Numerical Simulation of Effects of Nozzle Installation Direction and Spacing on Water Mist Characteristics and Thermal Radiation Attenuation Rate

In this study, the effects of nozzle installation direction and spacing on water mist characteristics and thermal radiation attenuation rate were investigated using a fire dynamics simulator (FDS). The upward installation condition yielded higher droplet concentration and wider spray width. Additionally, the upward installation resulted in 2.39- and 1.75-fold increases in thermal radiation attenuation rates under one-nozzle and two-nozzle installations, respectively, compared with the downward installation condition. Furthermore, under the latter, the droplet concentration in the region between the nozzles was, respectively, high or low when the nozzle installation spacing was narrow or wide. However, under the upward installation condition, the droplet concentration in the region between the nozzles was also high when the nozzle installation spacing was wide. Under the downward installation condition, the thermal radiation attenuation rate was the lowest when the nozzle installation spacing was the narrowest; the differences in the thermal radiation attenuation rates between the wider nozzle installation spacing conditions were minimal. In contrast, under the upward installation condition, it increased consistently, as the nozzle installation spacing increased.