A flammability test method for spacecraft materials screening is proposed based on a confined opposed flow flame spread geometry. The basic approach has been proven by flowing oxidizer through transparent PVC tubing open to the atmosphere and applying an ignition source to the inner surface. For flammable conditions for this geometry, a flame propagates at a measurable speed against an opposed oxidizer flow. Atmospheric pressure results at various inner diameters reveal that buoyancy effects are suppressed at intermediate diameters, which is an important consideration for space applications. Effects of oxygen concentration and inert diluent type show the strong role of flame temperature and thermal diffusivity on the flame spread process. This method can be extended to allow for routine material flammability tests at various pressures and oxidizers, especially those considered for future space exploration atmospheres at elevated oxygen and reduced pressure applications. Materials to be tested are formed into a tube through which the flame will propagate. A thermocouple array will be developed to track the flame spread rate, and its measurement of spread rate will be compared with video imaging of flame spread rate for transparent materials.
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