A novel method for dynamic heat flux measurement based on the double-layer thin film microsensor: Mathematical modelling and experimental verification

Heat flux is a fundamental parameter for investigating the thermal load and protection of high-temperature components in aerospace, whose accurate and efficient measurement over extended durations is of vital significance. Existing thin-film heat flux sensors exhibit slow response through steady-state calculations, while transient heat flux models involve complex formulas and struggle to provide accurate long-term measurements. Hence, this work presents a novel method for dynamic heat flux measurement based on a thin film microsensor, mainly consisting of a thermal resistance layer and two sensitive layers. A mathematical model is established that discerns the heat transfer state of the resistance layer and computes the heat flux by tracking instantaneous temperature fluctuations across both sides of the sensor over time. Utilizing MEMS technology, sensor prototypes are fabricated to conduct experimental verification. The static and dynamic calibration indicates a response time of 80 μs, a sensitivity of 0.189 °C/(kW/m²), and an operational capability of up to 350 °C for the sensor based on the presented calculation model. Subsequent wind tunnel experiments successfully validate the capability to monitor heat flux variations on the surfaces of turbine blades and aircraft wings. This work provides a promising application prospect for the rapid and precise long-term measurement of high-frequency dynamic heat flux.