Shielding of Fire Radiation With the Use of Multi-Layered Water Mist Curtains: Preliminary Estimates

Abstract

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A comparative analysis of shielding of thermal radiation of fires using mist curtains containing droplets of pure water or sea water

“…As one can expect, the complexity of general computational models is an obstacle to their widespread use. The relatively simple engineering approach suggested in [10,11] is considered by the authors as a good alternative basis for engineering applications. A series of calculations enabled us to suggest a decrease in the size of supplied water droplets with the distance from the irradiated side of the mist layer to improve the shielding properties of the mist curtain.…”

An infrared scattering by evaporating droplets at the initial stage of a pool fire suppression by water sprays

“…A similar model has been recently used in analysis of water mist curtains [8,9]. This simplified evaporation model is also sufficient for qualitative estimates of the present paper because of very fast heating of moving droplets and large molar fraction of water vapour in the flame.…”

“…The exact Mie calculations are time-consuming, especially for large droplets with x ) 1. Therefore, as it was done in recent studies [8,9], we use the following analytical approximation suggested in [30] for semitransparent particles: …”

“…This optical effect, which is commonly observed in the visible for the natural mists, has been recently considered as a promising way to improve shielding of fire radiation by multi-layered water sprays [8,9]. It is important that the gaseous combustion products in the fire do not scatter the radiation.…”

Two-Step Iterative Method for Radiative Transfer Calculations in Axisymmetric Flames Containing Absorbing and Scattering Particles

“…The radiative power absorbed by droplets is neglected because it is much less than the heat supplied by convective heat transfer to the droplets from hot combustion gases in the flame. The effect of radiation could be also taken into account in more detailed calculations as it was done in recent papers on shielding of fire radiation by water mists [16,17] and also in the problem of a space vehicle shielding from solar radiation by a cloud of sublimating particles [18]. The calculated transient flame is three-dimensional, but deviations of the main parameters from the axisymmetric case are not significant.…”