High-Sensitivity Atomic Layer Thermopile Heat- Flux Sensor and Its Application in Hypersonic Low-Density Wind Tunnel Tests

Measuring the heat-flux density is one of the main tasks in the research field of hypersonic experimental aerodynamics. Considering the fact that refined wind tunnel tests require small-sized sensors, and the sensitivity of atomic layer thermopile (ALTP) heat-flux sensor is dependent on the effective length of the sensitive element, the sensitive elements are connected in series by conductive films. New-generation ALTP sensors with multiply enlarged sensitivities are developed in this study. The general features of new ALTP sensors, including the sensitivity, linearity and amplitude-frequency curves, are obtained by static and dynamic calibration tests. Then a discussion is presented on the tradeoff between high sensitivity and fast dynamic response. Finally, the practice performance of new ALTP sensors is confirmed by experiments conducted in the hypersonic low-density wind tunnel, since the frequently used thin-skin calorimeters and infrared thermographic techniques have the problems of short effective time and low signal-to-noise ratio.