Numerical Analysis of Fillet Shape and Molten Filler Flow during Brazing in the Al–Si Alloy of Automotive Radiator

Abstract

In the brazing process of an automobile radiator, eutectic melting of the Al–Si filler alloy of the clad sheets, fillet formation in the brazed joints, and the flow of the molten filler metal on the solid core metal between joints occur continuously. With regard to designing heat exchangers, the optimum placement of the filler metal, considering the flow of the molten filler metal, is an important subject. In this study, a new numerical analysis was applied to predict the shape of the fillets and the molten filler flow. The molten filler flow was calculated using the difference method applied to a one-dimensional unsteady flow that is assumed to be a uniform flow of incompressible viscous fluid between two parallel plates. Among some numerical results, when the hydraulic mean depth of the flow path was reduced 0.3 times, the calculation results were consistent with the actual values. It was necessary to narrow the flow path because it was calculated assuming that the flow of brazing was between two parallel flat plates, whereas the actual flow path of the molten filler metal was not flat and a large flow resistance was produced.

Comparison of actual and numerical data for fillet membrane at each joint.