The Impact of Molecular Radiation Processes in Water Plasma on Performance of Water-Vortex and Hybrid-Stabilized Electric Arcs

Summary form only given. Numerical investigation of properties and processes in the worldwide unique type of thermal plasma generator with water vortex stabilization (Gerdien arc) and combined stabilization of arc by argon flow and water vortex, the so-called hybrid arc, has been carried out. In the hybrid arc two arcs in series are used: The first one is a short gas stabilized argon arc with low gas flow rate. This arc creates a cathode for the second arc stabilized by water vortex. Parameters of the generated thermal plasma jet and plasma composition can be controlled by a change of parameters of both arcs and by-conditions of their interaction. A two-dimensional axisymmetric numerical model describes the region between the inlet and outlet nozzles in the arc discharge chamber. It is assumed that plasma flow is steady, laminar, compressible, in the state of local thermodynamic equilibrium. The governing continuum, momentum and energy equations with temperature-dependent transport and thermodynamic properties are solved numerically by the finite volume method. Here we study the contribution of water molecular species on radiation transport within the discharge region of water and hybrid arcs. Radiation losses from the arc are calculated by the partial characteristics method for atmospheric pressure water and argon-water discharges. In contrast to our previously published results, band spectra of H₂, O₂, O₂ ⁺, OH and photodissociation of O₂ and OH molecules have been included in the partial characteristics. Results carried out for 150-600 A and for argon mass flow rates of 7.5-27.5 slm proved that plasma temperature and velocity increased up to several per cent compared to the case with omitted molecular contribution. The amount of reabsorbed radiation also increased in both types of arcs. Comparison between present calculation and available experiments shows good agreement.