Experiments with Two Flow-Swallowing Enthalpy Probes in High-Energy Supersonic Streams

Abstract

Certain arc-heated plasma facilities are capable of producing plasma streams with enthalpies to 200 Mjoule/kg. However, these test streams are obtained at low densities (pro < 10 kg/ m) with large local gradients, which, in turn, make total energy determinations difficult. Because of the importance of this stream property, a program was undertaken to determine it by measuring local total power balances on captured stream tubes. Two flow-swallowing enthalpy systems were studied, one with an attached shock and the other with a detached shock. The probe system having a detached shock was not scaled to sample sufficient mass flux at the low densities and, therefore, produced no meaningful data. However, with the attached shock-probe-system centerline total enthalpy up to 98 Mjoule/kg in air, nitrogen, and argon was measured. The error in these measurements is estimated to be less than 12%.