HEAT RADIATION SHIELDING BY THE POLYDISPERSE WATER CURTAINS

The problem of thermal radiation shielding in a fire zone by means of the polydisperse water sprays is considered. The mathematical model of monodisperse water curtain earlier developed on the basis of a geometrical optics approximation is put in a basis of the work. It is known that the actual water sprays created by means of drencher systems and fire trunks, are polydisperse. The technique developed in this paper allows taking account of droplet size distribution of a water curtain. The received calculated formula allows carrying out calculations of transmission spectra of polydisperse water curtains for thermal radiation of near infrared region of 1–10 *m. As an example water curtain with logarithmic normal distribution function of droplet sizes have been considered. According to results of the executed calculations, the transmittance of thermal radiation strongly increases in process of increase in width of this distribution function. Possibility of replacement of an polydisperse water curtain by its monodisperse analog with the equivalent shielding properties is investigated, and the calculated formula for droplet diameter is derived. Use of the equivalent monodisperse curtain allows significant simplifying a calculation procedure of polydisperse curtain shielding properties. Calculation of polydisperse curtain transmittance for the black body radiation allowed defining its dependence on temperature and width of droplet size distribution function.