The aim of this work is to develop a numerical model for the deflection of dc transferred arcs using an external magnetic field as a first step into the modelling of industrial arc furnaces. The arc is deflected by the use of a conductor aligned parallel to the arc axis through which flows an electric current. The model is validated by comparing the results of axisymmetric calculations to modelling results from the scientific literature. The present model is found to be a good representation of the electric dc arc as differences with the literature are easily explained by model parameters such as the critical boundary conditions at the electrodes. Transferred arc cases exhibit the expected behaviour as the temperature T, the velocity v⃗ and the electrical potential drop Δϕ all increase with the arc current I and the argon flow rate Q. Three-dimensional geometry is implemented, enabling one to numerically deflect the arc. For the deflected arc cases, the deflection increases with the arc current I and conductor current Iconductor and decreases with the flow rate Q and x0, the arc–conductor distance. These deflection behaviours are explained using physical arguments.

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Recuperated cycles can significantly increase the efficiency of small gas turbines that are today operating with low pressure ratios and uncooled or lightly cooled turbine blades. However, for mass-driven applications such as aeroengines, the efficiency benefit is typically outweighed by the increased weight associated with the heat exchanger (HX). Increase in specific power could overcome this penalty by reducing the mass flow through the system and therefore its weight and size. To do so, the Turbine Inlet Temperature (TIT) must be increased by ∼250 K over state-of-the-art small gas turbines. The Inside-out Ceramic Turbine (ICT) propose a new path to increase TIT of small turbines, where blade cooling schemes are impractical and costly. This new architecture increases the achievable TIT by using ceramic blades loaded in compression under centrifugal loads supported by an air-cooled rotating composite rim. This paper provides a system-level evaluation of the power-density to efficiency trade-off for the sub-megawatt class turbines using the ICT configuration. The numerical simulation includes 3 submodels to provide cycle efficiency and mass estimates for various cycle and HX design: (1) a station-based thermodynamic model; (2) a 1D-FEM HX model for a straight counterflow recuperator; and (3) a system-level mass model of the recuperated engine configured for a turboprop or turboshaft. At a TIT of 1550 K, the optimal ICT configuration provides a power density of 3 kW/kg and 40% thermal efficiency, which is 4 times lighter than recuperated turbines at 1300 K for the same efficiency level. Further increase in TIT to 1800 K would reach current state-of-the-art turboprop power densities (up to 5 kW/kg) while still achieving over 40% thermal efficiency or — for applications where power density can be traded for efficiency — up to 50% thermal efficiency while maintaining low pressure ratios and associated simplicity.