Simultaneous Voltage and Heat Transfer Measurements Along an Arc-Plasma Wind-Tunnel Constrictor

Abstract

Experiments were conducted to simultaneously quantify the voltage distribution and heat losses along the length of an arc-plasma wind-tunnel constrictor employing air and argon gas. The objective was to generate a detailed data set and make it available electronically to the scientific community. High-spatial-resolution voltage measurements allowed the identification of a wavelike structure in the upstream part of the constrictor. It was postulated that electrode erosion produced an unstable arc geometry that was further distorted by the imposed magnetic fields. Alternatively, the wavelike structure could be related to vortex precession commonly observed in swirl-stabilized flows. Measurements of heat transfer to the wall, based on differences in cooling water temperature across each segment, revealed a mainly uniform heat transfer distribution along the constrictor, with elevated heat transfer near the cathode and anode due to the strong electric field strengths in the near-cathode and near-anode regions. By varying either the mass flow rate or current, these measurements also allowed, for the first time, the estimation of differences in radiation and convection heat transfer.