D131 Difference of Extinction Limit of Spreading Flame over Polyethylene Insulated Wire Between Opposed Air Flow and Concurrent Air Flow

Tests with flames spreading over wires in microgravity were performed at external opposed flow and concurrent flow conditions to examine the influence of flow direction on the extinction limit. In the experiments, low density polyethylene insulated Nickel-chrome and Copper wire samples were used. The experiments were conducted both in normal gravity and microgravity. Limiting Oxygen concentration (LOC) of microgravity is lower than that of normal gravity because of inhibited natural convection. LOC of Nickel-chrome is lower than that of Copper because of difference of heat conduction loss. The minimum LOC of concurrent flow is smaller than that of opposed flow in the range of 1-2%.