铝合金锭坯超声半连续铸造多物理场耦合数值模拟

对于有超声引入的铝合金大型锭坯半连铸过程,建立了声场、流场和温度场耦合的数学模型,合理地考虑了凝固过程不同状态铝合金的动力粘度和湍动粘度以及边界条件,并利用有限体积软件FLUENT求解得到了三维声场、流场和温度场分布.模拟结果显示,声场对流场和温度场影响很大.若超声振动的工艺参数设置合理,可使流场规模显著增加,有效地促进传热、传质和晶核弥散：可使温度场分布更加均匀,凝固前沿的温度梯度显著减小,对枝状晶向等轴晶转变有极大的促进作用.

Mathematical Simulation of Multi-fields Interaction in Semi-continuous Casting of Aluminum Alloy Billets

A new mathematical model describing acoustic, flow and thermal fields＂ interaction and coupling in the process of aluminmn alloy semi -ontinuous casting of large-scale billets with ultrasonic treatment was established. Dynamic viscosity and turbulent viscosity of aluminum alloy under different conditions in the solidification process along with boundary conditions were legitimately considered. And finile volume software FLUENT was used to solve 3D distribution of acoustic, flow and thermal fields. According to the simulation results, acoustic filed had significant influence on flow and thermal fields. If technological parameters of acoustic vibration were settled reasonably, the scale of flow field could be increased significantly, thus heat transfer, mass transfer and crystal nuclei dispersion were effectively promoted, and the distributinn of thermal field was become more uniform, temperature gradient of solidification front was significantly reduced, which played a great role in promoting transition from dendrites to equiaxed grains.