Synchronous measurement of temperature and deformation by an ultraviolet imaging system and monochromatic pyrometry at extreme temperatures

摘要

Synchronous measurement of temperature and deformation at elevated temperatures is highly critical, yet challenging in evaluating mechanical properties of thermal protection systems. An ultraviolet (UV) imaging system is proposed to obtain noncontact, in situ, synchronous, and full-field temperature and deformation. The established system consists of a monochromatic UV illumination with a bandpass filter for radiation suppressing, a UV CCD camera for image capturing, and an infrared pyrometer for temperature recording. Additionally, an improved monochromatic radiation pyrometry method is proposed, while a deformation measuring method using the UV digital image correlation (UV-DIC) and natural textures-generated speckle is introduced. Furthermore, through camera calibration at room temperature and real-time exposure time adjusted at elevated temperatures, the influence of reflection on radiation pyrometry and unfiltered radiation on DIC analysis is eliminated. Synchronous temperature and deformation fields of C/SiC subjected to flame heating are experimentally measured with a temperature range of 500 degrees C-1500 degrees C, and results demonstrate the efficacy and potential of the proposed system and method. Finally, the importance of exposure time on balancing the light intensity of radiation and reflection is also discussed. (C) 2021 Optical Society of America