HEAT TRANSFER IN STRUCTURAL HONEYCOMB COMPOSITES AT HIGH TEMPERATURES
Technical rept. Dec 1963-Dec 1964
AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH
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The use of superalloy and refractory alloy honeycomb composites for heat shield and structural components in re-entry vehicle applications is outlined followed by a detailed comparison between experimentally measured and analytically predicted thermal conductance values on superalloy honeycomb composites. The experimental thermal conductance determinations on L-605 cobalt alloy panels of variable geometry were made in high vacuum and air environments using a high temperature absolute thermal conductivity apparatus. Measurements were made over the range from 500 to 2000 F maintaining the temperature drop across the specimens below 200 F. Average precision of the results was plus or minus 7 while the accuracy was established to be plus or minus 10 based on initial calibration. The thermal conductances in air environment were between 60 and 100 above comparable values for the panels tested under vacuum conditions. Analysis of the results indicated that gaseous conduction and convection accounted for only a small fraction of the difference, the main effect being a large increase in the radiative contribution produced by increased emittance of the alloy through surface oxidation.
- Structural Engineering and Building Technology
- Unmanned Spacecraft