Analysis of Smoke-Propagation Characteristics for Wall Fires in Underground Passageways Based on Temperature Measurement Data

This study experimentally analyzed the effects of fire source location (middle and wall) and ceiling height on smoke layer characteristics in underground passageways using temperature measurements. In particular, wall effects were considered. The results showed that the wall fire had higher temperatures directly above the fire source and faster smoke layer arrival characteristics than the middle fire owing to wall effects, along with asymmetric thermal behavior. In addition, the dimensionless temperature decreased, and the arrival time increased with increasing r/H under all conditions. However, the experimental results differed from those of the conventional ceiling jet correlations and arrival time prediction equations. In particular, in the far region, the temperature decrease was more gradual, and the smoke layer arrived faster. These results indicate the limitations of existing ceiling jet prediction models developed for open spaces when applied to wall-confined spaces, such as underground passages, and suggest that new prediction models that account for such spatial characteristics are required in future studies.