Experimental study of model fire seats extinguishing by the distributed in time and space water droplet flows

Abstract

In this paper the main attention is paid to a problem of increase of efficiency of major forest fires suppression. The main popular way of wildfires extinguishing - local dumping of water with use of aircraft was considered. The approach providing suppression of the fires by the distributed in time and space water flows is offered. When carrying out researches the model fire seats corresponds (in temperature and height of a flame) to ground and crown forest fires were used. For model fire seats production the pine whetstones and the typical forest combustible materials making a basis of a forest laying are used. As means of suppression the spray nozzles generating a polydisperse droplet flow with droplet radius of 0.02-0.35 mm were applied. For continuous movement of nozzles over the model fire the special system was used. The system consisted of a set of coordinate mechanisms with adjustable parameters - acceleration and speed of movement. Various ways of water spraying in a fire zone are considered. With using of the model fires (ground and crown forest fires) use of various combinations the spraying nozzles is tested. With use of high-¬speed video registration equipment and panoramic optical methods of flows diagnostics such as PIV and SP, the optimum parameters of dispersion (relative positioning and combinations of spray nozzles) providing smallest times of suppression of the model fire seat and the minimum volumes of the water spent for suppression of a flame are revealed. For the model fire seats corresponding to ground forest fire, the mini¬mum times of suppression were 45 sec, volumes of the spent water - 0.03 l, for the model fire seats corresponding to crown forest fire - 110 sec and 0.135 l. The sizes of sprayed water droplets corresponding to each scheme of dispersion necessary for effective fire extinguishing are determined. For the model fire seats corresponding to ground and crown forest fires these ranges were 0.02-0.25 and 0.08-0.35 mm, respectively. The expediency of the use of such systems in the liquidation of fires in rooms is proved.