Arc-Tunnel Stagnation Enthalpy Measurements Utilizing the Copper-Line-Ratio Method Corrected for Self-Absorption Effects

摘要

Detailed measurements of the copper emission spectrum at 5106 A and 5153 A were obtained while observing radiation from the free-stream and model nosecap regions of an arc-heated wind tunnel flow. The ratio of peak line intensities and the absolute width of the 5106 A line were used to infer gas temperature (i.e., enthalpy) and copper density corrected for self-absorption effects. Line shift measurements were also obtained in order to corroborate the use of Lindholm's collision broadening theory in the self-absorption analysis. Final enthalpy results for the peaked profile mode of operation indicated that a significant correction to measured enthalpy resulted when self-absorption was taken into account. The resulting average stagnation enthalpy value of 5250 Btu/lbm was in good agreement with previously obtained results utilizing a combined heat flux and ptiot probe technique. (Author)