Notes on the use of fusible temperature indicators to bound the temperature of hot graphite in the NAVSWC hypervelocity wind tunnel facility

Temperature sensors, which indicate by melting whether or not a particular temperature level has been reached, were used to determine upper and lower bounds on the peak operating temperatures of a clamping fixture that is made of graphite. The clamp secures an electrically powered carbon-carbon heating element to its graphite support base in a pressure vessel that is part of the hypervelocity wind tunnel located at the US Naval Surface Warfare Center in Silver Spring, Maryland. During wind tunnel testing the clamp was exposed to an extremely hostile environment that included: temperatures to 3700°C (6700°F), intense thermal radiation, pressure to 22500 psi, hot chemically reactive carbon and carbon vapor, electrified parts, stray electromagnetic fields, and an intense aerodynamic loading