Heat Transfer in High Temperature Multilayer InsulationHigh temperature multilayer insulations have been investigated as an effective component of thermal-protection systems for atmospheric re-entry of reusable launch vehicles. Heat transfer in multilayer insulations consisting of thin, gold-coated, ceramic reflective foils and Saffil(TradeMark) fibrous insulation spacers was studied both numerically and experimentally. A finite volume numerical thermal model using combined conduction (gaseous and solid) and radiation in porous media was developed. A two-flux model with anisotropic scattering was used for radiation heat transfer in the fibrous insulation spacers between the reflective foils. The thermal model was validated by comparison with effective thermal conductivity measurements in an apparatus based on ASTM standard C201. Measurements were performed at environmental pressures in the range from 1x10(exp -4) to 760 torr over the temperature range from 300 to 1300 K. Four multilayer samples with nominal densities of 48 kg/cu m were tested. The first sample was 13.3 mm thick and had four evenly spaced reflective foils. The other three samples were 26.6 mm thick and utilized either one, two, or four reflective foils, located near the hot boundary with nominal foil spacing of 1.7 mm. The validated thermal model was then used to study relevant design parameters, such as reflective foil spacing and location in the stack-up and coating of one or both sides of foils.
Document ID
20080013560
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Daryabeigi, Kamran (NASA Langley Research Center Hampton, VA, United States)
Miller, Steve D. (Miller (S. D.) and Associates Flagstaff, AZ, United States)
Cunnington, George R. (Cunnington and Associates Palo Alto, CA, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2007
Subject Category
Fluid Mechanics And Thermodynamics
Meeting Information
Meeting: 5th European Workshop on Thermal Protection Systems and Hot Structures