Effect of Fiber Reactivity and Permeability on Mass Loss and Surface Recession in Ablative Thermal Protection Systems

Grants and Contracts Details


Ablative Thermal Protection Systems in atmospheric re-entry vehicles typically utilize a carbon phenolic material to reduce heat flux into the inner surface of the craft. This material undergoes pyrolysis at extreme temperatures and ejects its material into the surrounding environment. This behavior is governed by both the reaction limited regime, the ability of the carbon fibers to oxidize, and the diffusion limited regime, which is defined by the amount, or lack thereof, of oxygen to react. Previous studies focused on either one of these regimes or the other. Focusing on the reaction limited regime typically utilizes a model that allows oxygen to penetrate the material and react inside the heat shield. This model allows a connection to be made between permeability and mass loss, but does not have an accurate bearing on surface recession. Alternatively, models of the diffusion limited regime allow for accurate observation of surface recession, but lack accuracy in observing overall mass loss. The relationship between fiber reactivity and initial permeability to both overall mass loss and surface recession is, as yet, undefined. The research proposed would seek to obtain this relationship through utilization of a sophisticated material response code and verification with previously obtained experimental data. The results could then be integrated into better design of Thermal Protection Systems in the future.
Effective start/end date1/1/1512/31/15


  • National Aeronautics and Space Administration


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