FLOW3D铸造-进阶培训-物理选项.ppt

放热套 Exothermic sleeves are used to add heat to the risers to extend their feeding function. The heat is released when the riser reaches a certain temperature and is produced over a fixed period of time. Q t t1 t2 Q0 Full heat transfer model must be activated. An exothermic sleeve is defined as a component with a heat source. The heat source is defined as a function of time (not temperature) via the prepin file; it can be defined in terms of either total power, POBS, or power per unit volume, SPOBS: 放热套 : 定义 OBS tobs(1)=t1-e, POBS(1,n)=0.0, tobs(2)=t1, POBS(2,n)=Q0, tobs(3)=t2, POBS(3,n)=Q0, tobs(4)=t2+e, POBS(4,n)=0.0, / where n is the component number and e is small compared to t2-t1 谢谢! - activate variable density model (no heat transfer can be used then) - set air density - activate drift-flux model with the escape option set average air bubble size bottle filling 激活卷气模型 variable density model air density average bubble size air escape at free surface activate drift-flux model 紊流 flow inside mold during filling is usually at high Reynolds numbers ( 20,000) and is, therefore, turbulent; out of the five available models, the RNG model is the best choice; RNG CPU load is not excessive, 20%; but typically, better mesh resolution is needed to capture turbulence than for laminar flows; do not use turbulence when the flow is not turbulent. available turbulence models When using a turbulence model, Turbulent mixing length (TML) should be set. TML is related to the average scale of turbulent eddies in the flow. In casting, it is related to the smallest of the average wall thickness, d, and runner and gate width, h: TML=0.07*min(d,h) Hint: the larger the value of TML, the higher the level of turbulence. 紊流:紊流混合长度 d h turbulent mixing length Generally, turbulence models are not been validated for filling analysis in great detail, especially for high pressure die casting. The main experimental paramet