Effects of curved sidewall on maximum temperature and longitudinal temperature distribution induced by linear fire source in utility tunnel

In order to investigate the influence of curved sidewall on the maximum temperature and the longitudinal temperature distribution induced by linear fire source in utility tunnel, a sequence of experiments was conducted in a reduced-scale utility tunnel, whose fire source is placed at d (0, 10, 20, 30, 40, 50, 60 cm) away from the centerline. The result is as follows: (1) In order to represent the effect of portal-sealed sidewall and curved sidewall, a dimensionless correction coefficient lambda and the modified effective height of the ceiling H'(ef) are employed, respectively. Besides, a dimensionless empirical formula was proposed as (Eq. 13) to predict the average maximum temperature rise of plume impingement zone beneath the ceiling centerline induced by linear fire source in utility tunnel, which is related to d. (2) It is found that longitudinal temperature beneath the ceiling centerline could be divided into two zones: plume impingement zone and temperature decay zone. The temperature of the plume impingement zone is basically the same, while the temperature of the decay zone falls exponentially. An empirical formula based on experimental data was presented as (Eq. 15).