Numerical Evaluation of the Impact of Selected Physical Phenomena and Riser Shape on the Formation of Shrinkage Defects in the Casting–Riser System

Abstract

Understanding the complex physical phenomena involved in the casting process simulation requires continuous and complementary research to improve mathematical modelling.  The paper presents a mathematical model and numerical simulations of the solidification process of a cylindrical casting, taking into account the filling of the mould cavity with liquid metal and feeding the casting through the riser during solidification.  The basic mathematical model that considers only thermal phenomena is often insufficient to analyse the metal solidification process.  Therefore,  more  complex models are formulated  that  include  coupled  thermal  and flow phenomena.  The  mathematical  description  then  consists  of  the system  of  Navier–Stokes differential equations, the equations of the continuity of flow and energy.  Such  a  mathematical  model  was used in  the  paper because the mutual  dependence  of thermal and flow  phenomena has a significant impact on the solidification process.  The  finite  element method was used to solve the problem, and changes in thermophysical parameters were considered as a function of temperature. The impact of the riser shape on the effectiveness of feeding of the solidifying casting was also determined and an appropriate selection of the riser  shape  was made to obtain  a  casting without  shrinkage  defects, which  was the aim of this work.