Infrared temperature measurements on 3D objects with surface recession

Abstract

The VKI Plasmatron is the world's largest inductively coupled plasma facility, which allows to reproduce on ground the high-enthalpy, chemically reacting boundary layer over a re-entry body. Test conditions are suitable for qualification of re-entry thermal protection systems and for material response characterization. Infrared thermography provides a valuable mean of non-intrusive surface temperature measurement on the test sample materials. However, infrared data are available in the form of two-dimensional images, while the test object usually has a three-dimensional shape. Moreover, the test material can undergo significant surface recession when exposed to the plasma flow. In this work, we propose a novel methodology to reconstruct three-dimensional temperature maps on a receding surface. First, an optical calibration technique is used to provide the necessary mapping parameters between the real world coordinates and the IR camera image pixels. Then, an auxiliary measurement of surface recession allows to determine the time evolution of the object shape. The surface temperature is hence reconstructed on the inferred time-varying geometry.

3D infrared temperature maps measurements of ablative materials during plasma wind tunnel experiments

“…In this paper we build on our previous findings [34,35] to develop a robust technique for IR metrology in PWTs that allows to reconstruct time-resolved three-dimensional temperature maps over the ablating surface of a material sample exposed to the plasma flow. The novelty of this work exists in two main aspects.…”