Abstract: A new kind of two-stage atomizing high pressure spray nozzle for fire suppression is developed, which provides a way to solve the problem that the spray protecting diameter of spray is small. The sauter mean diameter (DSM), flow velocity of the nozzle, flux and jet breakup length are computed. In the computational fluid dynamics (CFD) simulation, the spray velocity field and water volume-fraction distribution of the two-stage atomizing nozzle are compared with those of the one-stage atomizing nozzle, respectively, then the structural parameters of the two-stage atomizing nozzle are optimized. The DSM, spray velocity and spray density distribution are measured to verify the simulation results. The research shows that the optimized two-stage atomizing nozzle has a 0.34 m protection diameter and its spray density distribution is uniform. The protection diameter of the two-stage atomizing spray head with multi-nozzle is more than 2 m, which is very practical in fire protection.

Key words: Computational fluid dynamics (CFD), Fire suppression, Atomization, Spray nozzle, Water mist