Experimental study on fire suppression by water film on the exterior facade of concave structures

A series of vertical fire suppression experiments were conducted by water film over external facade of concave structures based on a self-built experimental platform. The evolution of characteristic parameters—including average flame height and flame morphology—was investigated during typical insulation material(extruded polystyrene-XPS) flame propagation under varying structural factors (α) and external radiative heat flux conditions. The critical water film flow rates for protecting XPS materials from sustaining combustion under different α and external radiative heat fluxes were determined. The results indicate that the cooling effect of the water film can effectively suppress upward flame spread. Critical water film flow rate rise with increasing external radiative heat flux. When there is no external radiation, it is found that the critical water film flow rate changes little with α increase. When α ≤ 1.0, the critical water film flow rate increases with α increase. When α > 1.0, the critical water film flow rate remains essentially unchanged with the increase of α. The experimental findings provide critical insights for designing, implementing, and optimizing exterior wall water spray systems, thereby mitigating fire risks in high-rise structures and enhancing building resilience.