Emission spectroscopy measurements in the post-shock layer in front of low density ablative material samples of different shapes were obtained in the NASA Langley HYMETS arcjet facility. A horizontal line of measurement positions was imaged on the entrance slit of the spectrometer allowing detection of the entire stagnation line in front of the samples. The stagnation line measurements were used to compare the post-shock layer emission signatures in front of PICA and FiberForm. The emission signatures of H, NH, and OH are characteristic for pyrolysis gases and consequently were only observed in front of the PICA samples. CN and C were found in front of both materials and are mainly due to interactions of the carbon fibers with the plasma. In all tests with instrumented samples, the emission of Mn, Cr, and Ni was observed when the thermocouple temperatures reached or exceeded ~1, 500 K, strongly indicating erosion of the molten thermocouple tips. Temperatures in the post-shock layer were estimated from comparing the CN band emission to spectral simulation. The resulting rotational and vibrational temperatures were on the order of 7, 000 to 9, 000 K and close to each other indicating a plasma condition close to equilibrium. In addition to the stagnation line configurations, off-axis lines of observation were investigated to gather information about spalled particles in the flow. From a comparison of measured continuum emission with simulated Planck radiation, average particle temperatures along the measured line of observation were determined for two cases. Particle temperatures between 3, 500 and 2, 000 K were found. A comprehensive investigation of the entire amount of data set is ongoing.
|Published - Jun 13 2016
|46th AIAA Thermophysics Conference, 2016 - Washington, United States
Duration: Jun 13 2016 → Jun 17 2016
|46th AIAA Thermophysics Conference, 2016
|6/13/16 → 6/17/16
Bibliographical noteFunding Information:
Financial support for the experimental work at NASA Langley and the spectral analysis was provided by NASA Kentucky EPSCoR Award NNX10AV39A. The authors would like to thank M.J. Wright, N.N. Mansour, G. Gonzales, J. Wang, J. Seibert, and J. Mach from NASA Ames Research Center for their support, F. Taylor and H. Mefford at the University of Kentucky for their assistance in designing and machining many of the components necessary for this project, and H. Koch for his help in preparing the measurement campaign. Finally, the authors are grateful to W. Geouge and J. Gragg for their immense support during testing at NASA Langley Research Center
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ASJC Scopus subject areas
- Aerospace Engineering
- Mechanical Engineering