净铝器石墨搅拌机构高温失效分析及数值模拟

Failure Analysis and Numerical Simulation of Graphite Stirring Mechanism of Aluminum Purifier at High Temperature

为分析净铝器石墨搅拌机构的失效特性,利用流体软件Fluent中的多重参考系法、流体体积函数和标准的湍流模型对搅拌炉内铝液和气体流动进行数值模拟,获得净铝器搅拌过程中的流体运动特性,通过试验进行验证。结果表明:铝液槽内搅拌叶轮附件区域流速最大,石墨搅拌叶轮外边缘存在应力集中,铝液槽内气-液交界面存在气体积聚现象。结合实际试验,石墨搅拌机构高温失效特性主要在气-液交界处和浸入铝液区,气-液交界处因氧化气体聚集,其失效特性主要为氧化磨损;铝液区,石墨棒反复提起和浸入铝液,造成较大温度差,其主要是石墨氧化和残余拉应力共同作用而导致开裂失效。

To analyze the failure characteristics of graphite stirring mechanism of aluminum purifier,the flow of liquid aluminum and gas in stirring furnace was numerically simulated by using multiple reference frame method,fluid volume function and standard turbulence model in fluid software Fluent.The distribution characteristics of flow field and stress in the stirring process of aluminum purifier were obtained.The results show that the flow velocity in the attachment area of the stirring impeller in the aluminum tank is the largest,stress concentration occurs at the outer edge of the graphite stirring impeller and gas accumulates at the gas-liquid interface in the aluminum tank.Combined with the actual test,the high-temperature failure characteristics of graphite stirring mechanism mainly emerges at the gas-liquid interface and the area immersed in aluminum liquid.Due to the accumulation of oxidizing gas at the gas-liquid interface,the failure characteristics mainly takes on oxidative wear.In the molten aluminum area,the graphite rod is repeatedly lifted and immersed in the molten aluminum,resulting in a large temperature difference,which is mainly caused by the joint action of graphite oxidation and residual tensile stress.