Preparation and Performance Evaluation of a Miniature High-Temperature Heat Flux Sensor With Centralized Thermal Insulation Structure

The internal hot-end components of aeroengines operate in a high-temperature environment are susceptible to cracks or falling blocks due to thermal fatigue and other effects. The rapid changes in heat flux at these defects can lead to engine failure. We propose a miniaturized sensor capable of monitoring heat flux change in a high-temperature environment. The sensor is based on a thermopile, connected in series with the platinum-10% rhodium/platinum (Pt-Rh10/Pt) thermocouples as the basic unit on a ceramic plate sized 10 x 10 x 1 mm(3). Nanocomposite silicon dioxide is adopted as a thermal insulation material to generate a temperature difference at the hot and cold junctions, which is distributed in the center and results in a thermal voltage output in the millivolt range. The heat flux sensor (HFS) can operate at temperatures up to 1000 degrees C with a good repeatability. The output voltage at a heat flux of 189.6 kW/m2 is 0.4113 mV, and the dynamic response time of HFS is 0.25 s. The screen printing process enables the batch preparation of micro-HFSs for high-temperature device surfaces with small areas.