Opposed flame spreading along a structured PMMA sample in exploration atmosphere under microgravity



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50th International Conference on Environmental Systems


As part of SAFFIRE V experiments on the ISS supply spacecraft CYGNUS, flame propagation along different surface structures on a PMMA sample was investigated in opposed flow. The sample was 200 x 400 mm (length x width) with a thickness of 10 mm and contained ribs of different widths (1-10 mm), each 3 mm high, on both sides, arranged in the flow direction. The total thickness of the specimen was thus 16 mm for the ribs. For the first 360 s after ignition with a Kanthal wire, the flow velocity was 20 cm/s in the opposed direction. Then the flow velocity was reduced to 5 cm/s for a duration of 300 s before it was switched off to terminate the experiment. The experimental pressure was 761 hPa and the oxygen concentration was 26.9 vol %. These conditions correspond to atmospheric conditions envisioned for future exploration missions. It was found that the flames ignited downstream propagated forward along the rib edges surprisingly fast with up to 0.88 mm/s (1 mm rib width). Also, it was observed that the wider the rib, the slower the propagation. The widest rib (10 mm) already showed two largely independent edge flames. Unintentionally, the experiment showed how sensitive the flames are to small perturbations of the flow field, as remnants of a preceding and upstream experiment disturbed the incoming flow stratification partially.


Christian Eigenbrod, University of Bremen, ZARM
Florian Meyer, University of Bremen, ZARM
Grunde Jomaas, The University of Edinburgh
Sandra Olson, NASA
Paul Ferkul, USRA
David Urban, NASA
Gary A. Ruff, NASA
Balazs Toth, ESA-ESTEC
ICES509: Fire Safety in Spacecraft and Enclosed Habitats
The 50th International Conference on Environmental Systems was held virtually on 12 July 2021 through 14 July 2021.


Fire Safety, PMMA, structured samples, opposed propagation, SAFFIRE