Near-Surface Vapour Bubble Layers in Buoyant Low Stretch Burning of Polymethylmethacrylate

摘要

Large-scale buoyant low stretch stagnation point diffusion flames over a solid fuel (polymethylmethacryalte) were studied for a range of aerodynamic stretch rates of 2-12 s~-1 which are of the same order as spacecraft ventilation- induced stretch in a microgravity environment. An extensive layer of polymer material above the glass transition temperature was observed. Unique phenomena associated with this extensive glass layer included substantial swelling of the burning surface, in-depth bubble formation, and migration and/or elongation of the bubbles normal to the hot surface.