Research On High Pressure Water Mist Sprinkler

As the development of science technology, and the enhancement of people's enviromental awareness, Halon fire extinguishing agent, which was once widely used in fire protection, is gradually phased out by its harmful side effect of destruction to ozone layer. High pressure water mist system is an environmental and safe fire protection instrument, with excellent fire-fighting capability, less water dosage and waterlogging pollution. It is recognized as the mainstream alternative technology of Halon agent. But water mist technology in our country is still in the development stage. And the research on high pressure sprinkler, which is used in wet pipe system, is nearly vacant. Therefore, conducting study on high pressure sprinkler has great significance. The main contents in this dissertation are as followed.Developed a high pressure sprinkler for wet pipe water mist system. Research the spray characteristics of the sprinkler and spray nozzles, with the methods of theoretical analyse, numerical simulation and experiment. And the response characteristic of sprinkler is also studied. The experiment results show that, the sprinkler has excellent sealing and spray characteristic, which satisfies the fire-fighting requirement on water mist.In chapter 1, the research and application status of water mist technology are summarized. The research object of this dissertation is to develop a high pressure wate mist sprinkler. And relative key problems of the research are proposed.In chapter 2, a series of two-stage atomizing nozzle and two-stage jet-crash nozzle with different spray structure are designed. And the flow field inside nozzle is researched. A new high pressure water mist sprinkler is developed. The stress of the sealing component is analyzed. And the influence of spray nozzzles' amounts and location on the sprinkler's spray characteristic is also discussed.In chapter 3, the flow field inside nozzle is numerical simulated in FLUENT. The impact of nozzles'stucture parameters and spray pressure on nozzles'oulet velocity and turbulence distribution is researched.In chapter 4, the response characteristic of the sprinkler is simulated with FDS software. The influence of sprinkler's height, thermal index of RTI, and the fire scale on the response time is analyzed. In chapter 5, a wet pipe system is developed, and the sprinkler's sealing experiment is conducted. Experiments on the sprinkler, two-stage atomizing nozzle and two-stage jet-crash nozzle are carried out by the use of flowmeter, high speed camera and laser particle size analyzer, which focus on the flow characteristic, spray characteristic and process. The experiments show that the sprinkler has excellent sealing and spray performance, and satisfies the fire-fighting requirement on water mist.In chapter 6, main conclusions of this dissertation are given. And some new research views in the future on high pressure water mist sprinkler are putting forward.