关键词: 发泡珠粒, 两相流, 射料充填过程, 数值模拟, 消失模, Hilbert-Huang变换, 故障诊断, 集成噪声重构经验模式分解, 微弱特征增强

Abstract: A mathematical model based on the two-phase theory is built to evaluate the main factors influencing the filling process of the expanded beads in the lost foam casting. In the model, Eulerian-Eulerian method is used to describe the gas and particle phases and the continuity. Momentum equations are solved by SIMPLE algorithm to obtain the flow, phases concentration distribution. To benchmark the numerical results, experiment on the filling process of expanded beads is carried out and the experimental result is recorded with a camcorder. In the beginning of the injection process, the large air velocity carries the beads from the mold bottom to the top where they accumulate. The beads begin to deposit at the bottom as 2/3 of the whole injection process has progressed and at final stage an elliptical vortex forms. The vortex becomes smaller and smaller and disappears as the filling process finishes. The preliminary results show that the calculation is in agreement with the experiment results.

Key words: Expanded beads, Filling process, Lost foam, Numerical simulation, Two-phase flow, Fault diagnosis, Ensemble noise-reconstructed EMD, Hilbert-Huang transform, Weak feature enhancement