Rigorous Characterization of an Advanced Instrumented Aluminum Nitride (AlN) Electrical Heater for High-Heat Flux and High-Temperature Aerospace Applications

摘要

High-speed, transient aerothermal studies produce excessive temperatures and heat fluxes in laboratory-, ground- and flight-test experiments. Experiments are performed for (1) understanding the response of test vehicles under various induced thermal environments; (2) verifying computational codes and input parameters; and, (3) evaluating thermophysical and mechanical characteristics of new materials. In addition to these rationales, the reconstruction of the surface heat flux from in-depth or backside instrumentation is an important inverse application. At the University of Tennessee, research has led to an alternative view of inverse heat conduction based on calibration principles performed in the frequency domain leading to a novel "parameter free" inverse heat conduction measurement equation. The final mathematical framework reveals that the resolution of a first kind Volterra integral equation for the surface heat flux prediction containing only experimental data sets. This type of mathematical formulation is highly ill-posed and subject to instability issues. This paper focuses on the design, fabrication and preliminary test campaign of a new electrical heating cell for producing a verifiable heat flux source that was designed about limited resources. The feasibility investigation demonstrates the merits of system modeling, experimental design, and a comprehensive test plan. Validation studies are presented leading to favorable outcomes. Slug calorimetry composed of pure copper is used in the validation campaign.