Study on the effect of tunnel dimensions on the smoke layer thickness in naturally ventilated short tunnel fires

摘要

Smoke layer thickness is a key parameter in tunnel fire research. In this paper, the effects of the dimensions of the tunnel cross-section and Heat Release Rate (HRR) in naturally ventilated short tunnel fires were studied. A series of numerical simulations with Fire Dynamics Simulator (FDS) were carried on, and some tunnel model experiments were conducted in a 1/10 scaled short tunnel model to verify the results of the numerical simulation. The thickness of smoke layer in the simulations and experiments was determined by the integral ratio method, which is more subjective and has been applied in FDS. The effects of different tunnel lengths and widths were studied. The results show that the smoke layer thickness increases with the increment of tunnel length, and conversely, with the increased tunnel width, the thickness decreases. The HRR is also a main factor influencing the smoke layer thickness, and with the increase in the HRR, the thickness increases. In addition, a prediction model of the smoke layer thickness was proposed, which presented a good agreement with the results of simulation and experiment. This work was supported by National Natural Science Foundation of China (Grant No. 51974361), Natural Science Foundation of Hunan Province of China (No. 2020JJ3046) and the Fundamental Research Funds for the Central Universities of Central South University (Grant Nos. 502501004 and 502045009).