Abstract: : Taking LNG tank vehicle operation box as research object, by buliding unsteady numerical model of watermist inhibiting combustion after leakage in confined space, effects and mechanisms of different nozzle heights, intervals and spraying angle on fire inhibition were studied. The results showed that with the increase of nozzle height, intervals and spraying angle, the relative humidity in the control cabinet first increases and then decreases. The higher the nozzle height, the faster the initial rise rate of evaporation rate and average humidity, the higher the peak value of evaporation rate, and faster the decline rate after reaching the peak value. Reasonable arrangement of water spraying device can significantly accelerate the flow rate of the flow field, uniform flow field distribution, prevent leakage gas accumulation, increase average humidity, and prevent fire and explosion.

Key words: fire protection, LNG tank vehicles, leakage, emergency disposal, water spraying