ELECTRIC ARCS IN TURBULENT FLOWS, IV

Heat, mass, and momentum transfer were investigated experimentally in very long cylindrical axial flow arcs in laminar and turbulent flow conditions. Special attention was given to assure that the end of the arc tube had a section of fully developed flow. In this section the number of significant terms in the energy balance equation is reduced and interpretation of experimental results is implified. Strong evidence is presented for the existence of turbulence by the fact that all three transfer mechanisms are considerably accelerated in what we condier the 'turbulent mode' and also by direct optical study of the arc by a light probe. The onset of turbulence was found with all our methods to occur around 1.5 gram/sec gas flow rate. A considerable number of measurements of heat and momentum transfer are presented in the following operating ranges: Gases-argon and nitrogen; tube diameters-0.5 and 0.7 cm; tube length-50 cm; mass flow rates-0.1 to 15 gram/sec; ambient pressure -1 to 20 atmosphere; currents 25 to 200 amperes (some higher). (Author) See also AD-674 614.