Research on atomization characteristics of high-pressure water mist atomizer for fire suppression

High-pressure water mist system is a new type of fire-fighting unit using water hydraulic technology. The advantages of water mist include friendly environmental situation, fast and effective fire suppression, minimum quantity of water requirements and low water losses. It has been widely expected as the most potential substitute of Halon fire-fighting system. The inner flow state of the vital execute component - direct jet atomizer is analyzed by using the axial symmetrical boundary momentum integral method. The atomizer shape dimension's influence on two inner flow parameters, boundary layer thickness δ and accelerate factor K is assessed. Besides, the outer atomization characteristics related to fire-fighting performance, such as the outlet velocity and the Sauter Mean Diameter (SMD) are analyzed. Simulation results are experimentally verified. The results show that the system working pressure is the most important factor to those outer atomization characteristics and 8-9 MPa is the appropriate area of stable atomization pressure for this prototype of direct jet atomizer. The atomizer shape dimensions include contract angle α, and the length of atomizer neck l/d has influence on inner flow parameters and outer atomizer characteristics, but not distinct. The optimum atomizer's inner structure is selected.