An experimental study on gas temperature characteristic in tunnel fires: The influences of sidewall restriction and sealing effect

This work provides a comprehensive experimental study on the influence of fire source position on gas temperature characteristics during the sealing process. A function correlating the ceiling maximum gas temperature and transverse fire source position factor and the sealing ratio was proposed based on the-oretical analysis. Then, a series of methanol pool fire experiments were conducted in a reduced tunnel, considering three fire source positions and five sealing ratios, to investigate the influence of sidewall re-striction and sealing effect on the maximum gas temperature and longitudinal distribution pattern. The results demonstrate that the maximum gas temperature does not increase continuously as the fire source moves toward the sidewall. There exists a position in which the lowest gas temperature beneath the ceil-ing is generated as a result of the combined effect of the flame on air entrainment and the enhanced radiation of the flame to the sidewall. Moreover, the maximum gas temperature rise is found to linearly increase with the sealing ratio and vary as a quadratic function of the transverse fire source position factor. Finally, the calculation model for the longitudinal distribution pattern of ceiling gas temperature rise is developed, which can provide reasonable predictions for different fire scenarios considering fire locations, sealing ratios as well as fire sizes.& COPY; 2023 Published by Elsevier Ltd.