Laboratory Experiments on the Effects of Wind Direction on Behavior of Fire Whirls Downwind of Fire

Fire whirls cause destructive damage in and around large fires such as wild fires and city fires. In flat terrain they frequently have been observed downwind of fires. We investigated the effects of wind direction on behavior of fire whirls that occur downwind of a rectangular fire source. The experiments were performed on a horizontal artificial floor. Ten fuel pools with an inner size of 297 x 297–mm were placed in two rows in contact with each other flush with the floor at right angles or parallel to the wind. Total size of pools was 600 x 1510-mm. Methanol was used as the fuel. The fire whirls were visualized using a smoke wire flow visualization technique because the fire whirls considered in this study were air vortices. Fire whirl behavior for each wind direction is compared and formation mechanism of fire whirls is discussed.