Speaker
Description
Humanity's innate drive for discovery has fueled exploration beyond Earth's boundaries, from landing on the Moon to ambitious missions targeting other planets and celestial bodies. Achieving these goals requires meticulous planning and engineering. Engineering uncertainty tolerances are gaining importance, mainly as mission objectives demand transporting larger payloads, such as life-sustaining equipment for Mars colonization. Spacecraft atmospheric entry poses large failure risk mitigation challenges due to extreme heat loads, with Thermal Protection Systems (TPS) playing a critical role in safeguarding missions. Ablative TPS materials, which degrade to protect spacecraft, can account for up to 50% of the total vehicle mass, impacting payload capacity. To address this challenge, NASA developed the lightweight Phenolic Impregnated Carbon Ablator (PICA) [1] in the 1990s. PICA has since been successfully utilized in missions like Stardust (2006), Mars Science Laboratory (2012) [2], and Mars 2020 [3].
The interactions between the aerothermal environment and the material result in highly coupled, multi-physics problems that are critical challenges in optimizing design margins and mission risk. These complex issues involve coupled multiple physical phenomena, such as heat transfer, material degradation, structural integrity, etc. posing critical challenges in optimizing design margins and mission risk. A significant challenge remains in understanding the material response in off-design scenarios when the TPS is subjected to unpredicted conditions not captured by ground experiments. These off-design scenarios include the possibility of TPS cavities on the shield that are generated by micrometeoroids and orbital debris (MMOD) impact [4]— an alarming issue due to the significant increase in space debris— or internal cracks propagation due to internal pressure build-up [5].
Enabling design by analysis requires the development of high-fidelity tools that couple flow and material behavior. A main challenge lies in developing suitable and robust numerical techniques that accurately track the material interface and in defining proper boundary conditions that capture material degradation [6]. The material response in the presence of defects introduces added complexities, such as augmented heating, pyrolysis gas flow driven by pressure gradients, alterations to heat conduction due to material anisotropy, etc. A main concern with MMOD impact while in transit include gas flow through porous cavity walls and potential mechanical material failure.
In this work, we study TPS defects using a one-domain porous media model [7] based on the volume-averaged Navier-Stokes (VANS) equations [8]. We generalize the governing equations to solve the flow field and the material in a unified approach [9]. The strong coupling between each phase mitigates modeling assumptions in conjugate heat-transfer coupling. This allows for a natural progression of the material interface due to heterogeneous reactions and the blowing of pyrolysis gases from the porous material without the need for complex boundary conditions.
During the lecture, we will show a series of TPS defect test cases under extreme spacecraft entry conditions utilizing the one-domain porous media model.
| References | [1] Tran, H.K., Johnson,C .E., Rasky, D.J., Hui, F.Y.C., ta Hsu,M.,Chen, T.S., Chen, Y.-K., Paragas, D., and Kobayashi, L., “Phenolic Impregnated Carbon Ablators (PICA) as Thermal Protection Systems for Discovery Missions,” NASA TM-110440, 1997. [2] Willcockson, W.H., “Stardust Sample Return Capsule Design Experience,” Journal of Spacecraft and Rockets, Vol.36, No.3, 1999, pp. 470–474. [3] Edquist, K.T., Hollis, B.R., Johnston, C.O., Bose, D., White, T.R., and Mahzari, M., “Mars Science Laboratory Heat Shield Aerothermodynamics: Design and Reconstruction,” Journal of Spacecraft and Rockets, Vol. 51, No. 4, 2014, pp. 1106–1124. [4] Christiansen, E. L., Arnold, J., Davis, A., Hyde, J., Lear, D., Liou, J.-C., Lyons, F., Prior, T., Ratliff, M., Ryan, S., Giovane, F., Corsaro, B., and Studor, G., “Handbook for Designing MMOD Protection,” Technical Report TM-2009-214785, NASA Johnson Space Center, Houston, Texas, June 2009. [5] NASA Identifies Cause of Artemis I Orion Heat Shield Char Loss https://www.nasa.gov/missions/artemis/nasa-identifies-cause-of-artemis-i-orion-heat-shield-char-loss/ [6] Schroeder, O., Shrestha,P., Palmer G., Stern, E. and Candler, G. V. “Material Response Modeling of MMOD Cavities”, AIAA SCITECH 2022 Forum, AIAA 2022-1908 [7] Valdes-Parada, F. J. and Lasseux, D. “A novel one-domain approach for modeling flow in a fluid-porous system including inertia and slip effects”. Physics of Fluids, 33(2):022106 [8] Quintard, M. and Whitaker, S., “Transport in ordered and disordered porous media II: Generalized volume averaging.” Transport in Porous Media, 14(2):179–206 [9] Dias, B., Panerai, F., Meurisse, J. B. and Mansour, N. N., “Numerical Simulation of FiberForm Using a Unified Flow-Material Approach: A Comparison With Flow-Tube Reactor Experiments”, AIAA AVIATION FORUM AND ASCEND 2024, AIAA 2024-3907 |
|---|---|
| Country | USA |
| Acceptance of the Terms & Conditions | Click here to agree |
