Abstract:  Based on the numerical simulation method, PyroSim software was used to build a curved tunnel model with a radius of 250, 300, 400, 500 m and 600 m and a straight tunnel model with a length of 130.8 m, respectively, to simulate the smoke spread in the condition of no longitudinal ventilation. Smoke temperatures at different heights of the center line of the two models were compared and analyzed. The simulation analysis shows that in the early stage after the fire, the smoke spread in the straight tunnel is basically symmetrical about the center line of the tunnel, while the smoke movement in the curved tunnel is inclined to the concave wall in the upstream and to the convex wall in the downstream. Under the stable state, the temperature above the fire in the straight tunnel is higher than the curved tunnel; no matter near-fire or away-fire zone, in the straight tunnel longitudinal temperature distribution has good symmetry with respect to the location of the fire source, and in the curved tunnelthe fluctuation of the near fire source is large, the temperature attenuation gradient of the far fire source is greater than that of the straight tunnel, and the temperature attenuation gradient of the upstream is greater than that of the downstream at 1.6 m height. The longitudinal attenuation index curve model of ceiling temperature in curved tunnel is put forward. 

Key words:  , tunnel fire, straight tunnel, curved model, ceiling temperature, smoke movement