Simulace procesů hašení pomocí počítačového modelování

Abstract

The aim of the doctoral thesis is to first obtain experimental data useful for validati-on of the fire suppression models and second to study whether a sprinkler droplet precipitation per surface area can be used as a design parameter in the fire suppression models and in relation to model input sensitivity study. Conducted ex-periments measured the surface intensity of the droplet precipitation on the floor of the experimental area. The measurement of the spray intensity was performed using cups of surface area of 4.8 x 4.8 cm placed at radial distance of 0.26 to 2.80 m from the sprinkler head axis. The obtained intensity of the droplet precipitation is thus very fine comparing to a commercial bucket test performed by the sprinkler manu-facturers. Four types of sprinkler heads with the same design purposes in terms of fire safety of buildings were studied. The measured values were used for comparison with the computer simulation. The simulation of the sprinkler chamber space was performed in Fire Dynamics Simula-tor version 6.7.6. A sprinkler head behavior is defined the same as in the experiment in terms of pressure and flow rate. The device generates a spray described as a stream of droplets of a given minimum and maximum diameter and size distribution, initial velocity and angle of the spray. The intensity of the droplet precipitation is determined by a model quantity that sums the droplets falling on the area of interest given by the cell dimension of the computational grid. Two simulation scenarios were prepared and their outputs were compared with the experimentally measured droplet precipitation intensity. A sensitivity study of the model output to the values of the input parameters was performed. Impact of each parameter on the simulation predictions is evaluated and recommendations for the users are drawn.