Date of Award
Master of Science (MS)
The classification and study of thermal protection systems (TPS) relies heavily on the accurate measurement of surface temperature. The best way to measure surface temperature in ground test facilities is through optical pyrometery due to the non intrusive nature of this method. Optical pyrometric devices use the emission of a greybody curve to calculate temperatures. These devices are left susceptible to parasitic radiation coming from the plasma generated in ground test facilities. The parasitic radiation comes from the emission lines of the test plasma in the investigation region of the devices. The parasitic radiation from the plasma and short comings of devices negate the ability to accurately measure emissivity in ground test facilities. This work developed testing methods to measure the surface temperature and identify potential sources of parasitic radiation. Measured emission suggests SiC in Ar, ZrB$_2$-SiC-W in air, ZrB$_2$-SiC-W in N$_2$, and POCO in air cases all have near 20$\%$ change in temperature from the Dual Wavelength Ratio Thermography calculated temperature. All other test cases have 10$\%$ change in temperature. This leads to the conclusion that pyrometer in two color mode is 10$\%$ off from the true temperature, save for the cases mentioned near the 20$\%$ change. Temperatures retrieved from pyrometers are hotter than temperature calculated from the experimental emission.For future works temperature readings from the pyrometer should have a temperature buffer applied to them that is dependent on the material and gas composition. For POCO graphite a buffer of 100 K in Argon, 100 K in N$_2$, 300 K in air, and 200 K in CO$_2$ should be applied. For SiC 300 K in Argon, 200 in N$_2$, 150 K in air, and 150 K in CO$_2$. For ZrB$_2$-SiC-W the temperature readings should include a buffer of 150 K in Argon, 200 K in N$_2$, and 300 K in air.
Number of Pages
Plante, Owen, "Surface Temperature Measurement Fidelity in High Enthalpy Plasma Test Facilities" (2023). Graduate College Dissertations and Theses. 1649.