All-Ceramic Heat-Flux Sensor for Continuous Measurement Under High Temperature and Harsh Environmental Conditions

Abstract

In this study, an all-ceramic heat-flux sensor with high temperature resistance and no water-cooling system was designed to address the problems of short effective lifespan and low sensitivity of heat-flux sensors under harsh ultra-high temperatures and high heat-flux conditions. The sensor components comprised high temperature resistant ceramic materials, that is, alumina (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ), indium tin oxide (ITO)-In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thermopile, and nano SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Structural parameters of the proposed heat-flux sensor were optimized via simulations. A high-temperature test platform was built to evaluate the sensor performance; the sensor exhibited an excellent thermoelectric performance. The output voltage of the sensor reached 9.96 mV at 1300 °C, and the average sensitivity in the range of (50–340) kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was 31.5 μV/(kW∙m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ). The drift rate of the proposed sensor in the high-temperature maintenance experiment at 1200 °C for 5 h was 2.7 (kW/m²)∙h <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The time constant of the sensor under pneumatic heating was 2.3 s. The proposed sensor can continuously work at ultra-high temperatures; therefore, it can be practically employed in the heat flux measurement of turbines and supersonic aircrafts.