A numerical study of the interaction of water spray with a fire plume

Abstract

Water spray-based fire extinguishing equipment such as sprinklers has been widely used in fire suppression and control. However, the fire extinguishing mechanism in such devices is not well understood due to the complexity of the physical and chemical interactions between water spray and fire plume. Currently, quantitative approaches (e.g. numerical modeling) to estimate the performance and effectiveness of water spray systems have not been developed to a stage where they can be used to optimize the design for different operating environments and types of fire. In the present work, a numerical simulation approach is introduced to provide a quantitative analysis of the complex interactions occurring between water spray and fire plume. The effects of several important factors (namely water spray pattern, water droplet size and water spray flow rate) on the fire suppression mechanism are investigated. The simulations show that the water spray with solid cone pattern and finer water droplet size is more effective in extinguishing fires than the one with hollow cone pattern and coarse water droplet size. To suppress a fire, the water spray flow rate has to be more than a certain critical value. However, using too high water spray flow rate does not increase fire suppression efficiency but only leads to increased operational cost because of the excess water flow rate. In the current paper, the principles of fire suppression with water spray are also discussed, which are useful in designing more effective water spray fire suppression systems.