PI(s): J.I. Frankel and M. Keyhani University of Tennessee-Knoxville (UTK)
A transformative calibration methodology is proposed for predicting the surface heat flux based on in-depth temperature measurements. Instrumenting interior locations of a test article is often necessary in order to alleviate the sensor's direct exposure to a hostile environment. A physics based and mathematically derived calibration framework is proposed for studying a variety of heating conditions that appear in aerospace applications. This investigation integrates analytical and experimental activities in a complementary manner for verifying the science of inverse prediction over a large temperature range and under various heating scenarios. The calibration concept substantially reduces systematic errors since it does not require the specification of the probe position, probe characteristics, and thermophysical properties. Full system characterization is inherently contained in the resulting calibration equations. Being ill posed, a new regularization method is proposed for stabilizing the numerical predictions. Ill-posed problems are highly sensitive to noise in the collected data. This new, local-future time approach exploits the behavior of the calibration equation for extracting an optimal prediction. This unique characteristic may be a consequence of the novel calibration formulation. Experimental verification of the derived calibration equations will be performed using either an electrically heated sandwich facility or high-powered laser facility that are both maintained at UTK. Multidimensional and multi-regional geometries; and, isotropic and orthotropic material samples will be studied owing to their importance in the aerospace sciences for thermal protections systems associated with external skins of hypersonic vehicles and surfaces in hypersonic combustors. This research is focused on developing methodologies that can use in-depth temperature data to accurately predict the surface heat flux for material evaluation and locating transition.
This project will provide new insight into inverse problems through an integrated analytical and experimental approach based on producing calibration equations. This contrasts the conventional doctrine that views experimental data as input to a numerical method for estimating the surface conditions. Hence, the proposed concept can be expanded to a large class or arena of problems affecting many areas of physics and engineering including fire and combustion sciences; metal casting, crystal growth, and welding sciences. Additionally, several European institutions will be involved in the overall plan indicating the merit and significance of the approach to future high-speed aerospace studies.
