Fire Safety Science Digital Archive

The rate of burning of fires in enclosures is usually assumed to be proportional to the ventilation factor A?h. This paper reports an experimental program designed to investigate the influence of opening width and enclosure shape on the burning rate by comparing the burning rate and behavior of fires in long enclosures and wide enclosures with similar openings. Fire tests were conducted in enclosures 1500 mm by 600 mm by 300 mm high with ventilation openings of several widths. It was found that the burning behavior and fuel mass loss rates of fires in long and wide enclosures differ markedly when the width of the ventilation opening is less than the full width of the enclosure. When the ventilation opening width is equal to that of the enclosure, the flows within the enclosure are essentially two dimensional, but when the opening width is less than that of the enclosure the flows within the enclosure are more complex and three dimensional. The mass loss rates for the same opening sizes in wide enclosures were found to be substantially greater than those in long enclosures for both full width (in the long enclosure) and partial width openings.