C. X. Zhao, I. M. Richardson, Materials Innovation Institute/Delft University of Technology, Delft, Netherlands; V. V. Steijn, Z. S. Saldi, C. R. Kleijn, Delft University of Technology, Delft, Netherlands
To explore the physical mechanisms governing fluid flow in the weld pool, measurements of flow behaviour on the surface of a weld pool were undertaken. To date, most of the reported experimental results evaluate the surface flow by tracing single particles, rather than the whole flow field. In this paper, we calculated the whole surface flow field for a gas tungsten arc (GTA) weld pool by studying the movement of the natural oxide layer on a 316L stainless steel substrate. The surface flow is reconstructed based on high-speed camera imaging and particle image velocimetry (PIV). Unsteady flow fields were captured, which contain strong rotational flow.
The Reynolds number, a dimensionless number to characterize single phase flow was calculated to analyse the flow motion and determine whether the flow in the weld pool is laminar or turbulent. The maximum velocity based on a theoretical analysis is compared with our experimental results. Finally, an analysis of error sources is made for the computed velocities and some suggestions are provided to reduce the error in the two dimensional flow fields.
Summary: A experimental method for acquiring the surface velocity field of the weld pool was reported in this paper, which provides experimental results to understand how fluid flow on the weld pool surface.
