Combustion and extinction of PMMA cylinders during depressurization in low-gravity

Combustion and extinction behavior of a diffusion flame over polymethyl met hacrylate (PMMA) cylinders during depressurization in low gravity are exami ned experimentally and via numerical simulations. Low-gravity conditions we re obtained using the NASA Lewis Research Center's reduced-gravity aircraft . Effects of reduced pressure and transient depressurization on the visible flame are examined. The flammability of the burning solid is determined as a function of pressure and solid phase center temperature at constant velo city; as the solid-phase temperature increases, the extinction pressure dec reases. The numerical model assumes a two-dimensional model with a quasi-st eady gas phase and an unsteady solid phase. A parametric study is conducted to examine the effects of forced flow, heating of the solid phase, and dep ressurization rates on the extinction boundary. One case with conditions si milar to the low-gravity aircraft experiments is presented in detail. The p redicted extinction boundaries from the parametric study are quasi-steady i n nature and could be relevant to the International Space Station's fire fi ghting scenario. Published by Elsevier Science Ltd.