Evaluation of Reusable Thermal Protection System Materials Using a High-Velocity Oxygen Fuel Torch

We studied a candidate TPS (thermal protection system) material for reusable re-entry space vehicle applications. The material was based on a high-temperature-resistant material called Cerakwool. A total of six specimens were fabricated with substrate densities of 0.45 g/cm(3), 0.40 g/cm(3), and 0.35 g/cm(3), with two specimens for each density. All specimens were coated with high-emissivity TUFI (toughened unpiece fibrous insulation), with coating thicknesses ranging from 445 to 1606 mu m. The specimens were tested using an HVOF (high-velocity oxygen fuel) material ablation test facility. For each density specimen pair, one specimen was tested at 1 MW/m(2) and the remaining one was tested at 0.65 MW/m(2). The average stagnation point temperature for specimens tested at 1 MW/m(2) was similar to 893 degrees C, approximately 200 degrees C higher than those tested at 0.65 MW/m(2). This suggests a similar to 200 degrees C increase in stagnation point temperature for a 0.35 MW/m2 rise in incident heat flux. During the tests, internal temperatures were measured at three locations. For all tested specimens, regardless of heat flux test conditions and density, the temperature at similar to 40 mm from each specimen's stagnation point remained around or below 50 degrees C, well within the 180 degrees C design limit set for the TPS back face temperature. Post-test visual inspections revealed no signs of ablation or internal damage, confirming the material's reusability.