Fire Safety Science Digital Archive

Schlieren imaging was trialled as a technique for investigating thermal properties of a flame in a narrow channel apparatus. The method was used in conjunction with direct photography to gain knowledge of heat transfer in the flame and the profile of the flame front. Quantities including crosssectional flame shape, gaseous thermal length and solid thermal length were able to be measured. The experiment was carried out for floor and ceiling spread in a horizontal chamber at two different channel heights (6.5 and 4 mm), and for low and high flow rates of pure oxygen (4.5 and 16.5 cm/s respectively). It was found that the combustion conditions did not successfully approximate a microgravity environment for the 6.5 mm channel at low gas flow rates, with floor and ceiling spread flames differing significantly. This is believed to be due to poor transport of hot fuel vapour away from the fuel surface. These effects were reduced in the 4-mm channel and at higher flow rates.