Study On Numerical Simulation Of Gas-Liquid Two-Phase Flow During Mold Filling Process

The gas-liquid two-phase flow (GLTF) simulation is an advancing research on Computational Fluid Dynamics (CFD). Based on the application of the latest technique of CFD, the simulation of GLTF during the mold filling process is developed in this research, which has a great meaning on improving casting simulation technique.Precisely describing the interface movement is the key and basis to the GLTF simulation during mold filling process. Level Set method, which adopts high order discrete schemes, is a new interface tracking method developed in recent years. In this study, Level Set is introduced to simulate the interface movement between the gas and the liquid. And the GLTF during mold filling process is modeled by the combination of SOLA and Level Set, in which the conventional algorithm SOLA is modified to calculate the compressible gas movement, and Ghost Fluid Method is adopted to deal with the problem of large jump in density across the interfaces.The validity of the presented method is verified by experiments and commercial CFD software. Firstly, water analog experiments based on similarly laws are carried out. Comparison between experimental and simulation results shows that the self-developed method is efficient to deal with complex interfaces movement, and also suitable for the calculation with large density jump. And then, the simulation results are compared with that by the commercial CFD software FLUENT, which confirms that this study has a good reliability.The casting process involves coupled effects of fluid flow and heat transfer. In order to simulate the mold filling process properly, heat transfer during the fluid flow must be taken into account. Therefore, a numerical simulation program coupling fluid field and temperature field of GLTF during casting process has been developed.Finally, using the commercial casting software InteCast CAE to simulate the complex 3-D castings, and compare the results with that of self-developed method, the reliability and validity of this study can be further tested. It can be found that the method in this study can correctly simulate the complex filling process of 3-D castings, and furthermore, the effect of backpressure on the liquid metal, and also the air entrapment during the filling process, can be quantificationally simulated in this study. Therefore, the presented method for GLTF has a profound meaning on casting production.