Design And Research On New Marine Water Mist Nozzle

Ship water mist fire extinguishing system consists of water hydraulic components and spraying nozzle. Compared to other systems, the main advantage lies in its security, high efficiency, energy-saving, environment-friendly, less second pollution, lower environmental requirements, and economic. It is widely recognized as the ideal fire fighting techniques. As the alternative Products of traditional halon fire extinguishing system, water mist fire extinguishing system has a big market and a bright future. Because of high-pressure on board. It is very expensive.which limits it's development. Therefore, it is urgent to decreasing the system pressure, Water mist fire extinguishing spraying nozzle is the key device to the whole system which directly impacts on the fire extinguishing effect. Thus, by the means of improving the spraying nozzle, we can pull down the system pressure.Through theoretical investigation on the atomization mechanism and performance of nozzle, this thesis refers to empirical formula and designs a brand new fine-spray nozzle based on the conclusion of performance of various nozzles. This nozzle adopts double-layer spiral channels spraying in retrograde rotation, which helps not only stream guidance but also the formation of strong rotational flow。The distinct design of channel and nozzle makes fine spray have a relatively rotating direction and increases the effect of shearing and disturbing of the fine spray, which greatly enhances the effect of atomization making the injected spray atomized easily in the air and SMD average diameter reduced to obtain a good atomization under low pressure condition. The nozzle model is optimized through emulation analysis. Finally, flow features, the angle of atomization, the distribution of atomization space and the particle diameter of the fine-spray nozzle are determined by trails and fire-extinguishing experiments are made to compare with that of other nozzles both at home and abroad. This thesis aims to achieve a new type of marine fine-spray fire-fighting nozzle under low pressure by means of design, emulation and trials comparison.