NASA EPSCoR: Improving Heat Shields for Atmospheric Entry: Numerical and Experimental Investigations of Ablative Thermal Protection System Surface Degradation Effects on Near-Wall Flow

Grants and Contracts Details

Description

Advancing space exploration, including new interplanetary spacecraft and recent commercial orbital spaceflight successes, exposes the need to improve technologies for safe atmospheric entry. The “friction” generated by a planet's atmosphere is an efficient way to decelerate a vehicle for safe landing. The kinetic energy of the spacecraft is rapidly transformed into heat and convected into the adjacent gas. Because a fraction of that energy still reaches the vehicle, its surface must be shielded from excessive heat via a Thermal Protection System (TPS). Current TPS technology constrains the size and speed of future spacecraft due to mass and temperature limits. The 2012 NASA Space Technology Roadmap identified improvement of heat shields as a High-Priority Technology and specifically the TPS spallation phenomenon as a key to understanding Thermal Management in the Top Technical Challenges. We propose an integrated multi-dimensional research program to improve understanding of atmospheric entry physics, enabling innovation in TPS development. This research will improve our ability to model and predict deterioration of the re-entry vehicle TPS and associated effects on the surrounding flow field. Specifically, we seek to investigate surface oxidation and spallation within the material and effects on the near wall flow, as well as impacts that surface roughness and momentum injection via pyrolysis gases have on boundary layer turbulence structure and transport. The chemical composition of the boundary layer will also be examined by taking into account effects of spalled particles ejected from the ablated surface. Numerical simulations will be performed using an in-house hypersonic CFD code coupled with ballistic particle tracking capabilities and a material response code. The computational efficiency of this code will be improved by incorporating GPU-based acceleration techniques. Recent data obtained from the Mars Science Lab TPS confirms the need to better understand the interaction of the flow field with the ablated surface. The effects of spalled particles on the flow field are not well known, and the proposed study will provide the underlying tools to do so. This research will be conducted in close collaboration between academic and NASA partners. Experiments will be conducted in various facilities including a specialized wind tunnel at the University of Kentucky as well as the HYMETS facility at NASA Langley Research Center. Researchers at NASA Langley will provide data collected while conducting arc-jet experiments in which surface spallation is observed. Researchers at NASA Ames will collaborate in development of material response codes and researchers at NASA Johnson will collaborate with implementation of coupling methods, a key issue for integration of turbulence models into the numerical code. In Kentucky, we will develop important computational models of atmospheric entry, build a unique experimental infrastructure, leverage a new supercomputer facility, increase specialized knowledge of early career faculty, and generate collaboration with the state’s only minority-serving institution. The TR-PIV system is state of the art, providing a significant infrastructure investment that increases the flow-field measurement capabilities and supports future research funding success. The work aligns with the 2012 Kentucky Science and Innovation Strategy priority for High-Value Research and Development. All four NASA Mission Directorates benefit by advancing aeronautics and space launch capability, helping NASA overcome high-priority technical challenges, and aiding scientific research via improved landing systems for heavier scientific instruments. It has potential to assist NASA Technology Demonstration Missions and Commercial spaceflight partnerships, improve safety for future astronauts and space passengers, and enable potential spinoff technology for U.S. industries.
StatusFinished
Effective start/end date9/1/138/31/17

Funding

  • National Aeronautics and Space Administration: $705,000.00

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