Free-burning arcs where the work piece acts as an anode are frequently used for a number of industrial applications. Our investigation was concerned with developing a capability to model free-burning high-intensity argon arcs and enhancing the accuracy of numerical results according to a comparative study of turbulence models. For the arc modeling involved complicated interactions between the flow and electromagnetic fields, we modified the Navier-Stokes equations to take into account the radiation transport, the electrical power input and the electromagnetic driving forces with the relevant Maxwell equations. For the turbulence modeling, which is critical to the arc edges due to a steep temperature gradient between the arc column and the surrounding gas, zero- and two-equation eddy-viscosity models were used. The major arc parameters of temperature, axial velocity, electric potential difference and pressure-rise from ambient atmospheric pressure were summarized under laminar and turbulent conditions. It was found that the standard k-ɛ model modified to take into account the effect of a steep temperature gradient at the edge of free-burning arcs could predict reasonable temperature profiles better than the cases with the assumption of laminar flow and Prandtl’s mixing length model used for switching arcs.

Recently, as the industry develops, global energy consumption has been increasing. Power generation using various energy sources is used to meet energy consumption. The demand for renewable energy resources is increasing as well as the demand for fossil fuels. However, fossil fuel reserves offshore are limited, and the continued resource development is causing the depletion of fossil fuels. Accordingly, there is a demand for resource development not only offshore but also in the deep sea. In order to efficiently separate water and oil, it is necessary to study a compact in-line oil separator. In this study, the oil–water separation characteristics according to various airfoil vane configurations of the in-line type oil separator are numerically calculated. The maximum camber and location of the maximum camber of the NACA(National Advisory Committee for Aeronautics) airfoil model were selected as design parameters. As a result, the maximum separation efficiency of 63.9% was predicted when the maximum camber value was 13.51% and the maximum camber position was 50%.