In-situ 3D shape and recession measurements of ablative materials in an arc-heated wind tunnel by UV stereo-digital image correlation

摘要： In-situ three-dimensional (3D) ablation shape and recession measurements of ablative materials of hypersonic vehicles in high-temperature wind tunnel tests are essential to understand the ablation performance of these materials, which can provide necessary information for better thermal protection system (TPS) design. In this work, a novel ultraviolet stereo-digital image correlation (UV stereo-DIC) technique is proposed for in-situ measurements of 3D ablation shapes and recession in ablation tests. Specifically, a self-developed UV stereo-DIC system, combing a monochromatic UV illumination, two bandpass filters and two UV cameras, is first established. Using the UV stereo-DIC system, strong thermal radiation emitted from the heated sample and the heating device can be effectively suppressed. Natural textures formed from illuminating the rough sample surface by UV light are used as speckle patterns in stereo-correlation. In-situ 3D ablation shapes of a blunt cone subjected to arc heating were measured with a temperature range of 1000 °C to 1868 °C, and the UV stereo-DIC measurements showed good agreement with post-test measurement of the recession of the test articles. Based on the experimentally measured 3D shapes, several key parameters, such as full-field recession, dynamic recession rate, were calculated. The results demonstrate the efficacy and potential of UV stereo-DIC for 3D shape and recession measurements in ablation tests.