Graphite Shear Stress Measurements in the Fairfield Ludwieg Tube

Graphite shear stress sensors are proposed for use in test articles subjected to high-speed flow. Analyses for extracting shear stress and heat flux data from the graphite sensors are presented. Preliminary results are provided for a stretch sensor for loads in the ranges of 0-2.2 N and 0-0.08 N. A thermocouple sensor, composed of two grades of graphite, was also tested, measuring heating rates of 0.005 W, which corresponds to a heat flux of approximately 20-40 W/m^2. An unanticipated result in this sensor development was the identification of a thin-film thermistor, which can be used to measure heat flux with minimal noise. Work on an erosion sensor is still in progress. More work is needed to improve the response time of and reduce the noise in the sensors. More time is needed to incorporate them in the Fairfield Ludwieg Tube.