Numerical investigation of air curtain jet effect upon the compartment-facade fire safety protection based on temperature evolution and thermal impact

In this paper, the air curtain effect on the outcome of compartment-facade fire safety protection is investigated on the basis of temperature evolution and thermal impact. A compartment model sized 1.2 m x 0.9 m x 0.9 m is established, with the air curtain jet velocity, the heat release rate and the opening dimension adjusted to suit some typical fire scenarios. The vertical temperature and heat flux profile are obtained by using a series of devices deployed along the centerline of the facade wall for further analysis. According to the analytical results, there is a significant reduction in the vertical temperature and heat flux of the facade with the rise of jet velocity, which is due to the capability of the air curtain jet to form a virtual "wind blockage wall" at the opening. Meanwhile, the air curtain effect on temperature and heat flux varies with opening height to some extent. The temperature and heat flux reduction are shown to reach a more significant extent when the opening height is reduced, indicating a much more severe blockage of air curtain to hot smoke. Then, the vertical temperature rise under various fire scenarios are well correlated by dimensionless models according to different air curtain jet velocities and compartment-facade fire characteristics. Finally, a normalized temperature rise/heat flux factor of & omega; is defined to propose the new correlations for the dimensionless factor of & omega; and the Froude number at the opening.