PREDICTIVE MODELS FOR HIGH TEMPERATURE FIBROUS INSULATION
Abstract
Thermal insulation is essential for high temperature (Tgreater than 1000 K) applications where extreme operating conditions are found, as the case of re-entry aerodynamic heating. Given its mechanical, optical and economical characteristics, refractory ceramic-based fibrous materials are widely used. Due to the complex interaction of phenomena, the heat transfer in these materials is described using semi-empirical models, where some physical and structural properties are replaced for experimental determined parameters. The main limitation of this approach is that the empirical parameters must be determined for each possible material and must be determined again, even for the same material, if the physical structure is modified i.e., if properties as fiber size or bulk density change, which is undesirable from the point of view of the design and engineering. An interesting alternative is the use of the Electromagnetic Wave Theory to calculate the radiative properties considering distribution, size and orientation of the fibers. Previous research in the field has shown promising results at moderate temperature. However, this approach has not yet been evaluated in refractory ceramic-based insulators at high temperatures and vacuum and its application is restricted to long fibers of single materials which limits its effectiveness on composite insulators as Opacified Fibrous Insulations (OFI). In this project a model for heat transfer based on physical and structural properties of refractory ceramic-based insulators and composite materials will be developed and evaluated. The properties of the specimens will be measured independently using spectroscopic techniques. The model will be validated through measurement of effective thermal conductivity for temperatures between 25 degrees C to 1600 degrees C in vacuum and standard atmospheric pressures.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 06, 2024
- Source ID
- FA95502310335
Entities
People
- Jose Ramirez
Organizations
- Air Force Office of Scientific Research
- National University of Colombia
- United States Air Force