Full-scale experimental study on fire-induced smoke propagation in large underground plant of hydropower station

In this study, full-scale fire experiments in a large underground plant of a hydropower station were conducted to investigate smoke propagation under natural ventilation, and the overall temperature profile was measured through distributed thermometric cables. The smoke temperature variation with time, maximum temperature distribution in the upper and lower space, smoke stratification, and smoke front spread velocity were acquired based on full-scale measured data. Results indicate that under the fire sizes of 4, 6, and 10 fuel pans with combustion areas of 2, 3 and 5 m(2), the temperature rise of the upper smoke layer in the fire cross section against the ambient are 1.7, 2.3, and 3.8 degrees C, respectively, while they are 6.7-7.6, 9.0-10.8, and 12.9-13.0 degrees C above the ground of 0-3.5 m in the lower space of the plant. Owing to continuous heat loss to the surrounding, the maximum temperature in the smoke layer decayed as the smoke propagated longitudinally, and the attenuation trend decelerated or reversed in front of the end wall by enhanced accumulation of smoke and heat. The smoke stratification is distinct in the large underground plant and the smoke layer interface with fresh air descended within the height of 20-30 m. Moreover, the smoke front spread velocity were empirically determined for the three fire sizes. Conclusions from the full-scale fire experiments can provide on-site data and propagation characteristics for smoke control design, as well as scientifically guide the emergency response plan during fire accidents in large underground plant of hydropower stations.