Abstract: This paper systematically investigates the self-extinguishing effects of water curtain blockades in fires within semi-enclosed tunnel using numerical simulation methods. To evaluate the impact of different water curtain parameters on fire self-extinction, a coefficient Kw was proposed based on the oxygen consumption method, defined as the ratio of theoretical extinguishing time to actual extinguishing time. The results show that particle size does not significantly affect Kw within the droplet size of 200~400 μm, but a relatively higher self-extinguishing effect is observed at 300 μm; Compared to complete enclosure (partition wall blockage), water curtain blockades promote fire self-extinction under high HRR (10~30 MW), while they may exert some inhibitory effects under low HRR (5 MW); With a particle size of 300 μm, as the spray pressure increases from 0.01 MPa to 0.40 MPa, Kw first rises and then stabilizes. When the spray pressure reaches a certain threshold, further increasing the pressure has a diminishing effect on self-extinguishment but significantly enhances the attenuation of ceiling temperature; In cases where self-extinction can be achieved, increasing the number of water curtain rows may lead to a decrease in , although additional rows enhance the thermal decay of high-temperature smoke, the improvement is relatively limited.

Key words: semi-enclosed tunnel, water curtain, self-extinction, oxygen consumption method, FDS