Influence of Catalysis and Oxidation on Slug Calorimeter Measurements in Arc Jets

for Specialists’ Meeting AVT-199 /RSM-029 -on Catalytic Gas Surface Interactions Influence of Catalysis and Oxidation on Slug Calorimeter Measurements in Arc Jets Anuscheh Nawaz*, Dave Driver**, Imelda Terrazas Salinas*** *Anuscheh Nawaz, Sierra Lobo Inc., Thermophysics Facilities Branch, NASA Ames Research Center, MS 229-4, Moffett Field, CA **Dave Driver, Reacting Flow Environments Branch, NASA Ames Research Center, MS 230-2, Moffett Field, CA ***Imelda Terrazas Salinas, Thermophysics Facilities Branch, NASA Ames Research Center, MS 229-4, Moffett Field, CA Introduction and Motivation Arc jet tests play a critical role in the characterization and certification of thermal protection materials and systems (TPS). The results from these arc jet tests feed directly into computational models of material response and aerothermodynamics to predict the performance of the TPS in flight. Thus the precise knowledge of the plasma environment to which the test material is subjected, is invaluable. As one of the environmental parameters, the heat flux is commonly measured. The measured heat flux is used to determine the plasma enthalpy through analytical or computational models. At NASA Ames Research Center (ARC), slug calorimeters of a geometrically similar body to the test article are routinely used to determine the heat flux. A slug calorimeter is a thermal capacitance–type calorimeter that uses the temperature rise in a thermally insulated slug to determine the heat transfer rate, see Figure 1(left). Current best practices for measuring the heat flux with a slug calorimeter are described in ASTM E457 – 96 . Both the calorimeter body and slug are made of Oxygen Free High Conductivity Copper, and are cleaned before each run. Figure 1 (left) Example of hemispherical slug calorimeter used to determine heat flux. (right) Color change of slugs exposed to different arc jet conditions suggests oxidation of