Thermal Engineering of Mars Entry Carbon/Carbon Non-Ablative Aeroshell - Part 2

Candidate Aeroshell Test models composed of a quasi-isotropic Carbon/Carbon(C/C) front face sheet (F/S), eggcrate core, C/C back F/S, Carbon Aerogel insulation, C/C radiation shield and the C/C close-out were constructed based on the analytical temperature predictions presented in Part One of this work[1]. The analytical results obtained for a simulated Mars entry of a 2.9 meter diameter cone shaped Carbon-Carbon Aeroshell demonstrated the feasibility of the design. These results showed that the maximum temperature the front F/S reached during the decent was 1752 °C with the resulting rear temperature reaching 326 °C in the thermal model.

Part Two of this work documents the thermal modeling and correlation for the Mars Aeroshell test sample and fixture. A finite difference, SINDA/G, thermal math model of the test fixture and sample was generated and correlated to data from an arc jet test conducted at the NASA Ames Research Center's interactive heating facility. A transient thermal analysis was executed for 175 seconds to simulate the heating and part of the cooldown of the sample. Heat transfer coefficients and convective couplings were varied to achieve a good correlation. Results showed that after 45 seconds of heating, the predicted arc jet temperatures versus test data for the front face-sheet were 1396°C versus 1412°C, the predicted temperatures versus test data for the copper coated face-sheet were 1275°C versus 1302°C and the predicted temperatures versus test data for Aerogel core rear surface were 41°C versus 75°C.