Convection Currents in Arcs in Air

Abstract

Convection currents in and around arcs in air have been studied by Kenty's method of photographing solid particles in the gas stream. By the use of BN powder the air velocities around an arc column with vertical axis are measured throughout the entire region of convection currents. These velocities vary from 130 cm ${\sec .\mathrm{}}^{-1\mathrm{}}$ at the arc axis to zero at a distance of 2.5 cm. By integrating over the velocity curve, the total heat flow is found to be 75 percent of the electrical input. That portion of the heat flow included in the luminous arc core is 7 percent of the total. By equating the buoyancy force and the viscous force at the arc boundary, the gas viscosity $\eta$ is measured. The gas temperature corresponding to $\eta$ is 7000°K, in agreement with known arc temperature measurements.