INVESTIGATION OF HEAT TRANSFER AND FLUID FLOW BEHAVIOR IN PLASMA ARC WELDING PROCESS USING FINITE ELEMENT BASED NUMERICAL MODEL

Abstract

The keyhole welds are produced by the use of highconstrictedarcof plasma arc joining operation. Although, keyhole stability is one the major issue which will determine overall stability of the joining process and weld integrity. In the current article, a 3D model is developed to examine the effect of process parameters and investigate the flow behavior in the melt pool during joining operation. In the present analysis, ANSYS-WORKBENCH environment is utilized to develop a 3D physical model of the specimen. Thereby, the3D model is imported into commercial Computational Fluid Dynamics (CFD) solver ANSYS-FLUENT 15. The CFD is based on Finite Volume Method (FVM) which will discretize the whole domain into smaller elements andcompute the governing equations and different boundary constraints. A Gaussian distributed double ellipsoidal heat source model is used for simulation of plasma arc welding process. The classical constraint of physical process involved during welding is replaced by a well-defined double ellipsoidal volumetric energy source of Gaussian distribution along with different fluid flow forces such as surface tension, buoyancy,Marangoni stress, Electro Magnetic Force (EMF) and gravity. The velocity filed, temperature distribution and geometrical features of weldment is computed from the computational model and evaluated against experimental data. And, a fair agreement was achieved between experimental and numerical model.