Non-destructive ultrasonic thermometry for internal temperature field mapping in high-speed aircraft structures

A non-destructive ultrasonic-based method is proposed to measure the surface heat flux and internal temperature field of high-speed aircraft structural shells during service. First, a mathematical model for ultrasonic temperature measurement is established, followed by the development of a dedicated measurement system. To meet flight test requirements, the ultrasonic device is upgraded with optimized miniaturization and high-temperature resistance. The experimental scheme is designed, and the ground verification experiment is carried out on the basis of the improved device, and preliminary results validate the reliability of both the ultrasonic method and the measurement instrument. Subsequently, an ultrasonic temperature measurement device is deployed onboard a high-speed aircraft for the first time, enabling real-time determination of one-dimensional temperature distributions along the wall thickness direction and outer wall heat flux at specific measurement points. The results are closely aligned with those obtained from K-type thermocouples. Both ground and flight tests demonstrate that the ultrasonic method effectively captures transient temperature distributions within high-speed aircraft structures, offering a novel, non-invasive solution for thermal parameter measurement and thermal safety assessment.