Niu Xiaofeng, Song Zhenliang, Fang Zhao, Hu Lei, Wang Hongxia, Zhao Jingyu, Bo Yanqiang
College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
Xi'an University of Architecture and Technology, Xi'an 710055, China.
J Nanosci Nanotechnol. 2018 Dec 1;18(12):8169-8177. doi: 10.1166/jnn.2018.16383.
The actual casting filling process can be deemed as the coupled flow of air, molten metal and solid-phase particles (such as slag) inside the cavity, which may cause air entrapment, slag inclusion and other casting defects, and affect the quality of casting. Through computation simulation of the casting filling process on the basis of smoothed particle hydrodynamics (SPH) method, it can not only precisely track the motion trajectories of air, molten metal and slag particles, but also precisely predict air entrapment, slag inclusion and other casting defects. This paper established a mathematical model of gas-liquid-solid three-phase flow for the SPH-based casting filling process. The model eliminated the instability of gas-liquid interface pressure by introducing the corrected gas-liquid two-phase momentum equation, and maintained a clear interface between air and molten metal by introducing the surface tension model. In addition, it introduced the motion model of rigid body to deal with the coupled flow process of slag, air and molten metal. The mathematical model established in this paper was used to calculate the bubble floating and the flowing process of the gas-liquid two-phase during mold filling through the bottom side of the injection cavity and of the gas-liquid-solid three-phase flow during mold filling for casting of plate (the plate was composite reinforced with nano SiC, and the viscosity of the composite melt was calculated from the viscosity formula of the composite melt). The calculated results were compared with the experimental results to verify the accuracy and validity of the mathematical model established.
实际的铸件充型过程可视为型腔内部空气、金属液和固相颗粒（如熔渣）的耦合流动，这可能会导致气孔、夹渣等铸造缺陷，影响铸件质量。通过基于光滑粒子流体动力学（SPH）方法对铸件充型过程进行计算模拟，不仅可以精确跟踪空气、金属液和熔渣颗粒的运动轨迹，还能精确预测气孔、夹渣等铸造缺陷。本文针对基于SPH的铸件充型过程建立了气-液-固三相流数学模型。该模型通过引入修正的气液两相动量方程消除了气液界面压力的不稳定性，并通过引入表面张力模型保持了空气与金属液之间清晰的界面。此外，引入刚体运动模型来处理熔渣、空气和金属液的耦合流动过程。本文建立的数学模型用于计算通过注射型腔底部进行充型时气液两相的气泡上浮和流动过程，以及平板铸件充型时气-液-固三相流（平板采用纳米SiC复合增强，复合熔体的粘度根据复合熔体粘度公式计算）。将计算结果与实验结果进行比较，以验证所建立数学模型的准确性和有效性。
