Vaporization of Graphitic Materials at High Mass Transfer Rates
Abstract
The thermochemical sublimation response of ATJ-S graphite in both low and high mass transfer convective environments was studied both experimentally and analytically. ATJ-S graphite models were ablation tested in the NASA Ames Advanced Entry Heating Simulator (AEHS) test facility at 0.1 and 1.0 atmosphere impact pressure test conditions. Ablation tests were run under both subsonic and supersonic flow conditions at both pressures. High quality recession rate and surface temperature from the ablation tests were correlated with various thermochemical ablation predictions. Results from the low subsonic flow conditions (low mass transfer rates) exhibit good agreement with the JANAF thermochemical model for carbon vapor species (C sub 1 - C sub 5). Results from these tests under supersonic flow conditions (high mass transfer) show the data to exhibit slight kinetic sublimation effects compared to JANAF equilibrium sublimation predictions. Extrapolation of the inferred kinetic sublimation effects to the high pressure regime of interest (10 - 300 atmospheres) shows the uncertainty in both surface temperature and recession rates to be less than 1 percent. The conclusion is made that the JANAF equilibrium sublimation model is most appropriate for graphite thermochemical ablation predictions under high pressure reentry conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1976
- Accession Number
- ADB014238
Entities
People
- C. A. Powars
- G. Hartman
- R. E. Maurer
- T. F. Foster