Study On Numerical Simulation Of Mold Filling Of A Casting Based On ANSYS Sofrware

Mold filling is the first process of a casting forming and it has an important influence on the solidification of the casting. Therefore, it is of importance for optimizing the quality of castings to understand and control the filling process. In this thesis, the flow field and the temperature field of a HT150 casting during filling were studied widely based on ANSYS--- a finite element method software. Using the governing equations of the incompressible viscosity fluid and the standard K ?εmodel, numerical simulation of water filling process was performed and proved rational according to the experiment result by YUAN Haoyang. The influence of the shapes of the bottom-pour-ladles on the inlet velocity of the melt, the order of filling the cavity and the state of the free surface was studied. When an improper bottom-pour-ladle was used, the inlet velocity fluctuated fiercely, and the air could be engulfed into the running channel. The filling processes of HT150 melt with different inlet velocities was simulated, and the filling order and the free surface shape were observed. When the inlet velocity was small, the filling process was windless, ant the melt did not engulf the air, and the free surface was smooth. However, when the inlet velocity was large, the melt impinged against the mold fiercely and engulfed the air severely, and the free surface was wavy.To simulate the melt flow more factually, changeable viscosity and density were used to simulate the coupled flow field and temperature field during filling of the HT150 metal, and the interaction between the flow field and temperature field was investigated, and the flow field with coupled temperature field was compared to the one without coupled temperature field. The result showed that under the forced-convection heat transfer condition, the flow field had a crucial influence on the temperature field, while the influence of the temperature field on the flow field was feeble. The fluid is the carrier of temperature, so the change of the flow field decides the change of the temperature field. The change of the viscosity caused by temperature is very small and the natural convection caused by the density is feeble compared to the forced convection caused by filling of the melt. As a result, the temperature field does not exert a considerable influence on the flow field, and the flow field with coupled temperature field and the one without coupled temperature field are almost the same. The inlet velocity, pouring temperature and the mold condition are important factors affecting the filling process. The inlet velocity had an obvious influence on both the flow field and the temperature field. When the inlet velocity was small, the melt filled the cavity windless, the time of filling process was long, and the heat loss was large. When the inlet velocity was large, the hot metal impinged against the mold fiercely and engulfed the air severely, and the heat loss was still large even though the filling time was short. With different pouring temperatures, the flow fields were almost the same, and, however, the pouring temperature directly decided the temperature of the melt in the cavity, but the influence of it on the change trend of the temperature field was faint. The mold condition affected the flow field indistinctively, but affected the temperature of the melt during filling process.Based on the simulation results and the reasons of the formation of casting defects, a mezzo inlet velocity is fit, and a lower pouring temperature is appropriate under the precondition for completely filling a casting.