New Paradigms for Inverse Heat Conduction Problems: Creative analytics and experiments utilizing advanced technologies

University Of Tennessee Knoxville, Knoxville TN

Investigators

Abstract

This project allows for the systematic investigation of problems that are highly elusive and difficult to solve owing to harsh thermal environments. These conditions appear in high-speed flight, combustion, material processing, airplane and automatic brakes, chemical and energy processes, fire research, geophysical sciences, and defense and national security applications. These applications render a difficult situation for surface instrumentation needed for interpreting engineering quantities of interest. As such, the methods under development at the University of Tennessee, Knoxville allow for in-depth or backside analyzes to be performed rendering the surface temperature and heat flux caused by the harsh environment. The proposed approach is both transformative and possesses a natural broader impact to other areas of engineering as it represents a new paradigm. Both computational and experimental studies will be performed indicating the merit of the methodology and a newly designed small sample test facility. Further, the research findings will be incorporated into undergraduate and graduate courses for enhancing creative problem solving. A short-course and workshop will be developed for presentation at universities; conferences; and, available to interested industries for assuring an international competitive edge. This project offers transformative analytical concepts and novel experimental developments for resolving inverse heat conduction problems applicable to both classical (parameters required) and calibration (parameter free) formulations. Experiments are designed based on component validation in the edifice of calibration test facility. Inverse analysis is receiving significant attention as applications are becoming extreme and thus creating instrumentation nightmares. High temperature and high heat flux applications can significantly damage surface instrumentation rendering it either useless or unreliable for future interpretation. Such situations arise where reliable surface assessments are fundamental to understanding the physical situation. This project promotes the development of new formulations for both linear and nonlinear studies that require experimental verification. Experimental verification is based on developing a small sample, open architecture test facility that allows for air, inert gas and light vacuum conditions using the latest instrumentation and heating sources. A benchmark quality test facility will be designed, fabricated and tested applicable to the aerospace and mechanical engineering communities. New high temperature and high heat flux electrical heaters represent the fundamental heating element. These heaters are composed of aluminum nitride with tungsten traces that are fully integrated with RTD?s in a thin package. Careful component studies can be initiated to accurately quantify the heat flux in a designed configuration. Thin film thermocouples will be adhered to the test specimen for estimating the surface temperature during the system calibration. The front condition, i.e., surface temperature and heat flux, will alternatively be estimated using a pulse-echo ultrasonic transducer for measuring round-trip time. Conventional inverse heat conduction is predicated on the availability of in-depth instrumentation and requires the specification of thermophysical and geometrical properties; and, sensor characteristics. Quantification of thermophysical properties and sensor characteristics is costly and requires a significant time effort. Insight gained from understanding a calibration view can be applied for improving classical inverse methods. In-house, calibration reduces costs and time delays if a test facility can be designed for turn-key results. Integrating acoustic instrumentation into the calibration approach is novel and will lead to accurate surface temperature and net heat flux predictions based on an opposing-side measurement.