Fire Safety Science Digital Archive

Experiments were conducted to characterise fire properties with longitudinal ventilation in a tunnel. Much of the focus was on flame shape, trajectory of hot current and effects of aspect ratio of a tunnel cross-section on these variables. Three types of model tunnel, having rectangular and horseshoe cross-sections, were employed. The aspect ratios, defined as height divided by width, ranged from 1/1 to 1/3. The flame tilt-angle from the vertical was obtained using the isotherm curves constructed with measured temperatures. An empirical model is proposed for the flame tilt-angle based on the balance of mass fluxes given by the upward hot current and longitudinal ventilation velocity. Empirical models for maximum temperature of smoke layer under the ceiling and its position are also presented.