2021-06-232021-06-237/12/2021ICES-2021-102https://hdl.handle.net/2346/87098Maria Thomsen, University of California BerkeleySonia Fereres, AbengoaLuca Carmignani, University of California BerkeleyCarlos Fernandez-Pello, University of California BerkeleyGary A. Ruff, NASA Glenn Research CenterDavid L. Urban, NASA Glenn Research CenterICES509: Fire Safety in Spacecraft and Enclosed HabitatsThe 50th International Conference on Environmental Systems was held virtually on 12 July 2021 through 14 July 2021.The spread of flames over the surface of solid combustible materials has been widely investigated and is known to be affected by environmental conditions. Variables such as flow condition, oxygen concentration, ambient pressure, and partial or microgravity, may change the material flammability and influence the fire dynamics. This is a critical fire safety issue for space exploration vehicles and future habitat atmospheres which will very likely have reduced pressure and enriched oxygen concentration environments, different than those currently used on the International Space Station. However, testing experimentally the materials to be used and qualified for space exploration under these conditions is a cumbersome and expensive task. The objective of this work is to provide a better understanding through numerical modeling of the dominant physico-chemical processes on the concurrent flame spread over thin fabrics under reduced ambient pressure (and in turn, buoyancy) under variable gravitational conditions. Numerical modeling is performed using the Fire Dynamics Simulator (FDS6) code with a single-step Arrhenius reaction rate for the solid phase decomposition. Different models are tested for the gas phase combustion kinetics. The model results are validated with experimental results obtained at similar reduced ambient pressure and flow conditions at 1 g. It is shown that as ambient pressure is reduced the flame spread rate over a thin fabric is also reduced, both experimentally and numerically. Numerical results are compared to an analytical approach previously developed to explain the experimental trends. Further interpretation of the model results provides information regarding the physics of the process and how they are affected by the lower pressure environments. The results of this work provide guidance for potential on-earth testing for fire safety design in spacecraft and space habitats.application/pdfengFlame spreadbuoyancyambient pressureFDS modelingPresentation