝合金熔体温度泡沫陶瓷孔隙率。最后对夹杂物过滤的数值模拟结果与泡沫陶瓷离心过滤铝合金熔体的实验结果进行对比,发现它们具有较好的趋势一致性,因此泡沫陶瓷离心过滤铝合金熔体的数值模拟结果对铝合金熔体的过滤工艺有一定的指导作用。为了提高泡沫陶瓷离心过滤铝合金熔体的效率,可以选用高孔密度和低孔隙率的泡沫陶瓷,同时适当提高铝合金熔体的温度和过滤装置的离心转速。
[Abstract]:Aluminum alloy is a widely used nonferrous metal structural material in automobile, electric power and national defense. It has a series of better properties than other nonferrous metals. However, the existence of metallurgical defects such as inclusions and gases in aluminum alloy melts will cause great harm to the mechanical properties and service properties of the products. Therefore, in order to produce high quality aluminum alloy castings and improve their comprehensive properties, it is necessary to remove impurities and purify the melt. Filtration technology is recognized as the simplest, cheapest and most effective method to remove inclusions in molten metal during casting. The foam ceramic filter is widely used in the metal melt removal and purification system because it can significantly reduce the slag inclusion of castings. When the foam ceramic filter with large pore density is used to improve the filtration effect, the flow of melt in the foam ceramic will be subjected to greater resistance, which makes the melt unable to pass through the filter. Therefore, based on the filtration method of foam ceramics under gravity field, the effect of centrifugal force field is introduced to increase the pressure of melt entering foam ceramics, so that aluminum alloy melt can pass through foam ceramic filter with small pore size. Thus, the effect of removing impurities and purifying foam ceramics is effectively enhanced. In this paper, the flow and heat transfer process of aluminum alloy melt in foam ceramic filter was studied by experiments and numerical simulation of centrifugal filtration of aluminum alloy melt. At the same time, the mechanism and efficiency of filtering inclusion particles by foam ceramic filter were studied. The key step of numerical simulation is to establish the unit which can characterize the pore structure of foam ceramics. The pore structure characteristic parameters of foam ceramics were obtained by scanning electron microscope, and then two ideal pore structure units of foam ceramics were constructed based on Weaire-Phelan foam model. Finally, the flow behavior of aluminum alloy melt and the movement track of inclusion particles were simulated by ANSYS-FLUENT software. The technological parameters of centrifugal filtration and the structural parameters of foam ceramics, such as melt temperature of aluminum alloy, centrifugal speed of filtration device, were studied at pore scale. The influence of the key parameters such as porosity and pore density on the distribution of flow field and temperature field and the movement track of inclusions in the filtration model. The results show that: (1) the resistance of aluminum alloy melt flow in ceramic foam increases with the increase of pore density and centrifugal speed of the filter. However, the increase of melt temperature and porosity of aluminum alloy will lead to the decrease of flow resistance. (2) the filtration efficiency of foam ceramics will increase with the increase of centrifugal speed, pore density of ceramic foam and melt temperature of aluminum alloy. However, the increase of porosity of foam ceramics will lead to the decrease of filtration efficiency. (3) the order of the influence of key parameters on the filtration efficiency of foam ceramics and the resistance of melt flow in foam ceramics is as follows: the pore density of foam ceramics is too high. The centrifugal rotation speed of the filtration device for aluminum alloy melt temperature foam ceramic porosity. Finally, the numerical simulation results of inclusion filtration are compared with the experimental results of foam ceramic centrifugal filtration of aluminum alloy melt, and it is found that they have a good trend of consistency. Therefore, the numerical simulation results of foam ceramic centrifugal filtration of aluminum alloy melt have a certain guiding effect on the filtration process of aluminum alloy melt. In order to improve the efficiency of centrifugal filtration of aluminum alloy melt with foam ceramics, foam ceramics with high pore density and low porosity can be selected, and the temperature of aluminum alloy melt and the centrifugal speed of filtration device can be increased appropriately at the same time.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG292
本文编号：2248100
[Abstract]:Aluminum alloy is a widely used nonferrous metal structural material in automobile, electric power and national defense. It has a series of better properties than other nonferrous metals. However, the existence of metallurgical defects such as inclusions and gases in aluminum alloy melts will cause great harm to the mechanical properties and service properties of the products. Therefore, in order to produce high quality aluminum alloy castings and improve their comprehensive properties, it is necessary to remove impurities and purify the melt. Filtration technology is recognized as the simplest, cheapest and most effective method to remove inclusions in molten metal during casting. The foam ceramic filter is widely used in the metal melt removal and purification system because it can significantly reduce the slag inclusion of castings. When the foam ceramic filter with large pore density is used to improve the filtration effect, the flow of melt in the foam ceramic will be subjected to greater resistance, which makes the melt unable to pass through the filter. Therefore, based on the filtration method of foam ceramics under gravity field, the effect of centrifugal force field is introduced to increase the pressure of melt entering foam ceramics, so that aluminum alloy melt can pass through foam ceramic filter with small pore size. Thus, the effect of removing impurities and purifying foam ceramics is effectively enhanced. In this paper, the flow and heat transfer process of aluminum alloy melt in foam ceramic filter was studied by experiments and numerical simulation of centrifugal filtration of aluminum alloy melt. At the same time, the mechanism and efficiency of filtering inclusion particles by foam ceramic filter were studied. The key step of numerical simulation is to establish the unit which can characterize the pore structure of foam ceramics. The pore structure characteristic parameters of foam ceramics were obtained by scanning electron microscope, and then two ideal pore structure units of foam ceramics were constructed based on Weaire-Phelan foam model. Finally, the flow behavior of aluminum alloy melt and the movement track of inclusion particles were simulated by ANSYS-FLUENT software. The technological parameters of centrifugal filtration and the structural parameters of foam ceramics, such as melt temperature of aluminum alloy, centrifugal speed of filtration device, were studied at pore scale. The influence of the key parameters such as porosity and pore density on the distribution of flow field and temperature field and the movement track of inclusions in the filtration model. The results show that: (1) the resistance of aluminum alloy melt flow in ceramic foam increases with the increase of pore density and centrifugal speed of the filter. However, the increase of melt temperature and porosity of aluminum alloy will lead to the decrease of flow resistance. (2) the filtration efficiency of foam ceramics will increase with the increase of centrifugal speed, pore density of ceramic foam and melt temperature of aluminum alloy. However, the increase of porosity of foam ceramics will lead to the decrease of filtration efficiency. (3) the order of the influence of key parameters on the filtration efficiency of foam ceramics and the resistance of melt flow in foam ceramics is as follows: the pore density of foam ceramics is too high. The centrifugal rotation speed of the filtration device for aluminum alloy melt temperature foam ceramic porosity. Finally, the numerical simulation results of inclusion filtration are compared with the experimental results of foam ceramic centrifugal filtration of aluminum alloy melt, and it is found that they have a good trend of consistency. Therefore, the numerical simulation results of foam ceramic centrifugal filtration of aluminum alloy melt have a certain guiding effect on the filtration process of aluminum alloy melt. In order to improve the efficiency of centrifugal filtration of aluminum alloy melt with foam ceramics, foam ceramics with high pore density and low porosity can be selected, and the temperature of aluminum alloy melt and the centrifugal speed of filtration device can be increased appropriately at the same time.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG292
【参考文献】
相关期刊论文 前10条
1 胡志雄;殷鹏;孙新民;吁安山;戴斌煜;;离心力场下铜合金熔体泡沫陶瓷过滤数值模拟[J];特种铸造及有色合金;2015年11期
2 吁安山;戴斌煜;陆磊;商景利;余新平;;铜合金熔体泡沫陶瓷过滤过程数值模拟[J];铸造;2014年11期
3 王雷;;旋转坐标系下旋转圆柱绕流的数值模拟[J];低温建筑技术;2014年02期
4 王耀;李宏;郭洛方;;钢液中球状夹杂物颗粒受力情况的数值模拟[J];北京科技大学学报;2013年11期
5 张新铭;王济平;谷沁洋;;孔隙随机结构对非均质多孔泡沫导热性能的影响[J];化工学报;2014年03期
6 柯东杰;Елена Александровы;陈群;李宇航;;提高泡沫陶瓷过滤精度的应用研究[J];轻合金加工技术;2012年07期
7 刘义虎;王冬成;杨明家;;真空状态下铝合金熔体中除气的研究[J];铸造设备与工艺;2010年03期
8 刘晓丹;冯妍卉;杨雪飞;张欣欣;;泡沫金属矩形通道中对流换热的实验和模拟[J];中国电机工程学报;2010年14期
9 魏兵;唐一林;祝建勋;张科峰;朱能山;龙礼贤;;铸造用金属液过滤器及其应用[J];铸造技术;2008年08期
10 尹卓湘;;铝及其合金中溶气的物理化学[J];轻金属;2006年01期
相关硕士学位论文 前5条
1 吁安山;铜合金熔体泡沫陶瓷离心过滤净化数值模拟与实验研究[D];南昌航空大学;2015年
2 石伯承;铝合金连续净化过程中夹杂物变化规律的研究[D];兰州理工大学;2012年
3 胡长松;柴油机尾气颗粒捕集性能研究及数值模拟[D];上海交通大学;2009年
4 徐正;7005/7075中高强度铝合金的应用研究[D];南京理工大学;2007年
5 李杰华;铝合金熔体旋转喷吹除气净化技术的研究[D];西北工业大学;2006年
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