Absorptance and transmittance of water spray/mist curtains

Water spray is a highly effective fire-protection agent, because evaporating droplets extract energy from the flame and combustion products as well as attenuate thermal radiation by absorption and scattering. The main objective of this paper is to characterize radiative transfer in a homogeneous water spray curtain (layer) and to calculate spectral transmittances and absorptances of a curtain. The spectral and total absorptances and transmittances reported in the paper provide fundamental understanding of radiation attenuation by water curtains. The empirical equation developed for the scaled spectral extinction coefficient of water sprays may be useful for modeling radiative transfer in spray curtains using CFD. Since the spray acts as a shield that attenuates radiation such global radiation characteristics can readily be used in simple, preliminary design analyses for mitigating and controlling fires.