Adjoint Optimization of conformal cooling channels for rapid prototyped mould inserts

The adjoint method is a powerful tool for gradient-based shape optimisation in computational fluid dynamics (CFD) simulations. The computational cost of the method is independent of the number of design variables, which makes it an attractive approach for problems with large design spaces. The method was originally developed by Lions and Pironneau [1,2] in the 1970s, and has gained popularity in the aeronautical industries [3], however to date, its uptake in heat transfer applications is limited. In this study, we use the adjoint method to optimise the shape of conformal cooling channels for aluminium casting mould inserts. Traditional moulding processes consist of three main phases, filling, cooling and ejection, where cooling occupies up to 80% of the total moulding cycle. Design of conformal cooling channels using solid freeform fabrication (SFF) methods such as 3D printing have been carried out by Sachs et al. [4] and show a significant reduction in cycle time and part distortion by 15% and 9% respectively, compared with conventional cooling lines from straight CNC drill. The objective of this study is to morph the shape of conformal cooling channels using various objective functions, such as those that maximise heat transfer, or minimise pressure drop, and to assess the impact of these shape modifications upon the performance of the mould insert.